The Ilyushin I-21, (''Istrebitel''-21, fighter-21), also known as TsKB-32, was a single-engined, single-seat
fighter produced in the
USSR
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nati ...
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.
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
Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an o ...
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
"Guap" is a song by American hip hop recording artist Big Sean, released on October 26, 2012, as the lead single from his second studio album ''Hall of Fame'' (2013). The song was produced by frequent collaborator Key Wane and Young Chop with ad ...
to use this system. Further development was halted in 1939 and the I-21 designation was re-used for the
Pashinin I-21
The Pashinin I-21 (not to be confused with the Ilyushin TsKB-32, also known as "I-21") was an early 1940s Soviet fighter prototype. Designed by Mikhail M. Pashinin, the I-21 was built to incorporate lessons learned from the combat experiences of ...
.
[
]
Variants
''Data from:OKB Ilyushin[
;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)
See also
References
{{Soviet fighter designations
1930s Soviet fighter aircraft
I-021
Abandoned military aircraft projects of the Soviet Union
Single-engined tractor aircraft
Low-wing aircraft
Aircraft first flown in 1936