Blueprint graph showing five different performance curves.
| Identifier | ExFiles\Box 180\M4\M4.2\ img023 | |
| Date | 25th February 1923 guessed | |
| [ "P CURVE.", "P CURVE.", "E.P. CURVE.", "P. CURVE.", "E.P. CURVE." ], | ||
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).