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).
Vehicle acceleration concerning car weight, engine power, and axle ratio, illustrated with graphs.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan35 | |
| Date | 12th June 1925 | |
| R.R. 493A (50 H) (D.D. 3L 12-6-25) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: (1) ACCELERATION. (a) Direct drive - car weight. The acceleration of two cars which are otherwise exactly similar will be inversely proportional to their weights throughout the whole range of their speeds. That is if one car weighing two tons has at 20 m.p.h. an acceleration of 3 ft/sec², an exactly similar car weighing one ton will have an acceleration of 6 ft/sec², at that speed. Axle ratio - engine power. The acceleration of a car does not improve in direction proportion to its increase in engine power or lower gear ratio. At low speeds (up to 30 m.p.h.) the improved acceleration will be very nearly proportional to the increase in engine power. At high speeds, however, a 20% increase in engine power may produce a 30% increase in acceleration. On A.{Mr Adams} B. New H.P. 16 Old H.P. 13 % power gain 23% Power to drive car 2 HP; available for acceleration. New H.P. 14 Old H.P. 11 % gain in accn. 27.3% In the same way on X.Y. % gain in power 17½% % gain in accn. 55% The same argument applies to axle ratio alterations as more power is then available at the same speed up to contd :- [Text from top right graph] Y-axis: Acc. FT/SEC² X-axis: SPEED M.P.H. Data lines: 1 Ton., 2 Tons. [Text from bottom right graph] Y-axis: H.P. X-axis: ROAD SPEED M.P.H. Plot labels: NEW H.P., OLD H.P., POWER AVAILABLE FOR ACCELERATION, POWER TO DRIVE CAR. | ||