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).
The testing and failure analysis of Aerolite pistons, detailing two separate tests and modifications made between them.
| Identifier | ExFiles\Box 86\2\ scan0140 | |
| Date | 8th November 1933 | |
| X296. To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} C. Wor.{Arthur Wormald - General Works Manager} By.{R.W. Bailey - Chief Engineer} C. MX.{John H Maddocks - Chief Proving Officer} AEROLITE PISTONS. The makers of these pistons supply M.G's who have had a remarkable run of racing successes. We have had a few thousand miles experience of them on an Alvis. In view of our troubles we obtained two sets. As with our own pistons, it is difficult to get the correct grinding form first time. However the set supplied were not very far out, a slight amount of hand bedding overcoming the initial tendency to seize which was accentuated by an over effective scraper ring. We ran them 21 hrs, at 4000, 4250, and 4500 R.P.M. and broke the engine crankcase. The pistons were O.K. except for a small crack in one skirt due to the form grinding being initially incorrect and causing a partial seizure. In view of the promise shown, we obtained a further set having the following modifications :- (A) Correct form grinding to overcome the initial difficulty of poor bedding. (B) Reduction in weight. The original Aerolite weighed 20% more than our own piston. The second design in R.R.T.50 alloy complete with rings and pin will be almost exactly the same weight as the latest strengthened split skirt R.R. to EB.1299. We have now run these pistons for nineteen hours at speeds of from 4000-4500 R.P.M., full throttle. During the test we broke the slipper wheel central plate. We again broke the crankcase, and also a valve head came adrift which smashed one of the pistons, but the remaining five showed no signs of cracks. After about fourteen hours there was a slight cold piston knock on No.3. cyl. but this did not get | ||