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 detailing the bench test results and specification failures of a new sleeveless type magneto from North & Sons, Ltd.
| Identifier | ExFiles\Box 65\3\ scan0030 | |
| Date | 10th June 1927 | |
| c. BY c. Mailing. X7791 EFC7/T. 10th June, 1927. Messrs. North & Sons, Ltd., Whippendell Road, Watford. Dear Sirs, We have now made complete bench tests of the new sleeveless type magneto No.98201 recently received from you. In regard to the various items in our General Specification of Performance of six-cylinder magneto for Phantom R.R. Car, there are one or two points in which this machine does not comply with said specification. (1) The range provided is 50º, whereas we say "it shall not, if possible, be less than 58º", and in Mr. Royce's letter dated April 26th to your Mr. North, he specified 55º. (2) The magneto is very poor on the utility performance as scheduled in item (5) of our Specification. It is quite true that the performance specified is perhaps a little bit stiff, and we should probably consider a magneto all right that did not quite come up to this performance, but we find this particular machine to be a good deal down on this performance in comparison with the standard sleeve type machine. (3) We find the magneto to fail to comply with the item (6) of our Specification - the maximum high speed sparking being 3400 r.p.m., for firing regularly in sequence six 5.5 mm. spark gaps in air, whereas 3500 r.p.m. is our specified speed, and most magnetos cover this with a good margin. In regard to silence, we find the machine to be very good. We are now arranging for trial of this magneto on a chassis and will let you know further, but in the meanwhile should be pleased to hear your comments on the matter of this machine not quite meeting our specification with which of | ||