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).
Experiments on various fan designs, analysing blade shape, curves, and overall performance.
| Identifier | ExFiles\Box 75\3\ scan0210 | |
| Date | 1st February 1925 guessed | |
| EFCL/T9.2.25. -3- Contd. as the Hispano, or as the others, the blades being apparently too narrow. Passing over No.25, we then arrived at a fan No.26, similar to No.22 but rather better as regards the leading edges of the blades, and finally we had a last fan made up similar to this one, a the curves for which, though similar, were still slightly better. These curves are labelled 27. The curves for the previous one No.26 lie roughly in between those for No.22 and No.27. From our experiments we think that No.27 is representative of the best performance that can be attained by fans constructed from sheet material in this manner and of this 18" tip diameter. We have two of these fans, Nos. 26 and 27 - nearly alike. We are asking for these to be put on 20 HP. chassis, first of all submitting the better one, No.27, to the D.O. for taking particulars of the actual shape. Following this our attention will be again given to the final improvement in efficiency of the EAC. fan. Further Note. A point worth recording is that within limits, the leading edge of the fan remaining the same, a slightly greater or less radius of the fan blade, though it materially alters the speed necessary to produce a given thrust, does not seriously alter the power required to do so. It appears from our tests that the leading edge of the fan is of main importance from the point of view of efficiency and the trailing edge from the point of view of | ||