How fast did the 1955 Ye-50 fly?

Short answer

The Ye-50 did not fly in 1955: the first of its three prototypes, the Ye-50/1, took off on January 9, 1956. On June 17, 1957, the second prototype, the Ye-50/2, reached Mach 2.33 and an altitude of 25,600 m. It combined a Tumansky AM-9Ye turbojet with a Dushkin S-155 bi-propellant rocket engine.

Published: November 1, 2026 · Updated: November 1, 2026 · Edited by Above Ten Thousand · Editorial policy

Pair of Soviet MiG-21s in flight, view from below

The Ye prototypes in the mid-1950s

Mikoyan's OKB had closed in 1954 the preliminary design study of a prototype designated Ye-1, the origin of what would become the MiG-21. That project was quickly reworked, after it was determined that the intended engine was underpowered, which led to the second prototype, the Ye-2. These and other early prototypes had swept wings. The first with the delta wing of the production variants was the Ye-4, which flew on June 16, 1955.

Turbojet and rocket engine

The Ye-50 was designed around a Tumansky AM-9Ye (RD-9Ye) turbojet with 3,800 kgf of afterburning thrust and a Dushkin S-155 bi-propellant rocket engine of 1,300 kgf. The first of the three prototypes, the Ye-50/1, flew on January 9, 1956. Its rocket-engine trials began on June 8, 1956. On June 17, 1957, the second prototype, the Ye-50/2, reached Mach 2.33 and an altitude of 25,600 m. The third, the Ye-50/3, received a lengthened fuselage nose and more internal fuel, and was lost during flight testing when its vertical fin broke away.

The batch that was never built

The Gorky factory was ordered to build a batch of 20 aircraft designated Ye-50A, with the AM-11 engine and the S-155 rocket, intended for operational evaluation. None were built: rocket engines were lacking, as the Dushkin OKB had meanwhile closed down.