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).
Explaining the use and application of various ignition and magneto specification curves for setting engine requirements.
| Identifier | ExFiles\Box 54\5\ Scan275 | |
| Date | 27th August 1924 | |
| Contd. -2- EFC {E. Fowler Clarke - Electrical Engineer} 9/T27.8.24. These tracings are labelled (in red) "R.R. Battery Ignition" "Scintilla AM-6-A Magnetos (average curve), "Scintilla AG-6-A Magnetos" and "General Magneto Specification". All these curves, except the last, have been experimentally determined on the bench in our own electrical laboratory using a revolving graduated disc, illuminated by a spark obtained from the unit on the test. The utility of these curves, which should materially assist in settling the requirements of the EAC.2, lies in the fact that any one of the tracings can be applied to (super-posed upon) either of the 20 HP. or EAC.2. sheets, and the advance possibilities provided by the various advance units compared with the desired curves. In applying the various tracings to the 20 HP. and EAC.2 curves, the vertical axes are naturally made to co-incide, but the short lower horizontal straight line on each pair of tracings, representing the extreme degree of retard, is so super-posed as to give the degree of extreme retard required, which degree of retard is usually 10 +5° a.d.p. for the battery ignition, and 3° or so degrees b.d.p. in the case of magneto ignition. There is also another curve [handwritten: characteristic] in this group, labelled in [handwritten: green] ~~red~~, "20 HP. advance figures supplied by EP. {G. Eric Platford - Chief Quality Engineer} " in which is a reproduction of the curve referred to in E's note, regarding which he queries whether Hs. {Lord Ernest Hives - Chair} is in agreement. Contd. | ||