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 endurance test detailing power output, cylinder detonation, piston and sleeve wear, and jointing material performance.
| Identifier | ExFiles\Box 178\4\ img093 | |
| Date | 18th May 1932 | |
| (2) light load, it was opened up to full throttle to check the power, this was 516 c/BHP @ 2250 RPM. Detonation was not observed on this run since the engine was running with open exhausts. On the endurance test A.6. cylinder could be heard detonating during the 90% power running. At full throttle a detonation intensity of 'Z'100 was recorded, but A.6. cylinder did not appear to be any worse than the others. Power at full throttle on the last 5 mins. was 504 c/BHP. at 2250 RPM. which was 12 BHP. down on that at the beginning of the run. When the engine was stripped, A 6. cylinder head and piston were found to be showing signs of heavy detonation, the piston being burnt so badly as to scrap it, furthermore, the crown had started to collapse. Evidence of a lesser degree of detonation was present on A.1., and A.4. pistons and cylinder heads. The attached photograph shows the three pistons and heads, and it will be seen that the detonation effects occur on the inlet side of the diameter at approximately 90° to the gudgeon pin centre line. All the rest of the parts were in normal condition - the stiffening of the cylinder walls around the ports had not improved the sleeve bedding - except A.6. sleeve which was slightly scored opposite the burnt portion of the piston, and appeared to have been driven into the ports by the gas pressures; quite a visible amount of wear had taken place where the sleeve moves adjacent to the horizontal - top edge - of the ports during the approximately rotary portion of its travel. This characteristic was evident to a slight degree on all the other sleeves and the possibility of sleeve failure at this point after prolonged running should be considered. Conclusions. The new water header auxiliary securing studs made it possible to obtain a much better water joint between the header and the cylinder block, and no trouble with leaking was experienced during the 2 hours test. Langite was used for the jointing material, but this was not entirely satisfactory, as at the end of the run it was seen to be standing proud of the face, and when the header was removed the langite had the appearance of having collapsed under the load which had been put on it. For future tests it has been decided to revert to the Vellumoid jointing material. As regards the detonation and the scrapping of A.6. piston. The cause of the failure of A.6. piston during the attempted Type Test on 25.11.31. is now known. The photograph appended hereto shows the A.6. pistons from each test, side by side. The similarity of the nature and position of the burning | ||