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).
Investigation into the cause of injector needle discolouration in an engine, a problem not previously encountered.
| Identifier | ExFiles\Box 179b\3\ img215 | |
| Date | 4th February 1933 | |
| Hs{Lord Ernest Hives - Chair}/Jd.{J. Draper - Frames}1/AM4.2.33 contd. -25- Discolouration of the Injector Needle. This never occurred in C.I.1 and was first noted in C.I.2 when the injector was overheating and at first it was thought to be caused by this but Tests Series 3 show that this is not so. The matter was investigated since it was felt that the discovery of the cause of discolouration might suggest the cause of the sudden power drop and the abnormal functioning of the engine. Laboratory experiments such as heating the needle valve in Airship and gas oil did not produce discolouration but alternating heating valve in oil and then in air did do so. The presence of air was therefore apparently necessary. The conditions in the engine are, however, somewhat different as the oil is under considerable pressure. To investigate the possibility of air entering the injector from the cylinder fuel line pressure indicator diagrams were taken which showed that at a static injector setting of 3000 lbs/sq.in. and using a Bosch unloading delivery valve, air might enter at the trough of the pressure surge if the inertia of the needle valve was sufficient to prevent sufficiently rapid closing. The possibility was, however, rather remote. Changing from Airship to Persian gas oil had no marked effect on discolouration. It was subsequently found that discolouration occurred even when the injector was adequately cooled. The cause of the discolouration is not fully understood. Hs{Lord Ernest Hives - Chair}/Jd.{J. Draper - Frames} | ||