From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison of Cowhawk fans from tests measuring wind velocity at three points on a Cowhawk-11 car.
| Identifier | ExFiles\Box 77\4\ scan0269 | |
| Date | 9th September 1922 guessed | |
| Handwritten: X4240 (Crossed out) X4240 X4237 Typed: COMPARISON OF COWHAWK FANS. Tests on 3-Cowhawk-11 car with original height of radiator - Wind velocity measured at 3 points - bonnet fitted during tests. Minus readings show when air is blown out from under bonnet. Pencil figs in M.P.H. 16" standard Fan and Pulley. Engine revs. | 1st. position. | 2nd. position. | 3rd. position. 500 | - 80 .91 | 210 3.5 | 270 3.06 1000 | - 450 5.1 | 760 8.6 | 640 7.25 2000 | - 1280 13.6 | 1800 20.4 | 1680 19.1 18" Fan and large pulley. 500 | - 150 1.7 | 290 3.3 | 220 2.5 1000 | - 470 5.35 | 790 9.0 | 720 8.2 2000 | - 1400 15.9 | 1800 20.4 | 1700 19.3 18" Fan and standard pulley. 500 | - 200 2.27 | 400 4.5 | 360 4.1 1000 | - 750 8.5 | 920 10.4 | 830 9.4 2000 | - 1700 19.3 | 2340 26.6 | 2100 23.8 18" Fan and std. pulley with cowling. 500 | 220 2.5 | 470 5.3 | 370 4.2 1000 | 450 5.1 | 1000 10.3 | 910 10.3 2000 | 910 10.3 | 2380 27.0 | 2320 26.4 Large pulley. 18" blades. cowling. 500 | 130 1.48 | 300 3.4 | 280 3.17 1000 | 380 4.32 | 800 9.1 | 710 8.1 2000 | 1000 10.4 | 1900 21.6 | 1500 17.0 | ||