Nikitin Shevchenko IS-4

Purpose: This was intended to be the ultimate biplane/monoplane fighter.

Design Bureau: OKB-30, chief designer VV Shevchenko

Dismissed by Shavrov in a single line, the IS-3 and IS-4 were the last of Shevchenko’s con­vertible biplane/monoplane projects. No IS-3 documents have been found, but brief details and a three-view drawing exist of the IS-4. Unlike its predecessors, this was a ‘clean sheet ofpaper’ aircraft, an optimised fuselage fitted with shutters to cover the retracted lower wing and landing gear. The latter was of the nosewheel type, the cockpit was en­
closed, and armament was to be the same as the IS-2. The engine selected was Klimov’s M-120, with three six-cylinder cylinder blocks of VK-105 type spaced at 120°, rated at l,800hp. When it was clear that this engine would not be ready Shevchenko reluctantly switched to the equally massive AM-37 Vee – 12, rated at l,380hp. In about 1942 he revised the IS-4 so that it would have been powered by a 2,000hp M-71F radial, and would have been fitted with slats on the upper wing to eliminate tail buffet. No photographs of the IS-4 have been found, though two documents insist that it was built and one even states that it flew.

Little need be added, beyond the report that, despite the considerable increase in weight over the previous IS fighters, the wings were smaller. Even with slats it is difficult to see how the landing speed could have been slower. In the conditions prevailing during the War it is stretching credulity to believe that this aircraft could have been built.

Shevchenko persisted with his biplane/ monoplane idea too long. His last project was the IS-14 of 1947, a jet with monoplane wings which not only were pivoted to vary the sweepback up to 61° but could also (by means unstated) vary the span.