JOSH BROWNE: At most of the race tracks, you're cornering for a large percentage of the lap. That's why you could
say the races are won and lost in the corners.
STEVE LETARTE: The corners are where all your speed is gained or lost. Sometimes you see a guy going down the straightaway
and you think this other car has fifty more horsepower because he drives right by him. Well, people don't understand that was all
momentum from what happened back in the corner. The guys that understand the corner the best, make the car change direction the
fastest and apply the power the best, they're gonna be successful.
NARRATOR: The roar of the engines, the squeal of the tires, then the race to victory lane. It all says, NASCAR. A race
car is much more than steel, gas, rubber and speed. A race car is a science experiment on wheels.
DIANDRA LESLIE-PELECKY: Driving a stock car is easy, right? Go fast and turn left. Turns out there's a whole lot more to
turning left than you might think.
STEVE LETARTE: Racing is usually all about the turns when it comes to NASCAR. Because you or I could probably drive a
straight line. Our speeds are not the 300 miles an hour. At 180 or 200 miles an hour, while that seems fast, straight is straight, and
it's pretty easy to do.
DIANDRA LESLIE-PELECKY: Straight is simple. In fact most things want to go straight. When I give this ball a push, it
goes straight, and it will keep going straight until something makes it change direction. Similarly, a race car going 180 miles an hour down
down the straightaway will keep going 180 miles an hour down the straightaway unless something makes it change direction.
That something is the centripetal force.
NICK HUGHES: In order to make the car go around a corner, we have to provide a force that is perpendicular to the
direction of travel.
DIANDRA LESLIE-PELECKY: When I tie the ball to a string and push the ball, the centripetal force generated by the string
makes the ball move in a circle. Of course, race cars don't have strings to make them turn. They have tires.
JOHN PROBST: The contact patch for the tire would be its footprint. You know, the tire itself's footprint,
relative to the track.
DIANDRA LESLIE-PELECKY: When sitting still, the contact patch for a single tire is about the area of a man's size eleven
shoe print. But tire camber, the banking of the track, and the way the car's weight shifts in the turn, may make it smaller. So for a
right front tire in a left turn...
BRANDON THOMAS: ...you're looking at a contact patch that's probably four inches wide, maybe two to three inches long. So
you're talking about a very small area producing a very large amount of force.
DIANDRA LESLIE-PELECKY: Taking turn one at Texas Motor Speedway at 180 miles an hour requires over 10,000 pounds of
centripetal force. That's something a driver notices.
JEFF GORDON: I'd rarely ever take my hand off the steering wheel in the corners. But you know, there are certain
tracks we go to where maybe I have had to do something. And the first time you do it, it's sort of a wake up call. You go, whoa!
You know, you gotta kinda catch your hand and be ready for it.
CARL EDWARDS: The time when I really notice it is if I go to grab my drink bottle or something, even under caution, my hand
pools up with blood, you know, and I have to bring it back and work it a little bit to make it quit tingling.
DIANDRA LESLIE-PELECKY: The couple of tons of force you need to make the car turn, doesn't only come from the tires.
STEVE LETARTE: If you go out into a parking lot and you try to drive around in a circle, you don't have a whole lot of
confidence because the parking lot's completely flat, and you have nothing really holding you up, and eventually you wanna slide out.
But now if you put angle or banking to that, and you pull two or three degrees of lateral G, well now that banking's really helping
you to go around and to the left.
BRANDON THOMAS: Banking makes the car think it's driving a straighter line. So if you have a corner radius, say a really
tight corner radius and there's no banking, you can only go around that corner, say, 50 miles an hour. But now take a similar corner
radius with a high bank, you can go 100 miles an hour.
DIANDRA LESLIE-PELECKY: The track always pushes on the car perpendicular to the track's surface. On a flat track the force
is straight up. On a banked track, only part of the track's push is straight up. The rest of the push is toward the center. The track
actually helps the car turn.
STEVE LETARTE: If you drive around the race track in a street car, you have to turn to the right. Because the banking alone
wants to slide you to the bottom of the track.
DIANDRA LESLIE-PELECKY: Even though Dover and Phoenix are both one-mile tracks, Dover has 24 degrees of banking, while the
highest banked turn at Phoenix is only 11 degrees. Cars get a lot more help turning at Dover than they do at Phoenix. Even air helps the
cars turn.
NICK HUGHES: The amount of grip that's generated by all four tires basically sums together with the side force that's
aerodynamically pushing on the car, to sum to a force that will dictate how hard you can corner the car.
DIANDRA LESLIE-PELECKY: Aerodynamic side force is the force of the air pushing the car sideways, just like you'd feel when
you're driving past a semi-trailer on the expressway. Side force is also one reason for the end plate on the rear wing.
JOHN PROBST: If we had ten pounds of side force, which would be aerodynamic side force, basically air pushing the car back
to center, if you will, so trying to steer it straight, then that's directly ten pounds going to help turn the car.
DIANDRA LESLIE-PELECKY: The next time someone tells you that all there is to driving a stock car is turning left, you tell
them, it takes a combination of tires, the track, and the air, to generate the thousands of pounds of force necessary to get a car
into and out of a turn at 180 miles an hour. Guts, and a heavy right foot help. But in the end, you need the right science to turn left.