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).
Analysis and comparison of short circuit ampere-speed curves for various chassis magnetos.
| Identifier | WestWitteringFiles\S\March1928-May1928\ Scan173 | |
| Date | 8th May 1928 | |
| To R.{Sir Henry Royce} from EPC. c. BJ. E.{Mr Elliott - Chief Engineer} c. By.{R.W. Bailey - Chief Engineer} Wor.{Arthur Wormald - General Works Manager} c. Re. ORIGINAL EFC1/T8.5.28. X8790 X7791 CHASSIS MAGNETOS It will be recalled that we have been in the habit of quoting the results of observations of the short circuit ampere-speed curves of the primaries of various magnetos. We have now made an analysis of a selection of these in the following manner :- We have called the current in amperes at 3200 r.p.m. 100%, and expressed the amperes for each magneto at all lower speeds in the form of percentages on that basis. Curves have been plotted of the ampere-speed characteristic of each selected machine on this percentage basis, and these are exhibited, duly referred to a table, on the photostat sheet herewith. Inspection of the curves will reveal that the best are those of the Bosch and Scintilla, being those which rise very quickly in the early stages. The best Scintilla machine is the only one in this group which is of the inductor type. The best curve for a British machine is that of the Simms. Going to the other end of the scale, it will be seen that generally speaking the worst curves are those of the Watford EC6. and EW6. magnetos. We propose to send a copy of these curves to Messrs. North with a Query as to whether the principles which are involved in the good primary current curve are sufficiently considered. EFC. Photostat of curves attached. | ||