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).
Alterations and performance issues with Watford IS.12 magnetos for the Falcon X engine.
| Identifier | ExFiles\Box 43\4\ Scan055 | |
| Date | 31th January 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} By.{R.W. Bailey - Chief Engineer} c. Rg.{Mr Rowledge} Wd.{Mr Wood/Mr Whitehead} c. AID. Y4021 EFC6/T31.1.27. WATFORD IS.12 MAGNETOS FOR FALCON X. Y4021 X3832b Please find attached copy of my assistant's report WC.1 in connection with the two most up-to-date IS.12 type magnetos recently received for Falcon X., also copy of report WC.3. The slight non-compliance with the slow speed sparking characteristics of one of the two magnetos is due to the fact that these magnetos have apparently, at our suggestion, been altered in such a way as slightly to retard the whole range of operation in time relation to the functioning of the armature. As a result of this it is now found on the bench test that the platinum point gap can be increased from the normal amount of .010" to the excessive amount of .019" before misfiring on a 5.0 mm. gap in air occurs at 4200 r.p.m. This we consider to be a definite advantage in view of the possibility of the platinum point gap increasing during a run or flight, and of more consequence than the exact compliance with our low speed requirements. There was also, as explained in our EFC1/113.12.26, trouble with the B.T.H. magnetos in this respect, and we have requested them to make a similar alteration which, however, they do not seem disposed to do, as they say they are not allowed to make any alteration without the permission of the Air Ministry. WCL/3 attached. EFC. | ||