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 trouble for Condor and Phantom engines, proposing a new design and a formula for reliability.
| Identifier | ExFiles\Box 66a\2\ scan0053 | |
| Date | 11th July 1927 | |
| To RG.{Mr Rowledge} Hs.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} E.{Mr Elliott - Chief Engineer} from R.{Sir Henry Royce} c. to BJ. Wor.{Arthur Wormald - General Works Manager} Da.{Bernard Day - Chassis Design} f8060 R2/M11.7.27. X2993 X3616 CONDOR RR.F. PHANTOM, ETC. VALVE SPRINGS. As discussed with Hs.{Lord Ernest Hives - Chair} on Friday last, it is understood that valve spring trouble promised to be considerably reduced by the adoption of the lower max. stress and greater stress range type of valve spring. This has already been proved more reliable in the RR.F. case, and it is imperative to produce (as proposed by me last year) the best springs of a similar type that can be suggested for our other engines, both aero and car, especially Condor, and Phantom. It is greatly to be regretted that our enthusiasm in this direction was not followed up and tested to the bitter end, considering how easy, inexpensive, urgent, and important, the matter has always been. I trust every effort will now be made to get the best possible proportions for these springs. In the future we must endeavour to allow slightly more space so that the stress range and the maximum stress can be kept lower. I think there should be some formula (outside the phenomenon of surging) which should give hopeful prospects of spring life. This might be of the order of maximum stress, plus half the stress range, giving a figure inversely proportionate to reliability. E.{Mr Elliott - Chief Engineer} translates this to - 100,000 / (Max:stress, plus stress range / 2) = figure of merit. This might give good results if figure of merit is over 1.33. Hs.{Lord Ernest Hives - Chair} has handed the best we could do for Condor until more room is found, but those given were thought to be distinctly superior to those in use. It was decided to rush them forward for proof testing. R.{Sir Henry Royce} | ||