had proved that the hitting power of these larger weapons was necessary to overcome the thicker armour encountered on enemy aircraft as the war progressed. The aircraft was also used as a fighter-bomber, carrying 1 × and 2 × bombs, with rocket-projectile launch rails fitted as standard. Late production aircraft were built with the lighter, short-barrelled, electrically-triggered Hispano Mark V cannon. A total of 81 Mk 24s were completed, 27 of which were conversions from Mk 22s. The last Mk 24 to be built was delivered in February 1948 and were used until 1952 by 80 Squadron. Some of the squadron's aircraft went to the Hong Kong Auxiliary Air Force where they were operated until 1955. Introduced into service in late 1945, the F Mk 24 differed greatly from the Spitfire Mk I, was twice as heavy, more than twice as powerful and showed an increase in climb rate of 80 per cent over that of the prototype, K5054. These remarkable increases in performance arose chiefly from the introduction of the Rolls-Royce Griffon engine in place of the famous Merlin of earlier variants. Rated at , the 12-cylinder Vee liquid-cooled Griffon 61 engine had a two-stage supercharger, giving the Spitfire the exceptional performance at high altitude that had been sometimes lacking in early marks. Production After the destruction of the main Itchen and Woolston works by the Luftwaffe in September 1940, all Supermarine manufactured Spitfires were built in a number of "Shadow Factories"; by the end of the war there were ten main factories and several smaller workshops which built many of the components. The main Castle Bromwich factory was also aided by a smaller number of the shadow factories. The breakdown of production figures is taken from Air International 1985, p. 187. Information as to when the first production aircraft emerged is from the serial number lists provided in Morgan and Shacklady 2000. Because the first XIVs were converted from existing Mk VIII airframes the first true production serial No. is listed. Protracted development of the Mk 21 meant that this variant did not reach operational service until January 1945. Specifications (Spitfire Mk.XIV) See also References Citations Bibliography Air International (article). "Spitfire: Simply Superb part three" Air International Volume 28, Number 4, April 1985. Bromley, Kent UK. Air Ministry. Pilot's Notes for Spitfire XIV & XIX: Griffon 65 or 66 Engine. Air Publication 1565T & W. London, UK: Air