Stories of the Battle of Britain 1940 – Constant-Speed Propellers

Martin Waligorski

01 February 2022

10 min

BLUF

In early 1940 the Spitfire appeared to be no match for the German Messerschmitt Bf-109 during aerial combat; however, switching the Spitfire's variable speed propellor to a constant speed propellor—dramatically improved the Spitfire's performance and more than made it a match for the Bf-109.

Summary

This article makes the following points:

The RAF asked De Havilland if the two-pitch propellers on the RAF Spitfires could be converted to constant-speed operation. De Havilland's response was, 'Yes'.
A constant-speed propeller was a superior alternative as the pitch can be adjusted to match engine RPM, optimising the thrust for any condition in flight.
The company modified one Spitfire in four days.
The modified Spitfire had a shorter take-off run, was much faster in climb, and its maximum altitude increased by 7,000 feet to a service ceiling of 34,400 feet (10,500 m).
On 22 June, Lord Beaverbrook instructed de Havilland to convert all the Spitfires, Hurricanes and Defiants.
On 24 June, de Havilland sent engineering parties to 12 Spitfire stations.
By 16 August, every Spitfire and Hurricane had been converted to constant-speed propellers, over 1,000 aircraft, just in time when an edge in altitude, speed or climb could make all the difference.