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).
The performance curves and tests of various Goshawk dynamo configurations.
| Identifier | ExFiles\Box 50\5\ Scan174 | |
| Date | 3rd May 1923 | |
| Contd. -2- EFC {E. Fowler Clarke - Electrical Engineer} 1/T3.5.23. Sheet I gives curves for our experimental standard R.R. GoshawkAero EngineCodename for 20HP Car / Aero Engine after KestrelAero Engine dynamo. Sheet II " " for standard R.R. GoshawkAero EngineCodename for 20HP Car / Aero Engine after KestrelAero Engine Dynamo No. 288 quite recently taken from production. Sheet III " " for our expl. standard machine temporarily modified to 140 turns of 20 SWG. for the field coils. Sheet IV " " for experimental machine with thicker carcase (.375") and smaller air gap (.012") as against .015"). Though there are one or two apparent inconsistencies in the groups of curves, due probably to vagaries of main brush and particularly control brush bedding, it will be agreed upon examination of the various groups, that position 4 for the main brushes is, the most generally satisfactory. N.B. There is very little inconsistency in the rising part of the characteristics and this portion for position 4 definitely gives as early cutting in and output as any position. Though this is not apparent from the curves, it was nevertheless observed throughout the test that the commutation corresponding to the (4) curves was at least as good as any commutation observed. All these tests have of course been done with the standard Z Le Carbone brushes, and The curves for the R.R. GoshawkAero EngineCodename for 20HP Car / Aero Engine after KestrelAero Engine dynamo with thicker carcase and smaller air gap did not seem so consistent as the others, the curve for neutral position particularly appearing to be a freak result. Though the performance for this machine in the early stages (cutting in and rising current) is improved, it is admitted that there is no net gain in performance on the whole range. Contd. | ||