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 of rivetless bonnets, focusing on shutter pivot placement, symmetry, and the use of countersunk rivets.
| Identifier | ExFiles\Box 119\4\ scan0027 | |
| Date | 31th August 1931 | |
| X385 Da{Bernard Day - Chassis Design}/Ev.{Ivan Evernden - coachwork} from Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. By.{R.W. Bailey - Chief Engineer} R.{Sir Henry Royce} Hs{Lord Ernest Hives - Chair}/Lid{A. J. Lidsey}2/AD31.8.31. RIVETLESS BONNETS. With reference to Da{Bernard Day - Chassis Design}/Ev{Ivan Evernden - coachwork}2/M27.8.31, we are putting the shutter pivot centre in the middle of the flap on the experimental rivetless bonnet we are making because R.{Sir Henry Royce} very definitely points out on the standardisation sheet for flip flap shutters that he thinks this modification will make them easier to open, a point which he thinks needs improvement. With regard to PN{Mr Northey}'s request for shutter symmetry, this was made in Sg{Arthur F. Sidgreaves - MD}'s presence when they approved of the now standardised flip flap shutters. It was thought that the distance between the edges of the middle and outer shutters should be twice the distance from the edge of the outer shutters to the bonnet ends thus :- [Diagram showing three shutters. The space from the bonnet edge to the outer shutter is marked 'x"'. The space between the outer and middle shutters is marked '2x"'.] This was not possible at the time because it was necessary to use up the existing bonnet sides already panelled for the sliding type of shutter. We are trying countersunk rivets for the flip flap shutters because you definitely asked us to do so in Da{Bernard Day - Chassis Design}/Ev{Ivan Evernden - coachwork}2/M23.6.31. In addition Sg.{Arthur F. Sidgreaves - MD} approved of countersunk rivets for the flip flap shutters (Sg{Arthur F. Sidgreaves - MD}18/L6.7.31). The appearance of these was pointed out to him at the time (some of them had cracked the paint) and it was agreed that the appearance was less unsightly than snap headed rivets. The light along the bonnet sides is always very much worse than on the top panels and small defects are difficult to notice. Our chief reason for not proceeding with N.Sch.3304 was that on the drawing it is stated that you do not like the construction very much because it is feared the side plate may unfold the hinge. You will recollect you gave us this design after we had sent you particulars of the | ||