Some Wikipedia stuff:

On 14 May 1953, after Joseph Stalin's death, the Sukhoi OKB was reopened[2] and by the summer, it began work on a swept-wing front-line[N 1] fighter. The first prototype, designated S-1, was designed to use the new Lyulka AL-7 turbojet engine. It was the first Soviet aircraft to utilize the all-moving tailplane and a translating centerbody, a movable inlet cone in the air intake for managing airflow to the engine at supersonic speeds.[3] The aircraft also had a dramatic wing sweep of 60°, irreversible hydraulically boosted controls, and an ejection seat of OKB's own design.[2]

The S-1 first flew on 7 September 1955 with A. G. Kochetkov at the controls. Fitted with an afterburning version of the AL-7 engine after the first eleven flights, the prototype set a Soviet speed record of 2,170 km/h (1,170 kn, 1,350 mph, Mach 2.04) in April 1956.[3] The prototype was intended to be armed with three 37 mm Nudelman N-37 cannon and 32 spin-stabilized 57 mm (2.25 in) unguided rockets in a ventral tray.[3] The second prototype, S-2, introduced some aerodynamic refinements. Testing was complicated by the unreliable engine, and S-1 was lost in a crash on 23 November 1956, killing its pilot I. N. Sokolov.[2] Only 132 had been produced between 1957 and 1960, and the aircraft entered service as Su-7 in 1959.

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