SA6
SA6
The SA6 "Gainful" low altitude surface to air missile (SAM), was first designed at Tushino in 1956 but was not seen in public until 1967 and entered full service in 1970.
Straight Flush is the NATO designation given to the radar and command guidance system used with the Gainful missile system. The system performs the following functions:
Limited search capabilities. 
Low altitude detection and acquisition.
Target tracking and illumination.
Missile radar command guidance.
Secondary radar missile tracking.
The arrangement of the system can be seen in the pictures included on this page. The upper tracking radar antenna assembly is able to rotate independently of the lower assembly. The two antennas and associated apparatus can be rotated relative to the carrying vehicle on a turntable, on which the whole assembly is mounted.
Straight Flush has a similar chassis to that of the Gainful but with radar equipment mounted on top. The radar has an estimated range of 55 to 75 Km depending on target size. Some modified vehicles have TV cameras fitted to enable the system to remain in action even if the radar is being jammed or forced to shut down because of the threat of anti-radiation missiles.
Further information on the equipment maintained at RAF Spadeadam can be found in the links below.
Scud Missile