Nikitin-Shevchenko IS-1

Perhaps the most innovatory single-seat fighter to undergo flight testing in the late 'thirties was the IS-1. Polymorphic in concept in that it could translate from biplane to monoplane configuration and back again in the air, the IS-1 (Istrebitel Skladnoi or folding fighter) was conceived by Vladimir V Shevchenko and designed in collaboration with Vasili V Nikitin. The IS-1 was intended to take-off as an unequal-span biplane, subsequently retracting its main wheels pneumatically into the lower wing and then folding this wing (again pneumatically), the centre section into recesses in the fuselage sides and the outer panels into shallow depressions in the upper wing. Theoretically, the lower wing could be extended during combat to increase manoeuvrability. The IS-1 was powered by a 1,100hp Shvetsov M-63 nine-cylinder radial and carried an armament of four 7.62mm ShKAS machine guns. Construction was all metal and the prototype was flown for the first time on 6 November 1940, the lower wing being successfully retracted and extended within 7-10 seconds during subsequent trials. Refinement of the basic design for series production had meanwhile re- suited in the IS-2, only one prototype of the IS-1 being completed.