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 issues of the E.A.C. dynamo compared to the Goshawk machine, particularly regarding magnetic reluctance.
| Identifier | WestWitteringFiles\K\November1923\ Scan69 | |
| Date | 23th November 1923 | |
| To R & E.{Mr Elliott - Chief Engineer} from EFC. C. CJ. WOR.{Arthur Wormald - General Works Manager} EX. X.9660 - E.A.C. DYNAMO. With reference to your RS{Sir Henry Royce's Secretary}/M21.11.23, presumably it would not be intended to equip the 40/50 car with a complete R.R. electrical system until the 40/50 dynamo was ready. At present the performance of the E.A.C. machine in the early stages is not as good as we anticipated. Attached is a sheet of figures in which some estimated and observed quantities for the Goshawk and E.A.C. dynamos, operating on the cutting in point as shunt machines in the hot condition are given, from which it will be seen that whereas the observed polar flux on Goshawk was only 10,000 less than the estimated flux, that on the E.A.C. was 42,000 less. N.B. Actually the estimated and observed figures in the E.A.C. case are for 18 gauge field windings, though we have decided experimentally, for other reasons, e.g. output, that 19 S.W.G. is better. From the above there appears to be some reluctance in the E.A.C. magnetic circuit not possessed by the Goshawk machine. This we think is the result of the use of cast iron pole pieces, the calculations having been based on laminated iron pole pieces, as on Goshawk. To demonstrate this point we are experimentally having made up a set of solid pole pieces in mild steel. Allowing for the cast iron pole pieces, the output performance of the machine appears reasonable for its Contd. | ||