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).
Instructions from Mr. Royce on an experiment for the 'SS' exhaust silencer, detailing the arrangement of baffles and holes.
| Identifier | ExFiles\Box 14\6\ Scan078 | |
| Date | 1st May 1929 | |
| Hs.{Lord Ernest Hives - Chair} from DA.{Bernard Day - Chassis Design} X. 7230 DAL/ML. 5. 29. 'SS{S. Smith}' EXHAUST SILENCER. Mr. Royce would like you to experiment with the SS.{S. Smith} silencer in the following way : (we have no details of the SS.{S. Smith} silencer, and therefore have referred to the Phantom, but the same principle applies.) Referring to E.74339 the .312 holes appear to be made by indexing a multiple punch. As far as we can see there are four indexes, the fourth one taking out only four holes. What Mr. Royce would like you to do is to arrange the baffles in the silencer, of which there are at the moment four, so that the front one has the full number of holes, (58 in the case of the Phantom, representing about 80% of the area through the main pipe.) The next two baffles would have two indexes only (because the fourth index appears to take out only a few holes) giving 36 holes, roughly half the area of the main pipe. The last baffle towards the rear has 18 holes only, giving an area slightly in excess of the fishtail at the rear. The object is to give an increasing restriction as the gas cools down and loses its velocity. Should this idea possess any merits then it is suggested it should be extended by increasing the number of baffles, varying the holes in the same way. We shall shortly be sending you an exhaust system for the 20 HP. on the lines of the SS.{S. Smith}, and any information you can give us as a result of experiments in the meanwhile will be useful. DA{Bernard Day - Chassis Design}, | ||