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).
Exhaust silencer design, noise, and vibration issues.
| Identifier | ExFiles\Box 173\1\ img288 | |
| Date | 12th February 1934 guessed | |
| IV Silencer is four times that of the cylinder swept volume ③ They use conical baffles in the silencer, a push fit on the outside dia, and are not troubled with "Clicking" on cooling. They get their worst clicking from the movement of the exhaust manifold. ④ They get silence with 2.5 lbs/[]" 'back' pressure at 3000 R.P.M. of which 1.5 lbs is due to the skin friction in the down take & tail pipe apart from the silencer. ⑤ They too are troubled with "Shell Noise". They find it is reduced if they use the largest practical dia of pipe from the manifold to the silencer. On the 12 this is 2 1/8 O.D. and .062 thick. ⑥ They think one reason why we may have failed to get away without a front expansion box is pipe vibration. They find flexible mountings a very variable asset and frequently have to clamp certain of the pipe sections very rigidly to eliminate a vibration that sounds exactly like a boom. They tie the | ||