Granville Bradshaw
Granville Bradshaw was a controversial figure, described as an excellent conceptual engineer and a great salesman.
During WW1 he worked on a number of aircraft engine projects, designing one of the first British radial aircraft engines that went into production. The 9 cylinder ABC Dragonfly radial was rushed into production before it was fully developed. Despite good initial results the engine overheated at high power and the cylinder head joints leaked causing further overheating. Twelve months of intensive work by the Royal Aircraft Establishment and pioneering work by Sam Heron finally solved the problems.
Bradshaw designed a number of motorcycle engines. In 1923 he designed the overhead valve engine for the P&M Panther, based on the earlier robust engine-cum-frame design of the 4-1/2hp sv engine; it stayed in production until the early 1960s. In 1927 he designed the P&M Panthette, an unusual and very advanced machine for its time, with an across-the-frame inline 250cc V twin, a car type gearbox and leaf springs controlling the valves.
Granville Bradshaw also designed unusual oil-cooled motorcycle engines with the cylinder barrels encased in oil baths. These were manufactured under licence by J Walmsley & Co (Preston) Ltd. The flat-twin 500cc version of this engine was used in the Zenith-Bradshaw motorcycle from 1921. A single cylinder 348cc version emerged in 1922, offered as an option by a number of companies like OK-Supreme, Sheffield-Henderson, DOT, Orbit, Toreador and Coventry-Mascot. An 1100cc V-twin version of this oil-cooled engine was adopted for the Belsize light car.
Granville always claimed that BMW copied his concept of an across the frame flat twin. However BMW were already producing the Victoria fore and aft flat twin and it does not take a great leap to see the advantages (and disadvantages) of placing the engine across the frame. Post WW1 Granville made a fortune designing and producing an early form of “Pokey” machines, losing the lot when a business partner sunk the money into a sophisticated “Ponzi” scheme. A Toroidal engine project later dominated his life until his death in 1969.