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).
Critique of War Office proposals for modifying 'Eagle' engines for use in tanks, citing vibration and flywheel design issues.
| Identifier | Morton\M21\ img064 | |
| Date | 8th October 1920 | |
| To H.R. J.O.G. Copy to C.J. H.H. R.W.H. C.R.F. H.S X.4-205 R.{Sir Henry Royce} CRITICISES UNSOUND PROPOSALS FROM THE W.O. ORIGINAL from R.{Sir Henry Royce} Ref Z 8-10-20 R8/G29/10/20. RECEIVED 11 NOV 1920 4 RE MODIFICATIONS TO "EAGLE" ENGINE FOR TANKS. (W.O.RG{Mr Rowledge}/H21/10/20.) Referring to the modifications for fitting "Eagle" engines into tanks, I think the designs provided by the War Office are unsatisfactory. It will be noticed that the web of the crank is unsuitable for a large bending stress. That the flywheel and fan as shewn will have a considerable amount of inertia, and a long distance from the support (overhang) and therefore a rather slow period of vibration, due to the flexibility of the web etc. This would most likely set up a vibration which would probably cause a fatigue fracture of the crank web. If it is necessary to overhang the flywheel and fan, it would be advisable to substitute for our reduction gear case, an aluminium casting carrying an adjustable bearing, as was embodied in the design of the "Hawk" for carrying a propeller. The flywheel will be close to the bearing, and the control will be independent of the crank web, the fan near to the flywheel, and the universal joint inside. Would they wish us to make this modification to their designs ? We should think the fan rotor should be constructed of aluminium. We do not know what the vibratory period of the mass as shewn is, but we feel sure it would be within the range of speed of the engine. Also, we do not like the idea of rivetting on the flywheel, it should be bolted on. We are a little doubtful as to whether the studs transmitting the drive to the universal joint would really give satisfaction. We assume that at times the engine would be driving (Contd.) | ||