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 fuel mixture distribution under the effects of acceleration, engine mounting tilt, and induction pipe design.
| Identifier | ExFiles\Box 123\1\ scan0080 | |
| Date | 27th January 1941 | |
| Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}3/ET.27.1.41. - 2 - 2. The cone of mixture leaving the discharge tube will now descend at 5 1/2° out of vertical. Together with 1 1/2° backward tilt on the engine, this means that the fuel is descending at 7° towards the rear of the car-burettor. These effects are shown in the sketch below. [Diagram Annotations] NORMAL FUEL LEVEL FUEL LEVEL INCLINATION 5 1/2° DUE TO 3 FT/SEC^2 ACCEL. 1 1/2° DUE TO ENGINE MOUNTING DIRECTION OF TRAVEL THROTTLE SPINDLE PARALLEL TO CSHAFT. 3. The accelerator pump, which operates only during the first half of the throttle opening, i.e. that part of the range under considera-tion, shoots petrol towards the rear of the carburettor. 4. On the Wraith type induction pipe the long straight branches are about 6" long and each feeds one cylinder. The gas speed at 15 M.P.H. is less than 12 ft/sec. and, since the inertia of fuel is nearly 60 times that of air, there is a ten-dency to strengthen the rear cylinder and weaken the front one. This effect is not great, but we have calculated that it would make 1 1/2% or a quarter of a ratio difference between front and rear. | ||