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).
Developing a formula for the ignition break position for starting the Goshawk engine.
| Identifier | ExFiles\Box 54\5\ Scan252 | |
| Date | 9th January 1924 | |
| 9.1.24. (Handwritten Notes: Revised 31.10.24 See X5680) X.3485 - GOSHAWK BATTERY IGNITION. X.3949. Development of formula giving position of lever on quadrant, at which ignition break should take place on retarding lever, for starting engine. The position for which a formula is required depends upon four quantities, each of which is represented by general symbols in the first instance. The quantities are :- (1) The make ratio of the contact breaker which we will call r (usually .5 to .55). N.B. The make ratio is defined as the fraction Period of make --------------------------------------------- total period (period of make+period of break) (2) The fully retarded ignition setting of the engine. (usually about 10°). Let this be d degrees after dead point. (3) The available range of advance (hand advance only and reckoned on engine). This for the present ignition is 40°. Call this R degrees. (4) The position in which the engine has stopped. Assume this to be 8° before dead point for some particular cylinder. (This will be in the neighbourhood of 60°). Since fully retarded break is set to d degrees after dead point, the fully retarded make will be 120 r-d degrees before dead point. Contd. | ||