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).
Ignition system design, focusing on optimizing current at break and condenser capacity for platinum point life.
| Identifier | ExFiles\Box 35\6\ scan 252 | |
| Date | 12th March 1927 | |
| -2- EFC3/T4.3.27. 1 COPY to F.T.B. & V.T.D. 1 COPY to Contd. 1 COPY to D.O.V.T. (Faint bleed-through text) AERONAUTICAL INSPECTION DIRECTORATE FOR CHIEF INSPECTOR OF ENGINES (2/E.U.S.H.) would be obtained by having a very small inductance, large capacity, and small period of make, as was done in the Atwater Kent ignition with the trip operated contact which could not remain closed. This also gives a high efficiency because of the small resistance loss, and we should imagine this would be very good for platinum point life. To obtain a reduced value of current at break ------------------- condenser capacity with a longer period of make, would necessitate as a result of the increased primary inductance, an increase in the number of secondary turns for the same secondary voltage and energy. We do consider that it is an advantage to reduce the absolute value of current at break ------------------- condenser capacity as much as possible, but are of the opinion that the speed of break in relation to the value of this quantity is not of much consequence. In our own case where the current at break is maintained approximately the same for varying speeds, there is little improvement with the quicker break. Further, any advantage that could be obtained by lowering this ratio by altering the duration of the make without altering coil and condenser to suit, would result in a reduction of energy and therefore of sparking capabilities at the higher speeds. We have no information yet as to whether Delco or American Bosch are any different as regards the life of the points, but should imagine they would have similar life. (Handwritten text) Condenser VOG102/32 12/7/27 Date 12/3/27 EFC. (Reversed stamped text at bottom) ROLLS-ROYCE AERO ENGINE SPARES CERTIFICATE OF INSPECTION BY A.I.D. CERTIFICATE NO. | ||