Hi,   On our Polish forum we've been researching the use of those two missiles on the MiG-21 and pretty much all sources we found suggest that only aircraft with RP-21 family radars could employ them. The RP-21 and RP-22 despite the similar names are very different designs - the first uses conical scanning, while the second is a monopulse radar. This leads to the first radar being compatible only with the older Kh-66 and RS-2US missiles, and the second with the newer R-3R. Since all three missi