Supermarine Falcon F Mk-II
When at the end of
the 1940s it became clear that the jet engine would never be a reliable
power source for aircraft a new impulse was given to the further
development of the piston engines.
The problem was however with the propeller which had to convert all this power to propulsion. This led to problems with compressibility and propeller blades exceeding the speed of sound. In practice this meant that the piston engine aircraft were limited to a maximum speed of around 800km/h.
In the 1960s new forms of propellers were designed enabling higher speeds. The first US fighter aircraft to benefit from this was the General Dynamics F-93 Falcon. This was powered by two Allison 18 cylinder engines producing 4500hp each and driving a push and a pull propeller. This first flew in 1971.
The British RAF ordered 100 F-93s as the Falcon F Mk-I but were disappointed with the performance of the new fighter. The top speed was 850km/h where the demand was for speeds in excess of 900km/h.
The Supermarine aircraft factory, which was producing the F-93 under license took one production Falcon F Mk-I and installed two Rolls Royce Condor engines producing 5650hp each. This boosted the top speed to 975km/h and because the higher fuel efficiency also expanded the range.
The RAF ordered 260 Falcon F Mk-II fighters which were delivered from 1974 onwards. The USAF was also very interested in the Rolls Royce powered variant and this was produced in the USA as the F-93C.
This was very successful and eventually more than 7000 Falcons were produced for a number of air forces around the world.