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).
Spark plug development for aircraft engines, including types, sizes, and manufacturer feedback.
| Identifier | ExFiles\Box 178\2\ img002 | |
| Date | 17th May 1940 | |
| COPY Serial No. 134. Oy.5/D/May.17.40. May 17, 1940. Spark Plugs. Rolls Royce Ltd., Derby. Rm{William Robotham - Chief Engineer} Heron and Val Cronstedt of Pratt & Whitney agree that the best which they can see at present in ceramic plug development for aircraft engines suggests that 18 m/m plugs will be essential for a plug with good life. They think that the move to 14 m/m plugs on aircraft engines was a mistake. All American engines of any note use 18/m/m.{Mr Moon / Mr Moore} The British Purchasing Commission is buying large quantities of B.G. plugs, which Sam Heron describes as probably the best of the mica plugs. The face-firing plug is made by a small concern (the Onan Company?) in Boston. I wrote you about this some weeks ago. It is flush-ended and fires across the face of the insulator. On the Ethyl Lab's extreme test these plugs broke down. Heron tried to get the makers to use better materials and workmanship, but, at that time, two years ago, was unsuccessful in persuading them to spend the money. OY. | ||