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).
Engine and temperature tests on 'Sinterkorund' insulated sparking plugs, including conclusions on performance and deterioration.
| Identifier | ExFiles\Box 58\2\ Scan077 | |
| Date | 3rd May 1934 guessed | |
| 5. E&I.827. With the exception of type A.G.20 No.1 there was a general increase in gas leakage. 7. Engine tests. Two of each type (A.G.10, 20 and 30) "Sinterkorund" insulated sparking plugs were fitted in a "Jupiter" VI on the bench. The plug gaps had previously been set to 0.012" and each plug had completed satisfactorily the test for sparking at 100 lb.per sq.inch air pressure. The compression ratio of the engine was 5 . 3/1, R.P.M. 1550, H.P. 400, fuel D.T.D. Specification No.134. The time run was 11 hours 40 minutes and the plugs functioned satisfactorily throughout the period. Examination of the plugs subsequent to the engine run showed that their condition was reasonably good. 8. Temperature tests on the "Sinterkorund" insulator. The effect of temperature upon the material was investigated. The range of temperature was from atmospheric to 350°C. No change in the insulation resistance occurred which remained constant at infinity as measured by 1000 volt megger. As regards the thermal cracking test the material remained unaffected up to 300°C. At 350°C. however, small cracks were observed at the terminal end of the "Sinterkorund" insulator. In the thermal cracking test the specimen is heated in a muffle and at specified temperatures it is plunged into cold water coloured with red pigment so that any cracking may easily be observed. 9. Conclusions. (a) This type of sparking plug functioned satisfactorily in the "Mercury" V single cylinder unit but the pre-ignition limit was found to be lower than that of standard aero sparking plugs. The gas leakage subsequent to the engine tests in the "Mercury" V showed an increase in the majority of the plugs. The leakage was from the top of the "Sinterkorund" insulator around the plug terminal showing that the cementation of the central electrode deteriorates with use. | ||