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 the efficiency between a six-bladed fan and a three-bladed fan, referencing horsepower curves.
| Identifier | ExFiles\Box 75\3\ scan0145 | |
| Date | 19th November 1924 | |
| Contd. -4- EFC2/T19.11.24. connecting link. This necessitates drawing curves of motor or engine power required to drive on a fan speed base instead of on a motor speed or chassis engine speed base. Accordingly this has been done for the two fans whose power curves have already been observed, with the result given on photostat sheet C. Finally, on photostat sheet D, curves of HP. on a thrust base are given for these same two fans, and it will be at once noted that the result of this comparison is that the six-bladed fan is decidedly more efficient at all thrusts (and consequently at all corresponding speeds) than the three-bladed fan. It must be remembered that the power given is not merely the power required to turn the fan, but the power required [strikethrough] which was delivered from the electric motor pulley and which may be assumed to be reasonably the same as the power which will have to be delivered from the chassis engine, inclusive of power required to flex and slip the belt, the belt being assumed to have, as in our tests, a reasonable degree of tautness. It is considered to be more practical to express the result in this way because after all what is important is the power which is taken from the engine. Further, in this case where the power taken from the engine is considerable, the mere duty of the fan, i.e. what it would do irrespective of the power taken to drive, | ||