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 for a 20/25 HP engine showing BHP and temperatures against RPM, with and without a fan.
| Identifier | ExFiles\Box 25\1\ Scan029 | |
| Date | 5th September 1932 | |
| STRICTLY CONFIDENTIAL TAKEN FROM T.C. N° 1192 ROLLS 20/25 H.P. ENGINE 6 BLADE FAN INCLUDED ANGLE 34° RATIO 1.35 TO 1 UP B.H.P. ENGINE R.P.M. B.H.P. WITHOUT FAN. B.H.P. WITH FAN BOIL VALUE 3 LBS/sq.in (AIR IN 100°F) T.D. WATER T.D. OIL TEMPERATURE DIFFERENCE (°F) Lbs/sq.in | ||