Supermarine Spitfire Mk V

Late in 1940 the RAF expected a sustained high-altitude bombing campaign by pressurised Junkers Ju 86Ps and began developing a pressurised Spitfire, the Mk VI. That would take time, so something immediate was needed: the Mk V, essentially a Mk I airframe around the new Merlin 45, rated at 1,440 hp for take-off and fitted with an improved single-stage supercharger. Carburettor changes also allowed negative-g manoeuvres without fuel starvation. Mk I and Mk II airframes were converted to the new standard and squadrons began receiving them early in 1941, with most production coming from Castle Bromwich.

The Va kept the A-type wing with eight .303 in machine guns and only 94 were built. The Vb, with the B wing — two drum-fed Hispano cannon and four machine guns — became the main version. The Vc introduced the "universal" C wing, whose belt-fed cannon carried twice the ammunition, along with a redesigned undercarriage, a re-stressed fuselage and extra armour; it could take anything from eight machine guns to four cannon, though the weight of the four-cannon fit discouraged its use. Many Mk Vs had clipped wingtips, reducing span to 9.8 m for a better roll rate at low level, and the cropped-impeller Merlin 45M, 50M and 55M engines — up to 1,585 hp — produced the LF versions.

The Mk Vb (trop), recognisable by its bulky Vokes filter under the nose, was the first Spitfire shipped overseas in quantity; the filter cost some 8 mph and 600 ft/min of climb, which was judged acceptable, and in Egypt the Aboukir maintenance unit produced lighter, more streamlined filters of its own. On 7 March 1942 fifteen Mk Vs with belly tanks flew off HMS Eagle near the Algerian coast on a 970 km flight to Malta, where the type blunted the Axis air offensive against the island. A Malta-based Vc, EP201, was the first Spitfire modified to carry bombs, one 250 lb weapon under each wing.

The arrival of the Focke-Wulf Fw 190 in August 1941 left the Spitfire genuinely outclassed for the first time, which is precisely why the "interim" Mk IX exists. Even so, Mk V production reached 6,479 aircraft — 94 Va, 3,911 Vb and 2,467 Vc plus fifteen reconnaissance airframes — shared between Supermarine, Castle Bromwich and Westland. Three hundred Vc (trop) went to Australia and 143 Vb to the Soviet Union, with further batches for Portugal, Turkey and Egypt; the last Portuguese examples were not withdrawn until 1952. No other single-stage Spitfire came close to those numbers or that geographical spread.