W. O. Bentley, Motorcyclist

Walter Bentley, Brooklands
Walter Bentley (left) with the 1910 IoM TT Indian team after winning 1-2-3 at Brooklands

Sunbeam V12
Sunbeam V12 273 horsepower

W.O. Bentley, of Australian parentage and founder of the Bentley car company, raced Quadrant, Rex, and Indian motorcycles in the years preceding the First World War, competing in two Isle of Man Tourist Trophy races.

He also sold and raced automobiles which he modified for increased performance by replacing the standard cast iron pistons with aluminium alloy units. His cars flogged the opposition mercilessly and he was not quick to give away the secret of his success.

When the guns of August thundered he revealed his secret*. He spoke to Rolls Royce who responded by fitting alloy pistons to their first aero engine. As is well known, Rolls Royce went on to build the Merlin engines fitted to Spitfires and Hurricanes, the planes which won the Battle of Britain.

He also spoke to Louis Coatalen, chief engineer at Sunbeam. Their aircraft engine plant expanded to cover several acres and produced thousands of aero engines during the war, all with alloy pistons.

Bentley became Mr Fixit for all things aviation, and one thing that desperately required attention was a French rotary engine made under licence in England. He bustled off to Humber, was given a workshop and a team, and designed a new rotary engine far superior to its predecessor and which became the powerplant of choice for several other aircraft.

He left the services as a full captain in the RAF with a grant of £8000 (approx £250k today) and an MBE.

Notes: Cappa used aluminium pistons in 1906, and the Borgo firm fitted them in 1911.

Sources:, wikiwand, History Website UK,, Museum Victoria

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