The HG series of Me 262 derivatives was believed capable of reaching transonic Mach numbers in level flight, with the top speed of the HG III being projected as Mach 0.96 at altitude. After the war, the Royal Aircraft Establishment, at that time one of the leading institutions in high-speed research, re-tested the Me 262 to help with British attempts at exceeding Mach 1. The RAE achieved speeds of up to Mach 0.84 and confirmed the results from the Messerschmitt dive-tests. The Soviets ran similar tests.