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).
Letter discussing the testing, comparison and potential standardisation of stabalite and mouldensite ignition coils for the Goshawk engine.
| Identifier | ExFiles\Box 61b\4\ scan0085 | |
| Date | 13th November 1922 | |
| Contd. -3- R1/M13.11.22. through the side of a present defective Elo case, as it may be that we are experiencing a loss of energy by direct leakage as well as by other dielectric actions, as we have a lot of metal work in contact with the bakelite, including the iron core, the holding down bolts, and the L.T. circuit. I should be glad if you could send me one of the stabalite coils for the Goshawk which is here, and also if you could let me know at an early date if you can detect any superiority of the stabalite coils over the mouldensite ones you are proposing for standardisation in the near future. Can you get a figure of merit for every coil, and particularly for every style of coil such as, with a standard spark gap say of 10 mm. in air, at a standard temperature of 90° C , and with a standard voltage of say 8 volts; regular sparking can be obtained from 100 to 1500 distributor revs. with a ballast resistance of ? ohms, the ballast resistance being varied to find the figure of merit of the coil; the only other convenient method would be the sparking distance with the standard ballast resistance, or with a given leakage in the H.T. circuit, equal to a leaky plug or other leaky insulating surface of materials. R.{Sir Henry Royce} | ||