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).
Modifications to the 'Goshawk II' carburettor to reduce noise and improve floatchamber performance.
| Identifier | WestWitteringFiles\G\October1921\ Scan64 | |
| Date | 1st October 1921 | |
| To HS.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} Copy to CJ. " " WOR.{Arthur Wormald - General Works Manager} " " DA.{Bernard Day - Chassis Design} " " BY.{R.W. Bailey - Chief Engineer} ORIGINAL. RE "GOSHAWK II" CARBURETTOR. X4228 With regard to the reported noisy intake of "Goshawk II", we felt sure that this would be proved to be due to the double ports and the air blowing over the sharp edge when entering one port with the other valve closed. Though this often occurs in nearly all multiple cylinder engines, it may not be so bad as in the particular head we have designed. We have sent you a drawing shewing how this can be altered, and we feel sure that this alteration should result in at least slightly reducing the noise. At the same time we have completed the design of the carburettor fitted with a silencer which can be used should it be advantageous. Some improvements have been made while altering the carburettor, such as the length of the stroke of the air valve, which should give the experimenter a better chance of varying the ports to get the mixture absolutely equal at all speeds and throttle openings. Regarding your trouble with the floatchamber, we are sure this was merely due to the float being made of too thick material, and therefore too heavy, but at the same time we have increased the diameter of this chamber and float so as to make it easier to get right and its action more vigorous. At the side of this chamber we have arranged a small carburettor with a moving throat, similar to the starting carburettor that you suggested should be put on the 40/50 H.P. We are not proposing to use this small jet, except for starting, so that it can be hand adjusted strong enough to always give a satisfactory start. We are pleased to hear that you could get quite satisfactory slow running with the usual low speed jet of the main carburettor, and we think that with suitable control from the steering wheel arranged to move the butterfly throttle | ||