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).
Reducing fan horsepower by testing a flexible blade fan design based on a Cadillac model for the Wraith.
| Identifier | ExFiles\Box 135\1\ scan0155 | |
| Date | 7th July 1938 | |
| 1135 To By/Ald.{F. Allwood - Experimental Design} from Rm{William Robotham - Chief Engineer}/Std. Rm{William Robotham - Chief Engineer}/Std.5/MH.{M. Huckerby}7.7.38. REDUCTION OF FAN HORSE POWER. We find that the five blade Wraith fan used in conjunction with the "Ferogrip" fan belt as standardised for Wraith, is effective and quiet but loses considerable power at high speeds, (approx. 12 h.p. maximum). It is important that on B.III, at least, we should reduce this power loss and we, therefore, wish to test on what amounts to a variable pitch fan. We think that the most economical way of doing this is to use a fan with flexible blades on the lines of the flexible blade Cadillac fan which we did some tests on two or three years ago. We made some flexible blade fans but used rivetting as the method of attaching the flexible blades to the spider, and had some trouble from cracking. We are now of the opinion that it would be advantageous to endeavour to use the Cadillac method of attaching the blades to the spider by rubber. We hand you herewith two flexible blade fans, one of R.R. manufacture, the other Cadillac. Will you please produce a scheme for a Wraith five blade fan fitted with flexible blades on the lines of the Cadillac fan in question. We wish the number, spacing, pitch etc. of the five blade fan to be retained exactly as the present production fan so that we start from a known basis of cooling and noise. There are various points regarding the design of this fan which Rm{William Robotham - Chief Engineer}/Std. would like to discuss with the person who is drawing this scheme. Rm{William Robotham - Chief Engineer}/Std. | ||