This is a replica of the British space plane called Skylon by REL, which uses closed cycle engines called SABRE engines to fly like a normal aircraft and switch into a rocket when a certain height is reached ( this replica can't do that). This craft isn't the fastest or the most stable thing in the air, but it does fly. It can sometimes hit 2000 mph if flown in a straight line (tip: go to an altitude of about 30,000 feet and dive, this will put a lot of air in the engines, therefore e allowing you to go faster after the dive). The craft is able to go at pretty high alttitudes, but once it starts running out of fuel, make sure you don't do anything crazy because it might flip out on you. THE TRUTH IS OUT THERE.