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).
Carburettor performance, discussing fuel boiling, and a review of the Bendix-Stromberg carburettor.
| Identifier | ExFiles\Box 27\3\ Scan231 | |
| Date | 15th May 1939 guessed | |
| 25. Over a wider range it weakens at the low speed end and richens at higher speed. There has also been serious trouble through boiling of the fuel - but I was told that this had been made use of to give altitude correction. Good reports were heard of the Bendix-Stromberg carburettor. Mr Hobbs is pleased with it, and it appears to have created a good impression everywhere. Mr Mock of Bendix-Stromberg said that the Army and Navy were so enthusiastic about it that they wanted it on Wright engines also. Mr Hobbs's two reasons for adopting the carburettor were its non-icing characteristics, and its suitability for aerobatics. With the fleet type carburettor he had found that on tipping into a dive the engine was inclined to cut out as the negative acceleration pushed the air through the fuel as they changed places in the float chamber. The Bendix-Stromberg carburettor is fully automatic, and has to reproduce a given curve within 1%. It operates by metering the fuel through fixed jets with a pressure head which is equal to the difference between the air intake and a small venturi which is placed in the main carburettor venturi. This pressure difference acts on an air diaphragm which is connected to a fuel diaphragm in parallel with the metering jets, so that the head across the jets is always equal to the air pressure difference. In addition there is a control unit giving enrichment for idling, rich and weak automatic settings for cruising, and automatic enrichment for take-off. The metered fuel is injected into the eye of the impellor of Pratt & Whitney engines. It will be remembered that the impellor on these engines is overhung, so that the injection nozzle is set to spray fuel on the boss of the impellor. An injection pressure of about 5 lbs/sq.in. is used. | ||