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).
Comparison of the moment of inertia for a 40/50 wheel fitted with 33 X 5 cord and balloon tyres.
| Identifier | ExFiles\Box 53\2\ Scan033 | |
| Date | 20th August 1923 | |
| X4565 20823 COMPARISON OF MOMENT OF INERTIA OF 40/50 WHEEL FITTED WITH 33 X 5 CORD AND BALLOON TYRES. X4565 I = 32 (Wrt^2 / 4π^2 - Wr^2 / g) Cord tyre W = 9.75 lbs. wt. r = 1.502 ft. t = 3.06 secs. I = 32 (9.75 X 1.502 X 3.06^2 / 40 - 9.75 X 1.502^2 / 32) = 87.5 lbs. ft.^2 units. Balloon Tyre. W = 9.75 r = 1.575 t = 2.84 I = 32 [9.75 X 1.575 X 2.84^2 / 40 - 9.75 X 1.575^2 / 32] = 74.5 lbs.ft. units. Decrease 13 lbs. ft.^2 on 87.5 lbs.ft.^2 units. = 14.88% Rm.{William Robotham - Chief Engineer} | ||