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 vehicle dynamics including precession torque, rolling resistance, camber, and skid pad results.
| Identifier | ExFiles\Box 170\3\ img148 | |
| Date | 21th January 1938 | |
| S.H. Grylls Esq., Rolls Royce Limited. Precession Torque. We had thought that fitting a front stabilizer would increase the total precession torque, because it certainly increases feel, but since the curves of precession torque against load are practically straight lines, the fitting of a front stabilizer does not affect total precession torque (Chart 3). Rolling Resistance. Rolling resistance or drag, increases rapidly with slip angle and becomes extremely sensitive to load. The difference between rolling resistance on the inner and outer wheels multiplied by the overhang of the centre of the wheel disc from the kingpin, is therefore the source of increased road feel through front stabilizer. (Chart 5). Reducing this overhang we know reduces road feel, and here is the explanation. In fact one can say that overhang of wheel from kingpin is a good way of getting road feel without using caster, caster being undesirable because of its sensitiveness in side winds and on cambered roads. The reason road feel is so sensitive to caster, overhang etc, whereas all these things are supplements to the actual precession torque of the tyres, is that what we feel is the excess of self centring effects over friction. Mixed Camber and Slip Angle. We know that the effect of camber angle is to lower the curves of cornering force against slip angle bodily, i.e. camber adds an additional outward force without greatly affecting the cornering power of the tyre. We thought that the wheel camber on an independent added to the precession torque. Apparently it doe'nt (See Chart 4). It slightly decreases precession torque in the low range but prevents it reversing at high slip angles. Skid Pad Results. Your skid pad results on 27 G VI sent on 24th December show typical results. The curve 1 shows a very nice moderate understeer, but apparently it is going to skid front wheels first with the front stabilizer. -3- | ||