Placeholder Image

Subtitles section Play video

  • In 1959, something happened that revolutionized

  • NASCAR's stock-car racing:

  • the introduction of Daytona International Speedway.

  • Daytona was unlike any race track

  • before it because of these:

  • banked turns.

  • Turns had towering walls that sloped

  • downwards to the center.

  • Walls that NASCAR's stock cars would drive onto.

  • Daytona's banks were a whopping 31 degrees,

  • significantly steeper than the relatively flat

  • 12-degree banks at Martinsville or Occoneechee Speedways.

  • In the first year of Daytona, stock-car drivers qualified

  • at speeds of more than 140 mph.

  • And today, at the same track, that speed is

  • more like 200 mph,

  • in large part because of the steep banks.

  • Which raises the question:

  • How do banked walls help cars go faster?

  • Detractors of NASCAR joke that, to finish a race,

  • all you have to do is turn left.

  • To NASCAR fans' chagrin, it's somewhat true.

  • For the majority of NASCAR races,

  • most of the lap is completed while turning, or cornering.

  • What critics misunderstand is that it's the turns

  • where good drivers earn their keep.

  • Viewers will see stock cars rocket past

  • each other in the straightaways and think,

  • "Well, the faster car had more horsepower."

  • Not so true.

  • The speed that the driver uses to pass

  • comes largely from the momentum they collect

  • in the curve they just left.

  • The winningest NASCAR drivers, then, are the ones

  • that understand the corners the best,

  • change direction the fastest, pick the best lines,

  • and apply power at the right times to navigate

  • the corners better than their competitors.

  • It's the corners where the races are won.

  • Going straight is easy.

  • Newton's law of inertia tells us

  • that an object going straight will keep going

  • straight until something makes it change direction.

  • So driving a stock car on a straightaway,

  • even at 180 mph, would be fairly easy for you or me.

  • It's turning that presents some challenges.

  • To turn, a force needs to push the car sideways.

  • That force is centripetal force.

  • Imagine a ball attached to a string.

  • When I twirl the ball in a horizontal circle,

  • the tension in the string provides

  • the centripetal force to make the ball curve.

  • Our stock cars don't have strings attached to them.

  • The centripetal force needed to move the car left is caused

  • instead by friction at the tires.

  • But at high speed, the force of friction at the tires

  • alone is not enough to pull the car to the left.

  • Let me explain by example.

  • Think about turning sharp circles in a flat parking lot.

  • The faster you go, the more unsteady the car will be.

  • With enough speed, the car will slide out.

  • Taking the first turn at Bristol Motor Speedway

  • at 130 mph requires an immense

  • 16,000 pounds of force

  • to move the car to the left.

  • That's where high banks come in handy.

  • When an object presses onto a surface,

  • the object feels an equal force in the opposite direction.

  • So for a stock car on a flat track, the track will push up

  • with a force equivalent to the weight of the car.

  • On a banked track, however, only part of the force

  • from the track goes straight up.

  • The angle of the track directs the rest

  • of the force towards the center.

  • And that's exactly the direction

  • the driver is trying to turn.

  • The extra force from the banked track,

  • combined with friction from the tires,

  • is enough to turn the car safely.

  • So the steep, banked turns let drivers maintain

  • greater speeds into and through the turns.

  • NASCAR's banks are for cars going at race speeds.

  • At lower speeds, the 33-degree bank

  • at Talladega Superspeedway would be enough to slide

  • a car down to the bottom of the track.

  • In fact, if you or I wanted to take a lap

  • around Talladega in, say, a street car,

  • we'd constantly be turning right

  • just to stay up on the wall.

  • But you don't need to be a stock-car driver

  • to test a banked turn for yourself.

  • Banked turns exist on our roads, too,

  • on freeway on-ramps and interchanges.

  • For heavy vehicles, like trucks and buses,

  • friction alone may not provide enough force to turn safely,

  • especially if the driver doesn't slow down enough.

  • A slightly banked turn, with a gentle grade of, say,

  • 15 degrees or less, can help push

  • the vehicle into the turn.

  • So, for NASCAR, banked turns simultaneously

  • create lateral force that, in addition to friction force

  • at the tires, create enough centripetal force

  • in total to get stock cars moving to the left,

  • but also enable them to travel at higher speeds

  • without sliding or flying off the track.

In 1959, something happened that revolutionized

Subtitles and vocabulary

Operation of videos Adjust the video here to display the subtitles

B1 US nascar stock track friction driver turning

The One Design Change That Made NASCAR Races Faster

  • 1 1
    joey joey posted on 2021/05/25
Video vocabulary