Variable geometry would improve maneuverability at subsonic speed, but at the cost of decreased fuel tank capacity. Because the reconnaissance aircraft would operate at high speed and high altitude, the idea was soon dropped. Another interesting but impractical idea was to improve the field performance using two RD36-35 lift-jets. Vertical takeoff and landing would allow for use of damaged runways during wartime and was studied on both sides of the Iron Curtain. The perennial problem with engines dedicated to vertical lift is they become mere dead weight in horizontal flight and also occupy space in the airframe needed for fuel. The MiG interceptor would need all the fuel it could get, so the idea was abandoned. The first prototype was a reconnaissance variant, designated Ye-155-R1, that made its first flight on 6 March 1964. It had some characteristics that were unique to that prototype, and some of these were visually very evident: the wings had fixed wingtip tanks with a capacity, to which small winglets were attached for stability purposes, but when it was found that fuel sloshing around in the tanks caused vibrations, they were eliminated. The aircraft also had attachments for movable foreplanes, canards, to help with pitch control at high speed (provisions for canards had previously been installed, but not used, on the Ye-152P). The first flight of the interceptor prototype, Ye-155-P1, took place on 9 September 1964. Development of the MiG-25, which represented a major step forward in Soviet aerodynamics, engineering and metallurgy, took several more years to complete. On 9 July 1967, the new aircraft was first shown to the public at the Domodedovo air show, with four prototypes (three fighters and a reconnaissance aircraft) making a flypast. Aviation records The Mikoyan-Gurevich design bureau soon realized that the performance of the new aircraft gave it great potential to set new flight records. In addition to their normal duties, the prototypes Ye-155-P1, Ye-155-R1, Ye-155-R3 were made lighter by removing some unneeded equipment and were used for these attempts. Under Federation Aeronautique Internationale (FAI) classification, the Ye-155 type belonged to class C1 (III), which specifies jet-powered land planes with unlimited maximum take-off weight. Records set included: The first claim was for world speed records with no payload and payloads of . MiG OKB Chief Test Pilot Aleksandr Vasilyevich Fedotov reached an average speed of over a circuit on 16 March 1965. For pure speed, with no payload,