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).
Formulas for temperature and pressure corrections on engine power.
| Identifier | ExFiles\Box 179\2\ img194 | |
| Date | 7th January 1932 | |
| COPY. Courbevoie, January 7th, 1932. TEMPERATURE AND PRESSURE CORRECTIONS. 1° - Back pressure corrections. C1 = (18p x Pb) / 100 where p back pressure (back pressure in the exhaust pipes in Kgs per square cm. + difference in Kgs per square cm. between the atmospheric pressure at the ground and the atmospheric pressure at the altitude. Pb = B.H.P. 2° - Temperature corrections. C2 = (500 + t0) / (500 + tz) where t0 = temperature at the ground during the test. tz = temperature at the altitude. Engine Power = C1 + Pb x C2 Example :- B.H.P. = 414 HP. Temperature at the ground = 18°C. Atmospheric pressure at the ground = 760 mm. of Hg. Pressure in the exhaust pipes .05 Kgs per sq.cm. Atmospheric pressure at 3500 metres = 493.2 mm. of Hg. tz at 3500 metres = 7°C,75. | ||