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).
Proposed magneto modification for the 20 HP chassis.
| Identifier | ExFiles\Box 57\2\ Scan183 | |
| Date | 17th May 1927 | |
| X5790 R.{Sir Henry Royce} c.EFC. BY4/H.{Arthur M. Hanbury - Head Complaints} 17.5.27. 20 HP. CHASSIS. RE PROPOSED MAGNETO MODIFICATION. X.5792 Referring to your recent suggestion that you would like to have the magneto on the 20 HP. chassis considered from the point of view of deleting the sleeve, I have discussed this matter with Mr.North, who points out that if we are to delete the sleeve and attempt to obtain the same amount of advance by increased armature diameter and a greater envelopment of the armature by the pole shoes, as under consideration for the phantom chassis, this scheme would involve reverting to the horse-shoe magnet, as used on the 40/50. The present design of 20 HP. magneto, with the short Cobalt magnet, is dependent upon a small armature with a low angle of envelopment of the armature by the pole shoes, the difficulty of course being that if the angle of envelopment is increased there will be a direct leakage between the magnet body and the tip of the shoe. It would not appear on the face of it, therefore, that there would be any reasonable gain by modifying the 20 HP. magneto in the manner suggested, as it would be very much more cumbersome and heavy, and the gain would therefore be more than counter-balanced by the increase of weight and somewhat clumsy appearance resulting. DESCRIBED BY.{R.W. Bailey - Chief Engineer} By RECEIVED STAMP: MAY 17 1927 DERBY ROLLS-ROYCE LIMITED | ||