Comparison of engine cooling fan performance, including a graph plotting thrust versus engine RPM for different fan models.
| Identifier | ExFiles\Box 178\1\ img034 | |
| Date | 15th February 1926 guessed | |
| - 18 - fan increases approximately as the cube of the r.p.m. This means that in order that a fan may produce a considerable flow of air through the radiator at low speeds, an immense strain must be thrown on the drive at high engine speeds. For this reason the majority of the Car Manufacturers do not rely too much upon their fan. Graph VIa which is compiled from laboratory tests on fans, shews that the Silver Ghost(1907 40/50 historic RAC 15,000 miles trial) fan is designed to deal with 100% greater weight of air than the Hispano. Though the Phantom fan runs slower (.95 of Silver Ghost(1907 40/50 historic RAC 15,000 miles trial)) from the laboratory tests it should deal with a slightly greater weight of air. Actually on road tests we cannot appreciate any gain when the fans are run at the same speed, GRAPH VIa THRUST WT. OF AIR. LBS RELATIVE COOLING FROM FANS SILVER GHOST(1907 40/50 historic RAC 15,000 miles trial) v HISPANO PHANTOM FAN THRUST------ SILVER GHOST(1907 40/50 historic RAC 15,000 miles trial) HISPANO ENGINE R.P.M. possibly due to the Phantom fan drawing air through the radiator more locally owing to its shape. The result of trying to induce the fan to do so much cooling is clearly shewn in Graph VII, contd. | ||
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).