Supermarine Spitfire Mk XVI

The Mk XVI was in nearly every respect a Mk IX. The difference was the engine: the Merlin 266, the Merlin 66 built under licence by Packard in the United States. The leading "2" did not denote a different engine so much as different tooling, and it was added precisely so that workshops would not confuse the parts. Because the Merlin 66 was optimised for low altitude, every Mk XVI was an LF fighter; the "L" referred to the engine rather than the wing, even though in practice almost all aircraft had clipped tips.

Packard-built Merlins had a slightly taller intercooler and rearranged accessories, which forced the introduction of a bulged upper cowling that later appeared on the last Mk IXs as well. Many Mk XVIs took the cut-down rear fuselage and bubble hood trialled on the Mk VIII JF299. Internal fuel grew with rear fuselage tanks of 75 gal combined, reduced to 66 gal on cut-down aircraft, giving the mark a radius of action comparable to the Mk VIII's.

Standard armament was the E wing fit: two 20 mm Hispano II cannon with 120 rounds each and two .50 in Brownings with 250 rounds apiece. One 500 lb bomb could go on the centre rack and a 250 lb bomb under each wing, and in early 1945 some Mk XVIs of No. 74 Squadron, alongside the unit's Mk IXs, carried a single RP-3 rocket under each wing — apparently the only RAF Spitfire unit to use rockets operationally during the war. Trouble with the licence-built engines delayed the type's arrival in front-line squadrons by several months.

1,054 Mk XVIs were built, all at Castle Bromwich. It was the final production version to use the Merlin — everything that followed had the Griffon — and several remained in service through 1950. Together with the Mk IX it forms the largest single block of the whole Spitfire family, of which 20,351 were built before the last one left the assembly line in February 1948.