Somewhere over central France in the late 1950s, test pilot André Turcat pushes a strange delta-winged aircraft past the speed where a normal jet engine begins to gasp for air. And that is when the Nord Griffon comes alive. Behind him, a ramjet the size of a small room ignites, and the acceleration slams him back into his seat. The machine is no longer flying on its jet engine. It is flying on fire and airflow alone.

The Nord 1500 Griffon was one of the boldest — and strangest — experiments in the history of jet propulsion. And the man in its cockpit would go on to fly Concorde.

An engine within an engine

The Griffon’s secret was a combined-cycle powerplant: a turbojet mounted inside a huge ramjet duct. A ramjet has no moving parts — it simply rams air in, burns fuel, and blasts it out — but it only works once the aircraft is already moving fast. So the Griffon used its turbojet to accelerate up to speed, at which point the ramjet lit and took over, delivering thrust a conventional fighter of the day could only dream of.

The result was ferocious acceleration and a top speed around Mach 2.19 — remarkable for the mid-1950s. But it came at a price: the ramjet generated brutal heat, gulped fuel, and made the aircraft fiendishly complex.

The pilot who would fly Concorde

At the controls was André Turcat, one of France’s finest test pilots. In the Griffon he set a world speed record over a 100-kilometre closed circuit, taming an aircraft that was as much a flying furnace as a fighter. A decade later, Turcat would take Concorde into the air for the first time — carrying the lessons of the Griffon’s heat and speed with him.

A magnificent dead end

For all its brilliance, the Griffon never had a future. The combined turbojet-ramjet was too complex and too hot to be practical, and it offered little a conventional interceptor could not do more cheaply. France put its money on the simpler, elegant Dassault Mirage III — which went on to become one of the great export fighters of the century — and the Griffon programme ended with just two aircraft built.

Today one survives in a museum, its enormous intake still gaping like the mouth of some mechanical predator. It never fired a shot in anger. But for a few years in the 1950s, it was one of the fastest, wildest things in the sky — and proof that French engineers were willing to try almost anything to catch the future.

Sources: Musée de l’air et de l’espace, Le Bourget; Flight International archives; French aviation historical records.