I'm pretty certain Hürkuş can fly well beyond 310 knots. But like you said, it probably won't be able to maintain that speed for an extended period. Unless of course, the aircraft is nose down most of the time which doesn't seem to be the case regardless. Could be TISU, although I have doubts surrounding that theory. I don't think it's the Hava SOJ, that aircraft has a specific designation. It could still be the Hürkuş 2...Hurkus' max speed is 310 knots and cruise speed much lower. This vehicle maintained 319ish knots for prolonged periods. Most likely not Hurkus. My vote on TIUS or the EW warfare aircraft they are currently building.