One of two Mikoyan Ye-152 experimental interceptors built, this airframe is the second one, Ye-152-2. The first airframe, Ye-152-1, was used to set a series of world altitude and speed records in 1961 and 1962. To attempt to hide the true identity of the aircraft from Western sources, the Soviets registered the records with the FAI as being accomplished by the fictitious Ye-166, hence the E166 markings on the nose. This airframe, while not the record breaker, was further modified into the Ye-152M, with a new version of the Tumansky R-15 engine, and, among other improvements, canards mounted on the nose. The canards were removed some time during the test program, however. Following the aircraft's retirement, Ye-152-2 was painted in the markings of Ye-152-1, in a further attempt to confuse Western observers.