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).
Engine vibration, stiffness, and V-angle design for both aeroplane and car applications.
| Identifier | ExFiles\Box 137\4\ scan0039 | |
| Date | 6th October 1929 guessed | |
| -3- know where to add the stiffness. Alternative (1) would probably increase the weight of the engine a lot. We feel inclined to recommend the second alternative, namely the damped spring drive. If the period were reduced to say 1500 R.P.M. the throttle would never be wide open at this speed with a prop. fitted and the vibration would never be serious. It would involve less extra weight. It should also help to reduce prop. and reduction gear vibrations, always undesirable in a private aeroplane, and should also improve the smoothness and freedom from torque-reaction vibrations. In considering the two alternatives it would be advisable to know more closely where the period is likely to be. If the engine were to be fitted in a car, and the reduction gear omitted and a flywheel fitted, it would be easy to work out the required stiffness of the crankshaft, as the case would then be similar to our car engines. If the V-angle of the engine were made 45°, we believe the 4-per-rev. period would vanish. This would interfere somewhat with the balance and the even firing impulses. Some cars such as the Lincoln, are now made with a 30° V-angle, to help with torsional vibration periods. We are going more closely into the mathematics of this and will give in a subsequent report the speeds at which lower periods could be expected, and also the effect | ||