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).
Specifications and volume requirements for a battery ignition condenser for a 12-volt coil.
| Identifier | ExFiles\Box 34\1\ Scan017 | |
| Date | 20th April 1918 | |
| X.2572 To R.{Sir Henry Royce} from EFC. c. to CJ. c. to E.{Mr Elliott - Chief Engineer} EFC3/T20.4.18. X.3173 - BATTERY IGNITION. X2572 With reference to your note R1/G17.4.18, and Mr. Elliott's note E4/G18.4.18, regarding the above, we have telegraphed you today to the effect that the minimum overall volume of the condenser of suitable capacity to suit the R.R.12 volt coil, should be 2 1/2 cubic inches, preferably 25% greater if space allows. The actual capacity required is .15 microfarad to suit the 12 volt coil as designed and built, this we have confirmed by an actual test on this coil in which we obtained very good results. We are sending herewith for your inspection a small magneto condenser which has been kindly given to us by Mr. Young of the R.T.H. You will see that this is marked .1C5. This is the capacity of this condenser in microfarads and we find that our measurements of this by our usual methods give us this figure as nearly as we can measure. You will see, therefore, that we require a condenser of volume at least 50% greater than this one, because we shall not obtain the same space efficiency as in this one until we have made a few of these, and found out how to obtain the best results. It is already proved by the condensers we have made up for this ignition that we require considerably more space to get the same capacity, even if the thickness of the di-electric be apparently the same. Contd. | ||