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 boost control adjustments and performance under various throttle and altitude conditions.
| Identifier | WestWitteringFiles\U\August1930-November1930\ Scan055 | |
| Date | 11th September 1930 | |
| -2- In this particular case the aneroid was adjusted to give the required -1/2 lbs/sq.in. boost with the engine operating under altitude conditions - i.e. with air intakes throttled by means of air boxes. Examination of the chart shows a progressive increase in boost with pilot's throttle movement as the engine is opened up from slow running. After about 40% throttle lever movement the induction pipe pressure reaches -.5 lbs/sq.in. and the piston starts to rise, therefore any further movement of the throttle lever is neutralised by the counter movement of the piston. Constant boost and R.P.M. are maintained until the pilot's throttle lever is about 15% from full open, at which time the operating piston reaches the top of its stroke. The further 15% opening of the lever results in increasing the boost and R.P.M. to the "take off" value of 1.6 lbs/sq.in. The R.P.M. was 1850 which we considered would be the ground running R.P.M. for such an engine. The brake was then opened up to 2250 R.P.M. which would represent the R.P.M. on the climb. It will be noticed that with the increase in engine speed the boost automatically falls to + 1.3 lbs/sq.in. and from this value it progressively falls down to the rated -1/2 lb/sq.in. at 4500 ft. altitude. After this altitude the boost remains constant up to 10000 ft. again commencing to fall with increase of height. We have to take particular care to eliminate as much | ||