Tuesday, December 7, 2010

Cornering part 1


In this article we will discuss the first things you should know about cornering at high speed, there are several techniques with different results.  Your braking point is affected by
wether you have ABS or not. Its safe to say that you should brake earlier if you are not familiar with the track and you can brake later and later over time depending on your skill level. If you want to test how well your car can brake, you should brake until the wheels are locking and then release the braking pedal a little bit. If your wheels have lost traction, do not try to steer!
Turn-in point
To get the line right, it is vital to turn in at the correct point. Leave it too late and you'll miss the apex, too soon and you'll have to tighten your line mid corner. Get this right and you'll have set yourself up for a good line. Remember that the apex may be further round the turn than you can see, so make sure you learn the track and the apex points before driving in anger.

The apex is the point at which you are closest to the inside of the corner, also referred to as the clipping point. Once you have hit the apex you should be able to reduce the steering lock and increase the throttle.


All these factors determine your braking point. It's a sensible strategy to brake earlier as you're learning the track and your car, and progressively shorten the braking area as your experience grows.

The rule of thumb is to get most of the braking out of the way before turning into a corner, although a light brake pressure on entry can help to reduce under-steer and can give a better turn in (this is known as trail braking).

Threshold braking is the technique you should aim for, but if the wheels do lock, quickly ease off and reapply the brakes with slightly less pressure until you get it right.



 
There are two different types of apex, the geometrical apex and the racing apex. The geometric apex of a constant radius corner is the central point on the inside and this may also be the racing apex, which depends on the context. Confusing!
This is where your strategy comes into it. There are several generic strategies for cornering including:

Carrying speed in the corner
Minimising the severity of the turn
Getting the power on early


The geometric apex - carrying speed and minimising the turn severity
To carry maximum speed through a corner, you need to take the route that minimises the tightness of the corner arc.

This minimises cornering force and frees up precious grip for maintaining speed. This route tends to use the geometric apex of the corner and is usually know as the classic racing line.

The turn illustrated is a constant radius 90 degree right hander and the geometric apex is exactly half way around the corner.

 Pros of the classic / traditional racing line:
Smoothes out corners in the most efficient way
Maintains momentum (especially useful for low powered cars)
Maximises fuel economy
Reduces the chances of understeer or oversteer
Preserves the life of tyres
Cons:

Not necessarily going to yield the fastest possible lap times
Late apex - getting the power on early
Oddly enough, carrying the highest average speed round corners may not actually be the quickest way around a track.

If the corner leads onto a straight it can be better to take a late apex, straighten the car out early and get the power on for a high speed exit.

This is generally regarded as the best strategy for racing, with a slightly lower entry speed but a faster exit speed. The amount of grip available is the factor which determines how late you can brake and apex.

 Pros of the modern racing line:
Increases the chances of a fast lap in a powerful car
Allows the power to be applied earlier
Maximises the use of any straights following the corner
Allows late braking
Useful for overtaking on a corner
Cons:

May not be the fastest route in a low powered car
Places greater demand on the tyres
Common mistake:
It's very common for drivers to apex too early due to nerves about the approaching corner and eagerness to take the turn.

The racing line apex which is often out of view at the point of turn in, or further round the corner than you expect.

This is where experience and track knowledge come in.


Hairpins
A hairpin is a corner which turns 180 degrees.

In this case, the apex for the racing line is about three quarters of the way around the bend.

A useful guide is that half way through the turn you should be roughly in the middle of the track.


The position of the next corner
The position and direction of the next corner also affects the choice of line. For example, if the next bend is a left hander you'll need to move over to the right hand side of the track, and thus will need to apex later and take a tighter, slower line.

However, if the next corner is another right hander a wider, faster arc can be used.

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