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).
The rigidity testing of different frame cross-member designs, comparing the Hotchkiss and Spectre types.
| Identifier | ExFiles\Box 94\4\ scan0045 | |
| Date | 22th May 1935 guessed | |
| -2- Fig. 4. A similar cross was then tested, having an arched top and bottom plate with transverse swaging, such as is used on the Hotchkiss frame. The rigidity was slightly improved as the swaging more than compensated for the curvature of the compression and tension plates, and the torque for permanent set was put up to 242 in.lbs. This cross was 19% less rigid than SpectreCodename for Phantom III Fig.1 and 66% less rigid than SpectreCodename for Phantom III Fig.2. General Conclusions. The SpectreCodename for Phantom III cross design with its continuous top and bottom tension and compression members is much more rigid than the more usual design with an open centre. It would appear that a considerable increase in the rigidity of the SpectreCodename for Phantom III cross would be effected by a reinforcement of the top and bottom plates at the centre, for a very small addition of weight. We are proposing to try this on a full size frame, and to measure the increase in torsional rigidity. The central portion of any cross is inherently its weakest part. Ev.{Ivan Evernden - coachwork} ATT: | ||