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).
Table of fan speeds corresponding to various thrusts for different 20 HP fans.
| Identifier | ExFiles\Box 75\3\ scan0049 | |
| Date | 6th February 1925 | |
| FAN SPEEDS CORRESPONDING TO VARIOUS THRUSTS OF VARIOUS FANS. -20 HP- | | Standard 20 HP fan. | Hispano fan. | Final modfn. to expl. 20. HP. fan. | |---|---|---|---| | 1 | 850 | 820 | 870 | | 2 | 1200 | 1160 | 1210 | | 3 | 1500 | 1430 | 1450 | | 4 | 1725 | 1630 | 1680 | | 5 | 1930 | 1815 | 1890 | | 6 | 2120 | 1980 | 2060 | | 7 | 2290 | 2130 | 2220 | | 8 | 2450 | 2270 | 2380 | | 9 | 2600 | 2440 | 2510 | | 10 | 2740 | 2600 | 2640 | | 11 | | | | | 12 | | | | | 13 | | | | | 14 | | | | 6.2.25. | ||