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).
And comparing various output curves for Phantom I and Phantom II armature machines.
| Identifier | ExFiles\Box 165\6\ img241 | |
| Date | 14th December 1929 | |
| -8- Secondly, representative output curve of Phantom, I standard 57 coil 29 slot armature machine (Labelled 1). Thirdly, representative output curve of Phantom II 56 coil 28 slot thinner armature stamping machine (Labelled 2). Fourthly, maximum permissible output curve of 48 coil 24 slot intermediate output armature with arrangement of brushes as found most satisfactory from the heating point of view (Labelled 3). This is called the major output, and is the output curve proposed to correspond with the higher output Phantom I machine of which, as in the 20 HP. case, a number were given to special customers. Fifthly, reduced or minor output of this same machine. This being the output now proposed for ordinary Phantom II standard (Labelled 4), though it is doubtful if it is really a better curve for alround performance than the curve labelled 2 which it would thus supersede. Curve 2 as pointed out for the 20 HP. case contains the point which corresponds to the maximum ampere hours per mile at a road speed, in this instance, of 19 miles per hour. Further Phantom II machines of the intermediate output type are in progress, and one or two machines will shortly be fitted to experimental cars. | ||