The Bristol Basileus (British but with a hint of Gallic flair)

**Spinners** · August 8, 2015

Bristol Basileus Mk.I - No.74 'Tiger' Squadron, RAF Fighter Command, 1937

The challenging Air Ministry Specification F.7/30 issued in 1931 called for a new interceptor-fighter for the Royal Air Force and demanded a top speed of at least 250 mph and an armament of four machine-guns. Going against the grain, two competitors boldly decided to ignore Air Ministry advice to use the new Rolls-Royce Goshawk evaporatively cooled in-line engine and proposed aircraft powered by alternative engines.

Gloster elected to develop the SS.37, essentially an advanced version of the Gauntlet with a fully enclosed cockpit, single-bay wings, a cantilever main undercarriage and powered by an advanced version of the Bristol Mercury radial engine. First flown in September 1934 the SS.37 would become the Gloster Gladiator gaining an initial order for 23 aircraft to Specification F.14/35 in December 1934 followed by a more substantial order for 180 in September 1935.

Meanwhile, Bristol chose to eschew their own Bristol Mercury radial engine (and also their Goshawk powered Type 123 design) and develop their advanced Type 125 design featuring the proposed Fairey Prince V-12 liquid-cooled inline engine in a clean, streamlined biplane design featuring an open-cockpit with single-bay wings and with all four machine-guns mounted in underwing gondolas. However, the adoption of the Prince engine would initially prove to be a nightmare for Bristol leading to them always running several months behind their rivals at Gloster. Nevertheless, the Prince engine was installed and test flown in a Fairey Fox II biplane in 1934 and then transplanted into the prototype Type 125 just in time for a maiden test flight from Filton on December 31st, 1934. During 1935 the Type 125, now named Basileus, slowly started clawing back some of the time lost to their nearby rivals up the A38 in Gloucester and Bristol were rewarded with an initial order for 60 production aircraft to Specification F.14/35 in March 1935 and with a further order for 140 aircraft in September 1935.

Entering service with No.74 Squadron in March 1937 the Basileus was the last open-cockpit biplane fighter to enter service with the Royal Air Force and was quickly replaced in the home service by the faster. more heavily armed Hawker Hurricane and Supermarine Spitfire fighters but two Basileus squadrons were used in the unsuccessful Norwegian campaign of 1940. The Basileus was also used with great success against Italian opposition during the North African campaign during 1940 and early 1941 before being withdrawn from service in April 1941.