Yeah, so downwind and didn't make it. Throw it from a plane, dive vertically to the ground and lithobrake, you are sure to "break" "world speed record" even more.

Apparently, Felix Baumgartner ("passive" skydiver) reached 380 m/s (1368 km/h) in "free fall", so you have a long way to go...

You can call an event "landing" if the flying device is able to fly again without repairs ("airworthy").

If this is to be a competition and a "record" in anything, there should be rules like:
- it starts and it lands airworthy,
- airspeed measured, not ground speed; for test runs on windy day you can average downwind and upwind;
etc.