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).
Design and material choice for rivetless bonnets, comparing them to an Armstrong-Siddeley scheme.
| Identifier | ExFiles\Box 119\4\ scan0017 | |
| Date | 4th July 1931 | |
| Hs.{Lord Ernest Hives - Chair} from Da.{Bernard Day - Chassis Design} c. Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} By.{R.W. Bailey - Chief Engineer} X385 Da{Bernard Day - Chassis Design}2/M4.7.31. X.7260 X.385 P.2. - N.2 SERIES RIVETLESS BONNETS. We have already sent you N.sch.3294 showing a bonnet having hinges the rivets of which are concealed. After receiving your Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey}5/KT22.6.31. and the print showing the Armstrong-Siddeley rivetless bonnet we have endeavoured to incorporate the construction which they use in the design of our bonnet, and send herewith N.sch.3304 showing this construction of hinge applied to the bonnet of N.sch.3294 We are a little dubious about this construction when it is applied to our bonnet. The top hinge seems to be alright as it is under similar conditions to that on the Armstrong-Siddeley. It is the side hinge that offers the difficulty. The Armstrong-Siddeley side hinge is below the hip of the bonnet and is under direct tension. We have not ventured to put our hinge there as we think that it will not be acceptable to have a joint line along the side panel of the bonnet some 2" below the side moulding. As in this scheme the bending strength of the hinge material is of paramount importance we have shown single thickness hinge material .064 thick in place of the double thickness .036 which we now use. To obtain still further stiffness we suggest that the hinge material be steel instead of brass. The problem of rust them arises, unless we have can make the tube of either brass, stainless steel, or even plated to make it rustless. It will be noticed that this bonnet utilises the same radiator and dashboard fittings of N.sch.3294. We are rather dubious of this scheme and so is R.{Sir Henry Royce} We therefore suggest that we ought to make N.sch.3294 without hesitation, and that if, after you have considered our N.sch.3304, you feel that the Armstrong-Siddeley scheme as applied to our bonnet has reasonable hopes of materialising into something useful, then we suggest you should make one of these also. Da.{Bernard Day - Chassis Design} | ||