Bristol aero engines. - Which came first, the engine or the aircraft?

In the case of the the G91 the answer is straightforward. Fiat engineers were able to start the G91 project because there was available a lightweight turbo-jet which satisfied exactly their design requirements. This engine was the Bristol Orpheus. The Orpheus itself had been initiated as a design project only two years earlier.

Objectives of the Bristol Orpheus project...
To produce a simple, lightweight turbo-jet engine of exceptional power to weight ratio suitable for the new generation of a lightweight fighters and also for trainers, transport and executive aircraft. The engine had to be low in cost and easy to manufacture in maintain.

Development programmes
A year after detailed design began, the first Orpheus engine was running. Six months later, unofficial 150 hours type test had been completed and the engine cleared for flight. In July 1955 the first Orpheus powered aircraft took to the air.

This unprecedented speed of development was largely due to the thinking on lightweight turbo jets which already existed when the Orpheus project was initiated, combined with the enormous fund of experience amassed at Bristol on turbine engine development.

Current position
The Bristol Orpheus B or 2 last year completed a declared type test is a static thrust of 4520 pounds. Now the Orpheus B or 3 has been type tested at 4850 lb for a weight of 810 pounds, given the thrust weight ratio of 6:1, higher than that of any other type tested engine. Still more powerful versions are under development, including the recently announced B or 12 to of 6810 lb thrust.

The Orpheus powers the Folland Gnat, the F.I.A.T G91 and Dasault Etendard VI all of which have flown: it is specified for the French Breuget 1001: which will fly shortly also for the Italian Aerfer Leone, the Japanese Fuji TIF 1 trainer, the Spanish Hispano HA 300 lightweight interceptor, and a number of other new aircraft.

Development potential
Now that the Orpheus is a proven engine with thousands of bench and flight hours behind it, many more roles await it... In fighters, strike aircraft, trainers, transport, and mixed power aircraft.