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).
Conclusion on the selection of a C.A.V. type DB dynamo for the Goshawk chassis based on its output characteristics.
| Identifier | WestWitteringFiles\H\November1921\ Scan29 | |
| Date | 1st November 1921 | |
| To R & E.{Mr Elliott - Chief Engineer} from KFC. c. to CJ. & PH. c. to Hy.{Tom Haldenby - Plant Engineer} & EP.{G. Eric Platford - Chief Quality Engineer} c. to Rg.{Mr Rowledge} &Ds. c. to R.R. of America Inc. ORIGINAL KFC2/T/1.11.21. X. 4359 - DYNAMO FOR GOSHAWK. We have now concluded that, as suggested in your R10/C9.11.21, of the output characteristics of the various dynamos submitted for the Goshawk, that of the C.A.V. type DB{Donald Bastow - Suspensions} machine is undoubtedly the best. When it is considered that the lamp load plus the ignition load may at times amount to 9 amperes, the necessity of the larger output curve is apparent, even though under certain conditions the battery may attain a full state of charge and still receive a comparatively large current. The fact that on this chassis the ignition is to be continuous load makes some difference, and all things considered, there seems little reason why this size of chassis should require a smaller dynamo than the large size. We look upon the C.A.V. type DB{Donald Bastow - Suspensions} curve (which characteristic cure is incidentally the only one of those submitted which complies with our specification entirely) as representing the most that can be done with a dynamo of this size. In the hot condition, the maximum of 9½ amps. of this dynamo occurs at a road speed of about 23 m.p.h. after which it falls away gradually to just over 5½ amperes at 56 m.p.h. Owing to the reduction in the length of the ballast resistance wire, we take more current for the ignition on | ||