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).
Frame stiffness, torsional rigidity, and engine mounting, comparing approaches with Packard and Lancia.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan428 | |
| Date | 19th September 1931 | |
| SG.{Arthur F. Sidgreaves - MD} FROM R.{Sir Henry Royce} C. to PN.{Mr Northey} HS.{Lord Ernest Hives - Chair} ORIGINAL re. FRAME STIFFNESS, BODIES, AND THE PACKARD. RD/M19.9.31. Sent off 23.9.31. x457 x4685 x4027 In most American motor cars the steel body constitutes a source of stiffness which may have a considerable influence on the behaviour of the chassis on the road. We are drifting in the direction of trusting almost entirely to the body for torsional stiffness. If this is what we think is probable we may be obliged to use stiff steel bodies. Especially does this apply to the "Peregrine". With a 6 cyl. engine we cannot take advantage of the stiffening effect of the engine in the frame, but we are using the engine inertia to enable us to damp the unavoidable deflections of the frame. With a 12 cyl. engine we consider that the engine would be smooth enough for us to have a simple rubber mounting comparable in its effect to that known as the sandwich feet mounting. We have as an alternative the possibility of using frames of increased vertical stiffness, and holding these more rigidly with the 'X' in the frame. We have asked H.S. to make this feature as an early experiment, and it may be that it will do well in conjunction with the torsional dampers mentioned above. If so, we should be less dependent upon the body, and also we should have a frame less liable to be distorted out of truth during construction. We notice in the descriptions of recent chassis that the Lancia have done all that is possible to make their chassis stiff independent of the body, and they claim the result of being able to run it at high speeds over very rough roads without serious vibration. We cannot believe that it is right and necessary to use inertia masses at the wider part at the end of front bumper bars - i.e. as Packard. R.{Sir Henry Royce} | ||