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).
Flight experience and proposed modifications for the Goshawk I carburettor's accelerating pump.
| Identifier | ExFiles\Box 179b\3\ img007 | |
| Date | 4th January 1933 | |
| ORIGINAL H.{Arthur M. Hanbury - Head Complaints} From HE/Pmr. c. to SG.{Arthur F. Sidgreaves - MD} c. to Sor. c. to Rs.{Sir Henry Royce's Secretary} c. to L. c. to RY. c. to EF. x4658. x 3933. HE/Pmr.7/MA.4.1.33. GOSHAWK I CARBURETTAR. ACCELERATING PUMP. Flight experience of the Goshawk carburetter, obtained from Kestrel 11S engine fitted in the P.V. Fury machine, has shown, as we anticipated from test bed results, that the functioning of the accelerating pump is too positive, in such a manner, that even the slowest movement of the throttle operating lever, allows the pump to supply fuel to the engine, and the mixture is richened on progressive throttle movement, to such an extent that when in flight, machine leaves a smoky trail, so long as the throttle is operated. We have carried out further tests in this respect, to avoid emptying the float chamber, when operating the throttle control when machine is standing. We consider now the requirements of the carburetter, are, that no delivery occurs from the accelerating pump on progressive throttle movement, but will respond immediately to any operation, approaching acceleration in advance of the normal metering of the carburetter. Two systems have been tried out statically, one system we used the existing pump with the addition of a light spring between the pump plunger and the plunger seating, with the result that for slow movement of the pump, the plunger will remain off the seat and the fuel will leak past the seating, resulting in the plunger traversing the fuel without exerting pressure. When the pump is operated sharply, the inertia of the plunger overcomes the spring pressure, and the plunger will close to the seating, and function as a pump, so long as the pressure exerted by the pump is greater than the spring pressure. The second system is similar to the "Stromberg" in which the pump plunger is provided with a radial clearance to the bore, to form a permanent leak, and the | ||