Yakovlev Yak - 1000 The Yakovlev Yak - 1000 was a Soviet supersonic technology demonstrator intended to evaluate the aerodynamic layout and field performance of the cropped delta wing discussed in captured German documents in combination with the new Lyulka AL - 5 turbojet . The tandem undercarriage proved to be unsatisfactory and there were serious flight stability problems related to the delta wing , enough so that it never flew after an accident during taxiing tests . Development . A June 1950 Council of Ministers directive ordered Yakovlev to develop a supersonic fighter that used the Lyul ' ka AL - 5 axial compressor turbojet . Based on a recommendation from one of TsAGI aerodynamicists , Yakovlev was directed to use the rhomboid or cropped delta - shaped wing covered in captured German research . The directive was extremely ambitious as it required the maximum speed to be Mach 1 . 7 at a time when the world speed record was barely over the sound barrier . This requirement had to be revised when the AL - 5 was delayed and a substitute engine had to be chosen . No other Soviet turbojet offered the same sort of power as the AL - 5 so the project was recast as a technology demonstrator to evaluate the novel wing aerodynamics . The Klimov RD - 500 was chosen and the maximum speed was expected to be at a take - off weight of . The Yak - 1000 had a circular - section , semi - monocoque fuselage with the engine air intake in the nose . The engine was mounted behind the pressurized cockpit and exhausted through a long tailpipe in the rear fuselage . Two air brakes were fitted on the underside of the rear fuselage . Forward and rear fuel tanks held and respectively . The entire rear fuselage and tail was removable to allow access to the engine . The three - spar wings were the most significant new feature on the Yak - 1000 . Small and rhomboid - shaped , they had an aspect ratio of only 1 . 46 with 60° leading - edge sweepback with 51°11 ' sweepback at quarter chord . The thickness / chord ratio was a remarkable 3 . 4 % at the root and 4 . 5 % at the tip . Skin was 1 . 5mm thick Duralumin . The trailing edge was swept forward 11° and consisted of a full - span flap with inset ailerons . The delta shaped horizontal stabilizer was set low on the tail and was shaped much like the wing , with 5 % thickness . The rudder was tiny , as were the mass - balanced elevators . The tandem " velosipednoye " ( bicycle ) undercarriage legs , similar to those of the Yak - 50 , retracted aft , although the forward wheel remained exposed when retracted . Small outrigger struts retracted aft into underwing fairings set at mid - span . On the ground the Yak - 1000 had a pronounced nose - high attitude , and the single nose wheel was steerable . Operational history . The prototype was completed on 27 February 1951 and it began taxiing trials on 2 March . On the following day it was taxiing at speed up to , but was blown off the runway when a strong crosswind caused the aircraft to bank which compressed the strut on the opposite side . This forced the aircraft to veer off the runway when the ailerons proved ineffective at countering the bank and the consequent damage forced the testing to be suspended . Some development was done to try to remedy the problems with instability already revealed , but Yakovlev was unenthusiastic about the whole project and it was cancelled in October 1951 . This decision was considered wise as the peculiar aerodynamics of delta wings would take the Soviets about another five years of experiments to validate in the Mikoyan - Gurevich Ye - 4 prototype of the Mikoyan - Gurevich MiG - 21 and the Sukhoi T - 3 delta - winged aircraft which both first flew in 1955 – 56 . Had the aircraft met its design expectations it was planned that the aircraft would reach Mach 1 . 65 ( 1 , 750 km / h , 1 , 087 mph ) without afterburner , and Mach 1 . 88 with afterburner .