test pilot Mikhail M. Komarov averaged over a closed circuit on 5 October 1967. On the same day, Fedotov reached an altitude of with a payload. The MiG eventually became the first aircraft to go higher than . Time to height records were recorded on 4 June 1973 when Boris A. Orlov climbed to in 2 min 49.8 s. The same day, Pyotr M. Ostapenko reached in 3 min 12.6 s and in 4 min 3.86 s. On 25 July 1973, Fedotov reached with payload and with no load (an absolute world record). In the thin air, the engines flamed out, and the aircraft coasted in a ballistic trajectory by inertia alone. At the apex the speed had dropped to . On 31 August 1977, Ye-266M again flown by Fedotov, set the recognized absolute altitude record for a jet aircraft under its own power. He reached at Podmoskovnoye, USSR in zoom climb (the absolute altitude record is different from the record for sustained altitude in horizontal flight). The aircraft was actually a MiG-25RB re-engined with the powerful R15BF2-300. It had earlier been part of the program to improve the aircraft's top speed that resulted in the MiG-25M prototype. In all, 29 records were claimed, of which seven were all-time world records for time to height, altitudes of and higher, and speed. Several records still stand. Technical description Because of the thermal stresses incurred in flight above Mach 2, the Mikoyan-Gurevich OKB had difficulties choosing what materials to use for the aircraft. They had to use E-2 heat-resistant Plexiglas for the canopy and high-strength stainless steel for the wings and fuselage. Using titanium rather than steel would have been ideal, but it was expensive and difficult to work with. The problem of cracks in welded titanium structures with thin walls could not be solved, so the heavier nickel steel was used instead. It cost far less than titanium and allowed for welding, along with heat-resistant seals. The MiG-25 was constructed from 80% nickel-steel alloy, 11% aluminium, and 9% titanium. The steel components were formed by a combination of spot welding, automatic machine welding, and hand arc welding methods. Initially, the interceptor version was equipped with the TL-25 Smerch-A (also referred to as Product 720) radar, a development of the system carried by the earlier Tu-128. While powerful and thus long-ranged and resistant to jamming, the system—due to the age of its