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).
Maximum dynamo revolutions and proposed speed ratios for the Peregrine engine.
| Identifier | ExFiles\Box 62\3\ scan0321 | |
| Date | 25th January 1933 | |
| - 2 - E.6/HP.25.1.33. Regarding the maximum dynamo revs. we think we have got to accept some extension of this as the range of performance of engines is increased. We suggest the best compromise is arrived at with a ratio of dynamo speed to engine of 1.2 as shown in the following table: | Engine. | Ratio of dynamo speed to engine speed. | Max. dynamo speed at 5000 r.p.m. or 82.5x m.p.h. on top gear. | Cut in speed. | |-----------|----------------------------------------|-----------------------------------------------------------------|---------------| | Peregrine.| 1.5(as now) | 7500 | 10.7. m.p.h. | | | 1.2(as proposed) | 6000 | 13.4. " | | | 1.0 | 5000 | 16.0½ " | Dynamo revs on 20/25 chassis are 5850 at 80 m.p.h.x and cutting in speed is 13.3 m.p.h. At the same time improvements are in hand to the dynamo which are expected to reduce the sparking at maximum speeds. x These speeds are not given as actual performances but only for comparison. We are also considering the Bensport dynamo speed, and will report later on this. E.{Mr Elliott - Chief Engineer} | ||