Demo
    A military aircraft is in flight, with a missile attached under its wing. The sky is clear and blue.
    The U.S. Air Force’s X-51A Waverider previously held the record for longest air-breathing hypersonic flight. Once released from the wing of a B-52 Stratofortress, the demonstrator's scramjet engine lit and accelerated the aircraft for 210 seconds during the final test flight of the program in May 2013.