The Cheetah R was a feasibility study into an extension of the Cheetah upgrade programme to include a specialist reconnaissance aircraft model while the upgrading of the Mirage III airframes to Cheetah standard was in progress.  Equipped with a Snecma Atar 9K50-engine, Mirage IIIR2Z 855, was chosen as the basis for the upgrade. 

This aircraft started life as one of four Mirage IIIR2Z tactical reconnaissance aircraft (854 to 857) but by the time all the Mirage IIIR2Z aircraft had been phased out, 854 and 856 had already been written off.  Ordered for the SAAF in December 1972, 855 was taken on charge on 22 July 1974 and attached to 2 Squadron.  In addition to the airframe refurbishment, Mirage 855 received a new nose design and the same radar as used in the Cheetah E, the twin DEFA 30mm cannons were removed and it was the only Cheetah type not to receive an in-flight refueling probe.

The SAAF decided not to proceed with the Cheetah R programme and the aircraft was then used as a prototype for development work in testing the Advanced Combat Wing (ACW), developed specifically to increase the turn rate.  The ACW also featured a fixed, drooped leading edge with a hard point and a wingtip launch rail to carry an air-to-air missile.  The ACW also incorporated four new fuel tanks that increased the aircraft operational radius of the aircraft by an additional 55 nautical miles.  Sustained turn rate was increased by 14% and maximum take-off weight (MTOW) was increased by 600kg while the minimum approach speed was lowered to 80 knots.

Despite intensive marketing, the ACW was never adopted by the SAAF and no other air force expressed any interest in the new development.  The Cheetah R was eventually withdrawn when the Cheetah E aircraft were withdrawn from the SAAF inventory, having been replaced by the far superior Cheetah C.  Cheetah R 855 was eventually scrapped and because the wings of this aircraft were no longer required, they were passed on to the SAAF Museum in 1998