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).
Graph plotting performance coefficients for various vehicle drive systems.
| Identifier | ExFiles\Box 170\3\ img169 | |
| Date | 8th February 1938 guessed | |
| COEFFICIENT .5 .6 .7 .8 .9 1.0 NORMAL ACC. IN GEARS. THEORETICAL 2-WL DRIVE WL DRIVE | ||