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).
Sparking plug voltage test results for a Merlin 'C'.15 engine at various altitudes.
| Identifier | ExFiles\Box 58\2\ Scan336 | |
| Date | 15th May 1936 guessed | |
| SPARKING PLUG VOLTAGE TESTS MERLIN 'C'.15. Sparking Plug: LODGE A14/D1. Set at .015". Cylinder: 'A' Side. No.1. Magneto Contact Breaker. Set at .012". Length of Air Gap. Altitude. Air. Temp. Glycol Out. Engine Revs. .026 6000 + 5 oC. 112 2740 .026 8000 0 112 2810 .025 10000 - 4 113 2870 .025 12000 - 7 113 2950 .028 14000 - 9 112 2970 .034 16000 -13 112 2940 .037 18000 -17 113 2920 .037 20000 -22 110 2870 | ||