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 to Major Carter at the Royal Aircraft Establishment regarding crankshaft stiffness, torsional vibrations, and V-8 engines.
| Identifier | ExFiles\Box 63\4\ scan0092 | |
| Date | 19th October 1929 | |
| X 4499. Hs{Lord Ernest Hives - Chair}/Tsn3/AD. 19th October, 1929. Major Carter, Royal Aircraft Establishment, South Farnborough, Hants. Dear Major Carter, Crankshafts. The attached print shows another shaft we have twisted recently. The stiffness per crank is 2.850 x 10⁶ lbs.ins/rad., against a calculated value by formula of 3.020 x 10⁶. The ratio calc./test is 1.06, which is rather closer agreement than we have been getting recently. The shaft has the same nose as E.54064 and the same lengths of journal bearings as E.54601, in the tables I sent you with my last letter. I have been comparing certain types of engines as regards liability to torsional vibrations recently, and was rather struck with the possibility of the V-8 type for a small aero engine. This appears satisfactory for C.T.V. in a car, where they manage to get enough stiffness to raise the 4-per-rev. period above the normal speed range. In an aero engine, with a reduction gear fitted, I believe enough stiffness would not be attainable. We have found, as I believe I told you once, that the reduction gear reduces the stiffness of the crankshaft by 50%. I should be glad therefore if you could tell me of any instances you know of 8-cyl. V type engines having trouble with this period. I believe the Hispanos during the War were so troubled. possibly you may have heard something of the air-cooled V-8 introduced by De Havilland some time ago. Yours sincerely, | ||