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).
Testing self-ignition and backward running in Phantom engines, specifically regarding the danger of firing the carburetter.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan259 | |
| Date | 28th June 1926 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ACL. c.c. to B.J. Wor.{Arthur Wormald - General Works Manager}✓ c.c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer}✓ c.c. to DA.{Bernard Day - Chassis Design} HY.{Tom Haldenby - Plant Engineer}✓ c.c. to PN.{Mr Northey} CWB.✓ ORIGINAL Hs{Lord Ernest Hives - Chair}/ACL1/LG28.6.26. X8080 X699 SELF IGNITION AND RUNNING BACKWARDS ON PHANTOM ENGINES. With regard to the self ignition after switching off, and this often results in the engine running backwards, it has been tested to see if there is danger in firing the carburetter under these conditions. We reproduced the phenomenon artificially by running the engine at about 1500 r.p.m., switching off in order to charge the exhaust system with fresh mixture and again switching on with fully advanced ignition just before the engine stopped. The general conditions so produced should be similar to those given by the hot exhaust valves when they cause reversing. Although the engine would reverse vigorously under these conditions, not once out of many times tested did we experience any flame reaching the carburetter. For the purpose of this test, in order to increase the possibility of firing when running backwards, one cylinder was cut out so that the fresh charge - now passing the reverse way through the cylinders - would mingle with the exhaust from the other cylinders in the induction pipe. The results were the same with no firing in the carburetter. It seems that the R-R carburetter possesses the virtue of being particularly good in resisting firing when popping back due to an over weak mixture. contd :- | ||