Comparative graph of Brake Horsepower vs. road speed for Phantom I and Phantom II engines.
| Identifier | ExFiles\Box 155\1\ scan0234 | |
| Date | 16th June 1936 guessed | |
| CURVES SHOWING COMPARATIVE B.H.P'S AT VARIOUS ROAD SPEEDS FOR P.I. x P.I. II B.H.P. M.P.H. P.I. II POWER CURVE STD. SILENCER ETC. P.I. POWER CURVE STD. SILENCER ETC. R.M. 155 C S S .36 8 . 6 | ||
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).