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).
The development of an air intake silencer for the Phantom II twin choke carburettor.
| Identifier | ExFiles\Box 182\M19\ img218 | |
| Date | 2nd August 1931 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} Hy.{Tom Haldenby - Plant Engineer} Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey}/AM2.8.31. Y7080. ORIGINAL P.II. TWIN CHOKE CARBURETTER, AIR INTAKE SILENCER. We attach particulars of an air intake silencer which we have evolved for the P.II twin choke carburetter. Various sizes of silencer and numbers of baffles were tried; the one illustrated being found to give the best results. The power loss as compared with a perfectly free air intake is negligible - 2 B.H.P. at 3000 R.P.M., whilst from the point of view of silence it is very good. If we use an additional inner tube we gain still more in silence, but immediately loose considerable power, more than is warranted by the improvement in silencing. We find that the biggest factor necessary to achieve silence without power loss is to make the silencer as large as possible, by this means we need not use restricted areas of baffles and so do not lose any appreciable power. The results obtained indicate that it is possible to silence effectively the air intake on the twin choke carburetter. The silencer is effective when using a standard Phantom II camshaft and also with the latest experimental camshaft to Lec.2919 (120° between cams). Neither of these two camshafts produce air intake roaring such as was experienced when the 110° R.{Sir Henry Royce} engine type cam form camshaft was used; we did not use the air silencer in conjunction with this latter camshaft, and we doubt whether it would be capable of suppressing the intake roar. Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} Print attached. | ||