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).
Analysis of engine 'running on' after being switched off, exploring causes like spontaneous combustion and temperature.
| Identifier | ExFiles\Box 34\2\ Scan106 | |
| Date | 15th May 1918 | |
| Contd. -5- E.1/LG15.5.18. causes that helps to warm the charge:- 1. At low speeds one would expect that the turbulence in the combustion chamber to be much less. 2. The charge is in the cylinder for a longer time so that it can be warmed up from the cylinder walls. As regards the engine continuing to fire after being switched off, all our tests go to show that the explosion is caused by a spontaneous combustion. We have tried scraping every particle of carbon out of the combustion chamber; this does not prevent. We have tried running full power, switching off the cylinder being observed and at the same time holding open the exhaust valve wide so that we could look into the combustion chamber; there was no signs of over-heating, yet, when we released the exhaust valve, as the engine died down, that cylinder would give one or two explosions. On the other hand, if we start up with the ignition cut out from the cylinder, though we ran with a temperature of 180°C in the jackets, that cylinder will not fire but if we switch on the ignition and warm up the cylinder, it will fire for a long time after it is switched.off. The temperature of the cylinder has a very big effect, for instance, with oil at 175°C in the jackets the engine will fire with all the ignition leads pulled off and the throttle shut on its stop for 4 minutes. Under the same conditions with th water at 30°C it will continue to fire for ¼ a minute. Whilst we are carrying out these tests, we are going to try the difference between the magneto and the battery spark. Our impression is that it is all connected with the Contd. | ||