This is an original Alvis Leonides radial aero engine, it’s a supercharged 11.8 liter 9-cylinder engine capable of up to 560 bhp. Interestingly, this would be Britain’s last high-powered piston aero-engine by the time manufacturing ceased in 1966.
The Alvis Leonides was developed from the outset to be used in both planes and helicopters, the latter still being a relatively new thing when it came to production versions that were being built in significant numbers.
The Alvis Leonides you see here is a 503 variant, meaning it would be capable of 560 bhp when in running condition.
A History Speedrun: The Alvis Leonides Radial Engine
Production of the Alvis Leonides began all the way back in 1936 when the first prototype, then named 9ARS, was first run on the test stand. It weighed just under 700 lbs and turned out 450 bhp, a significant output for the time.
A version of the engine was fitted to a modified Bristol Bulldog in 1938, and test pilot George Errington completed the first aerial tests of the engine, proving the concept. World War II broke out in Europe in 1939, as a result the development of the engine continued, but at a somewhat slower pace.
After the war, in 1947, the first production versions were ready for both planes and helicopters. The first production aircraft to be powered by the Alvis Leonides was the Percival Prince, followed by the Westland Sikorsky S-51 and Westland WS-51 Dragonfly helicopters.
The engine would remain in production from 1947 until 1966, almost three dozen variants would be made for a wide variety of aircraft, and power output would reach 650+ bhp in some versions. Relatively few remain today, having been replaced in aircraft use by jets and turbine engines long ago.
The Alvis Leonides Shown Here
The Alvis Leonides you see here is a 503 variant, meaning it would be capable of 560 bhp when in running condition. There is no mention of whether this engine can currently be run in the listing, though the engine is currently fitted to a heavy duty stand for display purposes.
There is no mention of whether this engine can currently be run in the listing, though the engine is currently fitted to a heavy duty stand for display purposes.
There are a handful of these still fitted to flying aircraft, mostly in the UK and Australia, so if the new owner wants to get the engine into full flying fettle the expertise is out there to make it a reality.
This Alvis Leonides engine is now due to roll across the auction block with Iconic Auctioneers, with a price guide of £4,000 – £6,000 or approximately $6,950 – 10,400 USD. If you’d like to read more about it or place a bid you can visit the listing here.
Images courtesy of Iconic Auctioneers
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