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).
Results of experiments on a 25 HP exhaust system to reduce noise.
| Identifier | ExFiles\Box 104\2\ scan0111 | |
| Date | 17th September 1934 | |
| To By.{R.W. Bailey - Chief Engineer} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} X5230 Hs{Lord Ernest Hives - Chair}/Wym.{G. Harold Whyman - Experimental Manager}3/KW.17.9.34. 25 HP. Exhaust System. We have now concluded a number of experiments on 20-G-IV with the 25 HP. Exhaust System, and consider that we have effected a considerable improvement generally; i.e., reduced the amount of noise emitted from the tail pipe, reduced the "titter" from the front of the exhaust system, and practically eliminated all traces of "boom" throughout the whole range of the car. All of our modifications are shown on drawings Hs.{Lord Ernest Hives - Chair}1436 and Hs.{Lord Ernest Hives - Chair}1514, and we recommend this scheme for production. Our experiments have shown us that with regard to "boom" periods, the chief factors are the front expansion box and the extreme rear end of the rear silencer, and the tail pipe noise is mainly affected by the continuity or otherwise of the centre pipe in the rear silencer, and in any future experiments to still further improve the exhaust system, these are the main factors to bear in mind. Hs{Lord Ernest Hives - Chair}/G.H.Whyman. | ||