I-21
Role Fighter
National origin USSR
Manufacturer Ilyushin
First flight late 1936
Number built 2

The Ilyushin I-21, (Istrebitel-21, fighter-21), also known as TsKB-32, was a single-engined, single-seat fighter produced in the USSR in 1936-7 in response to a government specification.

Design and development

The I-21 was an all-metal, low-wing, cantilever monoplane with retractable undercarriage and a closed cockpit. The wings were sharply tapered with straight trailing edges, which introduced sweepback on the leading edge. Two specially modified Mikulin AM-34RNF (also written AM-34FRN) liquid-cooled V-12 engines provided the power via a non-reducing gearbox, which was used only to raise the thrust line, and enable the use of shorter undercarriage legs.[1][2]

Cooling for the first prototype's engine used an evaporative system which dispensed with radiators and used condensers built into the surface of the wing centre section. The second prototype was fitted with a conventional cooling system using ethylene glycol coolant and a retractable radiator. Flight trials started but soon showed that the evaporative cooling system was inadequate with both the engine and the wing centre section overheating. Ilyushin was also very aware of the vulnerability of the system to combat damage, but he was ordered by GUAP to use this system. Further development was halted in 1939 and the I-21 designation was re-used for the Pashinin I-21.[1][2]

Variants

Data from:'OKB Ilyushin[1]

TsKB 32
(I-21 1st prototype) with evaporative cooling
TsKB 52
(I-21 2nd prototype) with conventional ethylene glycol cooling system, not completed due to engine delivery problems.

Specifications (I-21)

Data from OKB Ilyushin[1]

General characteristics

Performance

460 km (250 nmi; 290 mi) at 480 km/h (300 mph; 260 kn)

Armament

See also

Aircraft of comparable role, configuration, and era

References

  1. ^ a b c d Gordon, Yefim. (2004). OKB Ilyushin. London: Ian Allan. pp. 13–14.
  2. ^ a b Gunston, Bill (1995). The Osprey Encyclopedia of Russian Aircraft 1875–1995. London: Osprey. ISBN 1-85532-405-9.