The IS-1 (Istrebitel Skladnoi or folding fighter) was conceived by Nikitin's Test pilot Vladimir V Shevchenko and designed in collaboration with Vasili V Nikitin. Polymorphic in concept, it could translate from biplane to monoplane configuration and back again in the air. He created the IS-1 by modifying an I-153. He added a retractable lover wing that was pneumatically of hydraulically raised into the upper wing. Control was provided through means of a three-position switch with first raise the landing gear, then raise the wing.

 

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 resulted in the IS-2, only one prototype of the IS-1 being completed.

 

Engine: 1,100hp Shvetsov M-63

Wingspan: 8.60 m / 28 ft 3 in

Length: 6.79 m / 22 ft 3 in

Wing area: 13.0-20.8 sq.m / 139.93 - 223.89 sq ft

Take-off weight: 2300 kg / 5071 lb

Empty weight: 1400 kg / 3086 lb

Max. speed: 453 km/h / 281 mph

Range: 600 km / 373 miles

Armament: 7.62mm ShKAS machine guns