Thursday, 21 April 2011
Found this marvellous beautiful engine when I went to Duxford for my birthday treat. Aviation writer Bill Gunston says no aircraft engine equals the Liberty V12’s record of quick design, quick qualification and quick mass production. It had a long active life in aeroplanes up to 1935. One is still going, revised a bit, in Babs the exhumed Land Speed Record car of John Godfrey Parry Thomas, who died in it at Pendine Sands.
Produced in a hurry to meet a wartime emergency, the Liberty was designed by Jesse Vincent of Packard and EJ Hall of Hall-Scott in a Washington hotel between 30 May and 4 June 1917. One says ‘designed’ but of course it used features such as the water cooled separate 5x7 inch cylinders from Hall-Scott’s existing San Francisco engines as well as bits of Packard. The Vee was set at 45deg to fit narrow aircraft and the valve gear was exposed. By November 1918 20,478 had been made of the 27 litre engine which, coincidentally, was the same capacity as the 5.4x6in Rolls-Royce Merlin designed in 1933. Not many people know that. Surprise your friends.
Coil ignition was unusual for a 1917 engine
Engines had to be narrow to fit in slim aircraft
Valve gear lived outside
Babs was dug up in 1969 by engineering lecturer Owen Wyn Owen from what had become a military firing range and restored as a tribute to the brave Parry Thomas. The original Liberty, damaged in the crash had rusted over the years and was replaced by one built by Lincoln Cars, its twelve separate cylinders mounted on a Packard-Liberty crankcase.
Pictured at Brooklands in 2007, Babs was being worked up for a demonstration run. The chassis is braced by strut and wire, much as contemporary Bentleys were, to improve stiffness. Lots of batteries were needed to crank the enormous V12. What a noise history makes.