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).
Battery ignition issues on the Goshawk engine, specifically the 'Neinst' effect on porcelain conductivity at high temperatures.
| Identifier | ExFiles\Box 54\5\ Scan213 | |
| Date | 31th October 1922 | |
| X.3485. PNL/DN/31.10.22. TO EFC. {E. Fowler Clarke - Electrical Engineer} c. to R. {Sir Henry Royce} & E. {Mr Elliott - Chief Engineer} c. " CJ. c. " Hy. {Tom Haldenby - Plant Engineer} c. " TP. c. " Da. {Bernard Day - Chassis Design} FROM PN. {Mr Northey} X. 3485 RE BATTERY IGNITION ON GOSHAWK. With reference to your EFC {E. Fowler Clarke - Electrical Engineer} 1/T28.10.22, it would be interesting to know whether it has occurred to you that some of the troubles you speak of, which appear to arise only at times of highest temperature of engine, may conceivably be traced to the " Neinst" effect, i.e., that the porcelain or insulating material becomes comparatively a good conductor at the higher temperatures. Many years ago I carried out a great number of experiments on these lines and it was very marked that at a definite point of temperature-rise, all the porcelains then available became sufficiently conductive to enable misfiring to take place at times of full compression. The effect is of course practically that the porcelain constitutes itself a parallel circuit with the spark gap and it's only what one would expect that after reducing the ballast resistance and thereby increasing the amount of Watts passing, the degree of misfiring would become reduced. In experiments I made, the sparking plugs to be tested were fitted into a container representing the clearance of a combustion chamber, into which air was pumped to any degree of desired pressure, and a blow-lamp was erected to heat the plug in this position. It is instructive also to carry out this experiment in the dark, enabling in this way the amount of brush discharge between the terminal of the plug and its earthed portion, to be plainly seen. Probably certain porcelains are more affected as to their specific conductivity by variations of temperature than others, and I merely propose this as a line of thought. PN. {Mr Northey} [STAMP: RECEIVED Hs {Lord Ernest Hives - Chair} NOV 1 1922] | ||