How To Drive The Straightaway

Posted on January 24, 2013

1


How To Be Fast On The Straightaway

It’s not as easy at it looks

By: Rob Oakman

SRA karting at Goodwood

Straights. Like the B.S stories some drivers try to sell, some are short and some are long. But, unlike the B.S stories, a straightaway should be the easiest thing in the world to figure out. So why waste an article on them? Because some get it wrong. We have all seen a car run the straights as, well, straight as possible; others weave a bit along the way. Open wheel drivers like James Hinchcliffe – whom I asked about this. Thanks James – pull down on straights that have a wall close to it only to meet it again by the next corner while NASCAR boys stay tight to it all the way along. Why do they do that? And how should you run a Straightaway? I will answer this in 3 easy to follow rules.

First, let us see if the helmet you wear shouldn’t be a permanent part of your wardrobe and answer the question: what is a straight? A straightaway is just that; a straight piece of the track between two corners. Good. Now wipe the drool off the table. You can also call a stretch of track that you can run a straight line through a straight. If you have ever seen the logo for IMSA you see how two connected corners can be used as a straight. Though technically corners, you use them as a straight.

The straightaway is the second most important piece of real-estate you will encounter next only to the last corner leading to it. The reason is simple. The faster your top speed is the faster you eat up distance which means the faster your times are. At the vast majority of tracks the time you can gain on the straightaway outweighs that which can be gained in the corners. This is why you gear for the end of the longest straightaway; to attain the top possible speed (Le Mans before the chicanes were installed is the single most obvious example of this). It is also the best place to set up for the next pass. If it is long enough, it is also where you can check instruments, relax your hands, look around, read a pit board, look for other competitors on track, scratch unsightly places, etc… This doesn’t mean you can coast through the rest of the corners, obviously. The whole lap is important. A loss of a few tenths here and there are what add up to slow. However, when it comes to losing and gaining time, speed is king.

What you want to do on the straights is travel down them as straight as possible from corner exit to braking zone or, if there is no braking zone, corner entry. And here’s why in three simple rules.

Rule #1: Never drive a greater distance than you have to.

When you drive in a straight line from point to point you are traveling the least possible distance between those points. The longer the path that you travel the more time it takes to get to where you are going at a given speed. This is why you cut corners when you can and choose the lines you do throughout the entire circuit; to shorten the course as much as possible…within the rules and eyesight of any officials or cameras watching.

For instance, if your exiting a right and the next corner is a left with a small straight in between, you want to move to the left side of the track along the straight in as smooth a way as possible to set up for the next corner. If you are exiting a right and the next corner is a right, and you have used a proper racing line, than you should drive in a perfectly straight line to the next corner. Meandering along the straight just costs you distance which costs you time.

Even the basic racing line takes advantage of shortening the length of the corner while creating a smooth arch by which to make the forces getting you around it stable throughout. It is a balance.

So excess distance is bad, but is that it?

Nope.

Rule #2: Never waste energy on something that doesn’t make you faster.

When you move the steering wheel you also change direction, however slightly, and, if you remember your physics, in order to change direction, it takes energy, energy that you need to take from somewhere. Guess where it comes from. That’s right. The engine. All of the energy used to propel you forward is generated by the engine. If you use some of that energy on needless changes in direction on the straight then you are not using that energy to accelerate. It is inefficient.

Kart racing gives us the extreme example of this. Ever try to push a kart with the front tires turned? You learn very quickly that it’s easier to just pick up the rear end and shift it over until the nose is pointed where you want to go. The solid rear axle connects both tires so they roll at the same speed. This makes it very hard to turn because, in a corner, the outside tire, which travels a longer distance, wants to travel faster than the inside tire, which travels a shorter distance. The result is that one tire is always fighting the other for traction (The outside usually wins because of the shift of weight to that side) meaning that the other is scrubbing the road surface and turning energy into heat. That heat generated is energy stolen from the engine; Energy that is wasted. So the last thing you want to do is turn the steering wheel any more than you have to at any given time. This is also true in corners.

Even in split axle cars the same is true. Why do you think weaving from side to side generates heat in the tires? Though scrubbing tires is extreme compared to changing lanes on a straight, moving around on the straight still robs energy that should be used to make you go forward, not to the side. Every time you change direction the front tires scrub off a bit of energy on the track. The momentum of your car moving forward has to be overcome by the tires and track surface to change direction. The outside tires have to accelerate while the inside tires slow their rate of acceleration, the chassis flexes, all energy wasted.

But what about those open wheel guys that pull down off the wall? Why don’t they drive straight?

According to IZOD INDYCAR driver James Hinchcliffe Aerodynamics is why.

This brings us to the final rule.

Rule#3: Ignore all rules if it’s faster.

James (Hinch, The Mayor) Hinchcliffe

James (Hinch, The Mayor) Hinchcliffe
Hinchtown.com

When I asked James why open wheel drivers move away from the wall on a straight he responded with this. “The air we push bounces off the wall and hits the rear wheel making more drag. Close wheel cars don’t have that problem”.

When you drive close to the wall the air is squeezed between the vehicle and the wall. In a bodied car the air travels along the side, is squeezed and accelerates like a venturi until it reaches the back of the car (Sometimes under the car) and then expands into its wake. In an open wheel car however, the air is squeezed and accelerated between the wall and the front wheel than it expands again to fill the void behind the wheel along the side of the car. This would be fine if it all ended there. Problem is that it is then hit by the rear wheel. The drag created by the air hitting the rear wheel is a greater drain on speed than the distance added and friction created by changing direction down the straight. Remember Rule 2 about speed? Even some full or partially bodied cars may experience some form of aero drag that makes it prudent to pull away from the wall by a lane or two. Of course you pull back up to the wall to set up for the next corner and you never move farther than you have to. The way you decide if this is a necessary move for you is by the stopwatch.

Remember. The stopwatch determines everything you do and don’t do in the end.

Now that you know how to drive a straightaway stop weaving like a Wally.

If you have any questions or comments feel free to send them along below and follow OakmanOnRacing.

Advertisements
Posted in: How to Race