Hand-drawn graph comparing the Flywheel Brake Horsepower (B.HP) of a 'New Phantom' and a 'Bentley' against engine RPM.
| Identifier | ExFiles\Box 21\2\ Scan011 | |
| Date | 9th December 1925 guessed | |
| Flywheel B.H.P. 20 30 40 50 60 70 80 90 100 110 120 130 140 ENGINE RPM 500 1000 1500 2000 2500 3000 NEW PHANTOM(Codename for PHANTOM I) BENTLEY | ||
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).