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).
Test report on a Smith 4D dynamo for the Goshawk II engine.
| Identifier | WestWitteringFiles\G\October1921\ Scan3 | |
| Date | 17th October 1921 | |
| To R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} from EP{G. Eric Platford - Chief Quality Engineer} c. to CJr & FH. c. to Rg.{Mr Rowledge} & Dn. c. to By.{R.W. Bailey - Chief Engineer} & EP.{G. Eric Platford - Chief Quality Engineer} c. to R.R. of America Inc. ORIGINAL X.43895 - SMITH 4D DYNAMO FOR "GOSHAWK II". We recently received from Messrs. Smith a sample 4D dynamo for Goshawk II, which they have made up for us in accordance with our requirements mechanically. They have stated, however, on more than one occasion, that they did not think they would be able, and have not been able to obtain an output curve to our specification, with this size of machine. We know, however, that it can be done within the limits given in our specification. Our tests show that the performance of the machine falls short of the specification by quite a good deal. The dynamo is a reasonably good job and has run consistently well on the tests which we have carried out. The system of control is exactly similar to that of the 2D machines which we have previously tested, namely, the four-brush scheme, in which each main brush is connected to an auxiliary brush 90° in advance. There is practically no magnetic hum on the machine. The brushes are reasonably quiet. We attach photostat which gives hot and cold output characteristic curves of operating voltages, in comparison with our specified performance, and it will be seen how much poorer these are than those of the Rotax and Lucas previously tested. In the fully hot condition, an 'open circuit voltage of 13.6 is not attained until 955 r.p.m. | ||