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).
Cause of induction noise in the Goshawk 11 engine, comparing it to the 40/50 HP chassis.
| Identifier | Morton\M1.1\ img065 | |
| Date | 30th September 1921 | |
| 20 240/50 Not a fair comparison ORIGINAL To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to K.{Mr Kilner} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer}- c. to Wor.{Arthur Wormald - General Works Manager}- c. to EP.{G. Eric Platford - Chief Quality Engineer}- X4219 X2566 "GOSHAWK 11". Now that we have silenced the exhaust considerably and overcome the crankshaft periods, we find there is a large volume of noise coming from the induction system, in fact at high speeds, it is a roar. We find that the noise is there if we switch off the ignition and keep the throttle wide open. We have tried fitting another carburetter; we have fitted the Claudel. The noise, if anything, with this carburetter fitted, is worse. We have made comparative tests with a 40/50 chassis. There is no doubt whatever on the 40/50 H.P. we get no roar from the induction system, the noise we get is a swishing noise which is not objectionable. As we have no facilities for driving the engine with a motor, we made a test on the road towing both the Goshawk and the 40/50 chassis. We find that on the Goshawk the noise is there if we remove the carburetter altogether or if we remove the induction pipe altogether. With the carburetter fitted, it is the quietest condition. The most noticeable feature in comparing the two cars is the fact that the 40/50 H.P. carburetter reduces the volume of noise caused by the suction of that engine to a very much greater degree than the Goshawk Carburetter does on its engine. The only reason we can see for this is the difference in the two types of throttle. We can produce the noise on the Test Bench. We are therefore, making contd:- | ||