The Yakovlev Yak-1 () was a Soviet fighter aircraft of World War II. The Yak-1 was a single-seat monoplane with a composite structure and wooden wings; production began in early 1940. The Yak-1 was a maneuverable, fast and competitive fighter aircraft. The composite-wooden structure made it easy to maintain and the engine proved to be reliable. It formed the basis for subsequent developments from the Yakovlev bureau. It was the founder of a family of aircraft, with some 43,000 being built. As a reward, designer Alexander Yakovlev was awarded the Order of Lenin (Russian ) (the highest civilian decoration bestowed by the Soviet Union), a 100,000 ruble prize, and a ZIS motor car. Design and development Before the war, Yakovlev was best known for building light sports aircraft. His Yak-4 light bomber impressed the Soviet government enough to order the OKB to design a new fighter with a Klimov M-106 V-12 liquid-cooled engine. Formal specifications, which were released on 29 July 1939, called for two prototypes – I-26-1 with a top speed of at , combat range of , a climb to ) of under 11 minutes, armed with 2 × ShKAS machine guns and 1 × Berezin BS heavy machine gun. I-26-2 had a turbocharged M-106 engine with a top speed of at and armament of 2 × ShKAS machine guns. The design took full advantage of Yakovlev OKB's experience with sports aircraft and promised agility as well as high top speed. Since the M-106 was delayed, the design was changed to incorporate the Klimov M-105P V-12 engine, with a ShVAK cannon in the "vee" of the engine block, in a mount. I-26-I first flew on 13 January 1940 and suffered from oil overheating which was never completely resolved, resulting in 15 emergency landings during early testing. On 27 April 1940, I-26-1 crashed, killing its test pilot Yu.I. Piontkovskiy. The investigation of the crash found that the pilot had performed two consecutive barrel rolls at low altitude, which was in violation of the test flight plan. It was believed that during the first roll, the main landing gear became unlocked, causing it to crash through the wing during the second roll. It has been speculated that Piontkovskiy's deviation from the flight plan was caused by frustration that his aircraft was being used for engine testing while I-26-2, built with the lessons of I-26-1 in mind, was already performing aerobatics.