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).
Page discussing tractive resistance, carburation, and flywheel inertia in relation to car performance and acceleration.
| Identifier | ExFiles\Box 178\1\ img005 | |
| Date | 12th October 1925 | |
| - 3 - REF. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG121025. The same argument applies to axle ratio alterations as more power is then available at the same speed up to the peak of the power curve. The shape of the torque curve of the engine must be taken into consideration when allowing for gear ratios. (see Hill Climbing). Tractive resistance. The tractive resistance of a car is its resistance to movement. At low speeds this is due to bearing friction and tyre rolling resistance. While increase in these two factors may affect petrol consumption slightly, it is improbable that they will produce an appreciable affect on acceleration unless, due to something being definitely wrong, their value is augmented 50% or so. It is absurd to pretend that any difference in acceleration can be noted by the driver due to fitting balloon tyres for instance. At speeds above 60 m p.h. over 80% of the resistance (on a normal touring car) is due to windage. If therefore better high speed accrn. is required, the body must be streamlined. Carburation. It is unnecessary to emphasise the vital importance of carburation on slow speed top gear acceleration (up to 20 m.p.h.) The slightest alteration in the carburation is capable of reducing its slow speed acceleration performance 20%. (b) Indirect gears - flywheel inertia. If it is desired to produce a car having violent accrn. on low gears it is essential to incorporate a reasonably light flywheel. As an example, if on the present Phantom, when (contd). | ||