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 from F. H. Royce discussing potential modifications and reliability issues of magnetos for Eagle XVI, Packard, and Falcon X engines.
| Identifier | WestWitteringFiles\N\2July1925-September1925\ Scan113 | |
| Date | 8th October 1917 | |
| (2) a ring on the rotor. This brush could possibly be of the jump spark type. Most of this construction is well known, and so far as we can see there is no reason why it cannot be applied with but very little increase in the length of the machine, particu-larly if every move is made to use the space to the best advan-tage. For example it occurs to us that the hub of the half time wheel might be moved about .4" nearer the centre of the machine, with the bore recessed to leave the same amount of surface insulation at present allowed on the projection of the rotor carrying the central H.T. brush. Regarding the magnetic portion of the machine it appears possible to add 40% to the thickness of the magnets, and also the soft iron circuit, without increasing the overall width, then if the width of the magnets and soft iron poles be increased by 40%, it appears likely that the capacity of the machine will be doubled with about 1.3" extra length between contact breaker and mounting. If the overall increase in the length of the machine can be kept within this figure by making full use of the upper space for installing the double row of contacts, then the engine will not exceed the required width at the magnetos. It is understood that in the meantime we are complet-ing the first Eagle XVI's arranged for 4 single spark magnetos with our special timing adjustment, and that you will do what is necessary to secure a supply of these for our use. Regarding Packard (Splitdorf), this single machine for double sparks on a 12 cyl. engine does not seem to be entirely reliable, because, although it has separate contact makers, it has only one magnetic circuit, and if one of the primary or secondary became short circuited either by the L.T. contact maker, or otherwise, the damping effect would prevent the other circuit functioning - (probably Messrs The Watford Co., and our Mr. Clarke at Derby, would confirm this impression, or otherwise. Yours very sincerely, (Sgd.) F.{Mr Friese} H.{Arthur M. Hanbury - Head Complaints} ROYCE. The 12 cyl. single spark machine for Falcon X. presents no novelty except that we should want the same means of adjusting the timing and the spread on the distributor wires for the hand starting shaft. A print (LeC. 2145.) is attached to this letter, and also to the copy to the Watford Magneto Co., shewing a sketch of the magneto timing adjustment. | ||