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).
The Smith Variable Pitch Propeller and electrical generator requirements.
| Identifier | ExFiles\Box 179\3\ img148 | |
| Date | 4th April 1932 | |
| -7- (4) Smith Variable Pitch Propeller. We consider that this is by far the most promising of the four, in spite of the fact that it is the last to come upon the scene. It has been developed in conjunction with the hollow steel blade. Its principle is that a worm fixed to the crankcase or gear nose of the engine can be moved into contact with a screw thread which is rotating with the hub. The screw thread then varies the blade angle through a simple reduction gear. The piece which fits on the nose of the engine is exceedingly simple and there is no need to alter any part of the engine. The propeller blades are controllable through a 360° angle. The operating controls only have to work with a load of about 3 lbs. The Smith propeller has as yet been manufactured only in a few sizes and these are for un-geared engines, but the 500 HP. size only weighs 120 lbs. The interest being taken in propellers throughout the Government research departments is very noticeable. At Wright Field they have most elaborate equipment for measuring blade deflection under load, whirling tests etc. At Langley Field they can measure propeller performance under client test conditions in the full size wind tunnel (throat 60 ft. x 30 ft.) and they also have a high speed tunnel where velocities up to the speed of sound can be produced. Generally speaking, the Admiralty, Wright Field and Anacostia, - the latter corresponds to our Felixstowe - are all highly enthusiastic about this propeller. It has passed its whirling and overload tests and is now undergoing endurance tests on various machines. ELECTRICAL EQUIPMENT. Generators. They have three main requirements to cater for :- (a) Simple generator required for L.T. current for the battery. (b) L.T. generator required for the battery and H.T. current for the wireless. (c) As (b) but the H.T. generator being capable of being driven off the battery after a forced landing so that wireless can be used. | ||