Electrical and mechanical design differences between two motors and seeking clarification on design direction from Mr. Royce.
| Identifier | ExFiles\Box 39\2\ Scan077 | |
| Date | 31th August 1922 | |
| Contd. -2- EFC {E. Fowler Clarke - Electrical Engineer} 1/T31.8.22. identical form of winding. As regards the motor, the carcase and armature diameters as given on Lec.1214 are 5" and 2.750" respectively. Our Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) II motor is smaller in carcase, viz.4.500" but larger in the armature, viz. 3.000" We have made calculations for this machine (which we have) of the windings which have resulted in 21 slots and 63 comm. bars, using three coils per slot. Our Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) II. motor has 29 slots and 29 comm. bars (one coil per slot). We query if it is Mr. Royce's desire that this other motor be completed in a different electrical design as well as different mechanical design, or whether the present Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) II motor should be adapted. We are inclined to think Mr. Royce had in mind to adapt the Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) II motor to Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) I, because he asked us on one occasion for calculations showing the performance of the Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) II motor applied to the Gos.I engine, which we sent along (copy to you) under cover of our EFC {E. Fowler Clarke - Electrical Engineer} 1/T30.8.21. These calculations show that the motor efficiency when applied to Gos.I with the larger reduction ratio, was greater, and that the engine speed would be approximately the same, so that there seems little reason for departing electrically from our present design. Perhaps you will kindly let us have word re this matter at your early convenience. EFC. {E. Fowler Clarke - Electrical Engineer} | ||
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).