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 pressure and efficiency, with performance contour lines.
| Identifier | ExFiles\Box 179b\3\ img360 | |
| Date | 14th February 1933 guessed | |
| PRESSURE [" HG] EFFICIENCY 16 20 24 28 32 36 40% 50% 60% 70% 2250 2500 2600 2750 3000 | ||