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).
Investigating 'boom' and vibration issues on a Phantom II car, 27-EX.
| Identifier | ExFiles\Box 182\M19\ img135 | |
| Date | 31th March 1931 | |
| ORIGINAL To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to PH. By.{R.W. Bailey - Chief Engineer} c. to E.{Mr Elliott - Chief Engineer} Hs.{Lord Ernest Hives - Chair}9/WJ.31.3.31. x634. PHANTOM II BODY BOOMS. We have 27-EX. car running fitted with a new crankshaft with stiffer flange, flywheel with stiffened flange, and the four balance weights. This car, with its original standard engine, was a bad example of the characteristic 'boom' which is being complained of. Fitting the new parts to the engine (as mentioned above) did not improve the car for booms in the least but it did cause the engine to be abnormally rought at high speeds. We have since run this car with the balance weight removed and find it to be very much better. We are going into the question of whether or not some error has been made on these balance weights because whenever we have tried complete balancing with twelve balance weights we have never noticed this difference. The results on this car have been rather held up owing to the fact that this same car is fitted with the new gearbox with the third speed Epicyclic (It was the car which we intended should be sent to Le CanadelHenry Royce's French residence). The gearbox has given us a fair amount of trouble, as you will see from a separate report, which means that the car has been out of use for a considerable time. Since we have removed the balance weights we think that 27-EX. car is above the average for smoothness at very high speeds. That is, we may be gaining some advantage from the modification to the crankshaft and flywheel, but what we want to make perfectly clear is that this improvement if it is confirmed and proved is not such that it would help us to overcome the complaints we are getting. We are keeping our investigations at the moment confined to the difference between Phantom I and Phantom II. Phantom I engine, we are all agreed, actually vibrates more when it is run up with the car stationary and also with the car on the road, but it does not boom. Hs.{Lord Ernest Hives - Chair} | ||