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).
Letter proposing a new electrical speedometer for potential use in motor-cars and aero engines.
| Identifier | ExFiles\Box 165\4\ img206 | |
| Date | 14th July 1933 | |
| COPY 11, Cranbrook Road, Redland, BRISTOL, 6. 14/7/33 Col. L.F.R.Pell, Rolls-Royce, Ltd., 14/15, Conduit St.{Capt. P. R. Strong}, London, W.1. Dear Sir, I have been referred to you by the Bristol Aeroplane Co., with whose assistance, and that of the Professor of Automobile engineering, Bristol University, I have been for some months experimenting on a new type of electrical speedometer. A description of the properties of this instrument is given in the accompanying pamphlet, from which it will be seen that the above possesses very considerable advantages, both as an engine revolution indicator for use in aircraft and as a speedometer in large motor-cars, over anything at present on the market. In the former case an outstanding and unique feature is that the instrument requires no flexible connection to the engine nor electrical generator geared thereto, but is worked by tapping an infinitesimal amount of power from the magneto, the normal functioning of which is not affected thereby. In the application as a speedometer in motor-cars also the instrument is simpler and cheaper than any existing electrical tachometer and possesses no delicate parts such as springs, commutators, etc. Also the response is not affected in any way by vibration such as usually causes an ordinary electrical tachometer to develop an error after considerable usage (due to the loss of strength in the permanent magneto of this generator). It would be of considerable assistance to me in arranging for the commercial manufacture of this instrument if you could inform me whether your Company would be interested in such an instrument for application in your motor-cars and in connection with your aero engines. I should be therefore greatly obliged if you could let me know your views on this matter. Thanking you in anticipation. I remain, Sir, Yours faithfully, W. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} BIRD. | ||