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).
Engine testing, comparing bench tests to in-air performance regarding spark plugs and fuel mixtures.
| Identifier | ExFiles\Box 36\2\ scan 152 | |
| Date | 31th October 1927 guessed | |
| contd :- -2- than it does on the bench tests. This is proved by the fact that on the bench we found it necessary to use a very cool plug to prevent pre ignitions; with these plugs in the same engines in the air we were immediately in trouble with them failing because they were too cool. We are now using on all the engines in the air plugs several stages hotter than we can use on the test bench. If we can use a hotter plug it also follows we could run with less dope. In our opinion the 7/1 engine is quite a safe proposition on standard fuel when used in the way which it has been agreed with a gate throttle. The A.M. specification for fuel allows 30 to 38% aromatics - the usual 20/80 benzol/aviation mixture is on the low side. We are therefore running the type test with a mixture of 27/73 which gives us an aromatic content of approx. 36%. Except for the pistons and the gear ratio, all the details of the engine are identical to the F.12. Hs.{Lord Ernest Hives - Chair} | ||