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).
Fan modifications and the resulting power-thrust curves.
| Identifier | ExFiles\Box 75\3\ scan0064 | |
| Date | 20th March 1925 | |
| R.R. 493A (50m) (D.B. 175 25-9-24) J.H.D. -3- EXPERIMENTAL REPORT. Contd. Expl. No. REF: EFC3/T20.3.25. Subsequently we have experimented with another fan with which we started with the blades very wide, and the variations on this fan are represented by (16), (17) and (18), though in the cases of (16) and (17) only pairs of points are given. For our finally approved fan, No.18, the whole curve is given. Without going into further details, the progressive modifications have been (a) cutting away the leading edge, (b) varying the angle of attack of the leading edge, and (c) varying the curvature of the blade, and our observations, contained in EFC1/T9.2.25, on the effects of such procedures in the case of the 20 HP. fan, have been confirmed in this EAC. case. In our conception the first desideratum with regard to this fan problem is to obtain a low power-thrust curve (see sheet H) and our experiments show that the leading edge of the blade is of principal consequence in this connection. This being the case, fans Nos. 1, 3, 9 and 16 would be ruled out, and 10, 14, 15, 17 and 18 kept in for further consideration. The second desideratum would appear to be subsequently to choose that fan of this selection, which for a similar power-thrust curve, gives the lowest speed-thrust curve. Contd. | ||