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).
Technical memorandum discussing improvements to battery ignition systems, contact makers, and cam designs.
| Identifier | WestWitteringFiles\Q\January1927-March1927\ 128 | |
| Date | 12th March 1927 | |
| EFC.) TO H.I.) FROM R.{Sir Henry Royce} (At Le CanadelHenry Royce's French residence.) C to B.J & E (Handwritten and crossed out) BATTERY IGNITION. Are we making any progress? I have approved the off-set contact maker because even slight increase in the speed of break and slowness of make is in the right direction. E's drawing of the circular rotor - LeC. 2388. - is an improvement one would think. I can see that there is room for thought as to how the period of make can vary with the advance, because at slow speeds the make might be as short as 25%, increasing to 66% at high speeds, if this could be done practically. Many ways have occurred to me, but none so far good enough: they are - (1) Eccentric advance rocker going further away from cam in an advanced position. (2) Double contact rocker, one making, the other breaking, the make advancing quicker than the break. (3) Split cam, or a varying shaped cam, moving axially. I am assuming you are using the maximum self induction and ballast resistance to keep the current down, and the maximum condenser possible. But you can bear in mind that we do not mind if the engine will not run quite up to maximum speed with volts lower than those always available, but must get home at moderate speed with say 10 volts, although even in such an event we have the magneto. However we must get full spark at low speeds even with low battery volts, as when one starts turning engine with low down battery. You might make a test if we could gain more than double life with two contact arms one would get a rest to cool down. This could be tested by suitable cams and single rocker doing half the speed of ignition, but proper rate of make and break, 3 point cam and 75 off 25 on, running full speed on three cylinders. I feel sure we can make some progress to at least equal our competitors if we keep hard at work on this important point, and do not let less important things absorb us. X5790 I agree about 20HP, magneto. See what can be done to improve the ease of starting, and avoid spoiling our battery jump spark distributor. I will write Mr. North on the subject of electrical technical knowledge, quite diplomatically. I agree we do not get enough experimental magnetos and clocks from them to test. R.{Sir Henry Royce} | ||