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).
Carburetter design, including diffuser flooding, accelerating pumps, and future development for supercharged aero engines.
| Identifier | Morton\M19\ img066 | |
| Date | 7th May 1931 | |
| - 2 - of the needle valve and so allowing a straight passage of fuel through the carburetter. Slight diffuser flooding under certain conditions probably takes place on a good many carburetters, but we think this would be relatively unimportant when the engine was running. Flooding due to the needle valve opening, however, could be dangerous due to the quantity of petrol passing. Accelerating pumps are now practically universal on both car and aero carburetters. Previous to their use it was necessary to use high fuel levels in the diffusers to obtain anything like reasonable "snap" open- ing up. In order to cater for varying angles of tilt and avoid flooding with the high level, twin floats were employed, but now the tendency appears to be to return to single floats, lower levels, and depend upon the accel- erator pump for opening up. Strombergs and Bristols are amongst those now using accelerator pumps. One advantage is that it leaves the diffuser free to look after the metering, whereas a good economical diffuser is not in itself always good for acceleration. For future development we think it may be useful to look into the question of simplified float chambers and accelerator pumps for our supercharged aero engines. We are preparing some sketches of some of the novel points of the Zenith carburetter. Ha/Lov.{Mr Lovesey} | ||