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).
Page discussing the torsional stiffness of various frame members and constructions.
| Identifier | ExFiles\Box 94\4\ scan0015 | |
| Date | 5th November 1934 guessed | |
| -2- 5. There is no point in making the cross of torsionally stiff members. 6. The overall stiffness of a single tube 8" diameter by .100" thick is twice as great as that of the channel-section frame 50% cross-braced for the same weight of metal used in each. The torsional frequency of the single-tube frame would probably be proportionately higher still due to its reduced inertia. 7. Two tubes 4" diameter have only 1/4 the torsional stiffness of one 8" diameter, for the same weight. E/TSN. | ||