The Messerschmitt X-4 Was a (Fictional) Supersonic demonstrates aircraft designed by Germany, France, and the UK, in 1948. The American Bell X-1 was able to beat the X-4 before it could be tested. Although the X-4. Was not the first supersonic aircraft, it was the first aircraft to reach Mach 1.5. This was still a significant record and it recognized as so.CONTROLS/INSTRUCTIONS:Fly the Tug aircraft up to about 40000 ft and press AG1, the X-4 will detach and fore its rocket engine. Maintain level flight with the X-4 till the engine runs out. Once the engine runs out of fuel Press AG2, this will fire the second rocket motor and will propel you supersonic, once that runs out of fuel, Good luck gliding back!