Design of the Griffon originated in a late 1940s requirement for a high speed interceptor. Engineers at Arsenal de l'Aéronautique instigated studies into swept and delta wings using supersonic gliders, the Arsenal 1301 and Arsenal 2301. Results from these flight tests favoured the delta configuration, which was incorporated into design studies using a variety of powerplants. By this time Arsenal had been privatised as SFECMAS - Société Française d'Etude et de Construction de Matériel Aéronautiques Spéciaux. Powered by a large ramjet with turbojet sustainer, the Griffon was renamed from the SFECMAS 1500 Guépard after SFECMAS was merged with SNCAN to form Nord Aviation. Two prototypes were ordered initially in a letter dated 24 August 1953, with the final contract, in 1955. Although intended to eventually fulfil a requirement for a light interceptor capable of operation from 1,000m grass runways, the two prototypes were ordered without military equipment for research purposes only. Constructed mainly of light alloys, the Griffon comprised a large tubular fuselage which supported the middle set delta wings, fin with rudder and the forward fuselage, which extended forwards over the turbo-ramjet air intake. The forward fuselage housed the single-seat cockpit and carried small delta canards on either side of the cockpit. The tricycle undercarriage retracted into the wings and the underside of the air intake. The design of the Griffon featured a dual turbojet-ramjet powerplant, with the turbojet enabling unassisted takeoffs and the ramjet producing extra thrust at airspeeds above 1,000 km/h. To reduce risks in using the relatively new turbo-ramjet powerplant, the first Griffon was completed with only the 3,800 kgf thrust ATAR 101F turbojet component.
Flight testing
First flown by Andre Turcat on 20 September 1955, the Griffon I proved to be underpowered but plans to install the planned ramjet component were never realised. Despite the lack of power the Griffon I still managed to reach M 1.17. Flying with the Griffon I ceased in April 1957 in favour of the ramjet-equipped Griffon II. Visible differences between the two aircraft were limited to the smaller intake and two-position exhaust nozzle of the Griffon I. After proving the aerodynamic aspects and systems of the Griffon, the 1500-01 was retired in April 1957. Flying continued with the Griffon II after its first flight on 23 January 1957. With Major André Turcat at the controls, the Griffon II reached a top speed of Mach 2.19 in 1958, thus proving the soundness of the basic design. However, the aircraft met several technical difficulties, such as kinetic heating, due to the lack of temperature-resistant materials, such as Inconel or titanium, in the parts of the airframe experiencing the highest temperatures. The ramjet was found to work well at high speed, but was unstable at medium speeds. Production of operational versions, dubbed Super Griffon did not take place as it was found that the requirements could be met and exceeded with less complex and cheaper aircraft such as the Dassault Mirage III.
Variants
;SFECMAS 1500 Guépard ;Nord 1500-01 Griffon I ;Nord 1500-02 Griffon II ;Nord Super Griffon
