The first Supermarine aeroplane to bear the name Spitfire was a single-seat fighter designed to meet the Air Ministry F.7/30 specification. It was a low-wing cantilever monoplane with fixed landing-gear and was fitted with a 650 hp (485 kW) Rolls-Royce Goshawk engine. From this type, which was not successful, was evolved as a private venture a new prototype to which the name Spitfire was transferred and around which the Air Ministry F.37/34 specification was written. Into this prototype Mr. R.J. Mitchell incorporated the fruitful results of the experience gained in the design of his series of high-speed seaplanes which had previously established three world speed records.

The prototype F.37/34 Spitfire, which was fitted with one of the first Rolls-Royce Merlin engines, flew in March 1936. With a fixed-pitch wooden airscrew the prototype had a maximum speed of 342 mph (547 km/h), which classed it at that time as the fastest military airplane in the world. The soundness of the basic design was proved in six years of war, throughout which the Spitfire remained a first-line fighter.

Spitfire IX: Powered by one Rolls-Royce Merlin 61, 63, 63A, 66, or 70 engine. Basically similar to the Mk. VC but with the Mk VII engine and radiator installation.

Length (m): 9.5
Height (m): 3.7
Wing Span (m): 11.2
Top Speed: 408 mph
Ceiling (feet): 43,960
Weight (lbs): 9,500
Range: 435 miles
Crew: 1

Two 20 mm British Hispano cannon and four .303 in Browning machine-guns. Racks under each wing for one 250 lb (113 kg) bomb and/or under fuselage for one 250 lb (113 kg) or 500 lb (227 kg) bomb.

Single-seat fighter, fighter-bomber, and reconnaissance aircraft.