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).
Comparing the design, complexity, and efficiency of a proprietary air silencer against a Packard equivalent.
| Identifier | ExFiles\Box 104\2\ scan0171 | |
| Date | 4th February 1936 | |
| X523 To H.{Arthur M. Hanbury - Head Complaints} C. to FCR. C. to By.{R.W. Bailey - Chief Engineer} C. to Da.{Bernard Day - Chassis Design} C. to RMC. C. to Sft.{Mr Swift} In reply to the rather caustic comments contained in memo. Sft{Mr Swift}/Set.1/RM.{William Robotham - Chief Engineer}20.12.35. regarding the apparent simplicity of the Packard air silencer as compared with the complicated and expensive Rolls-Royce air silencer, I attach herewith a photograph of both articles, sectioned. An examination of the photograph definitely gives the lie to the so-called complicated design of the Rolls-Royce product and the simplicity of the Packard design, in fact, we think the idioms should be reversed, and it is quite comprehensible why the research department and others foster such designs as our air silencer (see paragraph 4 of article on air silencer contained in above memo.) We use only one centre tube and 3 simple baffles, whilst the so-called simple Packard one contains a centre tube, 3 other tubes, and 4 baffles, the top one of which is complicated in shape. The assembly of this silencer other than by American methods permissible due to quantities would be infinitely more expensive than our own. With regard to the criticism of mounting the silencer, we would point out that this is governed by the shape of the carburetter intake, hence the 3 different mountings for Bentley, 25 HP. and Ph.III. Incidentally, the Packard silencer is not a one-piece fixing. It has a strengthening stay fitted, similar to our own, from the outside shell to the cylinder head. We consider the only reasonable criticism that can be levelled at the R.R. air silencer is the size of it, but this again is governed by B.H.P. loss and efficiency, and whilst we get no horse power loss and 100% efficiency of silence, the Packard has a B.H.P. loss of 8 and only 70% of silence efficiency. Ha/C.H.Whyman. | ||