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).
Technical memo discussing design options and suggestions for the 'Kite' frame, specifically concerning spring anchorage, cross members, and frame width adjustments.
| Identifier | ExFiles\Box 75\3\ scan0303 | |
| Date | 17th December 1920 | |
| R.R. 256A (100. T) (S.H 159, 11-8-20) G 2800 To R from DA.{Bernard Day - Chassis Design} Copy to DRS. Copy to EFC. X.4260 A1/CB17-12-20. [STAMP: RECEIVED] [STAMP: P.W.D. 20 DEC 1920] X.4260 Re "Kite" Frame. We send herewith a print of "N" Scheme 671 shewing the anchorage of front end of rear spring and the 3rd cross member. Fig 1 shews an arrangement similar to the present Goshawk design, with a tubular bracket supporting the inner end of the spring bolt, which we suggest on Fig 2 might be replaced by an I section bracket as being easier to make. Also in Fig I as it would appear to be a little difficult to get the spring of any bodied car, we suggest at Fig 3 that it might be desirable to turn the bolt round. In other respects the design is similar to the Goshawk. We also send a print of "N" Scheme 689 shewing the front and rear dumb irons. The front dumb iron shewn on Fig 6 is similar to that for the Goshawk. For the rear dumb iron we make five suggestions - We thought that the spring pin ought to be case-hardened, and if this is done it makes it difficult to braze in the rear cross member. We accordingly suggest on Figs 1, 4, & 5, that the spring pin might be put in separately, either after the cross member is built up in the frame or the whole of the cross member and dumb irons might be put in together. The above difficulty also appears to hold if the spring pin is made of nickel steel with a high brinell, as is the case with the present spring pins. But in case it is considered that it is not of sufficient importance to warrant the additional trouble, we suggest in Figs 2 & 3, two methods of building up the cross member with the spring pin solid with - either the cross member, or with the dumb iron. A point arises in connection with these fittings which also concerns us in the rear and front axles, and the exhaust system. When the last frame side member drawing was sent us, the track was 52", and after we had received that drawing, it was increased to 54". We are not certain how you wish us to deal with the additional width, as we suppose that it would be desired to keep the rear springs as wide as possible, while the front springs would remain at 29" as now, in order to keep the look good. If this is so, then it means that the joggle in the plan view of the frame side members should be increased 1" on each side. The alternatives are to keep the side members as now, and spread the frame 1" both back and front, or secondly, to have 1" greater overhang on the rear springs. In working out our back and front axles, and in working out this spring details, we have assumed that the back of the frame would be increased to 36", and the front remain at 29". DA.{Bernard Day - Chassis Design} | ||