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 new experimental mushroom type H.T. rotor, comparing its performance on open circuit to the standard type.
| Identifier | ExFiles\Box 32\5\ Scan063 | |
| Date | 22th October 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. BY.{R.W. Bailey - Chief Engineer} c. E.{Mr Elliott - Chief Engineer} Wor.{Arthur Wormald - General Works Manager} X6096 EFCL/T22.10.27. X5690 X4041 MUSHROOM TYPE H.T. ROTOR. A test has been made of the new experimental mushroom type H.T. rotor, of a nature similar to some tests we made and reported some considerable time ago on a rotor of the present standard type, as a result of which we pointed out that the gap in the distributor head, which was supposed to act as a safety gap, did not so act, and that the insulation of the distributor head would fail by tracking should the H.T. delivery of the distributor be open circuited. The following is a copy of my assistant's report on the mushroom type H.T. rotor, from which it appears that the circumstances of running this distributor on open circuit are very much less serious than running the present standard. From this point of view, therefore, the mushroom rotor may be considered an undoubted advantage in the prevention of rotor failure by tracking. "Tests have been carried out with one of the above rotors running in a distributor open-circuited so that H.T. sparks occurred inside the distributor head. The head was cut away at the sides for the purpose of observing the paths taken by the sparks in jumping to the distributor base. It was observed that sparks passing from the edge of the rotor to earth traversed a portion of the lip of the rotor before jumping direct to the base as shown :- TIP OF ROTOR BASE | ||