Oleg - Spitfire Cockpit.

[KG26_Alpha]

Aeroplane and Armament Experimental Establishment
Boscombe Down
30 July 1940

Comparison of Performance of Rotol and DH Airscrews on Spitfire

Both the aircraft are similar externally and are fitted with bullet proof windscreen and armour plating over the tank, etc.

Aircraft R6774 is fitted with DH airscrew and N3171 with Rotol airscrew.

It will be noted that these aircraft are about 12 miles an hour down in speed against the previously tested K9793, but the relative comparison remains. This loss in speed is accounted for, by 6 miles an hour for the bullet proof windscreen and 6 miles an hour due to loss in engine power.

Level Speed miles per hour.

Aeroplane Altitude Feet

14000 16000 Max. speed 20000 22000
R6774 342 349 355 @ 17,800' 350 341
N3171 336 343 354 @ 18,900' 354 352

The above tests were all carried out using 87 octane fuel with boost limited to +6.25 lbs./sq.in. Climb figures were achieved using the 2600 rpm 1/2 hour climb limit. By the Battle of Britain all operational squadrons had changed over to 100 octane fuel and the engine limits on the Spitfires had been increased to +12 lbs./sq.in. 3,000 rpm with 1/2 hour climb limit increased to 2850 - 3000 rpm. Royal Aircraft Establishment figures for a Spitfire I using +12 lbs/sq. in. boost are 314 mph at Sea Level and 359 mph at a full throttle height of 11,500 feet.

From

http://www.spitfireperformance.com/spitfire-I.html