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).
Performance graph showing engine Horsepower (HP) versus Revolutions Per Minute (R.P.M.) for different test conditions.
| Identifier | ExFiles\Box 69\4\ scan0383 | |
| Date | 6th July 1928 | |
| H/S H.P. 90 80 70 60 50 40 30 20 R.P.M. 500 750 1000 1250 1500 1750 2000 2250 2500 2750 Average AL Average CL Proposed minimum Present minimum 6/7/28 | ||