Fagot vs Sabre, Myths and Truth

[Justo Miranda]

Fagot Versus Sabre​

The introduction of the MiG-15 Fagot in North Korea on November 1, 1950 was undoubtedly a bad surprise for the Western world.

The Gloster Meteor Mk.8, Lockheed F-80C and Republic F-84 G jet fighters were outclassed by the MiG-15 superior speed, rate of climb and maneuverability at high altitudes. Performances achieved thanks to the weight reduction program of the I-310 added to the excellent high-altitude behavior of its Rolls-Royce Nene Mk.II engine.

Fortunately for the Western world, the North American F-86 A-5 Sabre was sent to Korea entering combat with the Soviet fighter in December 17, 1950.

The MiG-15 could outclimb the F-86A at any altitude, as it had a smaller size and weight, the Nene had better acceleration than the J35, and the NS-37 cannon had an effective range twice than the 12.7 mm M3 machine gun. But the MiG could not benefit from this because of its“Polikarpov heritage snaking” at speeds exceeding Mach 0.86 that affected weapon precision during combat maneuvers.

The Soviet fighter also tended to stall, resulting in unpredictable loss of control at low speeds.

The F-86 had higher roll and turn rates at all speeds and altitudes and could dive at Mach 1 to break the fight against the MiG, whose rather ineffective airbrakes automatically opened at Mach 0.915 to avoid structural damage.

The almost constant narrow chord wings turned out to have extremely poor lift/drag ratio at low speeds and suffered severe flutter at high speeds.

After the accident of the La-160 prototype, the MiG-15 wings were perfected by the scientists of the TsAGI, thanks to the improvements made to the wind tunnel with German equipment, under the leadership of Professor Siegfried Günther.

The solution was reducing wing loading and increasing wing area by 4.7 sq. m resulting in a 27-degrees swept trailing edge.

The use of a wing-retractable main landing gear would allow the construction of a frontal fighter, suitable for rough-field operations. To achieve this, it was necessary to modify the internal structure of the wing to accommodate the landing gear units.

The modification caused insufficient wing torsional stiffness, skin cracks and structural failures at only 70% of the maximum design load.

At the time, the Soviet engineers lacked a practical method of predicting structural strength of swept wings and tried to solve the problem by increasing the structural weight by 20 kg in each wing.

Poor metallurgical skills and extremely inconsistent manufacturing processes created wings with dangerous structural shortcomings.

The Soviet industry was unable to make both wings absolutely identical, due to variations in skin thickness and riveting on the production line. This asymmetry meant that each wing had different lift/drag ratio.

The MiG-15 had a tendency to drop a wing (valyozhka-spontaneous rolling) at Mach 0.88 and it became uncontrollable at 960 km/h.

But the Soviet fighter was designed to knock down B-29s, not to dogfight.

After the Korean armistice on July 27, 1953, the USAF declared the loss in combat of 103 Sabres of the types A, E and F against 757 MiG-15 Soviet fighters.

The secret of the Sabre technological superiority was the German design of its wings, fitted with leading-edge slats that opened automatically at any speed and altitude according to the needs of combat.

On May 18, 1945, the USAAF ordered two prototypes of the NA-140 jet fighter project, under the designation XP-86. The mock-up with straight wings was approved on June 20, 1945.

The North American officials knew that the NA-140 program would be cancelled by the lack of speed, but there were only two possible solutions: reduce drag or use more powerful turbojets. Using the materials available at the time, it is considered physically impossible to reduce wing thickness without dangerously degrading its structural strength. And the new Allison turbojet would take too long to become available.

On April 29, 1945, a company of U.S. infantry occupied the Messerschmitt research center at Oberammergau and capturing the Messerschmitt P.1101 prototype, an experimental fighter with swept-back wings and tail surfaces, designed to fly at 612 mph (985 km/h).

The P.1101 was powered by one Heinkel-Hirth HeS 011 turbojet rated at 2,649 lb (1,200 kg) static thrust only.

Fortunately for North American the German research data on swept-wing flight was available in July 1945.

On September 14, 1945, wind tunnel tests were performed with a 1/23 rd. NA-140 scale model, with 35-degree swept wings.

These trials were extremely promising and the USAAF approved the modification, entitled RD-1369, on November 1, 1945.

On April 23, 1946, North American proposed a new design that could use two new types of swept wings but retained the fuselage and tail surfaces from the previous version.

The 5AR type had 37-degree swept, 5 aspect ratio and 37.07 ft. (11.3 m) wingspan to provide better stability.

The 6AR type had 39-degree swept, 6 aspect ratio and 40.8 ft. (12.44 m) wingspan to provide better range.

At that time there were doubts about the ideal configuration because the wings of the Messerschmitt P.1101 had been built with a variable swept that could be adjusted, in the ground, between 35 and 45 degrees. The prototype had been captured before performing its first flight, which was planned in June 1945.

The data captured from the Germans were only theoretical estimates.

On October 15, 1946, the NA-140 had 36-degree swept wings, 38-degree swept tail plane, 40-degree swept tailfin and circular air intake.

The wings were fitted with automatic slats in the 90 per cent of the leading edge to provide stability at low speeds.

NA-140 (15 October 1946 project) technical data

Wingspan: 11.34 m (37.2 ft.), length: 11.44 m (37.54 ft.), height: 4.4 m (14.49 ft.), estimated max speed: 1,046 km/h, (650 mph), armament: six 0.50 cal. M3 heavy machine guns, engine: one Chevrolet J 35-C-3 axial flow turbojet rated at 4,000 lbs. (1,812 kg) static thrust.

The prototype XP-86, with 35.2-degree swept wings, was rolled out on August 8, 1947, performing its first flight on October 1, 1947.

The wing thickness/chord ratio was optimized at 11 per cent inboard and 10 per cent at the wing tips, the airbrakes were moved to the rear fuselage sides and the canopy width was enlarged 30 cm (11.7 in) to allow the ejection seat operation.

On April 26, 1948, the XP-86 went supersonic, in a shallow dive, powered by one J 47-GE-3 axial flow turbojet rated at 5,200 lb. (2,356 kg) static thrust.

XP-86 (October 1, 1947) technical data

Wingspan: 11.44 m (37.54 ft.), length: 11.31 m (37.12 ft.), height: 4.5 m (14.79 ft.), wing surface: 25.45 sq. m (283 sq. ft.), max speed: 1,020 km/h, (634 mph), max weight: 7,446 kg (16,437 lbs.), ceiling: 13,260 m (43,500 ft.), armament: six 0.50 cal. M3 heavy machine guns, engine: one Chevrolet J 35-C-3 axial flow turbojet rated at 4,000 lbs (1,812 kg) static thrust.

 

[Justo Miranda]

MiG-15: Soviet propaganda and Western myths.

Despite its failure in Korea, the MiG-15 became very popular in the Western world when was presented by the myth-making Soviet propaganda services as the most advanced fighter in the world, and again the lack of information gave rise to all kinds of legends. Here below are some examples of rumors not confirmed by documentary evidence:


ONE

When the Soviets became aware of the technological superiority of the Sabre the Premier Joseph Stalin gave the order to “snatch” an F-86.

Soviet intelligence agents monitored USAF radio frequencies, interrogated prisoner pilots, and mobilized their spies in the USA to obtain technical information about the American fighter. According to an article published by Weekly Standard on March 28, 2011, the NACA employee William Pearl microfilmed 1,885 pages of F-86 tailplane and slats documents for the spy Martin Sobel.

In April 1951 a special group of test pilots, headed by Lieutenant Colonel Dzyubenko, practiced precision formation flying in MiG-15 with the mission of boxing an F-86 and forcing it to land in North Korea.

Although the “snatch” mission was a failure, the capture of the F-86 A (49-1319) landed in North Korean coast practically unscathed on October 6, 1951, and one F-86E on July 1952, gave the Soviets access to the American secrets of automatic slots, fully movable tailplane, Sperry APG-30 radar gunsight (which in 1957 was installed on the MiG-17F as SRD-1M Scan Fix rangefinder), G-suits and crash helmets.

On December 1951 the TsAGI engineer VV Kondratiev, who was testing the captured F-86 A, managed to get Stalin interested in the idea of reverse engineer the Sabre.

In December 1952 the Moscow Plant No.1 was reoriented to the mass production of IL-28 jet bombers and F-86 airframes, it was decided that the production of wings and tails will be transferred to the Saratov Plant Nº 292 and the pressurized cockpit and final assembly to the Kuibyshev plant, but the project was cancelled by January 1953.



TWO

From time to time, information emerges about the possible existence of a first I-310 prototype that was flown on July 2, 1947.

The rumor originates in the unified general theory of supersonic wings published by Mikhail J. Gurevich in 1947.

The Gurevich account refers to an initial prototype which flew on July 2 and was to be ready for the Tushino show, but it was destroyed in an accident.

Bill Gunston also wrote about this lost prototype in his book “Aircraft of the Soviet Union”, Osprey, 1983.

It was built with dihedral wings fitted with slats as the MiG-8, long jet pipe, T-tail plane and two NS-23 cannon. But there is no evidence for most of these suggestions.

Looks like the description of a jet version of the I-270 rocket fighter fitted with 20-degree (25% chord) swept mid-mounted wings.

Additional information can be found in a monograph on the MiG-15 published by Alain Pelletier in Le Fanatique de l'Aviation issues 169, 170 and 171.

The plane had 10.08 m wingspan, 10.10 m length, 35-degree (25% chord) swept wings and was powered by one Nene turbojet.

During the flight trials the prototype showed severe control problems at low speed and was destroyed at landing due to ailerons malfunction.

According to Pelletier the I-310 S prototype was flown, with the test pilot Weiss at the controls, on June 2, 1947. But it could be a strange confusion with the first flight of the Argentinian Pulqui II, piloted by captain Edmundo Osvaldo Weiss on June 16, 1950.

Ironically the Soviet designers considered that the leading-edge slats of the MiG-8 would complicate the mass production and removed them in the prototype S-01. The result was an airplane with poor flight performance at low speeds and a trend to lose control in dogfight.



THREE

During the Korean War around ten B-29 bombers and two RB-29 reconnaissance airplanes were downed by MiG-15 bis night fighters.

The UN pilots believed in some cases the MiG’s had AI radar (and this leaked to US press at the time) but there was no ELINT backing up such claims.

The Soviets did not use AI radars in the Korea War, all intercepts were done with help of GCI ground radar. The MiG-15 bis day interceptors were guided by the P-20 Periscop (Bar Lock) radar network until they could locate the bombers, with the help of searchlights or moonlight, and they attacked them using the Wilde Sau tactics developed by the Luftwaffe in 1943.

The B-29 bombers could be located by emissions from their H2X cartographic radars and IFF transponders and using the SHORAN navigation system which made their approach routes predictable.

Late in the war, a few MiG’s were fitted with experimental infra-red detectors based in the German IR seeker Zeiss FuG 280 Kiel Z.

In 1950 the prototype MiG-15P bis (SP-1) was flight tested with the experimental radars Toriy, and Toriy-A. All of them were equipped with a parabolic antenna which performed both search and tracking function.

The system proved to be too complicated to be used in combat because the antenna was operated manually for tracking the target.

The MiG-15P bis (SP-5) was a parallel development equipped with Korshun AI radar, it used two antennas for search and automatic tracking.

In 1958 a small series of five aircraft was built with the new RP-1 Izumrud-1 (Scan Odd) AI radar. These aircraft were used to develop new night combat tactics for the MiG-17P (SP-7) all-weather interceptor.

There is no evidence that any of these prototypes were used in Korea.



FOUR

When the USSR revealed the MiG-15, during the May 1949 parade, Western analysts noted that it strongly resembled the German Focke-Wulf Ta 183 A-0 jet fighter project.

Many Western books and magazine articles stressed the similarity of both designs and they assumed that the general aerodynamic layout of the MiG was influenced by German designs.

Perhaps the Soviets had continued to develop the Ta 183 after the war, as they did with the Junkers Ju 248, EF 126, EF 127, EF 131, DFS 346 and the Heinkel He 343/Ilyushin Il-22 projects.

Why not?

The USSR was within its rights to use the technology conquered with the sacrifice of its soldiers.

The importance of the German scientific and technological achievements was well understood both in the USSR and in other countries.

After the war ended, the Allied powers raced to seize aeronautic technology in occupied Germany and the aerodynamic configuration of these German projects, proof-of-concept prototypes, weapons, and operational airplanes were used in the first generation of the Cold War jet fighters.

The nose air intake/tubular fuselage/rear swept wings and tail surfaces configuration of the Messerschmitt P.1101 and Focke-Wulf Ta 183 fighters were used in North American F-86 Sabre, MiG-15 Fagot, MiG-17 Fresco, Lavochkin La-15 Fantail, Dassault MD 450 Ouragan, Dassault MD 452 Mystère, Nord 2200, Tank IAE 33 Pulqui II, Fiat G.91 Gina and Fuji T-1.

The delta wing configuration of Lippisch DM-1 and Messerschmitt P.1112/S2 was used in the Convair XF-92, Convair F-102, Nord 1402 Gerfaut, Sud-Est S.E. 212 Durandal, Dassault Mirage I, Avro 707, Boulton Paul P.111, Boulton Paul P.120, Handley Page H.P.115, Fairey Delta 1, Fairey Delta 2, BAC 221 and Short SC.1.

The maximum speed of the first prototypes XF-92 and YF-102 was limited to 0.98 Mach, due a transonic drag much higher than expected, but the problem was solved in December 1954 using the aerodynamic principle named area rule, patented by Junkers on March 1944.

Swept wings with two trailing-edge fins configuration from Arado E.583 and Junkers EF.128 projects was used in the Chance Vought F7U Cutlass naval fighter.

The “bat wing” of the Messerschmitt Me P.1109-01 and Blohm und Voss P.208 projects was used in 1996 in the prototype Boeing Bird of Prey.

The oblique scissors wing of the Messerschmitt Me P.1109-01 and Blohm und Voss P.202 projects were flight tested in 1979 with the NASA Ames AD-1 research airplane.

The forward-swept wing of the German projects Heinkel He 162 B, Blohm und Voss P.209.02, BMW Strahlbomber II, and Focke-Wulf P. 03028, was flight tested with the Grumman X-29 research plane in 1984.

The butterfly tailplane of the Heinkel P.1079A and Messerschmitt P.1110 projects were used in 1951 in the Supermarine Type 508 prototype and in the Fouga CM.170 Magister jet trainer in 1952.
The Versuchsflugel II crescent wing of the Arado Ar 234 V16 project was used in the Handley Page H.P.88 research plane in 1951 and in the Handley Page Victor strategic bomber in 1952.

The tailless configuration of the Messerschmitt Me 163 Komet was flight tested in the research planes de Havilland D.H.108 in 1946, Northrop X-4 in 1948, Payen Katy in 1954 and in the Douglas F4D Skyray naval fighter in 1951.

The double-delta configuration of the Henschel P.130 project was used by SAAB in their J35 Draken jet interceptor in 1955.

The jet/rocket mixed propulsion system of the Messerschmitt prototype Me 262 V074 and the Focke-Wulf Projekt VI Flitzer were used in the French interceptor Dassault Mirage IIIC in 1961 and in the British research airplane Saunders-Roe S.R. 177 in 1947.

The variable-geometry wing of the Messerschmitt P.1102-05 was used in the Bell X-5 and Mirage G prototypes, in the Grumman F-14 Tomcat naval fighter, in the MiG-23 fighter-bomber and in the Panavia Tornado bomber.

The radar rotating antenna of the airborne early warning airplanes Grumman E-2 Hawkeye and the AWACS Boeing E-3 Sentry, was developed in 1944 for the Arado Ar 234 C-3, to track a bomber stream up to distances of 45 km, using a FuG 244 Bremen 0 radar set with a rotating disc above the fuselage.

The heat-seeking missile AIM-9 Sidewinder and the Soviet copy R-13/AA-2 Atoll were based on the infrared homing devices and infrared proximity fuses developed by AEG and Kepka for the German missiles Messerschmitt Enzian, Henschel Hs 117 Schmetterling, EMW Wasserfall and Ruhrstahl-Kramer X-7 Rotkäppchen.
The annular wing developed by von Zborowski for the Heinkel Wespe VTOL project, was flight tested in 1958 with the French prototype SNECMA Coléoptère.

The French DEFA and British ADEN 30 mm cannon were developed from the German Mauser MG 213C.

The USAAF 0.60-caliber heavy machine gun was a straight copy of the German Mauser MG151.

The Mighty Mouse air-to-air unguided rockets fired by the all-weather interceptors Lockheed F-94 Starfire, Northrop F-89 Scorpion and North American F-86 D Sabre Dog during the Cold War, were developed from the Rheinmetall R4M Orkan 55 mm rocket, and their automatic firing radar system probably was a development of the German FuG 222 Pauke S fire control radar with Oberon-Elfe predictor system.

The ramjet propulsion of the German projects Lippisch P.13a, Skoda-Kauba SK P.12, Heinkel P.1080, Focke-Wulf Ta 283 and Messerschmitt P.1101L was flight tested by the North American F-51D c/n 44-63528 in 1946, the Lockheed F-80 Trijet in 1948, and the French prototypes Leduc 021 and Sud-Ouest SO 9000 Trident in 1953.

The turboprop configuration of the Focke-Wulf P.0310226-17 project was flight tested in 1953 with the McDonnell XF-88B prototype, and by the Republic XF-84 H Thunderscreech research plane in 1955.

The canard fore planes of the Blohm und Voss P.217 and Messerschmitt P.1110 (Feb 12, 1945) projects were used by the Dassault Mirage Milan in 1969.

Several versions of the Fieseler Fi 103 (V-1) cruise missile were manufactured in USA, as Republic-Ford JB-2 Loon, in France as ARSAERO CT-10 and in the USSR as the Izdeliye 10.

The EMW V-2 ballistic missile was manufactured in the USSR as the R-1 in 1948, in USA as RTV-G-4 Bumper and developed as the PGM Redstone rocket of the NASA Mercury project in 1958.

The Rheinmetall-Borsig Rheintochter surface-to-air missile concept inspired the Soviet SA-2 (1958) and the US Nike Ajax (1954).

The Doblhoff WNF 342 jet propelled rotor concept was used in the Hiller YH-32 Hornet helicopter in 1950, in the XH-26 Jet Jeep helicopter in 1952, in the Fairey Rotodyne compound gyroplane in 1957 and in the Fairey Gyrodyne prototype in 1957.

The SNECMA Atar 101 French turbojet was developed from the BMW 003 axial-flow turbojet.

However, the MiG-15 seems to be a special case. Over the past 72 years respected authors have published numerous works denying the Focke-Wulf heritage of the Soviet fighter and detailing the differences between the two designs.

They are certainly right about the Ta 183 A-0 Huckebein, which is the version best known for having won the Jägernottprogramm contest.

But the information captured in Berlin about the latest projects of the Bad Eilsen design team comprised eleven variants of the Ta 183 and nine scaled-up and scaled-down associated designs that shared the original basic aerodynamic layout.

These projects differed in the position of the wings (shoulder, mid and low) and tail planes (T, mid and low), had different wings with swept angles between 33 and 43 degrees, tail planes between 35 and 49 degrees swept, and tailfins between 41 and 67 degrees swept, at the leading edge in all cases. Most were equipped with fuselage retractable landing gear, but some retracted on the wings, such as the MiG-15.

The Soviet designers were able to adopt ideas from all of them by concentrating them in a single project.

The fuselage of the MiG-15 (built with Podberezhye semi-monocoque Duralumin structure) and the pressurized cockpit were both based on those of the Junkers Ju 248 V2 captured at Kassel and the ejector seat was based on that of the Heinkel He 162 A-2 captured in Vienna.

The wings were a modification of those of the Lavochkin La-160, which were in turn based on those of the Focke-Wulf designs captured in Berlin by the People's Commisariat of the Aviation Industry, and joined the fuselage in the same position as those of the Junkers Ju 248 V2.

The wing retractable undercarriage and the 45-degree swept tailplane were very similar to those of project Focke-Wulf P.011.025 (November 1944).

The engine was a British design.

But, according to the Soviet designers, the MiG-15 was an indigenous design.

This is true in the sense that they had been able to integrate different German and British technologies into a design adapted to the Soviet manufacturing standards and that no German TsAGI technicians had been involved in this process.

Ironically, the MiG OKB designers used Focke-Wulf T-tail planes on the MiG I-270 rocket fighter prototype and in the MiG-19 prototype SM-2/1, without success.

On July 15, 1944, the Luftwaffe Technisches Amt (Technical Office) requested through Proposal 222/I the design of an air superiority fighter, powered by a Heinkel HeS 011 A-0 turbojet, as part of the Jägernottprogramm (emergency fighter program) contest.

The new aircraft should reach a maximum speed of 1,000 km/h at 7,000 m, with a service ceiling of 14,000 m, an armament of two MK 108/30 heavy cannons with 60 rounds per gun and a fuel capacity of 1,000 liters. A high proportion of sparstoffe (non-strategic materials), such as steel, wood, and plastics, would be used for its construction.

The OKL ordered that large-scale production should start in February 1945 and reached a monthly production rate of 5,000 fighters in June. Initially the projects presented were the Blohm und Voss P.213.03, Heinkel P.1078 C, Junkers EF.128, Messerschmitt P.1101, P.1110/I and P.1111, as well as the Focke-Wulf Ta 183 A, Ta 183 B and Flitzer III.

In October 1944 only two contestants remained: the Focke-Wulf Ta 183 A and the Messerschmitt P.1101, a pod-and-boom design theoretically capable of reaching transonic speed during combat diving without losing maneuverability. But the wind tunnel tests performed by the AVA-Göttingen institute during the autumn of 1944, with P.1101 scale models, revealed that the maximum speed would still be below their expectations.

The reason was the turbulence generated in the joint of the rear fuselage and the engine nacelle, that had an '8' shaped section. It was discovered that the airframe generated a triple shock wave at transonic speed. The first one was formed around the cockpit hood, the second over the wing and the third one over the tailplane. The shock waves overlapped among each other with a braking effect like that of an arrow going through three disks of felt launched in the air.

The Messerschmitt designers tried to solve the problem replacing the cockpit hood with another of low drag, type Rennkabine, originally designed for a high-speed version of the Me 262. Wind tunnel tests performed with 'V' and 'T' shaped tail planes revealed that such modifications did not substantially improve aerodynamic performance and the P.1101 was cancelled at the end of 1944.