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, mixture control modifications, and flight test results.
| Identifier | ExFiles\Box 179\2\ img286 | |
| Date | 23th February 1932 | |
| -2- Their criticism was that while it was some 20% richer than weakest maintained at full throttle the consumption at throttled loads - over the cruising range - was weaker than weakest maintained and therefore giving greater economy. I pointed out that this was a very desirable characteristic providing the engine operation - opening up, smooth running, etc - was unaffected by the economical cruising mixture. This they agreed as they had proved in flight that the engine operation was unaffected. I admitted that the full throttle consumption with the mixture control full strong was a little higher than we desired but we were unable to alter it without extensive modifications which could not be ready for application to the present orders of unsupercharged engines. The metering characteristics of this carburetter are no different to the present std. model. Decision whether or not to use the new model carburetter actually depends upon Penn's report of flight tests and his recommendation to Major Bulman. I suggested that the question resolved itself into deciding if the other features - improved slow running and idling, non-susceptibility to intakes and preservation of test bed tuning, better heating and more positive A.C. justified the change while accepting that the metering was little different to the present standard which in our opinion was a good characteristic for cruising economy. He agreed that these carburetters were a distinct improvement over the present std and his report to Major Bulman would be on these lines. Penn showed me their automatic mixture control which is certainly an extremely neat and light unit - it weighs only 2 lbs. I asked if we could have one of these units for tests on the "3F" and he is keen for us to do some tests and consequently has laid one of these units on one side for us. It will first of all be necessary to obtain Mr. Wood's approval which I suggest we should do without delay as I understand Siddeleys are having trouble with the hopes of improving their service consumptions. I have obtained a drawing of the automatic mixture control showing how this can be fitted up on the Kestrel engine. Farnborough criticised the weight of our automatic boost control and suggested that it could be appreciably lightened. | ||