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).
Preliminary test report on a 20/25HP dynamo arranged for air cooling, detailing performance and noise issues.
| Identifier | ExFiles\Box 62\3\ scan0471 | |
| Date | 12th December 1934 | |
| Hs{Lord Ernest Hives - Chair}/Wst.6/MA.12.12.34. 20/25HP. DYNAMO ARRANGED FOR AIR COOLING. We have had a preliminary run with this dynamo in order to test the cooling effect etc. It will be remembered that the object of this fan is to increase the dynamo output for the usual temperature rise on the shunt dynamo. A standard small shunt 20/25 dynamo was fitted up with this fan and run on the bench. Preliminary tests consisted of a low speed heating test and a run at high speeds. As a result of the heating tests, an output of 28.5 amperes at 13 volts and at a speed of 1780 R.P.M. was obtained for a temperature rise of only 50°C. Our usual temperature rise is 55°C. It will be seen therefore that this fan provides ample cooling for the machine and enables us to put up an output of a figure which is in excess of what we should actually require. Unfortunately however when run at high speeds the fan was found to be very noisy giving quite a loud high pitched note similar to the whine of a supercharger, we are accordingly modifying the fan in order to reduce the tendency for this component to produce a high pitched note. Further tests on this machine will therefore consist of quietening the fan and increasing the current density of the brushes to deal with the extra output. Hs{Lord Ernest Hives - Chair}/Wst. | ||