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).
Photographic comparison of AC, Lodge, and KLG spark plug insulators after endurance testing on Vulture, Peregrine, and Merlin engines.
| Identifier | ExFiles\Box 27\3\ Scan262 | |
| Date | 10th October 1939 guessed | |
| AC INSULATOR AFTER 50hrs ENDURANCE. LODGE INSULATOR AFTER 100 hrs ENDURANCE KLG INSULATOR AFTER 100 hrs ENDURANCE VULTURE PEREGRINE MERLIN | ||