May 20, 1977 the first prototype designated T10-1 took off. After an evaluation it was discovered that the T10-1 did not fulfil its requirements for maximum range, and manoeuvrability, and thus proved inferior to its western counterparts. The prototype had aerodynamics problems, engine problems and fuel consumption problems. The second prototype the T10-2 crashed because of a fly-by-wire software failure which resulted in the death of the test pilot. After such disappointing results the from the T10 program Sukhoi seemed to stop T10 development, because there were no more T10 prototypes tested. They didn’t, by 1981 a new design was introduced loosely based on the old T10. The new aircraft was designated T10S which was to become what today is known as the Su27 Flanker. The T10S prototype flew on April 20, 1981. The T10S showed it self to be a masterpiece of engineering having no equal anywhere in the world in range, manoeuvrability, and combat effectiveness.
The Su-27, a Russian fourth-generation single-seat supersonic fighter, is recognised all over the globe as one of the best combat aircraft of the 20th century. Due to its perfect flight performances and operational characteristics, the fighter is rightfully popular with pilots and technicians. Top piloting capabilities of the Su-27 fighter demonstrated during multiple air shows around the world did not leave anyone indifferent. The Su-27 is in the top lines of the aviation record tables of the International
Aircraft Federation. To the date, the Su-27 is a record-holder of 27 world class flight achievements. The Su-27 is the forefather of a combat aircraft family of various functionality, including the Su-27UB trainer, Su-27K ship-borne fighter (Su-33), Su-30 twin-seat interceptor, Su-30MK twin-seat multirole fighter, Su-34 tactical bombers Su-35, Su-37 Su-35BM and other high-manoeuvrability multirole aircraft.
More about T-10 prototype click HERE