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).
Torsional stiffness tests carried out on various car frames, including the Spectre, Cadillac, and Bentley.
| Identifier | ExFiles\Box 92\1\ scan0126 | |
| Date | 2nd May 1935 | |
| To Eg. c.c. to WGR. c.c. to E.{Mr Elliott - Chief Engineer} c.c. to Da.{Bernard Day - Chassis Design} c.c. to By.{R.W. Bailey - Chief Engineer} c.c. to Rly. c.c. to EV.{Ivan Evernden - coachwork} Ha/Gry.{Shadwell Grylls}12/Ku.2.5.35. Frame Rigidity. Tests have been carried out on the torsional stiffness of complete cars and bare frames. We attach herewith results for the SpectreCodename for Phantom III car 30-EX in the original form with scuttle isolation; the Cadillac car; the SpectreCodename for Phantom III, Cadillac and Phantom frames, and also a Bentley frame with and without dashboard. The SpectreCodename for Phantom III frame is a great improvement on the Phantom, being almost exactly the same stiffness as the Cadillac. The Cadillac car, however, is at least 3 times as stiff as the SpectreCodename for Phantom III car from end to end, and at least 24 times as stiff as the bare frame. The type of body, therefore, and its mounting determine the frame rigidity of a complete car. In this respect the SpectreCodename for Phantom III needs considerable improvement. As regards the Bentley frame, the dropped cross member between the headlamps made no measurable difference (less than 2%) to the torsional rigidity. It does, however, steady the headlamps. During tests on complete cars the chassis rested on its four tyres and for frames the frame was supported in the centre of the front and shackled at the rear so as to allow "match-boxing". In all cases a fierce torque is applied at the extreme front. In conclusion, we recommend that for at least one Experimental car we should copy the Cadillac body construction for SpectreCodename for Phantom III, and can say that a Bentley frame on the lines of the SpectreCodename for Phantom III for the same weight will be far stiffer torsionally. Ha/Gry.{Shadwell Grylls} | ||