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).
Letter detailing information and test results for crankshaft torsional vibrations on various models.
| Identifier | ExFiles\Box 6\1\ 01-page126 | |
| Date | 23th April 1928 | |
| X74442 X5010 Expl: Dept: Hs{Lord Ernest Hives - Chair}/Tuhl/LG. 23rd. April 1928. X634 Major Carter, Royal Aircraft Est., St.{Capt. P. R. Strong} Farnborough, Hants. Dear Sir, CRANKSHAFT TORSIONAL VIBRATIONS. We send herewith promised information on crankshaft problems. Attached are : (1) The "turning drawings" of the standard 20 HP. Crankshaft: these are numbered E.54064, T.1, 2, and 3. They illustrate the tests we did on this crankshaft in various stages of machining, of which you have the results. (2) Single-throw drawings for various shafts, of most of which we have already sent you the overall dimensions. All the bearing lengths shewn on these drawings are the short intermediate ones. The crankshafts are : E.18881 - from 1-G-1 engine, an early experimental 20 HP. E.54064 - the standard 20 HP. E.78316 - the standard Phantom. E.78343 - an experimental 'Sports' Phantom shaft subsequently scrapped owing to torsional weakness. E.54640 - new experimental 20 HP. shaft; this embodies the oval webs and the .125" larger dia. journals, and is based on our experience with your stiffness formula. We have not sent you any data on this shaft before. Test results are as follows :- Stiffness in all 7 bearings : 26,100 lbs.ft/Radian. In only two or three bearings: 21,050 which is a drop of 19%. contd :- | ||