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).
Reduced insulating properties of bakelite at increased temperatures in a Goshawk coil.
| Identifier | WestWitteringFiles\J\November1922\ Scan8 | |
| Date | 10th November 1922 | |
| R.R. 385A (100 T) (S. H.{Arthur M. Hanbury - Head Complaints} 159. 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 ORIGINAL TO EFC. FROM R.{Sir Henry Royce} R2/M10.11.22. 4 X.3485 X4079 GOSHAWK COIL. It was quite unsuspected, if you find as anticipated that the insulating properties of bakelite are very much reduced at increased temperature. The insulation of the secondary winding, lead, terminal, and circuits, must at all temperatures be very high - 10. meg ohms would be about right. Kindly test the losses from this source. I propose the use of an electrostatic (Wimshurst) machine might be useful as a means of testing the leakage properties of such materials. This would remove the risk of wrong conclusions that may be drawn by using alternating current through electrostatic capacity, etc. Regarding the phenomenon of the touch on the coil and the hand around the coil, this might easily be due to the attraction and repulsion due to electrification, but why should this vary with temperatures? Does also the electro inductive capacity of bakelite vary with temperature; if so, might our condenser (oiled silk) be a source of variation in the efficiency of the ignition? RECEIVED NOV 15 1922 H8 R.{Sir Henry Royce} | ||