World War I Foreign Aircraft Exploitation Programs(?)

Dynoman

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I was looking into the possibility of the existence of WWI foreign aircraft exploitation programs after looking at a number of German aircraft in the hands of Allied troops during the war. I found that the US Signal Corps maintained a Foreign Data Section of its intelligence branch within the War Department and the British had the Technical Department of the Aircraft Production Department of the Air Ministry that gathered and collected technical information on German aircraft. However, I have not found any formal programs of flight testing enemy aircraft for the purpose of exploitation. Most of what I have found is individual squadron pilots taking up a captured aircraft to see how they flew in comparison to their own, but no formal program. Does anyone know of any such program during WWI?
 

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Douglas Wardrop of Aerial Age (circa 1917-1918) wrote a series of articles towards the end of the war, after visiting London and being given access to a special presentation of captured German aircraft. The display was particularly technical in nature and was focused on the engineering aspects of the German designs, but did not specifically mention any formal flight tests. He does mention that some of the designs were flown by the French and others.
 
The National Air and Space Intelligence Center traces its lineage back to 1917:
In 1917 the Foreign Data Section of the Army Signal Corps’ Airplane Engineering Department was established at McCook Field, and a NASIC predecessor operated the Army Aeronautical Museum[2] of the Material Division, August 22, 1935.

I recall the National Museum of the Air Force in Dayton OH, having some exhibits and aircraft that were tested by the Foreign Data Section, but I don't remember the particulars.
 
So far from what I have found, some of the aircraft were sent to aircraft manufacturers to be tested and important technologies examined or reversed engineered if necessary. In the case of Roland Garros, who was shot down on 18 April 1915, he and his aircraft were captured and his aircraft's Saulnier gun firing system was sent to Fokker for examination. This may have been similar to England's response by using the Technical Department of Aircraft Production to evaluate the engineering aspects of the aircraft. Some German engines were tested on British designs, so captured aircraft were also possibly stripped of valuable components, such as guns and engines and tested. However, I've not found a report of this.
 
According to Volume 2, History of Air Service Units Attached to the 3d Army. Gorrell's History of the American Expeditionary Forces Air Service, 1917–1919, the 278th Aero Squadron of the US Army Air Service conducted test flights after the Armistice in 1918 of surrendered German aircraft, including the Fokker D.VII, Pfalz D.XII, Haberstadts, and Rumpler aircraft. Unknown if this was an official program.
 
Assessment of German aircraft, in particular their guns, mountings, bomb dropping gear and other equipment was carried out at Orford Ness, then an outstation of Martlesham Heath.
 
Hood, thank you! Orford Ness was the site of flight testing for many aircraft systems and tactics and at lease one captured German aircraft during WWI. Clive Collett, a pilot in the RAF was killed while flight testing a captured Albatros D.V. there.

 
boelcke definitely had discussions of Allied aircraft test flown , possibly by himself and maybe his unit . (The Ace Factor , by Mike Spick)
 
A photo exists of Boelcke sitting in a captured British single seat Vickers fighter (found in his biography). The biography by Werner (1972), Knight of Germany, describes a diary entry by Boelcke indicating that he flew and used the Vickers aircraft as a demonstrator. He also had his dicta of air combat published in a brochure titled Experiences of Air Fighting, where he also describes various Allied aircraft capabilities and the best way to engage them.

The Idglieg or "Inspectorate of Flying Troops," which oversaw Germany military aviation during WWI also tested some captured aircraft. "The inspectorate concentrated on reorganizing its procurement bureaucracy and the aircraft industry and then coordinating procurement, In January 1917 it reorganized its aircraft depot under Maj. Felix Wagenfuhr and established an R-plane command to monitor the growing number of firms manufacturing the giant bombers. The two most noteworthy feathers of the new depot were its Scientific Information Burea (Wissenschaftliche Auskunftei fur Flugwesen, or WAF) and its department for evaluating captured aircraft." (Morrow, 1993, p. 223, The Great War in the Air: Military Aviation from 1909 to 1921).

The WAF was entrusted "with the task of editing a series of secret technical reports, the 'Technische Berichte' (TB). As was expressed in the preamble of these reports, the WAF intended to create a marketplace between the military, the nascent aircraft industry, and the sciences involved in aeronautical research" (Eckert, 2006, p. 60, The Dawn of Fluid Dynamics: A Discipline Between Science and Technology). I assume that the WAF's department for investigating capture aircraft would have used to the technical intelligence discovered from the testing of foreign aircraft to disseminate this information to its aircraft industry. Looking for any reports of this nature.
 
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The first intact German aircraft captured with gun synchronization gear was an E.III no. 210/15 occurred on 8 April 1916. It was tested at Upavon on 30 May 1916

According to Bradley (1994) A History and Development of Aircraft Instruments, the British received captured flight instruments and bomb sights from German aircraft, however they did not possess any advantage over what the British were using and not implemented into British instrument designs. The same was said for the German aircraft gun turrets.

It appears that aircraft factories on both sides of the war were used to test the occasional captured aircraft. Still haven't found a formal program yet.
 
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'Not Invented Here' had a very strong influence there I'd suspect.
 
The disposition of captured enemy aircraft during WWI seems to have moved markedly in different directions, depending upon the aircraft and its value to the war effort. Below is a generalized synopsis of the fate of captured aircraft in the war.

Some aircraft were sent to factories: Examples of captured aircraft or aircraft equipment sent to factories for testing were German engines being sent to the Royal Aircraft Factory where numerous test reports on various engines were written. Fokker received not only Garros' synchronization system in 1915, but also examined a Sopwith Triplane, which was used as the model to develop the Fokker Dr.I. The Germans also captured several Nieuport 17's and sent at lease one copy to Siemens-Schukert Werke, which would become the D.I fighter, a clone of the Nieuport. Russian manufacturer Lebedev received a captured German two-seat Albatros in 1915 and copied it to make the Lebed XI, which had additional Russian variants based upon the German design.

Some aircraft were sent to Government Testing Centers: Examples of captured aircraft being moved to testing centers include the Fokker Albatros D.V. that ended up at Orford Ness, near Farnborough, and flown by pilot Collett in which he was killed during the tests. The Germans had a department, organized by Major Felix Wagenfuhr, for the testing of captured aircraft within the IdFlieg. The Sopwith Triplane was taken to Adlershof for inspection and testing. This program may have been the closest to a formal ongoing program for the exploitation of enemy aircraft during the war. He also headed up the Scientific Information Bureau that was responsible for the distribution of military information and information on enemy aircraft technology and tactics.

Some aircraft were flown by squadron pilots for evaluation: There are numerous cases where squadron pilots with little or no flight test experience or training took enemy aircraft aloft to see what performance capabilities they possessed. The tests of the captured Sopwith Pup N6161 by the German pilot Meyer, who forced the aircraft down is an example. These type of test flights included Manfred Von Richthofen (Red Baron) who demonstrated captured aircraft to his men.

Some captured aircraft were flown in combat by the enemy: There are a few examples of captured aircraft being flown in combat by the enemy, such as Canadian Col. William Baker who flew a captured German aircraft into combat and the Russians who flew captured German aircraft that they painted what amounted to "Good Guy's" in Russian on the top and bottom of the aircraft so as to not being mistaken by anti-aircraft artillery crews or other pilots.

Many were placed on display: Captured aircraft were often placed on display for propaganda purposes during the war. After evaluation by the enemy it was not unusual to display the aircraft in public. The Germans displayed captured Allied aircraft in the Kriegsausstellungen, a five location moving display, that was done for propaganda reasons, while the British displayed numerous captured aircraft at the Horse Guard Parade in London Whitehall in November of 1915 and presented nearly 'every example' of German aircraft in the Royal Agricultural Hall at the end of the war.

Post-war evaluation of captured aircraft: Although the testing of captured aircraft after the war is beyond the scope of this discussion, which is centered on the exploitation of aircraft during the war, there were considerable tests conducted on German aircraft by the Allies after the war for a variety of purposes. As more aircraft became available following the signing of the Armistice various allied countries exported from the battlefields of Europe home for evaluation, use, and display. For example,142 Fokker D VII's alone made it to the US after the war for testing. Other nations obtained the same aircraft for inclusion into their air forces. Canadian pilot Albert Carter was killed in 1919 after test flying a Fokker D VII for the CAF.

Of course there were other paths that captured aircraft may have taken during the war, but these are just some of the most prominent. More investigation into the German department for captured aircraft under Wagenfuhr is a suggested area for further investigation.
 
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Hood, thank you! Orford Ness was the site of flight testing for many aircraft systems and tactics and at lease one captured German aircraft during WWI. Clive Collett, a pilot in the RAF was killed while flight testing a captured Albatros D.V. there.

A few things, the unit at Orfordness was the Experimental Armament Squadron, which moved to Martlesham Heath and had a number of enemy aircraft on its books as well as the Albatros in question. This was D V 1162/17, which was reserialed G'56 - captured aircraft received a G' prefix. Collett, a New Zealand born RFC pilot, as the RAF had not been formed in December 1917 when he lost his life, was not killed at Orfordness, but flying over the Firth of Forth demonstrating G'56 out of Turnhouse.

This image of G'56 was possibly taken at Martlesham Heath - note the British style pitot tube fitted to its Vee interplane strut. 1162/17 was forced down to land at Poperinghe in July 1917.
 

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Some of the Allied Great War machines captured by the Germans survived the turmoil in that country post-war and became museum exhibits in the Deutsches Luftfahrt Sammlung, Nazi Germany's aviation showcase museum just across the Spree River from the Reichstag in Berlin. At least two British aircraft survived the fire that devastated the museum following an RAF night bombing raid in 1943. These are a Sopwith Camel and Airco DH.9. The former survives at the MLP in Cracow, and the latter, the last surviving DH.9 is currently on display at the RAF Museum at Hendon.

A model of the Deutsches Luftfahrt Sammlung can be seen in all its glory at the Deutsches Technikmuseum in Berlin. This image shows the Camel and DH.9 next to a Spad XIII and Spad A.2 two-seater. The DH.9 at the RAF Museum today. This was swapped with the MLP in Cracow for a Spitfire, which was delivered through what was the DDR on the back of an RAF low-loader in the mid 1970s, which must have raised a few eyebrows in communist East Germany.
 

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You might want to get hold of a copy of Air Britain's Retribution and Recovery: German Aircraft and Aviation 1919-22. It covers in some depth the allocation and destruction of German and Austro-Hungarian aircraft following the Armistice and what became of the airframes and the efforts made by several nations and factions to hide or obtain airframes.
 
Nuuumannn, thank you for the clarification on Collett and the additional information! Do you have any information or a source for the evaluation of the German aircraft at Martlesham Heath?
 
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The British Ministry of Munitions made reports on at least 12 types of German aircraft during the War.

CIM No. 38 Final Report No. M119 on 220 Benz Aviatik (G. 24), Nov. 1917 (G.24)
CIM No. 55 Report on Albatross Scout, Dec. 1917
CIM No. 59 Friedrichshafen Biplane, Jan. 1918
IC 607 Report on AEG Bomber, Mar. 1918
IC 619 Report on Friedrichshafen Bomber, Mar. 1918
IC 620 Report on Fokker Triplane, Mar. 1918
IC 626 Report on Hannoveraner Biplane, Jul. 1918
IC 627 Report on the 2-Seater Rumpler, G. 117, Jul. 1918 (G.117)
IC 628 Report on AEG Armored Aeroplane, Jul. 1918
IC 620 Report on Fokker Single-seater Biplane, Sept. 1918
IC 642 Report on Halberstadt Fighter, Sept. 1918
IC 644 Report on Gotha Bomber with Notes on Giant Aeroplanes, Sept. 1918
IC 647 Report on the LVG Two-seater Biplane, Sept. 1918
IC 653 Report on the Pfalz (Type DXII) Single Seat Fighter, Oct. 1918 (G.141)

Unknown if these reports aided in the development of Allied air-to-air tactics or maneuvering concepts that could be used during the war.

List of captured "Enemy" aircraft via ukserials.com

 
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CIM No. 38 Final Report No. M119 on 220 Benz Aviatik (G. 24), Nov. 1917

The account of how it was acquired by the British RFC is found in the history of Australian pilot Bob Little:

"Little's log-book records the following entry for 24 April 1917: 'Triplane N5469, 1230 hrs. On the report of a hostile machine coming towards the aerodrome, I was sent up to engage it. I met the HA flying east over Auchel aerodrome at 12,000 ft. I dived and attacked it. I saw two Nieuport scouts also diving to attack it. The German pilot turned north and I followed him, firing whenever an opportunity offered itself. I noticed the observer W3.S not returning the fire, so I closed in on him. He was losing height all the time, and when a mile east of Bethune, I observed my tracers going into his fuselage. I was then firing at a range of to to 15 yards. He then nose-dived and I dived after him. He landed in a field, and I was unable to get my engine going after the dive and had to land alongside the HA. I ran into a ditch and turned over. I got out of my machine and went across to the Germans and took them prisoner. The pilot, Ltn Neurnuller (and the observer Ltn Huppertz) told me he knew he would never get back when he saw me coming to attack him."

"Friedrich Neumullcr and Hans Huppertz were serving with "Flieger-abteilung Nr 18 when forced down in their DFW C V, the latter being captured intact and receiving the RFC captured aircraft number G24, The story goes that as Little crawled out of his 'Tripe' to claim his prisoners, Neurnuller saluted smartly and said in English, 'It looks as if I have brought you down, not you me, doesn't it?' Apparently, the German crew had been taking photographs of the airfield at St-Eloi and the area around Bethune. During the battle the observer had got himself entangled in his machine gun's ammunition belt, and Little and Neurnuller had to free him."

The DFW CV was also produced by Aviatik, of which approximately 2,000 and 1,250 were produced by their respective companies. Halberstadt, LVG, and Schutte-Lanz were also licensed to manufacture the aircraft resulting in the DFW CV being one of the most widely manufactured aircraft of WWI.

littledfw G24.jpg G.24 DFW (Aviatik) CV, subject of CIM No. 38
 
IC 627 Report on the Two-Seater Rumpler Biplane, G. 117.

(260 H.P. MERCEDES 'ENGINE.)
Report by the Technical Department, Aircraft Production, Ministry of Munitions.

THIS machine, which was used by the enemy at the commencement of the year, is of the CV type, but differs only in detail from the earlier C.IV type.
The general shape and disposition of the wings is maintained, including the characteristic sweep-back of the main planes, and the fitting of ailerons to the upper planes only. Some important particulars follow :-
Weight empty (but with water), 2,439 lbs.; weight, fully loaded, 3,439 lbs.; total military load, 545 lbs.; area of upper wings (with ailerons), 217.6 sq. f t.; area of lower wings, 146 sq. ft.; total area of main planes, 363.6 sq. ft.; loading per sq. ft. of wing surface, 9.5 lbs.; area of tail plane, 22 sq. ft.; area of fin, 4 sq. ft.; area of elevators, 20.8 sq. ft.; area of rudder, 6 sq. ft.; total weight per horse-power, 13.2 lbs.; petrol capacity, 59 gallons; oil capacity, 3 gallons; water capacity, 10 gallons; endurance, about 4 hours.

Performance.
ft. m.p.h. revs.
Speed at 10,000 100.5 1,510
Speed at 15,000 87 1,390
Rate of climb
ft. m. s. revs. in ft. per min.
Climb to 10,000 16 0 1,375 400

Service ceiling, 15,500 ft. (estimated).
Estimated absolute ceiling, 17,500 ft.
Greatest height reached, 15,300 ft. in 38 min. 25 sees.
Rate of climb at this height is 125 ft. per min.

Control.
Longitudinal (elevators), good.
Lateral (ailerons), very heavy and very ineffective.
Directional (rudder), moderately light and quite effective.
It is reported that the machine is tiring to fly owing to the very poor lateral control; that it is nose-heavy, and rather liable to get into a spin.

Wings.
The upper wings have a maximum span of 41 ft. 6 ins. and a chord of 5 ft. 8 ins. The span of the lower wings is 40 ft., and the chord is 4 ft. 4 ins.
The wings are swept back through an angle of 3 degrees, and are set at 2 1/2 degrees dihedral angle. The wing sections of upper and lower planes are given in Fig. 1. Bath front and rear spars are of spruce, and are constructed in two halves, which are grooved and tongued, and then glued together. This is clearly indicated in Fig. 2. The ribs are built up of ply wood and strips in the usual manner, and are of good workmanship. Short ribs join the front spar to the leading edge, alternately with the true ribs.
The wing construction appears adequately strong. Steel compression tubes are placed between the spars, and are braced by ties varying from piano wire at the wing tips to cable and swaged rod at the inner end. The trailing edge consists of a flattened steel tube, to which the ribs are attached by copper rivets.
Ailerons are fitted to the upper wing only, which may in some measure account for that ineffectiveness of lateral control which is characteristic of nearly all German aeroplanes. The area of each aileron is 15.3 sq. ft.
The methods of attaching the main planes to the upper cabane and to the fuselage are designed to assist rapidity of assembly and dis-assembly, and are of considerable interest. They do not differ from the arrangement on CIV machines, and may be considered, therefore, to have been found satisfactory in practice. From the Fig. 4 it will be seen that the upper wings are locked by means of a guillotine lever, held in position by a pin passing through both levers and through two holes arranged in the centre section. The lower wings are locked in position by even simpler means (Fig. 3), requiring no moving parts. The ball at the end of the spar is simply introduced into the socket fixed to the fuselage, and the wing tip is kept lowered. When the tip is raised, the top portion of the wing attachment slips into position, thus locking the wing in such a manner that, even before the attachment of struts and bracing, movement is possible in only one way - i.e., by the dropping of the wing tip. A label bearing instructions and an explanatory diagram referring to these lower wing attachments is affixed on either side of the fuselage, near to the socket concerned.

Struts.
These are of circular section steel tube, encased in a wood fairing. A typical Rumpler strut attachment is shown in Fig. 5. The twin sockets are held down by two bolts, which pass right through the spars. The heads of these bolts are clearly shown.
The construction of the welded-up centre section cabane may be gathered from the photographs and from Fig. 6.
A cylindrical well of 3-ply and aluminium is incorporated in the lower wing close to the fuselage on the left side to accommodate the compass, which is thus convenient to the pilot's sight. Fig. 7 shows the construction of this well.

Fuselage.
The fuselage is a compromise between the several rival methods of construction. Wooden longerons and struts, braced with piano wire; steel tubes, and 3-ply are all used in varying degrees.
A braced girder of longerons and cross struts constitutes the principal factor, arid this construction is depended upon entirely in the rear of the observer's cockpit. Towards the tail, for a distance of about 6 ft. from the sternpost, the covering is of 3-ply, which thoroughly stiffens up the fuselage where the stresses due to the tailplanes may be most severely felt. The middle portion of the fuselage sides - i.e., between the 3-ply at the rear and the pilot's seat-has fabric covering, while forward of this 3-ply is again used.
The slightly arched top fairing is entirely of 3-ply, except for the aluminium cowl, which extends to the rear of the gunner's cockpit, as also is the bottom of the fuselage. The engine cowls are of aluminium, held in place by turnbuttons. From the rear of the observer's cockpit to the front of the pilot's seat the wood construction is reinforced by steel tubes, which have forked ends, and are bolted together.
The pilot's cockpit is particularly roomy and comfortably fitted. The gunner is provided with a seat of the piano-steel type with a rotatable head. This head is fixed on its shaft eccentrically, as may be seen by Fig. 8.

Landing Gear.
The undercarriage, of the usual V-type, while presenting few noteworthy features, is of workmanlike design and construction.
Both front and rear limbs are of stream-line section steel tubing. The upper extremities are placed well apart. At the lower extremities the tubes are welded together to form, together with the sheet steel axle fairing, the slot to accommodate axle travel. (See Fig. 9.) The front limb, which is of smaller section than the rear tube, is additionally faired with wood, while the rear limb is naked. The wood fairing has obviously been fitted as an after-thought, and not by the manufacturer. The job is clumsy and without finish, though effective. Landing shocks are taken by the familiar steel coil spring.
Four bracing wires are employed, connecting all four upper attachment points to the apices of the vees. Fig. 10 shows one of the front joints.

Tail.
The tail is practically of standard Rumpler - and, indeed, German - practice, but it is noteworthy that the elevators, which were of the balanced pattern in the CIV machine, are no longer so. As the longitudinal control is reported entirely satisfactory, it is evident that unbalanced elevators have been found all that is desired. The fin may hardly be regarded as adequate, in view of the side area presented in the nose of the machine, and the report that this aeroplane is somewhat liable to spin should be considered in this connection.
The four tail stays are of stream-line steel tube, and the lower pair have serrated edges to assist mechanics in remembering that these stays should not be grasped in lifting the machine or in holding it back on starting.
Although the fabric has not been removed, these members - the fin, rudder, and elevators - appear to be constructed of light steel tube welded in the usual way.
The tail skid is of ash, pivoted in the centre, and sprung at its upper end. The lower end carries a sheet steel shoe, whose shape is shown in Fig. 11.

Controls.
The control system is of considerable interest, inasmuch as the usual transverse rocking shaft operating the elevator controls is not used. The aileron control is actuated by a longitudinal rocking shaft of steel tube, which carries a welded cone-shaped portion supporting the vertical control lever. The aileron cables are attached to a lever pinned to the rocking shaft, and pass through the wings, operating the ailerons in the way that has become usual in German aeroplanes - i.e., the aileron lever lies in line with the plane, and is accommodated in a slot cut in the rear edge of the main plane.
The control cables pass over pulleys when they leave the lower plane to be attached to the aileron lever. These pulleys are situated behind the rear outer strut attachment, and are capped with a neat aluminium fairing.
The control lever operates the cables attached to the elevator levers, those attached to the lower extremities of the levers passing over pulleys mounted in the front portion of the rocking shaft. This shaft projects somewhat below the level of the fuselage bottom, and is neatly faired off by an aluminium shield screwed to the fuselage. The control system should be made clear by Fig. 12.
A welded sheet steel rudder bar of simple pattern, shown in Fig. 13, operates the rudder through the usual cables. The distance between the seat and rudder bar is not variable. Rubber sleeves and leather straps on either extremity guard against the possibility of the pilot's feet slipping.

Armament.
The pilot controls the fire of one fixed Spandau gun attached close to starboard side of the engine. The cocking lever is placed just outside the cockpit to the pilot's right. The gun itself is inaccessible during flight. A thumb lever shown in sketch (14) controls the fire through the usual clutch and synchronising gear.
The observer's gun is of the Parabellum type, and is mounted on the usual built-up wooden gun-ring, of the same kind as that found on most German machines.
Provision for the fitting of a bomb rack had been made, but none was fitted.
An aluminium tray with holes for 10 Verey lights was fixed to the fuselage.

Engine.
Rumpler is usually fitted with a 240 h.p. Maybach engine or a 260 h.p. Mercedes. The present example has 6 cylinder Mercedes of 260 h.p., which possesses the familiar combined throttle and altitude control. The exhaust gases are led into a welded manifold, the shape of which is indicated in the photograph.

Cooling System.
The radiator, made by Hans Windhoff, is slung over the rear portion of the engine, and fixed to the central cabane. (For photograph of the radiator and connections of the 2-seater Rumpler see Fig. 33 in the description of the Maybach engine, page 1035.) The honeycomb consists of circular brass tubes, expanded at their extremities into hexagons, and sweated together there. The total radiating surface is approximately 1.5 sq. ft. The shutters which regulate the cooling surface are shown in Fig. 15. They, are operated by cables passing over pulleys. One cable passes over the top of the radiator, while the other exerts a downward pull and passes underneath. German pilots have reported that these shutters are rarely required except during protracted descents.
The temperature of the water is indicated by a mercury thermometer easily visible from the pilot's seat, and the limits of the permissible range of temperature are defined by red marks-one at 60 degrees and the other at 85 degrees. The radiator may be considered thoroughly satisfactory, but must naturally obstruct the pilot's view to some extent.
The oil tank is situated at the port side of the engine, and the maintenance of an equable temperature of its contents is assisted by a thick covering of felt. The oil pump is embedded in the bottom of the crank case, and not only passes on the oil to the gudgeon pins and crankshaft, but at the same time mixes, at each pulsation, a certain quantity of fresh oil from the tank with the oil already in circulation.

Petrol System.
The main petrol tank - of 46 gallons capacity - serves as a support for the pilot's seat, while an auxiliary tank holding 13 gallons is fitted between the two cockpits, adapting itself to the shape of the fuselage top fairing and to the gunner's turret. Neither tank seems to possess baffle plates, and both work under pressure.
The initial pressure is obtained by means of hand pumps, of which there is one in each of the cockpits. An automatic air pressure pump driven off the crankshaft maintains the pressure, and a release valve incorporated in the pump regulates it. Each tank has its own pressure gauge on the dashboard. The petrol gauge on the main tank is of Laufer make, while a Maximall gauge is found on the auxiliary tank. All pipes on this machine are of copper, and the tanks of sheet brass.

Engine Controls.
Three 3-way cocks are fitted. They enable the pilot to shut off the petrol entirely; to supply from both tanks simultaneously, or to run on either of the tanks alone. The throttle controls are shown in Fig. 16. The placing of the Mercedes carburettor at the rear of the engine facilitates the direct nature of the control.
The Deuta tachometer, working on the centrifugal principle, is driven off the camshaft, and is graduated from 0 to 1,600 r.p.m. It is not illuminated, and no normal is marked.

Propeller.
The propeller is an "Axial," No. 6987, diameter 3,150 mm., pitch 1,830 mm. It is secured to the crankshaft by eight bolts, an extra pair being fitted between two of the pairs of the usual six.

Wireless.
The machine is internally wired, and a tapping key is fitted to the gunner's right hand. The rack intended to support the aerial reel is also to be found, as well as a sheet steel dynamo shelf near the engine.

Cameras.
Two types of cameras were fitted. One particularly large one was accommodated in the special fitting shown in Fig. 17. The light octagonal tray A is suspended from the floor boards by elastic shock absorbers.
The zinc well shown in Fig. 18 carried the second camera. A light ply-wood tube, 30 in. long and 5 in. wide, is fixed to the rear of the observer's seat. It is obviously intended to carry some object, probably a Goerz bombing sight.

This machine is now at the Enemy Aircraft View Room, Agricultural Hall, Islington, where it may be seen on production of a pass, obtainable from The Controller, Technical Department, Ap.D.(L.), Pen Corner House, Kingsway, W.C. 2.

Rumpler CIV no G 117.jpg G.117
 
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The Royal Flying Corps' 1st Aircraft Depot at Saint Omer, France is known to have tested at least five types of German aircraft during the War. These aircraft were an Eindecker EIII, Albatros DVa, Fokker Dr.I, Pfalz DIII, and an LVG CII. St. Omer was a large facility that was the backbone of RFC aviation support and logistics network for the repair, maintenance, and field testing of aircraft. Cross and Cockade has a very good article on St. Omer https://www.crossandcockade.com/StOmer/TheAircraftDepot.asp

The depot had a Pilots Pool, which comprised ferry and test pilots as well as pilots transitioning through the depot headed for a squadron in the field. Chief Test Pilot was WFC Kennedy-Cochran-Patrick, who wrote of trials where a test pilot flew a Fokker design against some of the Allied pursuit aircraft at St. Omer.

Q 10257  Captured German Pfalz D_III fighter biplane with the RFC identification marks on a Br...jpg Pfalz DIII at St. Omer, France

Captured Albatros DVa at St Omer given code G56 Former Jasta 4.jpg Albatros DVa at St. Omer. Captured No. G.56

st-omer-the-rfc LVG CII May 21 1916 Captured.jpg LVG CII tested at St. Omer

Fokker_EIII_210-16.jpg Eindecker EIII flight tested at St. Omer
Captured DRI minus engine and prop at St. Omer 1918.jpg Fokker Dr.I analyzed at St. Omer.
 
IC 653 Report on the Pfalz (Type DXII) Single Seat Fighter, Oct. 1918

THE PFALZ SINGLE-SEATER FIGHTER.
160 H.P. MERCEDES ENGINE.
(Described in Flight Magazine)

In our issue of April 18th, 1918, we published some photographs and a brief description of the Pfalz single-seater fighter. We have, since then, by the courtesy of the authorities, been permitted to examine in detail, and sketch, one of these machines exhibited at the Enemy Aircraft View Rooms. Owing to the fact that several of these machines have been captured, there is available a great number of parts, so that it has been possible to ascertain the internal construction of practically all the details, many of which are very interesting. As the Pfalz is, constructionally, rather different from the general run of German machines, we propose to devote a considerable space to it, hoping that the information thus conveyed will be found both useful and interesting to all concerned in the production and use of aircraft. - ED.]

As a type the Pfalz belongs to the single-seater fighter class with low-resistance body, which during the last twelve months or so has been given more attention in Germany than ever before. Up till that time German designers had, generally speaking, troubled little about cutting down head resistance on their machines, trusting, presumably, to their high-power water-cooled engines to pull them through. As, however, the machines of the Allies increased in speed and climb it became obvious that something more than mere engine power would be required to cope with the constantly increasing demands, and once this was realised several German firms began to look around for ways and means of improving the performance of their machines. Among these were the Albatros firm, which turned out some single-seater fighters, incorporating the Nieuport type wing bracing and the semi-monocoque body of stream-line shape. It was on machines of this type that the pilots of the "Richthofen Circus" did much of their fighting. Then there was the Roland fighter, in which attempts were also made at stream-lining the body, but which went rather farther and made the body so deep as to serve directly as a support for the top plane. Finally we have the Pfalz, in which stream-lining has been carried a little farther still, inasmuch as the attachment of the lower wings takes the form of wing roots formed integrally with the body and the object of which is presumably to avoid sharp corners at the juncture of wings and body. The wing arrangement of the Pfalz also differs slightly from that of the Albatros in that the inter-plane struts do not come to a point on a single lower spar, but are separate at their lower ends by a short horizontal piece, evidently so as to enable the struts to take care of the twisting moment due to the travel of the c.p. better than can be done with a point attachment.
An examination of the Pfalz biplane gives the impression, also conveyed in the accompanying drawings, of very low resistance indeed, and with an engine of 160 h.p. one naturally expects the machine to have an excellent speed. Tests carried out in this country do not, however, confirm this first impression, and the following particulars of performance can only be regarded as disappointing in view of the promising appearance of the Pfalz, and this is another proof of the difficulty of judging "by eye" the merits or otherwise of a machine.
According to the official report on the tests the following data were established :-

Pfalz Scout, No. G. 141.
Engine 160 h.p. Mercedes.
Number of crew One.
Military duty Fighter.
Propeller Axial, Berlin.
Total military load 281 lbs.
Climb to 10,000 ft. In 17 mins. 30 secs.
Speed at 10,000 ft. 102 1/2 m.p.h.; revs., 1,400 r.p.m.
Rate of climb 360 ft./min.; revs., 1,310 r.p.m.
Climb to 15,000 ft. In 41 mins. 20 secs.
Speed at 15,000 ft. 91 1/2 m.p.h.; revs., 1,325 r.p.m.
Rate of climb 100 ft./min.; revs., 1,280 r.p.m.
Estimated absolute ceiling 17,000 ft.
Greatest height reached 15,000 ft. in 41 mins. 20 secs.

The total military load is made up as follows :-
Riot 180 lbs.
Two Spandau guns 70 "
Dead weight 31 "
Total 281 "

Weight per sq. ft. 8.56 lbs.
Weight per h.p. 12.84 "

Total weight of machine, fully loaded 2,056 lbs.
Weight of machine, bare, with water 1,580 lbs.
Military load, less crew 101 "
Crew, as above 180 "
Petrol, 21 1/2 galls 155 "
Oil, 4 galls. 40 "
Total 2056 "

The first question that naturally comes to mind after studying this table of performances is. What is the reason for this poor performance, for it can scarcely be termed otherwise. Some of the figures given in the table may help to furnish the solution, although after perusing them there are still several remaining unanswered. For instance, the wing loading is somewhat high, but certainly not so much so as to account by itself for the low maximum speed and low rate of climb. The body appears to be of good streamline form, but against this must be placed the fact that the maximum cross sectional area is comparatively large, owing to the deep body reaching nearly to the top plane. As regards the wing bracing, this is simple enough as far as concerns the number of wires and struts, but the cables are not faired, and as they are of rather large diameter, their resistance at maximum speed may reasonably be assumed to be fairly high. If, however, the detrimental resistance is considerable, the wing resistance is probably no less so, the wing section being of the deeply cambered type so favoured by German designers, and which has, generally speaking, a somewhat high drag, although its lift is good. We have for some time held the opinion that German designers were deliberately employing deeply cambered sections with a view to obtaining better performance at altitudes, but we are bound to admit that the official tests of the Pfalz scarcely appear to bear out this contention. We would strongly urge that the authorities have tests carried out at the N.P.L. on all the German wing sections of which data are available, as the publications of the results of such tests would be of the greatest interest. We do not for a moment imagine that the sections would reveal any superiority over those more commonly employed by the Allies, but some interesting facts might nevertheless be brought to light, which might be of use to our own designers, if only as a warning regarding what not to do.
Constructionally the Pfalz single-seater is even more interesting, showing, as it does, considerable departures in detail design from other German makes of the same class, on which its fundamental arrangement is evidently founded. This refers especially to the Albatros fighter single-seater, which is characterised by the same main features, such as large top plane and small bottom plane, one pair of interplane Vee struts on each side, ply-wood streamline body, &c. Apart from minor differences in shape, the Pfalz designer has chiefly struck out along original lines in the construction of the body. Whereas in the Albatros one finds the same oval formers connected by longitudinal rails, the manner of applying the three-ply covering is totally different in the two machines. In the Albatros the ply-wood is put on in small pieces covering only a bay or so; the covering of the Pfalz is in the form of long strips spirally laid on, the strips of the two layers forming an angle with one another.
In Fig. 1 is shown the general arrangement of the Pfalz body. There are in all eight longerons, it will be noticed-one at the top, one at the bottom, one half-way up on each side and four at what would be the corners in a rectangular section body. These longerons run the whole length of the body, with the exception of the top one, which is terminated just to the rear of the engine, and are attached to the formers as shown in the sketch, Fig. 2. The longerons are stop-chambered so as to leave them solid where occur the formers, into which they are sunk and secured by a wood screw. The formers themselves are built up of smaller pieces of spruce, lap-jointed and covered each side with a facing of three-ply wood.
Reference has already been made to the fact that wing roots are formed integrally with the body. These roots can be seen in the side view, Fig. 1; and account for the peculiar shape of formers III and IV. Judging by these formers the cross-sectional area is unduly increased at this point, although this may be partly made up for by the shape of the-ply-wood covering, which merges the lines of the lower plane into the curves of the body. This is illustrated in the two sketches, Fig. 3. It is, perhaps, open to doubt whether or not this elaborate arrangement is worth while. Constructionally it must necessarily entail considerable extra work, and aerodynamically it does not look as neat and efficient as the Albatros way of doing the same thing by frankly letting the bottom plane abut directly on the curved sides of the body.
Fig. 4 is a perspective view of the Pfalz body, and serves in conjunction with Fig. 1 to explain the general arrangement of formers and longerons. Some of the formers, it will be noticed, are sloped in relation to the others. Thus, for instance, the former in the neighbourhood of the pilot's seat slopes back so as to bring it approximately into line with the rear chassis struts, while rigidity is lent to the front portion of the body by sloping one of the formers carrying the engine bearers until its top meets the top of the next former. In this point also the formers are joined to the front struts carrying the top plane, while one of them serves, at the point of attachment of the bottom corner longeron, to transmit the load from the front chassis struts.
One of the difficulties of monocoque body construction has always been that you cannot bend three-ply sheet over a double curvature. That is to say, in sheet form the three-ply will bend willingly to the curvature of the converging sides of a flat-sided body; but as soon as the sides are no longer flat but have a curvature, however slight, three-ply in sheet form cannot be employed. In the Albatros this difficulty is overcome by using small sheets, covering only one bay, and forming in reality, although it is not noticeable, a series of straight bays. In the Pfalz a different method has been employed. The body covering consists of two layers of three-ply, each less than 1 mm. thick. The plywood is evidently manufactured in sheets, and before applying to the body is cut up into parallel strips of about 3 to 4 ins. the width apparently varying considerably throughout the body. The first layer of three-ply is then put on by bending it diagonally around the body, attaching it by tacking to the various longerons, en route, and cutting each narrow strip at the top and bottom longerons, which form the terminals so to speak of the three-ply covering, which is thus applied in two halves. The second layer of strips is then laid on top of the first, but at a different angle, to which it is secured by glueing, and finally tacked to the longerons. The inside layer is reinforced, in the front portion of the body, by glueing tapes over the joint between adjoining strips of plywood. This and other details are shown in Fig. 5. In order to spread a joint in the ply-wood over as large an area as possible the joint is made, as shown, in a sort of saw tooth or serrated butt joint style. This, in brief, is the fundamental construction of the Pfalz body, and differs considerably from other makes. As to its efficiency - we cannot speak. The weight at any rate, judging from the comparatively low total weight of the machine, can scarcely be any greater than the girder type of body, but as regards strength we have no information. We have heard it said that the Pfalz machines have a habit of breaking their bodies just aft of the pilot's cockpit, but for the accuracy of this statement we cannot vouch. As a compromise between sheet three-ply covering and true monococque construction the Pfalz method would appear to have certain advantages.

At the stern the Pfalz body terminates, as shown in the illustrations in our last issue and further illustrated in detail in Fig. 6, in a somewhat elaborate framework of wood, which performs the various functions of forming supports for the tail plane, tail skid, and vertical fin with its rudder. The design of this part of the body must have provided some pretty problems in projection drawing, and one is inclined to think that a little less rigid economy in metal fittings might have resulted in a considerably simpler design. The second former from the stern is, it will be seen from Fig. 6, sloped backwards to form the leading edge of the vertical fin, and is reinforced above the body with other pieces of' wood to give it a rounded edge. The last former is in duplicate, its front half extending upwards to form a member of the fin, while the other half terminates just above the body and serves chiefly as a support for the short length of spar to which the front spar of the tail plane is attached. Between these two formers and sloping so as to form in side view a cross, are another two formers, built up in much the same manner as the main body formers. The angle formed by one of these and the longeron accommodates the leading edge of the small plane permanently fixed to the body, while the point of intersection of the two formers supports a short transverse cylindrical piece of wood, around which is wrapped the shock absorbers for the tail skid. The details of both these joints are shown in the sketches of Fig. 6. The small tail plane root is covered, on the actual machine, with plywood, but this has been omitted in the sketch in order to better show the constructional details.
The tail plane itself is in one piece, and fits into the slot provided for it in the body. The manner in which it is secured after being placed in its slot will be clear from an inspection of Fig. 7. The front spar rests in the slot in the body, and is secured against lateral tilting by a steel band on each side, overlapping the butt joint between the front part of the rib and the tail plane root, as shown in Fig. 7. The rear spar of the tail plane is locked in place by two long bolts and a stud. The two bolts are placed one on each side of the stern, as indicated in the sketch in Fig. 7, while the stud passes through a lug welded on to the extreme rear of the steel shoe surrounding the heel of the fuselage into another lug near the foot of the stern post. The whole tail plane with its elevator can therefore be removed by undoing five nuts, and, of course, the connections in the elevator control cables.
As regards the tail plane and elevator themselves, these are constructed along more or less standard lines and do not present any especially remarkable features. It has already been pointed out that the tail plane appears at first sight to have been put on "upside down," having a flat top surface and a convex bottom surface. The reason for this is not apparent, but it is possible that the disposition of the various weights and surfaces is such that there is either a lift-weight couple or a thrust resistance couple or both; and that this section tail plane has been employed to equalise such couples. However, in a later machine captured and now at the Enemy Aircraft View Rooms the shape of the tail plane had been altered to a symmetrical section, so that it would appear that the "inverted" section has either been found unsatisfactory in practice or the reasons for its employment removed in a later design. Structurally the tail plane is built up of spruce spars with ribs having ash flanges and poplar webs. The inner ribs an covered with three-ply to give extra rigidity for attachment to the body. The front spar is of I section while the rear spar is channel section, with recesses top and bottom for forming a flat surface with the rib flanges. There is no internal wire bracing, the necessary rigidity being obtained by means of diagonal ribs and by plates of three-ply placed over the joints between-ribs and spars. The leading edge, which is also bent back to form the tips of the tail plane, is laminated as shown in Fig. 7, and is lightened by spindling between the ribs. The laminations are probably steamed so as to be easily bent to form the rounded corners of the tail plane.
The elevator, owing to the fact that the rudder has no downward projection, is in one piece, and is built up in a manner similar to that of the tail plane. Its leading edge is formed by a box spar, and the ribs are similar to those of the tail plane. The attachment of the ribs to the trailing edge is somewhat unusual. Instead of the flanges of the ribs passing over the trailing edge they are thinned down and pass into a slot in the trailing edge as shown inset in Fig. 7. They are then secured in place by a small metal clip. The slots in the trailing edge appear to have been made with a circular cutter of about 3 in. diameter, the ends of the rib flanges being placed where the slot is deepest. The elevator hinges are formed by forked bolts passing through the rear spar of the tail plane, and corresponding with eye bolts through the leading edge of the elevator.
The elevator crank levers are of a type frequently found on German machines. The crank itself is of streamline section, and is welded to a channel section base plate surrounding three sides of the leading edge. Another base plate of similar shape, but made of lighter gauge, is slipped over the leading edge from the front, and forms a washer for the hinge bolt, which passes through the leading edge at a point coincident with the crank lever. The attachment of the elevator and rudder cables to their respective cranks is in the form of a ball and socket, joint, or, more correctly speaking, the ball portion of it is not a complete ball but a slice of a sphere, formed integrally with the bolt passing out of the socket into the barrel of the wire-strainer. The socket, and also the ball have a flat formed on one side so as to prevent the ball from turning in the socket. Behind the ball a small split-pin passes transversely through the socket, thus preventing the ball from dropping out of the socket when the control cables are removed. The socket is kept filled with grease.
The rudder, which, as already pointed out, is placed wholly above the elevator, is built entirely of steel tubing. The ribs are joined, not directly to the rudder post, but to a collar of very light gauge, which is in turn pinned and braced to the rudder post. The object of this construction probably is to avoid weakening the rudder post by welding, since all the rudder ribs can then be welded to their collars on a jig, the rudder post being inserted afterwards and the collars pinned in place. The rear end of the ribs is joined direct to the trailing edge by welding. The method of tapering the rib tubes down towards the trailing edge is different from anything we have yet seen on a German machine. A vertical slice is taken out of one of the tubes, and the edges thus formed are pushed over the other tube of the rib as indicated in Fig. 8, the two tubes being held together by short welds at intervals.
The foot of the rudder post rests in a cup or shoe on the trailing edge of the vertical tin, while additional hinges are provided at intervals. The form these hinges take is shown in Fig. 8. To prevent the rudder post from sliding up and down a collar is placed above and one below each hinge. To these collars are welded two U-shaped rods around which is wrapped fabric in order to form an air tight joint at the points where the hinge pierces the rudder covering. This is also shown in Fig. 8. The fabric wrapping has been omitted for the sake of clearness.
The tail skid is of somewhat unusual shape, as shown in the right-hand sketch of Fig. 7. Owing to the fact that there is no vertical fin below the body of the Pfalz, and no downward projection of the rudder, it has been possible to reduce head resistance of skid by making it horizontal for the greater part of its length, with just a downward curve at the rear to give greater clearance for the tail plane. The skid is pivoted on a bolt passing through a lug on the heel of the fuselage. Its free end is sprung by rubber cord from the short cylindrical piece of wood already referred to, and shown in Fig. 6. This attachment looks remarkably weak - a piece of wood, slotted at its ends to fit over the cross formed by the two sloping body formers. Yet in all the captured specimens of Pfalz machines that we have had an opportunity to examine, this particular member has never been broken, so that one can only infer that it is stronger than it appears. As to the skid itself, it is built up of ten laminations of wood, each about 5 mm. thick. At the rear the skid is provided with a sheet metal shoe to protect it against wear.

The seating accommodation of the Pfalz does not present any special features, except, perhaps, that the pilot's cockpit is quite roomy considering the area of the cross section at this point. This is, of course, a consequence of the peculiar body construction, which leaves, for a given cross section, more space inside than is possible when employing the girder type fuselage with rectangular main structure and the fairings added afterwards. Thus, in the case of a circular cross section, for a diameter of 3 ft. the inscribed square is only about 2 ft., while with the monocoque construction the whole circle is available for the accommodation of the pilot. This is another way of saying that the cross sectional area of a body of rounded section can be kept smaller with monocoque construction than with girder-cum-fairing construction, resulting in lower head resistance.
The seating itself is of the usual type, and was indicated in Figs. 1 and 4 of our July 25th issue. The front edge of the seat is supported on the sloping former, while the rear of the seat rests on a transverse member supported on a small false former slightly farther aft. Needless to say the pilot is equipped with a safety belt, which in the Pfalz is in the form of webbing, attached as shown in Fig. 9, to the longerons via a short length of coil spring.
The Pfalz controls are shown in Fig. 10. A tubular control lever, forked at its lower end, is attached to a longitudinal rocking-shaft, which carries at its front end the transverse cranks for the aileron controls. In connection with these it should be remembered that ailerons are fitted to the top plane only, hence two cables pass from each end of the crank and around pulleys, one of them being what might be termed the positive cable, running through the lower plane, over pulleys, and to the aileron crank; the other being the return or equalising cable running across the body through the opposite lower plane, over a pulley, and to the opposite aileron.
As is now general practice, means are provided for locking the elevator in any desired position. The manner of doing this in the Pfalz will be evident from an inspection of Fig. 10. The collar carrying the oaileron control cranks has welded to it a vertical forked lug, a bolt through which forms the pivot for a hinged stay rod, terminating at the top in a flat, curved, slotted strip, which may be locked in any position by means of a locking disc of aluminium. At its upper end the control column has welded to it two handles, bound with cord, of which the left is rotatable and operates the throttle much after the fashion of a motor cycle. Centrally placed are two triggers operating the two synchronised machine guns via Bowden cables. The handle is shown in Fig. 11. This sketch, it may be pointed out, has been drawn from the port side in order to better show the twisting handle, while the general sketch of the controls is drawn as seen from the starboard side.
The rudder bar of the Pfalz presents some rather unusual features. Thus the rudder cables are anchored to forked lugs on the front of the foot bar, through which they pass, and issue from the rear of the bar through channel section guides which act, when the foot bar is moved to the extremity of its travel, as quadrants for the cables. The object of this rather complicated arrangement is hot clear unless it has been done in order to get the forked lugs working in compression instead of in tension. The foot rests are in the form of flat forks inserted in sockets in the foot bar and provided with adjustment for length to suit individual pilots.
Where the rudder and elevator cables issue from the interior of the body they pass through small sheet steel plates carrying a steel tube fitted with a copper tube liner to protect the cables against wear. Internal and external views of one of these fittings are shown in Fig. 12.
The engine a 160 h.p. Mercedes is mounted in the nose of the body on two longitudinal bearers supported by four main formers. The details of the mounting do not call for any comment, and the general arrangement of the engine mounting will be sufficiently clear from Figs. 1 and 4. The main petrol tank is carried in the bottom of the body, resting on the spar roots of the lower plane built into the body as a permanent fixture. The usual hand-operated pressure pump and an engine-driven pump are provided for forcing the petrol from the main tank up into the service tank built into the top plane. The oil tank is carried by the side of the engine. The nose of the machine is rounded off, and terminates in a "spinner" fitted over the propeller boss, thus forming a very smooth entry for the air. Near the nose of the machine there are two scoops, that on the port side carrying air into the engine housing, while the scoop on the starboard side has a tube running to an opening in the crank case, which is ventilated by this means. These features, as well as the neat inspection doors provided in convenient places on the front part of the body, are shown in Fig. 13. The sketches are, we think, self-explanatory.
The undercarriage is of the Vee type, with struts of streamline section steel tube. The struts look somewhat spidery, being of rather small dimensions as regards their section. The major axis of the section is 48 mm., and the maximum thickness of the strut, occurring fairly far back, is 30 mm. The fineness ratio is therefore very low. The attachment of the chassis struts to the body is of interest. The rear struts are bolted, as shown in detail in Fig. 15. to an I section steel bracket built into the wing roots on the body. Thus the landing shocks are transmitted from this strut via the bracket to the fixed rear spar and its former, and to the sloping former surrounding the pilot's seat. The upper ends of the front struts are welded to elongated base plates of heaw gauge, which serve as lugs for the chassis bracing cables. In order to distribute landing shocks over a larger area a steel band is passed underneath the bottom of the body, so that the whole bottom part of the former to which the struts are attached rests in the loop of this strap. The arrangement is illustrated in Fig. 15.
The apices of the chassis Vees are connected by two cross struts, one in front and one behind the axle. As a matter of fact it is hardly correct to term the rear one a strut in the ordinary sense of the word, as it consists of short lengths of solid wood tapered to fit the steel socket attaching it to the chassis struts, the remainder of its length being made up of a thin strip of wood forming the top surface of the trailing edge, while its bottom surface is in the form of a sheet of three-ply passing under the axle to the front cross strut. The latter is a wood strut spindled out to a "D" section, and tapered at the ends to fit the tapered steel sockets which connect it by means of bolts to the chassis struts. The top of the streamline casing around the axle thus formed is a hinged lid of aluminium, which, as the axle moves up and down when the machine is running along the ground, opens and closes, lying of course, snugly against the rear cross strut when the axle is relieved of its load as the machine leaves the ground, thus forming a good stream-line section with, it is to be presumed, a fairly low head resistance. Cross bracing of the chassis is in the front bay of the struts only, and is in the form of stout stranded cable. As in the case of the wing cables, no stream-lining has been attempted, a feature fairly typical of even modern German machines.
The shock absorbers are in the form of cords which as regards outward appearance might easily be mistaken for rubber cord, but which on closer examination, are found to be spiral springs, one inside the other, enclosed in a woven cover similar to those employed for covering stranded rubber cords. These springs are wrapped around the apex of the chassis Vee and around the axle, and are prevented from slipping up along the chassis struts by lugs welded to the struts. Two lugs higher up serve as anchorage for the short loop of stranded cable which limits the travel of the axle. This length of cable is enclosed in a cover, as shown in Fig. 15, to protect it against wear. The tubular axle is a fairly large diameter - 55 mm., to be exact; but we have not been able to ascertain of what gauge the tube is made. The details of the undercarriage are shown in the perspective sketches of Fig. 15 and in section in Fig. 14.

FUNDAMENTALLY the Pfalz single-seater belongs to the type frequently termed by the Germans a one-and-a-half-plane, that is to say, it is a machine having a larger top plane and a smaller bottom plane. The type was, as is of course well known, originated by the French Nieuport firm, and the first machine of this type, if not actually making its appearance, was at any rate contemplated, before the outbreak of war. Since then, although comparatively recently, the enemy has copied the type fairly extensively, chiefly in the Albatros single-seaters and in the make at present under review. Aerodynamically this arrangement of the planes is of advantage on account of the fact that in a biplane the lower plane is the less efficient, and that therefore the more of the total surface is formed by the top plane the better the overall efficiency. Practically also certain advantages attend the arrangement. The effect of the smaller lower chord is twofold. The gap between the planes need not be so great as in the case of a biplane having both planes of the same chord, and for a given fuselage depth the top plane may therefore be placed at a smaller height above the top of the body, resulting in a better view forward. Again the smaller bottom chord does not obstruct the view downward to the same extent as does a plane of larger chord. Thus the "one-and-a-half-plane" forms a good compromise between the lighter structure of a biplane and the good visibility of the "parasol" monoplane, which latter is probably unsurpassed as a fighter as far as obstructing the view in all directions to the smallest extent is concerned.
In the design of its wing structure the Pfalz shows several interesting features. The outward slope of the struts connecting the body with the top plane was originated, we believe, by Sopwiths in their "one-and-a-half-strutter," while the Vee form inter-plane struts are typically Nieuport. Constructionally, however, the Pfalz is a good deal different in both these features, The Vee struts are not strictly speaking placed in the form of a letter V, as they do not quite meet in a point on the lower plane, which has two spars instead of the single spar employed in the original Nieuport. The object of having two spars is evidently to provide a more rigid structure better capable of resisting the twisting moment due to the travel of the centre of pressure. Owing to the fact that the inter-plane struts do not come to a point, incidence wires should be employed, but in their stead the struts are so built up as to form the bottom of a solid U which lends to the lower ends of the struts the rigidity usually provided by incidence wires. The same applies more or less to the body struts, which, as was shown in the illustrations published in our issue of July 25th, are in the form of an inverted, flattened U with its cross member adjoining the upper plane. Here, again, the construction of the struts has been designed to perform the function of incidence wires. While on the subject of these struts, attention may be drawn to a somewhat unusual arrangement of the transverse bracing cables. Generally these run from port top rail to top of starboard body struts and vice versa. In the Pfalz, however, this arrangement has been discarded and the arrangement indicated in Fig. 16 substituted. The cross wiring does not, it will be seen, run over the top of the body at all. Instead the cables from the upper ends of the struts on one side run to the root of the bottom- plane on the same side. The body struts pivot around their attachment to the body, and any lateral displacement of the top plane would therefore result in a raising of one side or the other with a consequent tightening of the corresponding cables. From a practical point of view this arrangement of the cables would appear to possess considerable merits. The crossing of the cables above the body generally necessitates piercing of the top covering, which in most machines is raised considerably above the top longerons, to which the lower ends of the cables are usually anchored. These wires are therefore as a rule difficult to get at, and from a rigger's point of view at any rate, the Pfalz arrangement appears preferable. Then again wires crossing above the body frequently interfere with the placing of the machine guns, or with the sighting tube and other accessories. Aerodynamically, it is true, the Pfalz arrangement is at some slight disadvantage, inasmuch as the length of cables exposed to the air is greater than in the case of cables crossing above the body. When, however, as in the Pfalz, the struts are designed to do away with incidence wires the total length of cables is probably no greater, and so, on the whole, one is inclined to consider the arrangement worth while.
The general arrangement of the Pfalz wings is shown in Fig. 19. Ailerons, it will be seem, are fitted to the top plane only, as is almost universal practice in Germany. They are hinged to a false spar, and have their crank levers working in slots in the plane, another feature characteristic of enemy machines. This part of the' wing is reinforced extensively by the use of three-ply wood. As shown in the drawing, the petrol service tank is built into the top plane, as is also the radiator, which is provided with a shutter that can, owing to the low placing of the top plane, be operated direct from the pilot's seat, a handle projecting aft from the radiator being provided for this purpose. This central portion of the top plane is also reinforced by a covering of three-ply.
The two wing sections of the Pfalz are shown in Fig. 20. The lower section is not, it will be observed, an exact geometrical reduction of the upper one, the trailing portion of its lower surface being more in the nature of a reversed curvature than is the case with the top section. The difference does not, however, appear to be great. The maximum camber of the sections appears to be smaller than one usually finds on German machines. At the same time the camber is very considerable for a machine intended for fast flying, and it is possible that the wing section is, at any rate partly, responsible for the inferior performance of the Pfalz.
The wing spars of both planes are of the box form, although not, as indicated in the sections of Fig. 20, made up in the usual way of two channel sections joined by a hardwood tongue and grooves. The flanges of the spars are of spruce, and of the section shown in the illustration. Front and rear faces of the spars are formed by plies of wood made up of two thin outer layers of three-ply with a thicker layer of spruce in between them. At points where the spars are pierced by bolts for the attachment of inter-plane struts or internal compression tubes, the space between top and bottom flanges is filled up solid by packing pieces. The attachment of the spar webs to the flanges is by glueing only, no tacks or screws being employed. The spar is afterwards covered for its entire length by fabric, to prevent moisture from attacking the internal glued joints and to reduce the risk of splitting. The fabric is not wrapped around the spar spirally but is laid uo straight, finishing off along one comer of the spar. As in most machines, the spars are not placed with their vertical faces at right angles to the chord line but at right angles to the line of flight.
Reference has already been made to the struts connecting the body with the top plane, and to the fact that these struts are pivoted at their attachment to the body. The exact form which this pivot takes is shown in Fig. 17. A circular base plate is bolted to the body formers where these are crossed by the tipper body rails. The base plate has welded to it a cup or socket into which fits a spherical male portion secured to a sheet steel shoe surrounding the lower end of the body struts. A pin (taper) passing through socket and ball secure the strut in place. The slot through the ball is of elliptical section to allow a certain amount of play for alignment.
Fig. 18 shows how the lower spars are attached to the wing roots formed integrally with the body. The fixed spar inside the body is split to receive the former occurring at this point, and is rounded off at its outer end to a circular section. A steel cap surrounds the end of the spar root, to which it is secured, as far as we have been able to ascertain, by a single pin. This cap is surrounded by a collar incorporating a fork for the attachment of the lift cable, and terminates at its outer end in a steel piece shaped like an eyebolt. The inner end of the wing spar is also surrounded by a sleeve, this, however, being secured by two bolts, the inner of which is an eyebolt that serves as an anchorage for the internal drift wiring. The wing spar sleeve carries at its inner end the female portion of the joint, a fork end, which engages with the eyebolt of the fixed spar, the two being held together by a quick-release pin as shown. In Fig. 18 the ribs have been omitted in the larger drawing for the sake of clearness, but they are indicated in the smaller inset.

THE top plane of the Pfalz is supported from the body by two inverted, flattened U's, as mentioned in our last issue. The attachment of these U's to the body was shown in Fig. 17. The attachment to the top plane is of a similar character, as shown in Fig. 21. The upper corner of the centre-section struts is provided with a sheet steel shoe to which is welded a socket or cup. A bolt passing vertically through the spar terminates in a ball-shaped head, which fits into the cup, and a taper pin passing through ball and socket locks the joint. The inter-plane cables are attached to little anchor pieces shaped as shown in the sketch, terminating inside the larger cup in a wide head shaped to fit the internal curve of the cup. A certain amount of play is therefore allowed. The right hand sketch in Fig. 21 shows, from a different point of view, the corresponding fitting on the rear spar.
The internal compression tubes of the wings are secured to the spar by a very simple fitting, shown inset in Fig. 21. A small steel plate is stamped out to form a shallow projection, the diameter of which corresponds to the internal diameter of the compression tube, which is thus prevented from slipping on the spar. This sheet steel plate is secured to the spars by two horizontal bolts, and its ends are shaped to form the lugs for the attachment of the drift or anti-drift wires, as the case may be. The drift wires of the Pfalz are in reality tie rods of circular section, threaded at their ends to fit directly into the barrel of the turnbuckles. The anti-drift wires are solid wires of about 12 gauge size.
The inter-plane struts of the Pfalz are, as mentioned in our last issue, approximately of Vee form, although they do not quite come to a point at their lower ends. In section they are, needless to say, stream-line, and constructionally they are built up of various laminations, as shown in one of the small insets of Fig. 22. The two outer layers are spruce. Then come, one on each side, two layers of thin three-ply, while the centre of the strut is formed by a piece of spruce. The whole is then covered with fabric. The same construction is employed for the centre-section struts. The angle formed by the vertical and horizontal arms of these struts is elaborately built up of laminations, the grains of which cross one another at various angles. The strength appears good, but the struts are certainly not light, compared with the ordinary hollow or even solid spruce strut.
The attachment of the inter-plane struts to the bottom plane is interesting. As the horizontal arm of the struts is shorter than the distance between the spars of the bottom plane the struts cannot be attached directly to the spars. Instead they are attached, by means of the usual Pfalz ball-and-socket joint, to a compression tube. Owing to the fact that this tube is subject to a lateral load, being loaded both as a strut and as a beam, the usual compression tube attachment already referred to would be inadequate. Instead the arrangement illustrated in Fig. 22 is employed. The compression tube is unlike those employed elsewhere in the planes, inasmuch as it is not of circular section, but is flattened so as to have fiat parallel sides and a top and bottom forming arcs of a circle. At its ends this tube is welded to a base plate of channel section, which partly surrounds the three sides of the wing spar. Before being welded to its end plates the tube is slotted at its ends to accommodate the lugs for the drift and anti-drift wires. These lugs are formed by bending a piece of sheet steel to a channel section, the bottom of the channel being welded to the base plate and the arms welded to the compression tube. The horizontal bolts securing the base plates to the wing spar have their heads filed flat so as to pass between the two drift wire lugs, and are thus at the same time prevented from turning when tightening up the nuts on the other side of the spar. The details of this part of the wing structure will be clear from Fig. 22.
The general arrangement and spacing of the wing ribs of the Pfalz were shown in Fig. 19 of our last issue. Constructionally the ribs are built up in the usual way of three-ply webs and spruce flanges. False ribs occur between the main ribs, running over the top of the spars, from leading edge to rear spar. These false ribs are made of ash. In connection with the main ribs mention may be made of a rather neat little "dodge" for attaching the ribs in place on the spars. As usual the rib flanges are tacked to the top and bottom faces of the spars. In addition the ribs are prevented from sliding along the spars by two vertical pieces of wood, each tacked to the spar. In the middle these vertical pieces are slotted to accommodate a small square block of wood about 1/2 inch square - which is glued to the face of the spar. The end of the rib web is recessed to give room for this block, the effect of which is, it will be seen, to relieve to a certain extent the shearing stress on the rib flanges at the corners of the spar. It is only a small detail we admit, but it is, we think worthy of mention, and has been included in Fig. 22.
The crank lever of the ailerons is shown in Fig. 23. As in all German machines, ailerons axe fitted to the top plane only, and their crank levers are horizontal, working in slots in the plane. The aileron hinges on a false spar. The crank levers are built up of two halves of sheet steel, pressed to form in section one half of an ellipse. The two halves are then welded together along the edges. The control cables are secured to the crank lever by the same ball-and-socket attachment as that employed for the rudder and elevator controls already described. The cables pass from the lever, around pulleys in the bottom wing, and through tubes to the controls. These tubes appear to be made of some sort of paper or cardboard, although whether made by wrapping the paper spirally or rolled up straight to form a tube we have not been able to ascertain.
Reference has already been made to the fact that the radiator of the Pfalz is mounted in the top plane. The cooling may be varied by an adjustable shutter which has a handle projecting back so as to be within the reach of the pilot. The arrangement of this shutter is shown in Fig. 26. The rod carrying the handle has a series of notches cut in it so as to form suitable stops for the shutter in any desired position. The details of the locking device will be evident from an inspection of Fig. 26.
The armament of the Pfalz consists of two synchronized machine guns of the Spandau type. The mounting of these is shown in Fig. 25. Two transverse tubes form the supports for the gun mounting, which appears very light, being made of light gauge steel suitably reinforced by webs in places. The rear attachment of the gun provides for vertical adjustment, while the front attachment enables a slight lateral alignment of the gun after the mounting has been bolted into place on the cross tubes. A peculiarity of the gun placing on this particular Pfalz is that the guns are entirely enclosed under the top covering of the body, with only the muzzle projecting. This is indicated in Fig. 24. On a later specimen of the Pfalz fighter the more usual placing of the guns above the body has been employed, whether because enclosing the guns was found unsatisfactory or not we are not in a position to say. Probably the enclosed guns were found to have a tendency to overheat.
In the Pfalz under review no attempt appears to have been made to camouflage the machine, which is painted with aluminium paint all over its body and wings. The rudder tail plane and elevator are painted a dark yellow.

Pfalz DIII G.141.jpg G.141
 
IC 607 Report on AEG Bomber, Mar. 1918

REPORT ON AEG BOMBER, G. 105.
[Issued by the Technical Dept. [Aircraft Production), Ministry of Munitions.] From Flight Magazine

THIS machine was brought down by anti-aircraft fire at Achietle-Grand on December 23rd, 1917.
On a label protected by celluloid, mounted on a tube in the nacelle, is the legend - " Abnahme am (Accepted on) November 10th, 1917. "
This machine, whilst carrying a similar power plant, is very different in construction from the Gotha type, which also embraces the Friedrichshafen Bomber reported on in IC 619.
Whereas the latter is generally constructed of weed, ply wood being used to a very large extent throughout, in the AEG steel is almost universally employed, not only in regard to the fuselage, nacelle, subsidiary surfaces and landing gear, but also in the wings themselves.
Needless to say, acetylene welding is freely resorted to throughout the construction, which, however, appears to be far from light.
On the whole, the AEG-aeroplane, judged by contemporary British standards of design, is decidedly clumsy, not only in detail work, but also in appearance. The performance is poor.
The leading particulars of the machine are as follows: -

Weight empty 5,258 lbs.
Total weight 7,130 lbs.
Arja of upper wings 395.2 sq ft.
Arja of lower wings 335.2 sq.ft.
Total area of wings 730.4 sq. ft.
Loading per sq. ft., wing sur. 9.77 lbs. per sq. ft.
Area of ailerons, each 17.9 sq. ft
Area of balance of aileron 1.8 sq.ft.
Area of tail plane 34.0 sq.ft.
Area of fin 11.5 sq. ft.
Area of rudder 20.8 sq. ft.
Balanced area of rudder 2.6 sq. ft.
Area of elevators 31.2 sq. ft,
Balanced area of elevators 3.6 sq. ft.
Horizontal area of body 206.4 sq. ft.
Vertical area of body 209.2 sq. ft.
Total weight per hp 13.7 lbs. approx.
Crew-Pilot and two passengers 540 lbs.
Armament 2 guns
Engines 2 260 hp Mercedes.
Petrol capacity 123 galls. = 861 lbs.
Oil capacity 11 galls. = 110 lbs.
Water capacity 13 galls. = 130 lbs.

Other dimensions are also shown on the drawings on page 612.

Performance.
(a) Climb, 5,000 ft. in 10.3 minutes. - Rate of climb at 5,000ft. - 390 ft. per minute. Climb, 9,000 ft. in 23.4minutes. Rate of climb at 9,000 ft. - 235 ft. per minute.
(b) Speed at Heights. - Level to 5,000 ft. - 90 miles per hour approximately. At 9,000 ft. - 86 miles per hour approximately.
(c) Landing Speed. - The aeroplane is best landed at a speed between 75 and 80 miles an hour; after flattening out it sinks to the ground quickly and pulls up rapidly.
(d) Control. - 1. Lateral - Good. 2. Elevators - Bad, especially when landing.
NOTE. - It is stated that it is not advisable to fly this machine without a passenger in the front seat.

Construction.
Wings.-As will be seen from the scale drawings, the wings are of characteristic form. The central portion consists of a rectangular center cell permanently attached to the fuselage. The lower wings support the engines. In this center cell the planes are set horizontally. At each side of it the lower main planes are swept upwards with a vertical dihedral of 2.75 °, the top planes being kept flat, and both main planes are swept backwards in the horizontal plane to an angle of 4 ° for the bottom plane and 3 ° for the top plane. As, the central portion of the upper main plane has 4 ins. of negative stagger relative to the bottom plane, this difference in angle brings their tips practically vertically over one another. The angle of incidence attains a maximum of 4 ° at the base of the engine struts, ie, 7 ft. 10 3/8 ins. from the center. At the second strut the angle is 3 1/2 °, and at the end strut 2 1/2 °. These angles are painted in circles on the surface of the planes, evidently for the convenience of riggers. The camber of both planes is washed out gradually towards the tips, and a representative section of the main planes taken at the junction of the engine bearer struts is given in Fig. 1. For purposes of reference the RAF 14 section is superimposed. This figure also shows the position of the main spars, which are of steel tube. These are 50 mm. in outside diameter, but their wall thickness is not at present known. In order to allow the thinning down of the wing section, these tubes are flattened out towards the extremity of the wing. They are chamfered down to a narrow end and a fiat plate acetylene welded on to each side; thus at the spar tip the section is roughly rectangular. The main spars are kept parallel throughout the whole of their length, and are attached to the central cell by means of pin joints, similar to those on the Friedrichshafen. The ribs are of solid wood and are constructed as shown in Fig. 2. It is rather notable in comparison with other German machines of all types that ply wood is almost entirely absent. In the AEG construction the rib webs are perforated and strengthened by wooden uprights at intervals and are glued into a grooved flange. The ribs are placed 300 mm. - 325 mm. apart and are not directly or firmly attached to the spars on which they are a relatively loose fit. Passing through the ribs of the bottom plane and extending from their junction with the center section to the extreme outside strut are two steel tubes, approximately 17 mm. in diameter, which act as housings for the aileron control wires. These tubes are very strong, and it is thought possible that they are also counted upon to lend rigidity to the wing structure. The leading edge, which is of the usual semi-circular section, acts as a distance piece, as also does the wire trailing edge. Thirteen inches in front of the last named is a stringer formed of a steel rod. Apart from this, the spars are the only longitudinal members of the wings. Between the main ribs are false ribs running from the leading edge to a point a few inches behind the leading spar and applying only to the upper surface. One of these false ribs is sketched in Fig. 3. It is secured as shown in the sketch by means of a semi-circular saddle and a wrapping of tape which passes as shown through holes in the rib. Where it meets the leading edge it is furnished with triangular packing pieces, which locate and hold it in position. The lower plane is covered as to its upper surface with sheet metal immediately under the engines, whilst between them and the fuselage is fixed a strip of corrugated aluminum which acts as a footway. The fabric is attached in the usual manner, and is stitched to the ribs both top and bottom. The two surfaces are stitched together behind the metal rod, which acts as a stringer, and by this means the actual trailing edge wire is relieved of a certain amount of tension. The wing structure is internally braced by means of steel tubular cross-pieces and stranded cables. A single fitting is employed for the attachment of the interplane struts and for that of the bracing tubes. This fitting is shown in Fig. 4. It is a tight fit on the spar, to which it is fixed by a bolt, and is formed with an extension lug which acts, as shown, as an anchorage for the bracing tube, whilst a sideways extension of the same lug carries an eye for the bracing wire. It is provided with a cup-shaped upper extension, into which there is screwed a steel dome which carries the ball of the strut socket fitting and also acts as a wiring plate for the interplane bracing wires. As shown in the sketch, the fabric is run into the space between the upper and lower flanges of this fitting, the whole making a very neat job. into which there is screwed a steel dome which carries the ball of the strut socket fitting and also acts as a wiring plate for the interplane bracing wires. As shown in the sketch, the fabric is run into the space between the upper and lower flanges of this fitting, the whole making a very neat job. into which there is screwed a steel dome which carries the ball of the strut socket fitting and also acts as a wiring plate for the interplane bracing wires. As shown in the sketch, the fabric is run into the space between the upper and lower flanges of this fitting, the whole making a very neat job.

Struts.
These are of streamline section steel tube and of uniform dimensions throughout. The section is 92 mm. long by 48 mm. broad. The ends are sharply tapered down, and into them is welded a cupped ferrule which drops on to the ball shown in sketch Fig. 4, and is held in position by a cotter pin. The attachment is shown complete in Fig. 5. This joint gives a considerable range of lateral freedom, as is the usual practice on machines of German design.

Fuselage
The whole of the fuselage is built up of steel tubes welded together. It is of plain rectangular section, and the cross tubes are attached directly to the main booms without the intervention of any clips. This detail of construction is shown in Fig. 6, which also illustrates the single and double lugs which are used for the purpose of securing the bracing wires. Under the nacelle and in the neighborhood of the main petrol tanks and the bomb racks the fuselage is reinforced with thin tubular steel tie-rods. Fig. 7 shows the manner in which the upper booms of the fuselage are provided with sockets for the inclined struts of the central cell. The fitting consists of two circular steel plates welded into position to form an integral part of the frame joint, the front one of these flanges being provided with lugs for the anchorage of bracing cables. The inclined struts are secured by a ring> of short set screws wired together as shown. If appearances are to be trusted, this form of attachment, whilst being strong and convenient, is excessively heavy. Unlike the practice which is pursued in the Friedrichshafen Bomber, however the main frame consists of three separate sections, that of the AEG is in one piece from stem to stern. The longerons are 30 mm. in diameter and the transverse members 30 mm., these dimensions being retained up to the extreme tail end. The nose part of the frame is covered-in with three-ply wood, but behind this a double covering of fabric is used, under which the tubular construction is completely hidden. Behind the after cockpit a single covering only is adopted and laced the whole of its length so that it is removable in its entirety.

Engine Struts.
These are of streamline steel tubing and embrace joints of a somewhat similar type to those used on the interplane struts; that is to say, a certain amount of free movement is provided. The mounting of the engines is clearly shown in the front and side elevations. In front there are four struts which converge to a joint on the leading spar, whilst at the rear there are two struts which meet at a joint on the trailing spar. The attachment of the former is shown in Fig. 8. The bell-shaped housing attached to a cup on the spar joint contains a ball-end set screw which screws into the foot of the four struts which are here united by welding. The inclined transverse struts are taken from the spars to the engine mounting and cross struts from thence again to the upper booms of the fuselage. In order to provide simplicity of erection these subsidiary struts are provided with a means of adjustment as shown in Fig. 9. At one end they terminate in a ball-ended set screw screwed into the tapered end of the strut and secured by a lock nut.

Engine Mounting.
The engine bearers are of steel rectangular section, measuring 40 mm. high by 30 mm. broad, with a wall thickness of approximately 2 mm. These bearers are welded to the struts which support them, as shown in Fig. 10, and for the greater part of their length are reinforced by a system of tubular tie-reds also welded in position. Box attachments welded to the engine bearers, as shown in Fig. 11, are provided for the crank-chamber holding-down bolts. The engine is not directly mounted on the steel bearers, but upon 1/2-in. wooden washers. Owing to the deformation inseparable from so much welding the engine mounting is of very clumsy appearance, and, in act, the quality of welding does not appear to be up to previous German standards, but the construction would appear to be light.

Engine Fairing.
As shown in the photographs, the engines are almost completely enclosed in a fairing composed of detachable aluminum panels. The necessary framework and clips are provided for panels totally enclosing the engine, but it would seem that this bonnet right over the heads of the cylinders has been discarded. The tubular framework which supports the panels is an elaborate piece of work comprising a multiplicity of welded joints. It consists of 16 mm. tubes, to which are attached lugs for carrying the necessary turn-buttons. The framework is made in two halves so as to be easily detachable, and a joint for that purpose is made, as shown in the sketch Fig. 12. It will be noticed that a narrow slot for the exit of air passing over the engine is provided at the rear end of the engine egg,

Engines.
The engines are the standard 6-cylinder 260 hp Mercedes. These engines have already been fully described, and no important novel points are adopted. A new shape has been adopted for the exhaust pipe, and this is clearly shown in one of the photographs - an inverted cone is placed in the belled mouth of the pipe. The usual water pump greaser is fitted and worked by a lever in the pilot's cockpit. It is of rather less clumsy design than that of the Friedrichshafen, but employs the same principle. The throttle is interconnected with the ignition advance as described in the Friedrichshafen report. A small fitting, the purpose of which is not very clear, is attached to the carburettor, and consists, as shown in Fig. 13, of a bell-shaped cover over the top of the float chamber, not directly connected thereto, but supported on a bracket clipped to the main water pipe. The bell is free to slide up and down the stem of the bracket, on which it is a very loose fit, but is prevented from falling over the float chamber by a small washer. It is conjectured that this fitting may have for its purpose the prevention of petrol having access to the hot exhaust pipe in the event of the machine turning over. Between the bell and the float chamber is a clearance of about 1/4 inch.

Petrol System.
The petrol system employed on the AEG is as set out diagrammatically in Fig. 14. There are two main tanks, each of 270 liters = 95 gallons total capacity, and these are placed tinder the pilot's seat in the main cockpit. Two subsidiary tanks used solely for starting purposes and giving a gravity supply are mounted in the center section of the top main plane and are of roughly streamline form. Beneath them is a small cowling containing their level gauges, which are visible from the pilot's seat. On the right hand side of the main cockpit is fitted a hand-operated wing pump, the object of which is to draw petrol from either of the main tanks and direct it to the gravity tanks. Pipes from all four tanks are taken to a distributing manifold on the dashboard, and by means of seven taps thereon the supply of petrol can be directed from any one of the tanks to either engine or both. Two additional taps are provided on the wing pump so that the fuel for the gravity supply can be drawn from either main tank as required. The photograph A clearly shows the arrangement of the petrol taps, which are of the plain plug type. It would appear that the troubles associated with this form of tap have been overcome, as they show no signs of leaking or sticking. The level of the main tanks is indicated on the dashboard by two Maximall gauges. Those attached to the gravity tanks are made by Laufer, and employ the static head principle. They read up to 45 liters each, from zero to this figure being given by one and a half complete revolutions of the indicating hand. Two additional taps are provided on the wing pump so that the fuel for the gravity supply can be drawn from either main tank as required. The photograph A clearly shows the arrangement of the petrol taps, which are of the plain plug type. It would appear that the troubles associated with this form of tap have been overcome, as they show no signs of leaking or sticking. The level of the main tanks is indicated on the dashboard by two Maximall gauges. Those attached to the gravity tanks are made by Laufer, and employ the static head principle. They read up to 45 liters each, from zero to this figure being given by one and a half complete revolutions of the indicating hand. Two additional taps are provided on the wing pump so that the fuel for the gravity supply can be drawn from either main tank as required. The photograph A clearly shows the arrangement of the petrol taps, which are of the plain plug type. It would appear that the troubles associated with this form of tap have been overcome, as they show no signs of leaking or sticking. The level of the main tanks is indicated on the dashboard by two Maximall gauges. Those attached to the gravity tanks are made by Laufer, and employ the static head principle. They read up to 45 liters each, from zero to this figure being given by one and a half complete revolutions of the indicating hand. The photograph A clearly shows the arrangement of the petrol taps, which are of the plain plug type. It would appear that the troubles associated with this form of tap have been overcome, as they show no signs of leaking or sticking. The level of the main tanks is indicated on the dashboard by two Maximall gauges. Those attached to the gravity tanks are made by Laufer, and employ the static head principle. They read up to 45 liters each, from zero to this figure being given by one and a half complete revolutions of the indicating hand. The photograph A clearly shows the arrangement of the petrol taps, which are of the plain plug type. It would appear that the troubles associated with this form of tap have been overcome, as they show no signs of leaking or sticking. The level of the main tanks is indicated on the dashboard by two Maximall gauges. Those attached to the gravity tanks are made by Laufer, and employ the static head principle. They read up to 45 liters each, from zero to this figure being given by one and a half complete revolutions of the indicating hand. and employ the static head principle. They read up to 45 liters each, from zero to this figure being given by one and a half complete revolutions of the indicating hand. and employ the static head principle. They read up to 45 liters each, from zero to this figure being given by one and a half complete revolutions of the indicating hand.

Petrol Pressure System.
The sketch, Fig. 14, also shows in solid lines the arrangement of the petrol pressure system. The usual pressure pump is mounted on each engine, and pipes therefrom are led to a manifold mounted on the dashboard. This is also connected to a large hand pump on the right hand side of the pilot's seat. Gauges reading the pressure from each engine pump are provided, and there is also a blow-off tap for relieving the pressure of the whole system.

Oil System.
This is the usual system as fitted to all 260 hp Mercedes engines. The main supply of oil is carried in the crank chamber sump and is continually being refreshed by a small additional supply of fresh oil drawn from an external tank. This tank has a capacity of 5 gallons, is of rectangular shape, and is mounted at the side of the engine nearest to the fuselage. It is provided with a visible glass level, over which is a celluloid covered window let into the engine fairing, so that the oil level is visible from the pilot's seat.

Radiator
Each radiator is composed of two halves bolted together, as shown in the sketch Fig. 15, which is to scale. The space between the two halves is partially covered with a sheet metal panel pierced with a hole 1 ft. 6 ins. high by 4 ins. wide. The radiator is not actually honeycomb, though representing that appearance. It consists of a series of vertical tubes with transverse gills. Each radiator cell measures 2 ft. 3 1/2 ins. high by 7 1/2 ins. wide, and has a uniform depth of 4 ins. Each complete radiator is provided with two shutters of roughly streamline section. These, when fully closed, cover over about one-third of the radiating surface.
They are controlled from the pilot's seat by two levers shown in Fig. 16, which work them through universally jointed rods. The articulation in these rods is very neat and of the form shown in sketch Fig. 17. Each radiator is fitted with an electric thermometer, full details of which device have been published. The dial of this instrument is carried on the dashboard and is furnished with a switch enabling the temperature of either radiator to be independently read.

Engine Control
The throttle levers are of the plain twin variety, and are constructed as indicated in sketch Fig. 18. They are placed close together so as to be easily worked either in unison or separately. The connections between the levers and the carburettor are made as simple as possible, and the levers operate the throttle through a couple of universally jointed rods which extend from each side of the body to the engine eggs. The universal joints used are of the type shown in Fig. 19, there being apparently no particular desire on the part of the designer to economise weight in these details.
Tail planes.
THE fixed horizontal tail planes are notable for their extremely bold curvature, both top and bottom. The framework consists entirely of welded steel tubing. The leading edge of the tail plane is mounted so as to be adjustable in case of necessity, a simple bracket being used for this purpose, as illustrated in Fig. 20. This is welded on to the fuselage upright at each side and strengthened with a transverse stay. It allows the tail plane leading edge to be fixed in one of three positions. The trailing edge of the tail plane is supported each side by a streamline section steel tubular strut.

Fin.
The fin, like the fixed tail plane, has also a very strongly marked streamline section at the base tapering off to flat at the top, where it abuts against the balanced portion of the rudder. At this point its framework, which is of light steel tube, is made rigid by a couple of tubular stays bracing the rudder post to the sides of the fuselage.

Rudder and Elevators.
These organs are built up of steel tubular framework, and present no points of special interest, except that in the case of the rudder that part which is above the fixed fin is made of grooved section.

Ailerons.
As may be seen from the plan view of the complete machine, the shape of the ailerons is somewhat unusual. These are applied to the top plane only and have a chord which reaches its maximum at their extreme ends and its minimum in the center of their length. For what purpose this peculiar shape is adopted is not clear. The framework of these ailerons is welded steel tubing, and the control crank is fitted in such a way as to lie partially hidden in a slot in the main plane. This crank is built up of welded sheet steel, and is arranged as shown in the sketch. Fig. 21, an elliptical hole being cut in the trailing edge of the main plane for the passage of the forward wire.

Control
The main control consists of a wheel mounted on a pivoted lever, the wheel operating the ailerons by means of a drum and cables, which pass direct over pulleys and along tubes running parallel with the wing spars and then over inclined pulleys up to the aileron cranks . The wheel column is pivoted to a long crossbar extending the whole length of the fuselage and carrying at each end cranks for the elevator control wires which at intervals are carried through fiber guides socketted to the frame. The cranks of the elevators are concealed inside the rear end of the fuselage, whilst those of the rudder (which is fitted with duplicate cranks and wires) are external. A modified dual control is fitted, which allows the assistant pilot to work the elevator and rudder only. For this purpose a socket is mounted on the pivot bar into which can be inserted a plain steel tube which is normally carried in clips behind the pilot's back. A second rudder bar, the design of which is shown in Fig. 22, is carried under the dashboard, and can readily be dropped into position into a square socket partially sunk into the floor of the cockpit and connected to the pilot's rudder bar by cranks and a link.

Personnel
Seats are provided for a crew of four, who are carried as follows: - One in the front cockpit; one in the pilot's seat; one at the pilot's side; one in the rear cockpit.
All can, if necessary, change places whilst the machine is in the air. Between the front cockpit and that of the pilot a sliding panel is provided through which the gunner can crawl. The seat at the side of the pilot folds up and slides back into a cavity under the coaming of the nacelle, and when in this position allows access down a narrow and inclined passage-way to the rear cockpit. The machine can hardly have been designed to satisfy the requirements of the average pilot in regard to view, as from the pilot's seat it is very difficult to see the ground properly on account of the position of the lower main plane and the width of the fuselage .

Armament.
Two Parabellum guns are mounted, one in the front cockpit, and one in the rear, and provision is made for mounting a third or for transferring one of the others on the floor of the rear cockpit, so that it can fire backwards and under the tail of the machine. For this purpose a large trap door, which is visible in the photograph B, is provided in the floor of the fuselage behind the rear cockpit. This trap door has celluloid windows and is normally kept closed by springs. It is lifted up by a small hand winch fitted with a ratchet. It is of passing interest to note that whereas in the Friedrichshafen a similar trap door was kept open by means of springs, in the AEG springs are used to keep the door closed. In the front cockpit the gun is supported on a carriage which runs round a partially circular rail which is strongly supported from the fuselage by a framework of steel tubes. Forming part of this frame is an inclined steel tubular column, the base of which is fitted in a swivel bearing in the floor of the cockpit, and on this is mounted an adjustable seat for the gunner. A toothed rack runs round the rail and engages with a spur pinion driven by a hand wheel so that the gunner, when occupying his seat, swivels himself round as well as the gun. This gun mounting is shown in photograph C, and a diagrammatic section of the carriage is given in Fig. 23. The vertical swivel of the fork-ended gun carrier is locked by a ball-ended lever and a similar lever is employed for locking the carriage itself to its rail. Forming part of this frame is an inclined steel tubular column, the base of which is fitted in a swivel bearing in the floor of the cockpit, and on this is mounted an adjustable seat for the gunner. A toothed rack runs round the rail and engages with a spur pinion driven by a hand wheel so that the gunner, when occupying his seat, swivels himself round as well as the gun. This gun mounting is shown in photograph C, and a diagrammatic section of the carriage is given in Fig. 23. The vertical swivel of the fork-ended gun carrier is locked by a ball-ended lever and a similar lever is employed for locking the carriage itself to its rail. Forming part of this frame is an inclined steel tubular column, the base of which is fitted in a swivel bearing in the floor of the cockpit, and on this is mounted an adjustable seat for the gunner. A toothed rack runs round the rail and engages with a spur pinion driven by a hand wheel so that the gunner, when occupying his seat, swivels himself round as well as the gun. This gun mounting is shown in photograph C, and a diagrammatic section of the carriage is given in Fig. 23. The vertical swivel of the fork-ended gun carrier is locked by a ball-ended lever and a similar lever is employed for locking the carriage itself to its rail. A toothed rack runs round the rail and engages with a spur pinion driven by a hand wheel so that the gunner, when occupying his seat, swivels himself round as well as the gun. This gun mounting is shown in photograph C, and a diagrammatic section of the carriage is given in Fig. 23. The vertical swivel of the fork-ended gun carrier is locked by a ball-ended lever and a similar lever is employed for locking the carriage itself to its rail. A toothed rack runs round the rail and engages with a spur pinion driven by a hand wheel so that the gunner, when occupying his seat, swivels himself round as well as the gun. This gun mounting is shown in photograph C, and a diagrammatic section of the carriage is given in Fig. 23. The vertical swivel of the fork-ended gun carrier is locked by a ball-ended lever and a similar lever is employed for locking the carriage itself to its rail.
This action is accomplished by a cam device which depresses the roller of the carriage and squeezes the rail section between the roller and an adjustable set screw which normally just clears the groove on the under side of the rail. In order to prevent the forward gunner from shooting the tractor screws, preventative shields of light steel tube are carried between the upper edge of the forward cockpit and the inclined struts of the center section. These impose a limit to the travel of the gun. In the rear cockpit the gun mounting is U-shaped in plan form, and here again the principle of a carriage running on a rail and driven by a spur gear meshing with a toothed rack is employed, though in this case the gunner's seat does not revolve with the gun. The carriage is of a somewhat similar type to that used in the front cockpit, but the method of locking it is different. This is shown diagrammatically in Fig. 24. The rail is provided with grooves both above and below, there being two rollers at the top and one underneath. Normally, when the gun carriage is free, the latter is clear of the rail, but when the locking mechanism is brought into action it is forced upwards so that the rail is gripped between the rollers, thus avoiding any possibility of shake at this point, and at the same time a positive lock is obtained on a second rail carried below the first. When the ball-ended hand lever is tightened, its effect is to squeeze the lower rail between two jaws. The movable jaw is, however, connected up by a link to a small cam, the base of which abuts against the foot of a fork-ended rod which carries the lower roller and is free to move up and down in a guide, to the base of which the cam is pivotted. By this means a very secure and rapid locking device is obtained. In the front of the rear cockpit a locker is provided which would be capable of holding ammunition, and beneath this a series of racks of the type shown in Fig. 25. These racks are not strong enough to hold anything very heavy, and are placed approximately 5 ins. apart. Their exact purpose is not known.

Bombing Gear.
Three racks for holding twenty-five pounder bombs are installed on the machine: two side by side on the left side of the rear cockpit, and one on the right side of the petrol tanks in the space between the pilot's and rear cockpits. This rack is covered by a detachable wooden lid which acts as the floor of the narrow gangway mentioned above. Underneath the center of nacelle provision is made for carrying two or more large bomb racks, which, however, were not in use on this machine. Underneath the lower main plane, two at each side of the nacelle, are fixed bomb clips which are capable of supporting bombs roughly 8 inches in diameter. They are held in position by a belly-band consisting of two steel strips, clearly shown in the photograph B. Eleven and a half inches in front of this clip is a bracket suitable for a circular section of 4 inches in diameter, and 13 1/2 inches in the rear of the clip is a second bracket suitable for a 5-ins. diameter section. The bomb would thus appear to be 50 kgs. In the photograph the belly-bands are shown clipped out of the way. At their fixed end they are supported on a crosshead, a sketch of which is given in Fig. 26. This in turn is carried on a bracket clipped to a steel tube running parallel to the wing spars and braced thereto by tubular steel girders. The cross head is free to swivel on the bracket against the action of a coiled spring which, when the bomb has been released, twists the crosshead round against a stop, so that the belly-band is forcibly swung round and now faces the direction of flight instead of lying edgewise on to it.
When the bombs are in position, the rings which are fitted on the free end of the belly-band are caught between the jaws of a trigger mechanism, illustrated diagrammatically in Fig. 27. This device is carried on the same tube which supports the crossheads, as already mentioned. Lying parallel to this tube and between it and the leading spar is a control rod fitted with two levers which are connected respectively to the two bomb trip gears, and this rod is operated by a quadrant lever mounted in the front cockpit. In order to allow one trip gear to be worked at a time, the link of the outer trip is provided with a slot where it is pivotted to the trigger release. On working the lever in the cockpit, therefore, its first action up to half way over the quadrant is to release the bomb nearest the nacelle, whilst a further movement releases the outer bomb. An exactly similar method is employed for operating the bombs carried underneath the other wing. The levers in the front cockpit are all mounted on a common bracket built up of steel tubes, and are arranged as follows: - First, there are the two levers which control the two bomb magazines in the rear cockpit. These are provided with thimbles and chains, so that they cannot be operated accidentally. Next, a single lever which controls the larger bomb clips on the right wing. These are capable of being secured by split pins inserted in their quadrants. Next, there is a lever which in this particular machine was furnished with no action at all, but is evidently designed for manipulating the large bomb-carriers when these are installed. Behind it are, first,

Landing Gear.
The landing gear of the AEG bomber is simply an elaboration of that which has become practically a standard fitting on single and two-seaters, except that in this machine the gear is in duplicate. It consists of two axles carrying two wheels a-piece, and suspended from pairs of V struts. One pair is connected to the spars of the center section immediately underneath the engine strut sockets, and the other to the spars midway between this point and the fuselage and at the same point from which diagonal struts are taken from the spars to the engine mounting and nacelle. This, together with the wire bracing of the landing gear struts provides a completely triangulated construction. The struts are, however, connected by ball joints similar to those used with the engine struts, so that in case of strain a certain amount of free movement can take place. The pairs of V struts carry at their foot a hollow steel crossbar having the section of a trough, and in this lies the axle which connects the two wheels. As shown in the sketch Fig. 28 and in the photograph D, the fixed beam has forward and rearward extensions, at each end of which are anchored the ends of the batteries of coil springs which act as shock absorbers, and at their other ends are hooked to a horn plate on the wheel axle. Each battery of springs, of which there are four to each axle, consists of 18 springs. A yoke of stranded steel cable restricts the movement of the axle beyond a certain limit. The tires are 32 ins. x 6 ins. - 810 x 150. A tail skid of massive proportions is used. This is of the shape shown in photograph E, and is built up entirely of welded steel. The springs against which it works are concealed inside the tail end of the fuselage.

Wireless
The machine is internally wired for wireless, and a special dynamo for supplying current for this purpose and also for heating is installed on the right hand engine. This dynamo bears the following inscription: -

Telefonken;
JP Flieg. C 1916. Type D.
Alternating current 270 watts. 5 ampAres. 600 frequency.
Continuous current 50 volts. 4 amperes, rpm 4,500.

The dynamo is mounted on brackets acetylene-welded to the steel engine bearers, and is normally completely enclosed in a detachable fairing. Its position is clearly shown in photograph F. The dynamo drive embraces the pulley which is a standard fitting on the 260 hp Mercedes, but in this particular case the clutch gear whereby the driving pulley can be disconnected from the engine as required appears to have been discarded. Two sets of wires are taken from the dynamo inside flexible metal conduits to a pair of plugs located at the junction of the fuselage and the right hand lower main plane. Here they terminate in plug sockets, so designed that the plugs cannot be inserted wrongly. One of these wiring circuits applies to the heating system, and wires for this purpose are carried to points in all three cockpits, whilst the other circuit is for wireless and terminates in a plug adapter in the rear cockpit. No wireless instruments were fitted. Two plug sockets for the heating installations are arranged in the rear cockpit; two in the pilot's cockpit and one for the forward gunner. A small plate on the pilot's dashboard carries the following inscription, but no definite information is given: -

FT Fitting. W / T Set.
Aeroplanes
Type 94. NY 1125/16.
Fitting, No. 85A.
Driving propeller. Type. Direct coupling.
Length of aerial wires - - -
Telefunken transmitter.- - - meters.
Huth transmitter, - - - - meters.
D transmitter - - - meters.
G transmitter - - - meters.

In addition to these two circuits, there is a lighting installation in conjunction with a battery carried in a box in the rear cockpit. From here, wires are taken to each cockpit and also to the tail and via the leading edge of the upper plane to the extreme outside strut of each wing. On these struts red and green lights are carried, the lamps for this purpose taking the form shown in. Fig. 29. Inspection, lights, are provided, at convenient points in each cockpit over the dashboard, instruments, & c.
For the most part the lighting wiring is contained inside a light celluloid conduit.

Instruments.
These components twin engine revolution counters, twin air pressure gauges for the petrol supply, electric thermometer, altimeter, petrol level gauges, & c. All of these are of recognized types and call for no detailed description.

Camouflage.
This machine is camouflaged in six different colors, on a uniform system covering every portion. The colors are arranged in hexagons measuring roughly 18 ins. across the flats, and the colors are sage green, reddish mauve, bluish mauve, black, blue and gray. These colors are not flat washes, but are softened by being stippled and splashed with paint of a lighter tone. The effect gained is well shown in photograph G. Considerable care appears to have been taken with this camouflage scheme, which is presumably effective.

Fabric and Dope.
The fabric throughout is of good quality, and the dope acetate of cellulose.

Propeller.
Diameter 10 ft. 3.8 ins. + .20 in. Pitch 59.3 ins.
The following table gives the thicknesses of the various laminae used in construction of the air-screw. The laminae are numbered from the trailing to the leading edge: -
Thickness
No. Material in inches.
1 Walnut 0.73
2 Mahogany 0.80
3 Mahogany 0.80
4 Mahogany 0.80
5 * Mahogany 0.80
6 Mahogany 0.80
7 * Mahogany 0.40
8 * Mahogany 0.40
9 Mahogany 0.80
10 Walnut 0.83
* These laminations were of a completely different kind of mahogany, probably African.

Only one air screw has been seen and dimensioned. Thus it is unknown whether all air screws would have laminae of similar thicknesses and of similar timbers. There is no apparent reason why these laminae should be of different thicknesses. It is surmised that either the enemy is short of timber or that he has a highly scientific reason for so doing that we do not know. The port and starboard air screws rotate in opposite directions.

G105 AEG Bomber.jpg G.105
 
Similar to the modern-day Nellis AFB Threat Training Facility (Petting Zoo) in Nevada, the British created a threat museum in Islington, England at the Royal Agricultural Hall in 1918. The display was set up for the public and the press to view at the end of the War as an exposition of the technology used by the enemy, however many viewed it as a display of war trophies as events such as this occurred elsewhere and included tanks and other captured equipment. The Australians, French (e.g. very popular display at the Place de la Concorde, Paris) and the Germans also conducted similar public displays of enemy war material throughout and after the war. An excellent book by Wellington (2017) Exhibiting War discusses the effort to display materials from WWI immediately following the War and their inclusion into some of Europe's great museums. These captured aircraft had been displayed in London early in the War as indicated by the 1915 Royal Horse Guard display in London.

captured-german-albatross-paraded-ludgate-circus-nov-1918.jpg Aircraft being moved for the public display. Jasta 23b_Pfalz D.IIIa 8151-17_Ltn Koumlnig_in London.jpg Photos possibly taken on the Royal Horse Guard grounds in London
Jasta 23b_Koumlnigs Pfalz D.IIIa_captured N of Gonnelieu.jpg
 
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The German research center at Adlershof was one of the primary test facilities (Doberitz the other) that included the flight test of captured aircraft. Here a Nieuport N.16 was captured in 1916 with rocket rails for ground attack missions, test flown and then stripped for structural evaluation.

Nieuport at Aldershof.jpg
Nieuport Stripped at Adlershof.jpg
 
You might want to get hold of a copy of Air Britain's Retribution and Recovery: German Aircraft and Aviation 1919-22. It covers in some depth the allocation and destruction of German and Austro-Hungarian aircraft following the Armistice and what became of the airframes and the efforts made by several nations and factions to hide or obtain airframes.
Do you know if the book has anything in it about those Aircraft held at the Royal Agricultural Hall, captured German displayed to the public in 1918-19. I am looking for some inventory, if it exists or existed.
 
Interesting to see to see reports on captured German aircraft. I'm looking at linen aircraft fabric production during WW1, it covered most if not all Allied planes. Germany used plywood as a cover quite extensively and produced all metal aircraft. My burning question is: was the Irish linen industry a military advantage in that it could supply all the linen needed - the Allies comfortably outbuilt the Germans in terms of numbers of aircraft especially in 1917 and 1918 - was this because the Germans were short of linen, even as just another one of the shortages that must have hampered aircraft production.
Does anyone have any insights?
 
IC 653 Report on the Pfalz (Type DXII) Single Seat Fighter, Oct. 1918

THE PFALZ SINGLE-SEATER FIGHTER.
160 H.P. MERCEDES ENGINE.
(Described in Flight Magazine)

In our issue of April 18th, 1918, we published some photographs and a brief description of the Pfalz single-seater fighter. We have, since then, by the courtesy of the authorities, been permitted to examine in detail, and sketch, one of these machines exhibited at the Enemy Aircraft View Rooms. Owing to the fact that several of these machines have been captured, there is available a great number of parts, so that it has been possible to ascertain the internal construction of practically all the details, many of which are very interesting. As the Pfalz is, constructionally, rather different from the general run of German machines, we propose to devote a considerable space to it, hoping that the information thus conveyed will be found both useful and interesting to all concerned in the production and use of aircraft. - ED.]

As a type the Pfalz belongs to the single-seater fighter class with low-resistance body, which during the last twelve months or so has been given more attention in Germany than ever before. Up till that time German designers had, generally speaking, troubled little about cutting down head resistance on their machines, trusting, presumably, to their high-power water-cooled engines to pull them through. As, however, the machines of the Allies increased in speed and climb it became obvious that something more than mere engine power would be required to cope with the constantly increasing demands, and once this was realised several German firms began to look around for ways and means of improving the performance of their machines. Among these were the Albatros firm, which turned out some single-seater fighters, incorporating the Nieuport type wing bracing and the semi-monocoque body of stream-line shape. It was on machines of this type that the pilots of the "Richthofen Circus" did much of their fighting. Then there was the Roland fighter, in which attempts were also made at stream-lining the body, but which went rather farther and made the body so deep as to serve directly as a support for the top plane. Finally we have the Pfalz, in which stream-lining has been carried a little farther still, inasmuch as the attachment of the lower wings takes the form of wing roots formed integrally with the body and the object of which is presumably to avoid sharp corners at the juncture of wings and body. The wing arrangement of the Pfalz also differs slightly from that of the Albatros in that the inter-plane struts do not come to a point on a single lower spar, but are separate at their lower ends by a short horizontal piece, evidently so as to enable the struts to take care of the twisting moment due to the travel of the c.p. better than can be done with a point attachment.
An examination of the Pfalz biplane gives the impression, also conveyed in the accompanying drawings, of very low resistance indeed, and with an engine of 160 h.p. one naturally expects the machine to have an excellent speed. Tests carried out in this country do not, however, confirm this first impression, and the following particulars of performance can only be regarded as disappointing in view of the promising appearance of the Pfalz, and this is another proof of the difficulty of judging "by eye" the merits or otherwise of a machine.
According to the official report on the tests the following data were established :-

Pfalz Scout, No. G. 141.
Engine 160 h.p. Mercedes.
Number of crew One.
Military duty Fighter.
Propeller Axial, Berlin.
Total military load 281 lbs.
Climb to 10,000 ft. In 17 mins. 30 secs.
Speed at 10,000 ft. 102 1/2 m.p.h.; revs., 1,400 r.p.m.
Rate of climb 360 ft./min.; revs., 1,310 r.p.m.
Climb to 15,000 ft. In 41 mins. 20 secs.
Speed at 15,000 ft. 91 1/2 m.p.h.; revs., 1,325 r.p.m.
Rate of climb 100 ft./min.; revs., 1,280 r.p.m.
Estimated absolute ceiling 17,000 ft.
Greatest height reached 15,000 ft. in 41 mins. 20 secs.

The total military load is made up as follows :-
Riot 180 lbs.
Two Spandau guns 70 "
Dead weight 31 "
Total 281 "

Weight per sq. ft. 8.56 lbs.
Weight per h.p. 12.84 "

Total weight of machine, fully loaded 2,056 lbs.
Weight of machine, bare, with water 1,580 lbs.
Military load, less crew 101 "
Crew, as above 180 "
Petrol, 21 1/2 galls 155 "
Oil, 4 galls. 40 "
Total 2056 "

The first question that naturally comes to mind after studying this table of performances is. What is the reason for this poor performance, for it can scarcely be termed otherwise. Some of the figures given in the table may help to furnish the solution, although after perusing them there are still several remaining unanswered. For instance, the wing loading is somewhat high, but certainly not so much so as to account by itself for the low maximum speed and low rate of climb. The body appears to be of good streamline form, but against this must be placed the fact that the maximum cross sectional area is comparatively large, owing to the deep body reaching nearly to the top plane. As regards the wing bracing, this is simple enough as far as concerns the number of wires and struts, but the cables are not faired, and as they are of rather large diameter, their resistance at maximum speed may reasonably be assumed to be fairly high. If, however, the detrimental resistance is considerable, the wing resistance is probably no less so, the wing section being of the deeply cambered type so favoured by German designers, and which has, generally speaking, a somewhat high drag, although its lift is good. We have for some time held the opinion that German designers were deliberately employing deeply cambered sections with a view to obtaining better performance at altitudes, but we are bound to admit that the official tests of the Pfalz scarcely appear to bear out this contention. We would strongly urge that the authorities have tests carried out at the N.P.L. on all the German wing sections of which data are available, as the publications of the results of such tests would be of the greatest interest. We do not for a moment imagine that the sections would reveal any superiority over those more commonly employed by the Allies, but some interesting facts might nevertheless be brought to light, which might be of use to our own designers, if only as a warning regarding what not to do.
Constructionally the Pfalz single-seater is even more interesting, showing, as it does, considerable departures in detail design from other German makes of the same class, on which its fundamental arrangement is evidently founded. This refers especially to the Albatros fighter single-seater, which is characterised by the same main features, such as large top plane and small bottom plane, one pair of interplane Vee struts on each side, ply-wood streamline body, &c. Apart from minor differences in shape, the Pfalz designer has chiefly struck out along original lines in the construction of the body. Whereas in the Albatros one finds the same oval formers connected by longitudinal rails, the manner of applying the three-ply covering is totally different in the two machines. In the Albatros the ply-wood is put on in small pieces covering only a bay or so; the covering of the Pfalz is in the form of long strips spirally laid on, the strips of the two layers forming an angle with one another.
In Fig. 1 is shown the general arrangement of the Pfalz body. There are in all eight longerons, it will be noticed-one at the top, one at the bottom, one half-way up on each side and four at what would be the corners in a rectangular section body. These longerons run the whole length of the body, with the exception of the top one, which is terminated just to the rear of the engine, and are attached to the formers as shown in the sketch, Fig. 2. The longerons are stop-chambered so as to leave them solid where occur the formers, into which they are sunk and secured by a wood screw. The formers themselves are built up of smaller pieces of spruce, lap-jointed and covered each side with a facing of three-ply wood.
Reference has already been made to the fact that wing roots are formed integrally with the body. These roots can be seen in the side view, Fig. 1; and account for the peculiar shape of formers III and IV. Judging by these formers the cross-sectional area is unduly increased at this point, although this may be partly made up for by the shape of the-ply-wood covering, which merges the lines of the lower plane into the curves of the body. This is illustrated in the two sketches, Fig. 3. It is, perhaps, open to doubt whether or not this elaborate arrangement is worth while. Constructionally it must necessarily entail considerable extra work, and aerodynamically it does not look as neat and efficient as the Albatros way of doing the same thing by frankly letting the bottom plane abut directly on the curved sides of the body.
Fig. 4 is a perspective view of the Pfalz body, and serves in conjunction with Fig. 1 to explain the general arrangement of formers and longerons. Some of the formers, it will be noticed, are sloped in relation to the others. Thus, for instance, the former in the neighbourhood of the pilot's seat slopes back so as to bring it approximately into line with the rear chassis struts, while rigidity is lent to the front portion of the body by sloping one of the formers carrying the engine bearers until its top meets the top of the next former. In this point also the formers are joined to the front struts carrying the top plane, while one of them serves, at the point of attachment of the bottom corner longeron, to transmit the load from the front chassis struts.
One of the difficulties of monocoque body construction has always been that you cannot bend three-ply sheet over a double curvature. That is to say, in sheet form the three-ply will bend willingly to the curvature of the converging sides of a flat-sided body; but as soon as the sides are no longer flat but have a curvature, however slight, three-ply in sheet form cannot be employed. In the Albatros this difficulty is overcome by using small sheets, covering only one bay, and forming in reality, although it is not noticeable, a series of straight bays. In the Pfalz a different method has been employed. The body covering consists of two layers of three-ply, each less than 1 mm. thick. The plywood is evidently manufactured in sheets, and before applying to the body is cut up into parallel strips of about 3 to 4 ins. the width apparently varying considerably throughout the body. The first layer of three-ply is then put on by bending it diagonally around the body, attaching it by tacking to the various longerons, en route, and cutting each narrow strip at the top and bottom longerons, which form the terminals so to speak of the three-ply covering, which is thus applied in two halves. The second layer of strips is then laid on top of the first, but at a different angle, to which it is secured by glueing, and finally tacked to the longerons. The inside layer is reinforced, in the front portion of the body, by glueing tapes over the joint between adjoining strips of plywood. This and other details are shown in Fig. 5. In order to spread a joint in the ply-wood over as large an area as possible the joint is made, as shown, in a sort of saw tooth or serrated butt joint style. This, in brief, is the fundamental construction of the Pfalz body, and differs considerably from other makes. As to its efficiency - we cannot speak. The weight at any rate, judging from the comparatively low total weight of the machine, can scarcely be any greater than the girder type of body, but as regards strength we have no information. We have heard it said that the Pfalz machines have a habit of breaking their bodies just aft of the pilot's cockpit, but for the accuracy of this statement we cannot vouch. As a compromise between sheet three-ply covering and true monococque construction the Pfalz method would appear to have certain advantages.

At the stern the Pfalz body terminates, as shown in the illustrations in our last issue and further illustrated in detail in Fig. 6, in a somewhat elaborate framework of wood, which performs the various functions of forming supports for the tail plane, tail skid, and vertical fin with its rudder. The design of this part of the body must have provided some pretty problems in projection drawing, and one is inclined to think that a little less rigid economy in metal fittings might have resulted in a considerably simpler design. The second former from the stern is, it will be seen from Fig. 6, sloped backwards to form the leading edge of the vertical fin, and is reinforced above the body with other pieces of' wood to give it a rounded edge. The last former is in duplicate, its front half extending upwards to form a member of the fin, while the other half terminates just above the body and serves chiefly as a support for the short length of spar to which the front spar of the tail plane is attached. Between these two formers and sloping so as to form in side view a cross, are another two formers, built up in much the same manner as the main body formers. The angle formed by one of these and the longeron accommodates the leading edge of the small plane permanently fixed to the body, while the point of intersection of the two formers supports a short transverse cylindrical piece of wood, around which is wrapped the shock absorbers for the tail skid. The details of both these joints are shown in the sketches of Fig. 6. The small tail plane root is covered, on the actual machine, with plywood, but this has been omitted in the sketch in order to better show the constructional details.
The tail plane itself is in one piece, and fits into the slot provided for it in the body. The manner in which it is secured after being placed in its slot will be clear from an inspection of Fig. 7. The front spar rests in the slot in the body, and is secured against lateral tilting by a steel band on each side, overlapping the butt joint between the front part of the rib and the tail plane root, as shown in Fig. 7. The rear spar of the tail plane is locked in place by two long bolts and a stud. The two bolts are placed one on each side of the stern, as indicated in the sketch in Fig. 7, while the stud passes through a lug welded on to the extreme rear of the steel shoe surrounding the heel of the fuselage into another lug near the foot of the stern post. The whole tail plane with its elevator can therefore be removed by undoing five nuts, and, of course, the connections in the elevator control cables.
As regards the tail plane and elevator themselves, these are constructed along more or less standard lines and do not present any especially remarkable features. It has already been pointed out that the tail plane appears at first sight to have been put on "upside down," having a flat top surface and a convex bottom surface. The reason for this is not apparent, but it is possible that the disposition of the various weights and surfaces is such that there is either a lift-weight couple or a thrust resistance couple or both; and that this section tail plane has been employed to equalise such couples. However, in a later machine captured and now at the Enemy Aircraft View Rooms the shape of the tail plane had been altered to a symmetrical section, so that it would appear that the "inverted" section has either been found unsatisfactory in practice or the reasons for its employment removed in a later design. Structurally the tail plane is built up of spruce spars with ribs having ash flanges and poplar webs. The inner ribs an covered with three-ply to give extra rigidity for attachment to the body. The front spar is of I section while the rear spar is channel section, with recesses top and bottom for forming a flat surface with the rib flanges. There is no internal wire bracing, the necessary rigidity being obtained by means of diagonal ribs and by plates of three-ply placed over the joints between-ribs and spars. The leading edge, which is also bent back to form the tips of the tail plane, is laminated as shown in Fig. 7, and is lightened by spindling between the ribs. The laminations are probably steamed so as to be easily bent to form the rounded corners of the tail plane.
The elevator, owing to the fact that the rudder has no downward projection, is in one piece, and is built up in a manner similar to that of the tail plane. Its leading edge is formed by a box spar, and the ribs are similar to those of the tail plane. The attachment of the ribs to the trailing edge is somewhat unusual. Instead of the flanges of the ribs passing over the trailing edge they are thinned down and pass into a slot in the trailing edge as shown inset in Fig. 7. They are then secured in place by a small metal clip. The slots in the trailing edge appear to have been made with a circular cutter of about 3 in. diameter, the ends of the rib flanges being placed where the slot is deepest. The elevator hinges are formed by forked bolts passing through the rear spar of the tail plane, and corresponding with eye bolts through the leading edge of the elevator.
The elevator crank levers are of a type frequently found on German machines. The crank itself is of streamline section, and is welded to a channel section base plate surrounding three sides of the leading edge. Another base plate of similar shape, but made of lighter gauge, is slipped over the leading edge from the front, and forms a washer for the hinge bolt, which passes through the leading edge at a point coincident with the crank lever. The attachment of the elevator and rudder cables to their respective cranks is in the form of a ball and socket, joint, or, more correctly speaking, the ball portion of it is not a complete ball but a slice of a sphere, formed integrally with the bolt passing out of the socket into the barrel of the wire-strainer. The socket, and also the ball have a flat formed on one side so as to prevent the ball from turning in the socket. Behind the ball a small split-pin passes transversely through the socket, thus preventing the ball from dropping out of the socket when the control cables are removed. The socket is kept filled with grease.
The rudder, which, as already pointed out, is placed wholly above the elevator, is built entirely of steel tubing. The ribs are joined, not directly to the rudder post, but to a collar of very light gauge, which is in turn pinned and braced to the rudder post. The object of this construction probably is to avoid weakening the rudder post by welding, since all the rudder ribs can then be welded to their collars on a jig, the rudder post being inserted afterwards and the collars pinned in place. The rear end of the ribs is joined direct to the trailing edge by welding. The method of tapering the rib tubes down towards the trailing edge is different from anything we have yet seen on a German machine. A vertical slice is taken out of one of the tubes, and the edges thus formed are pushed over the other tube of the rib as indicated in Fig. 8, the two tubes being held together by short welds at intervals.
The foot of the rudder post rests in a cup or shoe on the trailing edge of the vertical tin, while additional hinges are provided at intervals. The form these hinges take is shown in Fig. 8. To prevent the rudder post from sliding up and down a collar is placed above and one below each hinge. To these collars are welded two U-shaped rods around which is wrapped fabric in order to form an air tight joint at the points where the hinge pierces the rudder covering. This is also shown in Fig. 8. The fabric wrapping has been omitted for the sake of clearness.
The tail skid is of somewhat unusual shape, as shown in the right-hand sketch of Fig. 7. Owing to the fact that there is no vertical fin below the body of the Pfalz, and no downward projection of the rudder, it has been possible to reduce head resistance of skid by making it horizontal for the greater part of its length, with just a downward curve at the rear to give greater clearance for the tail plane. The skid is pivoted on a bolt passing through a lug on the heel of the fuselage. Its free end is sprung by rubber cord from the short cylindrical piece of wood already referred to, and shown in Fig. 6. This attachment looks remarkably weak - a piece of wood, slotted at its ends to fit over the cross formed by the two sloping body formers. Yet in all the captured specimens of Pfalz machines that we have had an opportunity to examine, this particular member has never been broken, so that one can only infer that it is stronger than it appears. As to the skid itself, it is built up of ten laminations of wood, each about 5 mm. thick. At the rear the skid is provided with a sheet metal shoe to protect it against wear.

The seating accommodation of the Pfalz does not present any special features, except, perhaps, that the pilot's cockpit is quite roomy considering the area of the cross section at this point. This is, of course, a consequence of the peculiar body construction, which leaves, for a given cross section, more space inside than is possible when employing the girder type fuselage with rectangular main structure and the fairings added afterwards. Thus, in the case of a circular cross section, for a diameter of 3 ft. the inscribed square is only about 2 ft., while with the monocoque construction the whole circle is available for the accommodation of the pilot. This is another way of saying that the cross sectional area of a body of rounded section can be kept smaller with monocoque construction than with girder-cum-fairing construction, resulting in lower head resistance.
The seating itself is of the usual type, and was indicated in Figs. 1 and 4 of our July 25th issue. The front edge of the seat is supported on the sloping former, while the rear of the seat rests on a transverse member supported on a small false former slightly farther aft. Needless to say the pilot is equipped with a safety belt, which in the Pfalz is in the form of webbing, attached as shown in Fig. 9, to the longerons via a short length of coil spring.
The Pfalz controls are shown in Fig. 10. A tubular control lever, forked at its lower end, is attached to a longitudinal rocking-shaft, which carries at its front end the transverse cranks for the aileron controls. In connection with these it should be remembered that ailerons are fitted to the top plane only, hence two cables pass from each end of the crank and around pulleys, one of them being what might be termed the positive cable, running through the lower plane, over pulleys, and to the aileron crank; the other being the return or equalising cable running across the body through the opposite lower plane, over a pulley, and to the opposite aileron.
As is now general practice, means are provided for locking the elevator in any desired position. The manner of doing this in the Pfalz will be evident from an inspection of Fig. 10. The collar carrying the oaileron control cranks has welded to it a vertical forked lug, a bolt through which forms the pivot for a hinged stay rod, terminating at the top in a flat, curved, slotted strip, which may be locked in any position by means of a locking disc of aluminium. At its upper end the control column has welded to it two handles, bound with cord, of which the left is rotatable and operates the throttle much after the fashion of a motor cycle. Centrally placed are two triggers operating the two synchronised machine guns via Bowden cables. The handle is shown in Fig. 11. This sketch, it may be pointed out, has been drawn from the port side in order to better show the twisting handle, while the general sketch of the controls is drawn as seen from the starboard side.
The rudder bar of the Pfalz presents some rather unusual features. Thus the rudder cables are anchored to forked lugs on the front of the foot bar, through which they pass, and issue from the rear of the bar through channel section guides which act, when the foot bar is moved to the extremity of its travel, as quadrants for the cables. The object of this rather complicated arrangement is hot clear unless it has been done in order to get the forked lugs working in compression instead of in tension. The foot rests are in the form of flat forks inserted in sockets in the foot bar and provided with adjustment for length to suit individual pilots.
Where the rudder and elevator cables issue from the interior of the body they pass through small sheet steel plates carrying a steel tube fitted with a copper tube liner to protect the cables against wear. Internal and external views of one of these fittings are shown in Fig. 12.
The engine a 160 h.p. Mercedes is mounted in the nose of the body on two longitudinal bearers supported by four main formers. The details of the mounting do not call for any comment, and the general arrangement of the engine mounting will be sufficiently clear from Figs. 1 and 4. The main petrol tank is carried in the bottom of the body, resting on the spar roots of the lower plane built into the body as a permanent fixture. The usual hand-operated pressure pump and an engine-driven pump are provided for forcing the petrol from the main tank up into the service tank built into the top plane. The oil tank is carried by the side of the engine. The nose of the machine is rounded off, and terminates in a "spinner" fitted over the propeller boss, thus forming a very smooth entry for the air. Near the nose of the machine there are two scoops, that on the port side carrying air into the engine housing, while the scoop on the starboard side has a tube running to an opening in the crank case, which is ventilated by this means. These features, as well as the neat inspection doors provided in convenient places on the front part of the body, are shown in Fig. 13. The sketches are, we think, self-explanatory.
The undercarriage is of the Vee type, with struts of streamline section steel tube. The struts look somewhat spidery, being of rather small dimensions as regards their section. The major axis of the section is 48 mm., and the maximum thickness of the strut, occurring fairly far back, is 30 mm. The fineness ratio is therefore very low. The attachment of the chassis struts to the body is of interest. The rear struts are bolted, as shown in detail in Fig. 15. to an I section steel bracket built into the wing roots on the body. Thus the landing shocks are transmitted from this strut via the bracket to the fixed rear spar and its former, and to the sloping former surrounding the pilot's seat. The upper ends of the front struts are welded to elongated base plates of heaw gauge, which serve as lugs for the chassis bracing cables. In order to distribute landing shocks over a larger area a steel band is passed underneath the bottom of the body, so that the whole bottom part of the former to which the struts are attached rests in the loop of this strap. The arrangement is illustrated in Fig. 15.
The apices of the chassis Vees are connected by two cross struts, one in front and one behind the axle. As a matter of fact it is hardly correct to term the rear one a strut in the ordinary sense of the word, as it consists of short lengths of solid wood tapered to fit the steel socket attaching it to the chassis struts, the remainder of its length being made up of a thin strip of wood forming the top surface of the trailing edge, while its bottom surface is in the form of a sheet of three-ply passing under the axle to the front cross strut. The latter is a wood strut spindled out to a "D" section, and tapered at the ends to fit the tapered steel sockets which connect it by means of bolts to the chassis struts. The top of the streamline casing around the axle thus formed is a hinged lid of aluminium, which, as the axle moves up and down when the machine is running along the ground, opens and closes, lying of course, snugly against the rear cross strut when the axle is relieved of its load as the machine leaves the ground, thus forming a good stream-line section with, it is to be presumed, a fairly low head resistance. Cross bracing of the chassis is in the front bay of the struts only, and is in the form of stout stranded cable. As in the case of the wing cables, no stream-lining has been attempted, a feature fairly typical of even modern German machines.
The shock absorbers are in the form of cords which as regards outward appearance might easily be mistaken for rubber cord, but which on closer examination, are found to be spiral springs, one inside the other, enclosed in a woven cover similar to those employed for covering stranded rubber cords. These springs are wrapped around the apex of the chassis Vee and around the axle, and are prevented from slipping up along the chassis struts by lugs welded to the struts. Two lugs higher up serve as anchorage for the short loop of stranded cable which limits the travel of the axle. This length of cable is enclosed in a cover, as shown in Fig. 15, to protect it against wear. The tubular axle is a fairly large diameter - 55 mm., to be exact; but we have not been able to ascertain of what gauge the tube is made. The details of the undercarriage are shown in the perspective sketches of Fig. 15 and in section in Fig. 14.

FUNDAMENTALLY the Pfalz single-seater belongs to the type frequently termed by the Germans a one-and-a-half-plane, that is to say, it is a machine having a larger top plane and a smaller bottom plane. The type was, as is of course well known, originated by the French Nieuport firm, and the first machine of this type, if not actually making its appearance, was at any rate contemplated, before the outbreak of war. Since then, although comparatively recently, the enemy has copied the type fairly extensively, chiefly in the Albatros single-seaters and in the make at present under review. Aerodynamically this arrangement of the planes is of advantage on account of the fact that in a biplane the lower plane is the less efficient, and that therefore the more of the total surface is formed by the top plane the better the overall efficiency. Practically also certain advantages attend the arrangement. The effect of the smaller lower chord is twofold. The gap between the planes need not be so great as in the case of a biplane having both planes of the same chord, and for a given fuselage depth the top plane may therefore be placed at a smaller height above the top of the body, resulting in a better view forward. Again the smaller bottom chord does not obstruct the view downward to the same extent as does a plane of larger chord. Thus the "one-and-a-half-plane" forms a good compromise between the lighter structure of a biplane and the good visibility of the "parasol" monoplane, which latter is probably unsurpassed as a fighter as far as obstructing the view in all directions to the smallest extent is concerned.
In the design of its wing structure the Pfalz shows several interesting features. The outward slope of the struts connecting the body with the top plane was originated, we believe, by Sopwiths in their "one-and-a-half-strutter," while the Vee form inter-plane struts are typically Nieuport. Constructionally, however, the Pfalz is a good deal different in both these features, The Vee struts are not strictly speaking placed in the form of a letter V, as they do not quite meet in a point on the lower plane, which has two spars instead of the single spar employed in the original Nieuport. The object of having two spars is evidently to provide a more rigid structure better capable of resisting the twisting moment due to the travel of the centre of pressure. Owing to the fact that the inter-plane struts do not come to a point, incidence wires should be employed, but in their stead the struts are so built up as to form the bottom of a solid U which lends to the lower ends of the struts the rigidity usually provided by incidence wires. The same applies more or less to the body struts, which, as was shown in the illustrations published in our issue of July 25th, are in the form of an inverted, flattened U with its cross member adjoining the upper plane. Here, again, the construction of the struts has been designed to perform the function of incidence wires. While on the subject of these struts, attention may be drawn to a somewhat unusual arrangement of the transverse bracing cables. Generally these run from port top rail to top of starboard body struts and vice versa. In the Pfalz, however, this arrangement has been discarded and the arrangement indicated in Fig. 16 substituted. The cross wiring does not, it will be seen, run over the top of the body at all. Instead the cables from the upper ends of the struts on one side run to the root of the bottom- plane on the same side. The body struts pivot around their attachment to the body, and any lateral displacement of the top plane would therefore result in a raising of one side or the other with a consequent tightening of the corresponding cables. From a practical point of view this arrangement of the cables would appear to possess considerable merits. The crossing of the cables above the body generally necessitates piercing of the top covering, which in most machines is raised considerably above the top longerons, to which the lower ends of the cables are usually anchored. These wires are therefore as a rule difficult to get at, and from a rigger's point of view at any rate, the Pfalz arrangement appears preferable. Then again wires crossing above the body frequently interfere with the placing of the machine guns, or with the sighting tube and other accessories. Aerodynamically, it is true, the Pfalz arrangement is at some slight disadvantage, inasmuch as the length of cables exposed to the air is greater than in the case of cables crossing above the body. When, however, as in the Pfalz, the struts are designed to do away with incidence wires the total length of cables is probably no greater, and so, on the whole, one is inclined to consider the arrangement worth while.
The general arrangement of the Pfalz wings is shown in Fig. 19. Ailerons, it will be seem, are fitted to the top plane only, as is almost universal practice in Germany. They are hinged to a false spar, and have their crank levers working in slots in the plane, another feature characteristic of enemy machines. This part of the' wing is reinforced extensively by the use of three-ply wood. As shown in the drawing, the petrol service tank is built into the top plane, as is also the radiator, which is provided with a shutter that can, owing to the low placing of the top plane, be operated direct from the pilot's seat, a handle projecting aft from the radiator being provided for this purpose. This central portion of the top plane is also reinforced by a covering of three-ply.
The two wing sections of the Pfalz are shown in Fig. 20. The lower section is not, it will be observed, an exact geometrical reduction of the upper one, the trailing portion of its lower surface being more in the nature of a reversed curvature than is the case with the top section. The difference does not, however, appear to be great. The maximum camber of the sections appears to be smaller than one usually finds on German machines. At the same time the camber is very considerable for a machine intended for fast flying, and it is possible that the wing section is, at any rate partly, responsible for the inferior performance of the Pfalz.
The wing spars of both planes are of the box form, although not, as indicated in the sections of Fig. 20, made up in the usual way of two channel sections joined by a hardwood tongue and grooves. The flanges of the spars are of spruce, and of the section shown in the illustration. Front and rear faces of the spars are formed by plies of wood made up of two thin outer layers of three-ply with a thicker layer of spruce in between them. At points where the spars are pierced by bolts for the attachment of inter-plane struts or internal compression tubes, the space between top and bottom flanges is filled up solid by packing pieces. The attachment of the spar webs to the flanges is by glueing only, no tacks or screws being employed. The spar is afterwards covered for its entire length by fabric, to prevent moisture from attacking the internal glued joints and to reduce the risk of splitting. The fabric is not wrapped around the spar spirally but is laid uo straight, finishing off along one comer of the spar. As in most machines, the spars are not placed with their vertical faces at right angles to the chord line but at right angles to the line of flight.
Reference has already been made to the struts connecting the body with the top plane, and to the fact that these struts are pivoted at their attachment to the body. The exact form which this pivot takes is shown in Fig. 17. A circular base plate is bolted to the body formers where these are crossed by the tipper body rails. The base plate has welded to it a cup or socket into which fits a spherical male portion secured to a sheet steel shoe surrounding the lower end of the body struts. A pin (taper) passing through socket and ball secure the strut in place. The slot through the ball is of elliptical section to allow a certain amount of play for alignment.
Fig. 18 shows how the lower spars are attached to the wing roots formed integrally with the body. The fixed spar inside the body is split to receive the former occurring at this point, and is rounded off at its outer end to a circular section. A steel cap surrounds the end of the spar root, to which it is secured, as far as we have been able to ascertain, by a single pin. This cap is surrounded by a collar incorporating a fork for the attachment of the lift cable, and terminates at its outer end in a steel piece shaped like an eyebolt. The inner end of the wing spar is also surrounded by a sleeve, this, however, being secured by two bolts, the inner of which is an eyebolt that serves as an anchorage for the internal drift wiring. The wing spar sleeve carries at its inner end the female portion of the joint, a fork end, which engages with the eyebolt of the fixed spar, the two being held together by a quick-release pin as shown. In Fig. 18 the ribs have been omitted in the larger drawing for the sake of clearness, but they are indicated in the smaller inset.

THE top plane of the Pfalz is supported from the body by two inverted, flattened U's, as mentioned in our last issue. The attachment of these U's to the body was shown in Fig. 17. The attachment to the top plane is of a similar character, as shown in Fig. 21. The upper corner of the centre-section struts is provided with a sheet steel shoe to which is welded a socket or cup. A bolt passing vertically through the spar terminates in a ball-shaped head, which fits into the cup, and a taper pin passing through ball and socket locks the joint. The inter-plane cables are attached to little anchor pieces shaped as shown in the sketch, terminating inside the larger cup in a wide head shaped to fit the internal curve of the cup. A certain amount of play is therefore allowed. The right hand sketch in Fig. 21 shows, from a different point of view, the corresponding fitting on the rear spar.
The internal compression tubes of the wings are secured to the spar by a very simple fitting, shown inset in Fig. 21. A small steel plate is stamped out to form a shallow projection, the diameter of which corresponds to the internal diameter of the compression tube, which is thus prevented from slipping on the spar. This sheet steel plate is secured to the spars by two horizontal bolts, and its ends are shaped to form the lugs for the attachment of the drift or anti-drift wires, as the case may be. The drift wires of the Pfalz are in reality tie rods of circular section, threaded at their ends to fit directly into the barrel of the turnbuckles. The anti-drift wires are solid wires of about 12 gauge size.
The inter-plane struts of the Pfalz are, as mentioned in our last issue, approximately of Vee form, although they do not quite come to a point at their lower ends. In section they are, needless to say, stream-line, and constructionally they are built up of various laminations, as shown in one of the small insets of Fig. 22. The two outer layers are spruce. Then come, one on each side, two layers of thin three-ply, while the centre of the strut is formed by a piece of spruce. The whole is then covered with fabric. The same construction is employed for the centre-section struts. The angle formed by the vertical and horizontal arms of these struts is elaborately built up of laminations, the grains of which cross one another at various angles. The strength appears good, but the struts are certainly not light, compared with the ordinary hollow or even solid spruce strut.
The attachment of the inter-plane struts to the bottom plane is interesting. As the horizontal arm of the struts is shorter than the distance between the spars of the bottom plane the struts cannot be attached directly to the spars. Instead they are attached, by means of the usual Pfalz ball-and-socket joint, to a compression tube. Owing to the fact that this tube is subject to a lateral load, being loaded both as a strut and as a beam, the usual compression tube attachment already referred to would be inadequate. Instead the arrangement illustrated in Fig. 22 is employed. The compression tube is unlike those employed elsewhere in the planes, inasmuch as it is not of circular section, but is flattened so as to have fiat parallel sides and a top and bottom forming arcs of a circle. At its ends this tube is welded to a base plate of channel section, which partly surrounds the three sides of the wing spar. Before being welded to its end plates the tube is slotted at its ends to accommodate the lugs for the drift and anti-drift wires. These lugs are formed by bending a piece of sheet steel to a channel section, the bottom of the channel being welded to the base plate and the arms welded to the compression tube. The horizontal bolts securing the base plates to the wing spar have their heads filed flat so as to pass between the two drift wire lugs, and are thus at the same time prevented from turning when tightening up the nuts on the other side of the spar. The details of this part of the wing structure will be clear from Fig. 22.
The general arrangement and spacing of the wing ribs of the Pfalz were shown in Fig. 19 of our last issue. Constructionally the ribs are built up in the usual way of three-ply webs and spruce flanges. False ribs occur between the main ribs, running over the top of the spars, from leading edge to rear spar. These false ribs are made of ash. In connection with the main ribs mention may be made of a rather neat little "dodge" for attaching the ribs in place on the spars. As usual the rib flanges are tacked to the top and bottom faces of the spars. In addition the ribs are prevented from sliding along the spars by two vertical pieces of wood, each tacked to the spar. In the middle these vertical pieces are slotted to accommodate a small square block of wood about 1/2 inch square - which is glued to the face of the spar. The end of the rib web is recessed to give room for this block, the effect of which is, it will be seen, to relieve to a certain extent the shearing stress on the rib flanges at the corners of the spar. It is only a small detail we admit, but it is, we think worthy of mention, and has been included in Fig. 22.
The crank lever of the ailerons is shown in Fig. 23. As in all German machines, ailerons axe fitted to the top plane only, and their crank levers are horizontal, working in slots in the plane. The aileron hinges on a false spar. The crank levers are built up of two halves of sheet steel, pressed to form in section one half of an ellipse. The two halves are then welded together along the edges. The control cables are secured to the crank lever by the same ball-and-socket attachment as that employed for the rudder and elevator controls already described. The cables pass from the lever, around pulleys in the bottom wing, and through tubes to the controls. These tubes appear to be made of some sort of paper or cardboard, although whether made by wrapping the paper spirally or rolled up straight to form a tube we have not been able to ascertain.
Reference has already been made to the fact that the radiator of the Pfalz is mounted in the top plane. The cooling may be varied by an adjustable shutter which has a handle projecting back so as to be within the reach of the pilot. The arrangement of this shutter is shown in Fig. 26. The rod carrying the handle has a series of notches cut in it so as to form suitable stops for the shutter in any desired position. The details of the locking device will be evident from an inspection of Fig. 26.
The armament of the Pfalz consists of two synchronized machine guns of the Spandau type. The mounting of these is shown in Fig. 25. Two transverse tubes form the supports for the gun mounting, which appears very light, being made of light gauge steel suitably reinforced by webs in places. The rear attachment of the gun provides for vertical adjustment, while the front attachment enables a slight lateral alignment of the gun after the mounting has been bolted into place on the cross tubes. A peculiarity of the gun placing on this particular Pfalz is that the guns are entirely enclosed under the top covering of the body, with only the muzzle projecting. This is indicated in Fig. 24. On a later specimen of the Pfalz fighter the more usual placing of the guns above the body has been employed, whether because enclosing the guns was found unsatisfactory or not we are not in a position to say. Probably the enclosed guns were found to have a tendency to overheat.
In the Pfalz under review no attempt appears to have been made to camouflage the machine, which is painted with aluminium paint all over its body and wings. The rudder tail plane and elevator are painted a dark yellow.

View attachment 634465G.141
Interesting to see to see reports on captured German aircraft. I'm looking at linen aircraft fabric production during WW1, it covered most if not all Allied planes. Germany used plywood as a cover quite extensively and produced all metal aircraft. My burning question is: was the Irish linen industry a military advantage in that it could supply all the linen needed - the Allies comfortably outbuilt the Germans in terms of numbers of aircraft especially in 1917 and 1918 - was this because the Germans were short of linen, even as just another one of the shortages that must have hampered aircraft production.
Does anyone have any insights?
Hi Dynoman;
Great thread! I came across it while doing a Google search for these British reports about German airplanes. Since they were published by the Ministry of Munitions, I hoped I might be able to find pdf copies online. I live in the U.S. and have been able to find pdf copies of old U.S. reports.

I have a question. Your text in this post of their report on the Pfalz XII is quite long. Do you have a pdf copy of the report or did you scan a hard copy & convert to text or did you type this out yourself?

I have always been interested in fighter aircraft and air combat. Until my recent turn to WW-1 aviation, I had always focused on WW-2 and later aircraft and air combat.

One of the things I have been trying to do is to find as many actual pilot reports as I can about flying WW-1 aircraft, both originals and fully faithful reproductions, meaning they use actual rotary engines for instance.

When I came across the titles for the Ministry of Munitions reports, I got excited thinking about the possibility of gathering more “truth data” about the combatant aircraft’s actual handling qualities and performance. This is in opposition to 100 + years of hearsay, legend, gossip, and misquotes on the topics.

Anyway, please let me know if you have anything relevant to share, whether it’s pdf files or URL’s with info.

I joined this forum to talk with you on this topic. I’ve not really done forums before.

Thank you.

Best regards,
Tree_Lvr
 
Tree-Lvr, I have a number of books and articles regarding WWI aviation, some which reference this Flight article. There were a series of books that compiled these reports and sold independently from Flight Magazine. This particular article was sourced from Flight Magazine in the Fall of 1918. I'll have to take a look when I get home as I am away from my home computer to see the specific issue. Until then, here is a link to archived Flight Magazine information. If you look at the issues of 1918 you will find a treasure trove of engineering data and analyzed German aircraft by the British.

Respectfully,

 
Tree-Lvr, I have a number of books and articles regarding WWI aviation, some which reference this Flight article. There were a series of books that compiled these reports and sold independently from Flight Magazine. This particular article was sourced from Flight Magazine in the Fall of 1918. I'll have to take a look when I get home as I am away from my home computer to see the specific issue. Until then, here is a link to archived Flight Magazine information. If you look at the issues of 1918 you will find a treasure trove of engineering data and analyzed German aircraft by the British.

Respectfully,

Thank you!
 

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