R-4 (missile)
The Bisnovat 'R-4' was an early Soviet long-range air-to-air missile. It was used primarily as the sole weapon of the Tupolev Tu-128 interceptor, matching its RP-S Smerch radar.
History
Development of the R-4 began in 1959, initially designated as K-80 or R-80, entering operational service around 1963, together with Tu-128. Like many Soviet weapons, it was made in both semi-active radar homing and infrared-homing versions. Standard Soviet doctrine was to fire the weapons in SARH/IR pairs to increase the odds of a hit. Target altitude was from 8 to 21 km. Importantly for the slow-climbing Tu-128, the missile could be fired even from 8 km below the target.In 1973 the weapon was modernized to R-4MR / MT standard, with lower minimal target altitude, improved seeker performance, and compatibility with the upgraded RP-SM Smerch-M radar.
The R-4 survived in limited service until 1990, retiring along with the last Tu-128 aircraft.