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 from a report analyzing the relationship between web thickness, stiffness, and inertia, including calculations.
| Identifier | ExFiles\Box 85\5\ scan0093 | |
| Date | 29th January 1935 | |
| -2- Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}31/KW.29.1.35. From these figures one can predict immediately the effect say of doubling the web thickness, in which case the equivalent length becomes 6½ instead of 9 and the inertia 18½ instead of 12. The ratio of stiffness to inertia is decreased. Halving the web thickness also decreases this ratio. Suppose the thickness of the webs be x times the present value, then the stiffness is x / (4x + 5) and the inertia (10 + 13x) / 2 and the maximum value of the ratio of stiffness to inertia occurs at a value of x given by √(25/26) = .98 It so happens therefore that our present web width cannot be improved upon and we are unable to obtain an increase in crankshaft stiffness by altering this width. This of course assumes Carter's formula sufficiently accurate for the differences involved. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||