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).
Technical explanation of carburetor behavior under sudden throttle opening, comparing car and aero engines.
| Identifier | ExFiles\Box 66a\1\ scan0215 | |
| Date | 28th January 1929 guessed | |
| contd :- -4- If now the throttle is opened suddenly from this low speed we have a very different condition. The engine speed will not follow quickly the rapid opening of the throttle due to the inertia and tractive resistance of the car, consequently the velocity through the choke will still be low. Therefore due to the resulting low and feeble suction on the diffuser combined with the inertia and surface tension effects of the fuel in the diffuser there will be a period of no fuel supply from the diffuser. The throttle being wide open and its edge away from the idling discharge xxxx slot there will be insufficient suction to draw fuel from this source. Therefore there will be a period of total xx absence of fuel supply and the engine consequently stalls. Fig 2. THROTTLE OPENED STEADILY. VEL. HIGH ENOUGH TO DRAW FUEL FROM DIFFUSER The case is very different with an aero engine driving a propeller. Due to the characteristic of an air screw where the resisting torque on the engine varies approx. as the square of the speed it is impossible to have a heavy resisting torque on the engine at low speeds. Consequently when the throttle is suddenly opened from idling speeds, the resistance being less, the engine accelerates more xkgxqqxrix contd :- Fig 3. THROTTLE OPENED SUDDENLY FROM LOW SPEEDS. SUCTN BREAKS DOWN ON IDLING SYSTEM AND VEL. THRO' CHOKE TOO LOW TO SUPPLY FUEL FROM DIFFUSER | ||