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).
Valve spring failures in service on Kestrel II S engines and the proposed solution.
| Identifier | ExFiles\Box 179\3\ img095 | |
| Date | 23th March 1932 | |
| ORIGINAL To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/LBH.{Mr Hall - Aero Design Engineer} c. to Rg.{Mr Rowledge} Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to HY.{Tom Haldenby - Plant Engineer} c. to Mr. Jaques. Hs{Lord Ernest Hives - Chair}/LBH.{Mr Hall - Aero Design Engineer}1/WJ.23.3.32. x3832. VALVE SPRING FAILURES IN SERVICE. KESTREL 11 S ENGINES. We are having trouble with valve spring failures on the 'Kestrel' 11 S engines fitted to the 'Fury' machines with 43 Squadron at Tangmere Samples of the broken springs have been examined at the Works and no defect could be found with the material. The frequency and extent of the breakages clearly indicate that engine speeds, in excess of those which the springs are safe, are commonly reached. The present standard springs outer to E.29832/1 and inner to E.29833/1, are not suitable for engine speeds approaching 3000 R.P.M., and with this Squadron of fighting machines there is little doubt that these speeds are frequently occurring during fast dives. This being so, if we are to avoid further trouble, stronger springs will have to be fitted. We have valve springs (outer to E.31025/1 and inner to E.31026/1) specially-designed for high speed work up to 3200 R.P.M. These springs have proved entirely successful for high speed running on development engines and have been Type Tested and standardised. Due to their greater diameter, the springs require new top washers and valve guides, which has so far prevented their adoption on production engines. In future the Ministry are to hold separate stocks of spares for the fully supercharged Kestrel, so that it is now possible to arrange for alterations applicable to these engines alone. In view of the urgent requirement for the high speed valve springs on the 11-S engines, we strongly recommend that a modification covering their use be arranged without delay. Attached will be found particulars of development running carried out on these springs, including Type Test running. Hs{Lord Ernest Hives - Chair}/I.B.Hall. | ||