Folland Fo.108

The Folland Fo.108 also known as the Folland 43/37 and by the nickname Folland Frightful was a large monoplane engine testbed aircraft of the 1940s.

Design and development
The Fo.108 was Folland's response to Air Ministry Specification 43/37 for an engine testbed. It was Folland's first design to be accepted by the Air Ministry for production. The Fo.108 was a large low-wing cantilever monoplane with a conventional cantilever tailplane and had a fixed tailwheel landing gear. It had a glazed cockpit for the pilot and a cabin for two observers behind and below the pilot fitted out so they could make detailed measurements of the engine performance during flight.

To enable the aircraft to be delivered from the Hamble factory and later ferried to new assignments, they were normally fitted with a Bristol Hercules radial engine. In service, the Fo.108 was fitted with a number of other engines including the inline Napier Sabre, Bristol Centaurus radial and Rolls-Royce Griffon V-engine.

The type was operated by the Bristol Aeroplane Company, Napier and Rolls-Royce, the last examples being withdrawn from service in 1945.