What is this fighter aircraft parked in the South African desert?
According to the unofficial South African Air Force forum it is a fake Mirage F1, intended as a decoy. It seems it works as intended.

According to that forum, approximately 30 were built. They were constructed of metal tubing, metal plates and glass fibre. According to one post they even contained heating elements to give infrared sensors on satellites the impression that the "exhaust" was hot.