an Entity references as follows:
The Nord 1500 Griffon was an experimental ramjet-powered interceptor aircraft designed and built by French state-owned aircraft manufacturer Nord Aviation. The Griffon was developed to become a Mach 2 follow on to the supersonic Nord Gerfaut research aircraft. Development of the aircraft began in earnest after the receipt of a letter of intent in 1953 for a pair of unarmed research aircraft. The design featured an innovative dual propulsion turbojet-ramjet configuration; the former being used to takeoff and attain sufficient speed to start the latter.