not procured by the Army. A pair of the 52 engines produced were destroyed by William Christmas testing his so-called "Christmas Bullet" fighter. Variants V-1650 An inverted Liberty 12-A referred to as the V-1650 was produced up to 1926 by Packard. The same designation was later applied to the Packard V-1650 Merlin, an engine with nearly identical engine displacement. This was a World War II Packard produced version of the Rolls-Royce Merlin, and is not to be confused with the earlier Liberty-based version. Allison VG-1410 The Allison VG-1410 was an air-cooled inverted Liberty L-12, with a geared super-charger, Allison epicyclic propeller reduction gear, and bore reduced to , giving a lower displacement of . Liberty L-6 A 6-cylinder version of the Liberty L-12, nicknamed the "Liberty Six", consisted of a single bank of cylinders, with the resulting engine bearing a strong external resemblance to both the Mercedes D.III and BMW III straight-six German aviation engines of World War I. Liberty L-8 An 8-cylinder V engine using Liberty cylinders in banks of four at 45°. Mikulin M-5License production (or copies) produced in the USSR. Nuffield Liberty The Nuffield Liberty tank engine was licensed and produced in World War II by the UK car manufacturer Nuffield. It was used in early cruiser tanks, the Crusader, the Cavalier, and finally Centaur tanks. It was a 27 L (1,649 in3) engine with an output of , which was inadequate for the increasing vehicle weights as the war progressed and also suffered numerous problems with cooling and reliability. The Nuffield Liberty ran through multiple versions: Mark I, US built engines modified in Britain. Modification incorporated new carburettors and a new induction system from Solex, revision of the crankcase breather, new timing gear, and revised crankshaft end thrust. This produced when governed to 1,500 rpm with the new carburettors. Mark II, British built engines. The air compressor (for starting) was not used, and was removed on later engines Mark III, IIIA and IIIB, made for the Crusader tank. This required a reduced height to fit in the engine bay, achieved by redesigning the oil pump and relocating the water pump. The air compressor was reinstated to enable pneumatically-operated braking and steering. Significant problems were experienced in desert use (the North African Campaign), and the Mk III went through multiple revisions. This included three different chain drive designs for the ancillary cooling fans, a revised valve adjustment