CORNERING AT SPEED.
CORNERING AT SPEED.
How to Maintain High Averages in Races and Competitions.
By MAJOR H. 0. D. SEGRAVE. (As Major &grave is recognised as one of the best drivers in the world, his views on Cornering at Speed are particularly valuable, especially at a time when hairpins are coming more into vogue in racing and competitive events.—Editor.)
TJP to the time of writing, in England the only racing events which have been held for motor-cars have been track racing, with the exception of the recent 2-)o miles race at Brooklands, but it has become obvious to the organisers of these events that track racing alone does not test every portion of the competing cars and consequently it is apt to produce the freak design functioning satisfactorily only under certain conditions. The races which are organised abroad, on the other hand, are devised with the intention of testing every single portion of the car, the chassis, springing, brakes, acceleration and change speed. Consequently it is obvious that races of this nature are of very much
greater utility to the advancement of automobile design. Thus we find the introduction of artificial corners in such events as the Two Hundred Miles Race, and
it is fairly certain that the precedent will be followed in the various speed trials arranged to take place at Brooklands during the coming season. My own view is that this innovation marks an important step in the progress of motor racing in this country, though of course cornering has been a big feature in Continental motor trials for years past. As for many amateurs, cornering at speed introduces new factors in fast driving; I am glad to have this oppor tunity of offering a little advice on the subject, for as was demonstrated in the big Brooklands classic, there
is cornering and cornering. By that I mean that it is one thing to simply get round a hairpin bend and another matter entirely to negotiate the curve in safety without losing those valuable fractions of seconds, which mean so much to the racing driver.
Two Methods of Cornering.
Broadly speaking, there are two ways of going round a corner fast, the first being to approach the bend on top gear, allow the car to ” roll round,” before changing gear and accelerating on straightening up; and, secondly, to change down at a predetermined point and go round “on the engine.”
As far as the time factor is concerned, there is very little difference between the two methods, as I have frequently proved by cornering against the stop watch, but after having made very careful comparisons in both cases I am sure that the second method is greatly to be preferred from many points of view. Perhaps it will be easier to explain matters by the aid of a few diagrams of a typical hair-pin bend, beginning and finishing with the dotted line A-B, shown in the accompanying sketches. In Fig. i the driver approaches the bend on top gear, say at 100 m.p.h., he decelerates at the point C, and changes down into the gear on which he proposes to negotiate the bend. By this method of changing down before the bend itself he saves the braking power of the car by using the over-run of his engine as a brake itself. The bend is then negotiated in the gear which will give him the maximum amount of acceleration upon leaving it, but from the point of view of safety and controllability of the car, there is no question but that this method is from every point of view by far the most satisfactory, because : For instance, when a corner is negotiated in top gear, if by any chance the driver shows lack of judgment and over-shoots his corner, or approaches it too fast, he has not got the power of the engine to help to extricate the car from the difficulties into which he has got. It has been proved through years of driving in races, on the road, that the one and only way to extricate a car from difficulties is to use the power of the engine in an emergency. Consequently, if you are on top gear at the time, the engine will be turning too slowly to develop its full power and will be incapable of skidding the back wheels. It is quite useless to
depend upon ” steering ” the car out of trouble in a case like this, because adhesion on the front wheels is not sufficient at high speeds to permit of the directional travel of the car being rapidly changed. Other advantages of this method of cornering are that wear on the brakes is to a large extent avoided, which is the most important thing on a long distance race. Also allowing the car to over-run the engine on the approach of the bend, a better cooling effect is obtained.
Hugging the Rails.
Until one realises the underlying principles of fast cornering, there is a prevalent tendency to take the shortest course on a bend, but considering the thing geometrically the driver should always follow the widest and most gradual curve possible, as indicated in rig. 2. Close cornering on bends is certainly spectacular, but races may easily be lost by striving too much after effect, and the driver who understands something of the stresses of his car and engine will use his judgment in avoiding any undue stresses, which not only jeopardise his chances by mechanical failures, but also slow the car down unnecessarily
A Hint on Practising.
After long experience in fast driving, one becomes accustomed to take corners at the right speed on all occasions, but like everything else, practice makes perfect where this phase of motor racing is concerned. If a driver has had no actual experience of cornering at speed, I would strongly recommend him to study the character of the curves well in advance of the event in which he intends to participate.
So much depends upon knowing just what the car will do, that it is unsafe to take any risks by going into a race unprepared for all eventualities.
It is not enough to be able to negotiate a corner successfully when one has the track quite clear, for in the race there may be someone in front who misjudges the curve, and allowances must oe made for this sort of thing.
The most important point to discover is the exact distance in which the car can be stopped, by a normal application of the brakes—thus leaving a little in hand for emergencies.
At each curve in a course, about three landmarks, such as trees or telegraph posts, should be selected. The first of these should mark the point at which the orakes should be applied if one has plenty of time in hand. The next should mark the point for braking if it becomes necessary to do an extra fast lap, and the third point marks the emergency braking spot, and under no circumstances should the brakes be applied after the third point, for any panic application of the brakes on the curve would mean an inevitable spill.
Cornering with Skids.
As a general practice I recommend what may be termed ” geometrical” cornering; but there are times when skidding is justified, as for example in the case illustrated in Fig. 3, in which the road is narrow and the hairpin very acute. On approaching the apex of the angle, one should start a wheel-spin to bring the car round, then decelerate, after which the pressure of the foot on the accelerator pedal should be regulated to a nicety, so that the car proceeds with increasing speed but without any .wheel-spin. Skidding certainly has its uses in cornering, but the driver who habitually goes into an intentional skid on approaching every corner loses more ground than the ” geometrical ” cornerer.
Effects of Tyre Designs.
The subject of tyre design is so complicated that it would be impossible to deal with it adequately in the present article, so I will pass on with a few remarks.
For road racing it is desirable to select a tread presenting a good area to the road and having three ribs of rectangular section. In my experience the best form of tread is that of the Pirelli type, which takes the form of separate squares, and this gives a perfect grip.
For track work, a tread of curved section is best, with fairly shallow and closely spaced ribs. If treads with projecting centre ribs are used for road work there is a danger of lateral float, due to the resiliency of the centre rib in a lateral direction, and, small though this may seem, such an action may easily make all the difference between keeping a straight course at speed and going into the ditch on either side of the road.
High pressure balloon tyres are ideal for fast cornering on account of the large surface presented to the road, and this form of tyre should be inflated to 40 or 50 lbs. per square inch.
Just one final word of advice to readers who have ambitions as motor racers. Whether you are on a road race or any sort of long distance competition, I would recommend as a regular axiom “Begin Slowly.” Do not endeavour to force matters at the start and let your engine feel its way, which also gives you the opportunity to become accustomed to the conditions of the contest and also creates a feeling of self-confidence, thus avoiding the state of nerves and overexcitement which has spoiled the chances of so many drivers in the early stages of their careers.