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).
Stiffness of the Wraith 80 frame and recommending modifications to match the Silver Wraith.
| Identifier | ExFiles\Box 109\1\ scan0072 | |
| Date | 12th November 1938 | |
| 666. To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} c. Da.{Bernard Day - Chassis Design} c. Roy{Sir Henry Royce}/Les.{Ivan A. Leslie} Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}9/MH.{M. Huckerby}12.11.38. WRAITH 80 FRAME. The present Wraith frame has a stiffness of 1,150 lbs-feet per degree twist. We think it desirable that the next Silver Wraith frame should be as stiff. The attached report shows that the stiffness of the first frame, as received, was 1,020 lbs-feet per degree, and the various modifications therein described increased it to 1,455 lbs-feet per degree. We recommend that drawings should be prepared showing the first two modifications only, i.e. the lattice boxing of the rear end of the cruciform member, the welding of the upper side of the front arms. This will stiffen both ends of the chassis. The lattice work at the rear end is, we think, unnecessarily heavy and enough stiffness should be obtained with only 8 lbs. increase in weight instead of 12 lbs. increase. This will leave the final weight of the frame at 326 lbs. and the stiffness at least 1,150 lbs-ft.per degree. Will Roy{Sir Henry Royce}/Les.{Ivan A. Leslie} order the frame when the drawings are ready. Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale} | ||