Fokker Dr. I Dreidecker Genesis - Draft by Inspektion der Fliegertruppen?

[HoHun]

Fokker Dr. I Genesis/Brief Summary of Leon Bennett's Perspective

Hi everyone,

I recently read "Three Wings for the Red Baron" by Leon Bennett. Quite a fascinating and surprising book, but I'm not sure how much of it is speculation and how much can is based on a solid foundation of verifiable sources.

Basically, the author claims that von Richthofen personally tried to pull strings to get a triplane into service, mostly because he felt that the Albatros fighters he was flying were not up the Sopwith triplane in terms of climb and turn performance, and also hampered by a weak lower wing that limited its diving speed.

The triplane at the time was a more or less well-understood concept, with contemporary studies showing that the layout offered only minor aerodynamic advantages confined to a narrow part of the envelope - near maximum lift coefficient, to be precise -, while suffering from a disadvantage in the form of higher drag than biplane or monoplane configurations throughout the rest of the envelope.

However, due to von Richthofen pulling the strings, two engineers of the Inspektion der Fliegertruppen took up studying the triplane - one aerodynamics specialist, one structures specialist. Basically, they agreed with conventional wisdom on triplanes, but still set out to sketch a triplane that would make the most of the configuration, based upon the secondary advantage of a triplane configuration to allow good strength at very low structural weight (due to the small moment arms of the short-span wings, and due to the opportunity to build the wing arrangement as an threedimensional spaceframe of spars, struts and bracing wires).

In the end, the aerodynamics specialist designed (or selected) a thick wing section particularly suited for the triplane configuration, and the structures specialist drew up a triplane with a large middle wing and small top and bottom wings, well-braced with a multitude of struts and wires. The expectation was that the fighter could not hope to compete in terms of top speed, but due to its low weight would exhibit excellent climb rates even on a relatively low-powered rotary engine, and great turn rates as well.

The Inspektion der Fliegertruppen turned over their draft to Anthony Fokker, who then proceeded to go for a completely different design, neither keeping the basic wing arrangement, the heavy wire bracing, nor the specialized airfoil. No reason for this is provided by Bennett (and Fokker's decisions generally don't seem to be well-documented elsewhere, either).

Anything you could add to this would be appreciated!

Regards,

Henning (HoHun)

 

[Jemiba]

As I understand, the Fokker Dr.I, as the first and in the event only Triplane was largely the result of Richthofen's
personal influence ? Interesting theory and to my opinion not implausible, as the German fighter aces are said
to have had a considerable influence on new designs.
But then, the so-called German "Triplane Craze" probably had another impetus, too, as nearly every German
manufacturer tried to get in the Triplane business in 1917. Fokker just seems to have been the one, getting the most advantages out of the concept, and minimising the disadvantages, as good, as possible.
Must admit, that my main source about this theme still is Jack Herris' "The German Triplane Craze", while Leon Bennett may will open another point of view.

 

[HoHun]

Hi Jemiba,

Must admit, that my main source about this theme still is Jack Herris' "The German Triplane Craze"

That's mostly a type-listing/illustration book, I guess? I have Herris' "German Seaplanes" from the same series, and it's completely focused on period photographs, with very little text and hardly any background information of the type I'm looking for.

If "The German Triplane Craze" is of the same descriptive nature, I think I have the content covered through a couple of other books and magazines that show the various unsuccessful triplane types that followed the Fokker Dr. I. (Trying to make up my mind on whether to buy Herris' book

Regards,

Henning (HoHun)

 

[Arjen]

I have been leafing through Fokker: The Creative Years by A.R. Weyl, Putnam 1965, and Fokker Aircraft of World One by Paul Leaman, Crowood 2001. Both write Anthony Fokker was invited by von Richthofen to view the Sopwith Triplane in action from a forward observation post, and was later allowed to examine a captured example. On his return to Schwerin, Fokker instructed his chief designer Reinhold Platz to finish the V.4 prototype as a triplane - overriding Platz's objections to the triplane configuration. The subsequent V.5 prototype was designed, then built as a triplane from the start. From what I've read so far, Fokker started without any quantitative data of the Sopwith Triplane, he had not made any notes while inspecting the captured example. He also started work on what became the Dr.1 before Idflieg issued a requirement for triplane prototypes to German manufacturers, therefore the start of Dr.1 work probably predates the specialists' research.

I will try to find more about this matter in my books.

 

[Arjen]

Air Enthusiast #8 of October 1978 has an article about the Dr.1 by Peter M Grosz and A E Ferko. They write systematic research into the aerodynamic and mathematical secrets of the triplane was begun in the Göttingen wind tunnel in late 1915, with the test results officially distributed to German industry in March 1917. Weyl writes Fokker 'hurried' to Schwerin in late April, after his visit to the front, immediately telling Platz to start on a triplane: "I have seen a good enemy triplane at the front. We must build one too". Weyl goes on to write that Platz was quite certain 'he had no information whatever about the Sopwith triplane'; and at Fokker's insistence, an interplane strut was added to the Dr.1, over Platz's protestations the strut wasn't needed. Beyond that, Fokker's involvement with the design was probably limited to points relating to the handling and armament - the Dr.1 was very much Reinhold Platz's design.

The AE-article states Pfalz and Siemens-Schuckert were the recipients of the first IdFlieg orders for three experimental prototype triplane fighters each. Leaman concurs, while adding Fokker was probably excluded by IdFlieg because of shoddy construction of previous aircraft. Leaman writes the original IdFlieg orders were placed on July 4 1917, but on July 14, IdFlieg relented and placed an order for twenty V.5 aircraft.

German Aircraft of the First World War by Peter Gray and Owen Thetford, Putnam 1962, states that no more than ten Pfalz Dr.1 aircraft were built, official type test in October 1917; the single Siemens-Schuckert Dr.1 crashed on its maiden flight in November 1917. Thetford and Gray write the Fokker Dr.1 entered service in August 1917. Of the Fokker Dr.1, 320 aircraft were built. A limited production run: Weyl and Leaman write about extensive evidence of bad workmanship.

Von Richthofen did push for a German answer to the Sopwith Triplane, but the AE-article states he angrily wrote as late as July 18 1917 he had heard nothing about new Fokker fighters for the German air force. Two days later, he wrote: "You will receive new Fokker triplanes. They climb like apes and are as agile as the devil" - though it is doubtful he had either flown or even inspected one at that time.

 

[Dagger]

Mainly from: 'The Fokker Triplane' by Alex Imrie, 1992:

Anthony Fokker regularly visited the front line to talk to pilots and in late April 1917 he was at Jasta 11, commanded by Manfred von Richthofen. There he saw the Sopwith Triplane, probably before any other aircraft manufacturer saw it, even before it was sent to Adlershof for appraisal.

After returning to Schwerin the design of the V.4, which originally was to be a biplane, was quickly revised into a triplane.
Like the V.1, V.2 and V.3 experimental biplanes the V.4 triplane had cantilever wings without struts.
The V.4 first flew around 25 June.
Also Anthony Fokker himself flew the V.4 and as a result changes were made, such as balanced ailerons and elevators and struts between the wings to avoid flutter.

Several service pilots, including Leutnant Werner Vogt, flew the V.4 at Schwerin.
Vogt was impressed and informed Manfred von Richthofen.

Fokker also started work on an improved triplane named V.5.

Although the Fokker triplane was already flying, Idflieg on 9 July only placed orders for design and construction with Siemens and Pfalz for three triplanes each.

Finally on 14 July Idflieg placed an order for twenty V.5's at Fokker.

Von Richthofen sustained a severe head wound in air combat on 6 July and was in hospital on 18 July when he wrote his famous letter about (among other things) the Fokker triplane. He did not know that 4 days earlier Fokker did get a contract to build 20 triplanes.

 

[Arjen]

Fokker Dr. I Genesis/Brief Summary of Leon Bennett's Perspectivee
In the end, the aerodynamics specialist designed (or selected) a thick wing section particularly suited for the triplane configuration, and the structures specialist drew up a triplane with a large middle wing and small top and bottom wings, well-braced with a multitude of struts and wires.

Pfalz and Siemens-Schuckert also appear to have largely ignored the specialists' design. Images from wiki, the Siemens-Schuckert is notable for being a push-pull design.
[edit] Siemens-Schuckert seems to have produced TWO triplanes, the DDr.1 (pictured, twin engined) and the single-engine Dr.1. In The Complete Book of Fighters by William Green and Gordon Swanborough, Salamander 1994, Siemens-Schuckert is said to have produced one prototype of both. Both aircraft crashed, the Dr.1 was reconstructed with increased wing area, then flown again. DDr.1 first flew in November 1917. Dr.1 first flew in July 1917.
[edit2] Die deutsche Luftfahrt 9 - Typenhandbuch der deutschen Luftfahrttechnik by Bruno Lange, Bernard & Graefe 1986, describes the Siemens-Schuckert Dr.1 as a rebuilt D.I, image from wiki.
Die deutsche Luftfahrt 4 - Entwicklung der deutschen Jagdflugzeuge by Rüdiger Kosin, Bernard & Graefe 1990, has this to say about triplanes:

Wo die treibende Kraft für die Dreideckeranstrengung gesteckt hat, ist schwer zu erkennen. In einer längeren Abhandlung über »Dreidecker gegen Zweidecker« in den Technischen Berichten der Flugzeugmeisterei Berlin-Adlershof aus dem Jahr 1917 steht als Schlußwort:

»Nach den Aussagen von Rittmeister Freiherr von Richthofen ist der englische Beutedreidecker von Sopwith das beste Flugzeug unserer Gegner. Er steigt besser, ist wendiger, verliert in der Kurve nicht so sehr an Höhe, ist schneller und läßt sich schneller stürzen.«

Ob dieses Urteil soviel Gewicht hatte? Allein, im Flieger-sonderbericht Nr. 8 der IdFlieg vom 23. Oktober 1917 folgt schon die Mitteilung:

»Bester feindlicher Einsitzer ist die SE 5. Sopwith-Dreidecker scheint sich nicht bewährt zu haben,öfters wurde an der Front beobachtet, wie er bei starken Beanspruchungen auseinanderbrach.«

Die Überlegenheit, von der Richthofen spricht, scheint mit Unterdimensionierung erkauft und keine Dreidecker-Überlegenheit zu sein.
In einem Bericht vom 29. August 1917 aus der IdFlieg:

»Siemens ist der Ansicht, daß mit guten Doppeldeckern in jeder Beziehung bessere Leistungen erzielt werden können, als mit Dreideckern.«

Trotzdem experimentiert die Firma damit genau wie zehn andere, nämlich AEG, Albatros, Aviatik, DFW, Euler, Fokker, Friedrichshafen, LFG Roland, Pfalz, Schütte Lanz, Siemens Schuckert.

It is difficult to see where the driving force behind the triplane effort lay. In a lengthy treatise on "triplane versus biplane" in the technical reports of the Berlin-Adlershof aircraft maintenance department from 1917, the closing words are:

»According to the statements of Rittmeister Freiherr von Richthofen, the English captured triplane from Sopwith is the best aircraft of our opponents. It climbs better, is more maneuverable, doesn't lose altitude as much in turns, is faster and dives faster."

Did this judgment carry so much weight? In the special pilot report No. 8 of the IdFlieg of October 23, 1917, the message follows:

"The best enemy single-seater is the SE 5. The Sopwith triplane does not seem to have proven itself, it was often observed at the front breaking apart under heavy loads."

The superiority that Richthofen speaks of seems to be achieved with underdimensioning and not to be a triplane superiority.
In a report from August 29, 1917 from the IdFlieg:

"Siemens believes that good biplanes can outperform triplanes in every respect."

Nevertheless, the company experiments with it just like ten others, namely AEG, Albatros, Aviatik, DFW, Euler, Fokker, Friedrichshafen, LFG Roland, Pfalz, Schütte Lanz, Siemens Schuckert.

 

[HoHun]

Hi Arjen,

Wo die treibende Kraft für die Dreideckeranstrengung gesteckt hat, ist schwer zu erkennen. In einer längeren Abhandlung über »Dreidecker gegen Zweidecker« in den Technischen Berichten der Flugzeugmeisterei Berlin-Adlershof aus dem Jahr 1917 steht als Schlußwort:

»Nach den Aussagen von Rittmeister Freiherr von Richthofen ist der englische Beutedreidecker von Sopwith das beste Flugzeug unserer Gegner. Er steigt besser, ist wendiger, verliert in der Kurve nicht so sehr an Höhe, ist schneller und läßt sich schneller stürzen.«

Thanks a lot! You translated Flugzeugmeisterei as "technical maintenance" ... is that accurate? When they weren't involved in the specification and purchase of new aircraft, I wondern what their professional interest in the tactical poperties of enemy aircraft might have been. (As you can probably tell, I'm not much of a WW1 expert!

I wonder if the "lengthy treatise" Kosin mentioned has been reproduced somewhere ... should be highly interesting, I'd expect!

Regards,

Henning (HoHun)

 

[Arjen]

I must confess I offered the German text to Google Translate, then corrected the most obvious glitches. I will happily accept a better translation for Flugzeugmeisterei.
Some of our native German speakers/WW1 experts might help here. I included the original German text, because things will always be lost in translation.

The organisation later known as Flugzeugmeisterei was known in an earlier form as Prüfanstalt und Werft (P. u. W.) der Fliegertruppe, which is a longer, more descriptive name, even if the organisation's purpose may have changed with the name change. I hope that helps.

 

[HoHun]

Hi Arjen,

I must confess I offered the German text to Google Translate, then corrected the most obvious glitches. I will happily accept a better translation for Flugzeugmeisterei.

Thanks a lot for the extra details! "Meisterei" really is a virtually extinct term in modern German, the only context it's ever used is as a name for road construction/maintenance depots, so I guess one would have to look at the organisational definitions of the Fliegertruppe to resolve this. I'll keep my eyes peeled!

Regards,

Henning (HoHun)

 

[HoHun]

Hi Arjen,

Die deutsche Luftfahrt 4 - Entwicklung der deutschen Jagdflugzeuge by Rüdiger Kosin, Bernard & Graefe 1990, has this to say about triplanes:

It is difficult to see where the driving force behind the triplane effort lay. In a lengthy treatise on "triplane versus biplane" in the technical reports of the Berlin-Adlershof aircraft maintenance department from 1917, the closing words are:

»According to the statements of Rittmeister Freiherr von Richthofen, the English captured triplane from Sopwith is the best aircraft of our opponents. It climbs better, is more maneuverable, doesn't lose altitude as much in turns, is faster and dives faster."

To nail down the source a bit more accurately, according to the "Bibleography of Aeronautics" at ...

Bibliography of aeronautics : Brockett, Paul, 1872-1946 : Free Download, Borrow, and Streaming : Internet Archive

Compiler: Paul Brockett

archive.org

... , it is:

Gries, Aloys van. Dreidecker gegen Zweidecker.

Techn. Berichte, Bd. 1, Nr. 6 (15. Okt. 1917), Charlottenburg, pp. 282-297, diagr.

Regards,

Henning (HoHun)