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).
Piston ring wear, cylinder finishes, and a comparison of various aircraft engine mounting systems.
| Identifier | ExFiles\Box 27\3\ Scan218 | |
| Date | 15th May 1939 guessed | |
| 12. an important bearing on piston ring wear, Mr .Cronstedt also stated that nitrided cylinders wear at twice the rate of soft cylinders and that they are considering going back to soft cylinders. The finish of cylinders for the Army is black enamel, but for the Navy an aluminium paint spray has been found useful to counteract corrosion. Engine Mountings. Wrights have evolved, in collaboration with Professor E.S.Taylor, of the M.I.T., a system of dynamic suspension which is very effective indeed in both quietening the power plant and isolating all vibration from the aircraft. This system is described in a Paper by K.A.Browne in the S.A.E.Journal for May 1939. We were shown a most interesting model consisting of a small electric motor giving 1st and 2nd order out-of-balance forces, driving an airscrew which could be put out of balance at will, and provided with a make and break which could simulate the effect of a missing cylinder. This was supported on an engine mounting of the standard type which could be fitted with orthodox rigid, Lord type, or two alternative schemes of dynamic suspension. The assembly was fitted with a cowling and mounted on a model wing. The orthodox Lord mounting reduced noise somewhat but did little to absorb vibration. The dynamic suspension however, definitely reduced noise and vibration to a considerable degree. Dynamic suspension aims at giving as much freedom of motion as possible, the springing being directional so as to avoid engine drooping. Wrights are busy and very enthusiastic about this. Pratt & Whitney have not gone so far with their designs as Wrights havem but they are fitting a simber version of the mounting. The mounting pillars now used on American engines have been adopted to enable the mounting to be taken off magnesium blower castings which are now in common use. The big Cyclone Duplex engine, as already mentioned, has its dynamic suspension mounting fitted to the rocker boxes of its rear row cylinders. | ||