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).
Engine cylinder pressure, induction stroke, back pressure, and compression diagrams.
| Identifier | WestWitteringFiles\K\September1923\ Scan67 | |
| Date | 1st September 1923 | |
| R.R. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. Expl. No. 4225 REF: HGB/LGZ1.9.23. considerably less than the Condor. The diagram of the induction stroke again indicates a positive pressure in the cylinder while the inlet valve is still open. In addition it shews that the cylinder is well filled up with something, for the compression line crosses the atmospheric 33° after B.D.C. The most peculiar feature is the positive pressure of about 7 lbs. per sq.in. which builds up in the cylinder towards the end of the exhaust stroke. This we have found to be due to, in a measure, back pressure as modifications in the exhaust system alter but do not entirely eliminate it. We have also established that it has a direct bearing on the engine roar, a report having been issued on the subject. The compression diagram cards were taken after the cylinder had been cut out for about 30 secs. to enable the conditions to become somewhat stabilised. It is apparent, owing to the lack of coincidence between the two lines, that either heat is being absorbed or incipient burning is occurring. we are inclined to think that the latter is the more probable as the compression temperature itself should be about 400°C while that of the circulating water is only 85°C. | ||