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).
Hispano engine mountings and a detailed analysis of the Bristol 'Mercury' engine.
| Identifier | WestWitteringFiles\V\December1930-February1931\ Scan036 | |
| Date | 20th December 1930 | |
| -6- Engine Mounting. The Hispano engine is carried by a flange formed by the top half of the crankcase and extending the whole length of the engine. In the Breguet Bomber the engine was bolted to a longeron by ten spring loaded bolts on each side. I could not see what provision was made for crankcase expansion. ENGINES. The best French engine appears to be the Hispano and a description of some interesting details and manufacture will be given in a report of a visit I made to the Hispano Suiza factory at Bois-Colombes. Bristol "Mercury". An interesting engine was the supercharged "Mercury" rated at 530 B.H.P. at 13000 ft. and 2000 R.P.M. Weight with reduction gear = 930 lbs. Bore 146 m/m.{Mr Moon / Mr Moore} Stroke 190 m/m.{Mr Moon / Mr Moore} The equivalent H.P. of this engine at ground level unsupercharged is stated to be 850 H.P. Diam. of engine 4.58 ft. It was fitted with a very neat automatic Boost Control. The actual carburetter throttles were operated by a double link which was controlled by the boost relay piston so that the equivalent length of connection between the hand control and throttles could be varied by the raising or falling of the relay piston. The carburetters were considerably altered in appearance to the usual Bristol "Triplex" and looked more like our supercharger carburetters. One large accelerating pump of roughly over 1" bore was situated at the side of the carburetter and connected with the throttles. We understand that this carburetter includes a richening up scheme when using max. take off boost to reduce detonation and have heard that under these conditions they run as rich as .7 pts/BHP/Hr. The scheme appeared a diffuser air or vacuum control but the method of operation and way of obtaining max. take off boost could not be seen as all the control rods were not fitted. The Bristol bevel type reduction gear was used and it was noticed that the rotating bevel wheel was larger diam. than the fixed bevel gear while the revolving planetary bevels had their axes inclined. This is to give a reduction higher than the usual .5 ratio. The carburetters were provided with a hot air intake drawing hot air from the cylinder fins. The valve springs of this engine were enclosed in telescopic cases. | ||