The
Su-11 was an upgraded version of the
Sukhoi Su-9 ('Fishpot') interceptor, which had been developed in parallel with the
OKB's
swept wing Su-7 fighter bomber. Recognizing the Su-9's fundamental limitations, Sukhoi began work on the
Su-11, which first flew in
1961 as the
T-47 prototype. The Su-11 shared the Su-9's
delta wing, swept
tailplanes and cigar-shaped fuselage, as well as the circular nose intake, but had a longer nose to accommodate the more powerful 'Oryol' (
Eagle;
NATO reporting name 'Skip Spin') radar set. A more powerful
Lyulka AL-7F-1 turbojet was installed, providing 9.8 kN (2,210 lbf) more afterburning thrust for improved climb rate and high-altitude performance (and to compensate for increased weight). The Su-11 can be distinguished from the Su-9 by the external fuel pipes atop the fuselage, aft of the cockpit. The Su-9's beam-riding
K-5 missiles were replaced by a pair of
R-98 (AA-3 'Anab') weapons, usually one R-98MR
semi-active radar homing and one R-98MT
infrared guided. Like many interceptors of the period, it had no cannon. Production of the definitive Su-11-8M began in
1962, ended in
1965, after about 108 aircraft had been delivered, although it is believed that at least some Su-9s were upgraded to Su-11 form. A conversion
trainer version, the
Su-11U 'Maiden,' was also developed; Similar to the Su-9U, it had full armament and radar systems for training purposes, but the second seat reduced its already marginal fuel capacity and was not intended for combat use. ==Operational history==