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).
Tests to determine the necessary degree of silencing for the Phantom II carburettor air intake.
| Identifier | ExFiles\Box 13\3\ 03-page245 | |
| Date | 22th October 1930 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/AJL. c. to SE. Sor. c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to EY. 87080 PHANTOM II CARBURETTOR SILENCER. We have carried out a series of tests to determine the degree of silencing necessary on the Phantom II carburettor air intake. It has been generally agreed that the latest design of air silencer (Lec.2803) is very much too noisy. The air valve hiss, which occurs at comparatively high engine speeds and large throttle openings, is certainly diminished when compared with the standard carburetter, but the suction noise from the main air intake, noticeable at low speeds when the throttle is opened suddenly, is very much too great considerably worse than standard. The noise is equally bad whether the metal outer tube on the wire gauze cleaner is used. The next previous design (Lec.2786) of silencer was then tested and although slightly quieter this does not give a sufficient degree of silence. To achieve reasonable silence it is found necessary to revert to the original four tube type of silencer shewn on Lec.2734 in conjunction with the large air valve part carburetter as on Lec.2803. The holes in the baffle tubes used are opened out considerably from the original design. the three outer tubes are opened out 33% and the innermost | ||