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).
Adjusting blade settings and pitch angles to resolve engine vibration.
| Identifier | WestWitteringFiles\N\July1925-September1925\ Scan86 | |
| Date | 15th August 1925 | |
| R.R. 493A (50 H) (D.D. 31, 12-6-25) J.H.D. EXPERIMENTAL REPORT. -3- Expl. No. REF Hs{Lord Ernest Hives - Chair}/TAG/LG15.8.25. of one of the blades, an intermediate was struck, at which the engine ran as smoothly as could be desired. In this case the blade settings at the Hub scale No.1. 0o No.2. +2o Pitch angle No.1. 19o No.2. 21o which gave 1840 r.p.m. at full throttle. The blades were then set at +1 & +1 on the hub scale and the angles were 19.5o & 20o. The results of this was, that the vibration was very bad. The discrepancy in the engraving of the hub scale made the difference in the variation of the pitch angle. One of the blades was then moved until the pitch angles were 19.5o and 21.5o and the vibration disappeared. Various blade settings were tried with similar results as the examples given above. The settings were altered to read:- Hub scale No.1 +1o No.2 +3o Pitch angle No.1 19.5o No.2 22o R.P.M. 1750 ----------------- Hub scale No.1 +2o No.2 +4o Pitch angle No.1 21o No.2 23o R.P.M. 1700 contd :- | ||