For today, two submissions made to Spec F.18/37, issued in March 1938 which resulted in orders for the Hawker Tornado and Typhoon.
F.18/37 called for a fighter to achieve 400mph at 15,000ft, service ceiling not below 35,000ft and armed with twelve 0.303in machine-guns.
Gloster F.18/37, shown here in the colours of 263 Squadron circa early 1941
Powered by a single Napier Sabre with wingroot radiators. Twelve machine-guns were housed in the nose. Ceiling was estimated at 38,000ft and should reach 15,000ft in 4.1 minutes. Apparently it reached mock-up stage but was replaced by a similar design with radiators on the ends of the booms and armed with five 20mm cannon. Gloster also offered a twin-engine design based on the F.9/37 fighter using elements of the F.18 fuselage with Bristol Taurus radials and twelve machine-guns in the nose. Shown here is the first design.
Bristol F.18/37, shown here in the three proposed versions and coloured in 6 Squadron markings circa 1943, 112 Sqn in the Middle East circa 1941 and 66 Sqn in late 1940
The Bristol design was offered in three versions with the Bristol Centaurus, Napier Sabre and the Rolls-Royce Vulture. No performance data survives but each wing had six machine-guns and a 100 gallon fuel tank. This design has an unusual radiator duct running along each fuselage and the absence of exhaust stubs on the plans seems to suggest they vented via the duct too. The design has some similarities with the odd turret-fighter proposed to meet Spec F.11/37 which Darthpanda has previously drawn.
Another of the F.18/37 submissions was the Supermarine 327, which I've drawn previously.
Supermarine 327