The Su 6 single seat assault aircraft was designed around the experimental M 71 engine and intended to compete with Ilyushin’s Il 2. The Su 6 offered a considerably higher performance than the Il 2, and carried a more effective armament, but by this time the Ilyushin design was already in production, and as manufacture of the M 71 engine had not begun.

Development started in 1939. Second Su-6-2 (improved) version was built in 1942, and the last one (Su-6-3), powered by liquid-cooled 2000hp AM-42 started flight testing early in 1944.

Engine: 1 x ASh-71F, 1620kW
Max take-off weight: 6500 kg / 14330 lb
Empty weight: 4000 kg / 8819 lb
Wingspan: 13.5 m / 44 ft 3 in
Length: 9.2 m / 30 ft 2 in
Wing area: 26.0 sq.m / 279.86 sq ft
Max. speed: 500 km/h / 311 mph
Ceiling: 8100 m / 26600 ft
Range w/max.fuel: 970 km / 603 miles
Armament: 2 x 37mm machine-guns, 3 machine-guns, 10 missiles, 400kg of bombs
Crew: 2

The development at the TsIAM (Central Aero Engine Institute) by K V Kholshchevnikov of the so-called “accelerator”, or VRDK (Vozdushno-reaktivny dvigatyel kompressorny, or Air-reaction engine compressor), prompted the development of mixed-power single-seat fighters as an interim means of meeting the potential threat of German turbojet-powered fighters. Both Mikoyan-Gurevich and Sukhoi bureaux were assigned the task of creating such fighters, the former developing the MiG-13 alias I-250(N) and the latter the Su-5 alias I-107. The VRDK provided 300kg thrust for up to 10 min at high altitude to boost the power available from the Klimov M-107A (VK-107A) 12-cylinder Vee-type liquid-cooled engine which delivered 1,650hp for take-off. An all-metal stressed-skin single-seat monoplane with a monocoque fuselage, the Su-5 had an armament of one 23mm engine-mounted cannon and two 12.7mm machine guns.

First flown in April 1945, the prototype was soon fitted with a new wing of laminar-flow type developed by the TsAGI, and during one subsequent flight test a speed of 793km/h was attained at 4350m, this being 25km/h faster than had been calculated for that altitude. The effect of the VRDK was a gain of 90km/h at low altitude rising to 110km/h at 7800m, at which it was anticipated that maximum speed would be 810km/h. Early in July 1945, before this speed could be attained, the M-107A engine suffered some damage in flight and when it was found to be irreparable, the Su-5 flight test programme was abandoned.

Engine: Klimov M-107A (VK-107A) V-12, 1,650hp & 1 x VRDK Air-reaction engine compressor
Max take-off weight: 3804 kg / 8386 lb
Empty weight: 2954 kg / 6512 lb
Wingspan: 10.56 m / 35 ft 8 in
Length: 8.51 m / 28 ft 11 in
Height: 3.53 m / 12 ft 7 in
Wing area: 17.00 sq.m / 182.99 sq ft
Max. speed: 810 km/h / 503 mph
Range: 600 km / 373 miles

An experimental version of the Su-2 with an M 90 engine, the Su 4, appeared in 1941, but this did not display a sufficient improvement over its predecessor, and was abandoned in favour of the Su 6 single seat assault aircraft designed around the experimental M 71 engine and intended to compete with Ilyushin’s Il 2.

At the time of the evacuation of the Sukhoi OKB to Novosibirsk, the prototype of a developed version of the Su-1, the Su-3, was under construction. Initiated under the designation I-360, the Su-3 mated the Su-1 fuselage and tail surfaces with an entirely new wing of revised profile with shorter-span outer panels resulting in a 2.00sq.m reduction in wing area. The radiator bath was enlarged, but in all other major respects the Su-3 was similar to the Su-1. Retaining the M-105P engine and the same armament, the Su-3 was completed at Novosibirsk and entered flight test in the late summer of 1942. Although the TsIAM had meanwhile undertaken much development work on the TK-2 turbo-supercharger, the principal defects were found to remain, and, as a consequence, development of the Su-3 was discontinued towards the end of 1942.

Engine: Klimov M-105P V-12, 1,100hp
Max take-off weight: 2860 kg / 6305 lb
Empty weight: 2490 kg / 5490 lb
Wingspan: 10.10 m / 33 ft 2 in
Length: 8.42 m / 28 ft 7 in
Height: 2.71 m / 9 ft 11 in
Wing area: 17.00 sq.m / 182.99 sq ft
Max. speed: 638 km/h / 396 mph
Range: 700 km / 435 miles
Armament: one 20mm cannon and two 7.62mm machine guns

During 1939, Sukhoi established his own design bureau, and began the redesign of the ANT 51 with an M 88B engine, a low wing and an increased offensive load, this emerging as the BB 1, entering series production in 1940, and being redesignated Su 2 in 1941.

The Sukhoi Su-2 entered service with the V-VS early in 1941 but, as far as is known, was not encountered during the Winter War which ended the previous year. Derived from Sukhoi’s ANT-51 and designated BB-1 during its early trials, the aircraft was fairly efficient by current standards once the M-87 engine had been replaced by the M-88 and then the M-88B.

Despite being further improved by installation of the 746kW M-88B radial, the Su-2 was found to be desperately vulnerable and virtually unable to defend itself with its single small-calibre machine-gun in the unwieldy manually-operated dorsal turret. Estimates suggest that about 100 were in service with the Frontovaya Aviatsya at the time that the German army rolled into the Soviet Union in June 1941, but that dozens were shot down by flak and fighters in the first few disastrous weeks.

The Su 2 was built in fairly substantial numbers, both with the IM 88B engine and with the more powerful M 82. The state of the Soviet aircraft industry in 1941 prevented much being done to remedy the immediate lack of suitable ground support aircraft (until production of the two-seat Il-2m3 could be stepped up) and recourse was made to further attempts to improve the Su-2 by installation of the 1134kW M-82 radial and freguent deletion of the dorsal turret, but with little tactical benefit. Accepting that losses would remain high, the Soviets therefore simply loaded the aircraft with further bombs and rockets on the supposition that the more explosive delivered against the enemy the better the chances of some degree of success. This version, as well as the completely redesigned Su-6, were abandoned in favour of all-out dependence on the Il-2m3. The Su-2 probably did not survive in production beyond mid-1942.

Engine: 1 x M-88B, 735kW
Max take-off weight: 4400 kg / 9700 lb
Empty weight: 3000 kg / 6614 lb
Wingspan: 14.3 m / 47 ft 11 in
Length: 10.3 m / 34 ft 10 in
Wing area: 29.0 sq.m / 312.15 sq ft
Max. speed: 460 km/h / 286 mph
Ceiling: 3800 m / 12450 ft
Range w/max.fuel: 1200 km / 746 miles
Armament: 5 x 7.62mm machine-guns
Bombload: 600kg
Crew: 2

Pavel O Sukhoi established his own OKB, or Experimental Design Bureau, in December 1938, and, early in the following year, was assigned the task of designing an advanced single-seat high-altitude fighter. Initially designated I-330, the fighter was of mixed construction, with a single-spar all-metal wing of comparatively high aspect ratio with flush-riveted light alloy skinning, and a wooden semi-monocoque fuselage with shpon, or bakelite-ply, skinning. Power was provided by a Klimov M-105P 12-cylinder liquid-cooled Vee-type engine rated at 1,100hp for take-off and fitted with a pair of TsIAM-developed TK-2 exhaust-driven turbo-superchargers, the radiator being accommodated in the fuselage aft of the cockpit and exhausting over the rear decking. Armament consisted of one 20mm cannon and two 7.62mm machine guns. Factory testing commenced late 1940, by which time the designation Su-1 had been adopted, State testing being performed in the following summer. The turbo-superchargers proved capricious and the Su-1 was flown on several occasions with the TK-2s removed. Although the fighter met its specified performance with the turbo-superchargers functioning, their failure frequency was unacceptable and the TsIAM had failed to improve reliability by October 1941, when the OKB was evacuated from Moscow to Novosibirsk, the Su-1 being damaged in the process. This prototype was not rebuilt, development continuing with the Su-3.

Engine: Klimov M-105P V-12, 1,100hp
Max take-off weight: 2875 kg / 6338 lb
Empty weight: 2495 kg / 5501 lb
Wingspan: 11.50 m / 38 ft 9 in
Length: 8.42 m / 28 ft 7 in
Height: 2.71 m / 9 ft 11 in
Wing area: 19.00 sq.m / 204.51 sq ft
Max. speed: 641 km/h / 398 mph
Range: 720 km / 447 miles
Armament: one 20mm cannon and two 7.62mm machine guns