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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).
Performance analysis of a Rotax dynamo, comparing its output curves, voltage, and current to specifications.

Identifier  WestWitteringFiles\G\October1921\  Scan25
Date  27th October 1921
  
Contd. -2- EFC1/T27.10.21.

it will be interesting to note the effect of exchanging this
Rotax dynamo for the Lucas, which can now be done almost
immediately.

Regarding the output of this machine with the
brush setting altered so that, running on the peak output,
our maximum specified temperature is not exceeded, please
find attached copy of photostat curves of output of the
machine in this condition, together with added specified
performance of output, also curves of field current. It
will be seen that whereas the starting cold and hot outputs
are sensibly lowered, that in the hot condition can still
be said to comply with our specification. Although it
falls below it at one point, it can be virtually made to
comply by altering the drive ratio and thus shifting the
curve bodily to the right. We consider, owing to the fact
that the area of the current speed curve in the early
stages is considerably larger than that of our specified
performance, we can say that this curve of output complies.

It is no doubt a very satisfactory curve, giving
a large volume of current in the quite early stages and a
rather smaller charging current at touring speeds.

The machine in the cold condition attained a cutting-
in voltage of 12.4 at 445 r.p.m. In the hot condition a
cutting-in voltage of 13.6 was attained at 525 r.p.m. Thus
it will be seen that in this respect the machine is somewhat
earlier than the four-connection machine of the standard

H'K' S2FV (100 L) (2 H' 188' 10-JS{Mr Johnson's Secretary}-50) C' 5011
  
  


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