Aerodynamics

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Daytona, Catchfences and Flying Cars

Track barriers originally were erected to keep cars separated from spectators. In addition to concrete walls to prevent the cars from driving off track, debris-spewing accidents necessitated fencing to contain airborne objects.

Catchfences should have the same properties as walls, but they can’t block the view. Chain link fence is a good compromise: It’s cheap, plentiful, easy to put up and surprisingly strong given its high visibility.

Chain-link fabric is an elastic metal mesh. It can give in two ways: gentle forces cause the mesh to deform. The diamonds stretch out of shape, but when the force is removed, the fabric springs back to its original shape. The fence can also deform by stretching the wires that make up the mesh. A large-enough force will break the wire entirely.

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Does Less Downforce Mean More Lift?

Last Tuesday, NASCAR announced aerodynamic modifications to be implemented for the Kentucky Speedway Sprint Cup race on July 11th. While the changes are (right now) only for that race, there’s every expectation that if they help reduce the dreaded ‘aero push’ problem, they may be extended (or modified) for other 1.5 […]

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How Fast Would NASCAR Cars Go at Daytona without Restrictor Plates?

Doug Yates was guest on Dave Moody’s SiriusXM Speedway last week. He brought up a conversion you hear a lot in the week before Daytona and Talladega. Every 25 horsepower in the engine translates to about a 1 second decrease in lap times. Dave did the math: Removing the plates would increase the engine by 450 horsepower. Four hundred and fifty more horsepower equates to 18 seconds off the lap time, assuming all other things equal. That last part was a very important qualification. It will come back to haunt us in a moment.

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The Flap over Roof Flaps

Why Roof Flaps? Roof flaps (the invention of which I detail in my book The Physics of NASCAR) help keep cars on the ground.  This is necessary because of Bernoulli’s law, which says basically that: Faster-moving air exerts less pressure. Slower-moving air exerts more pressure. A wing develops lift because the […]

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Keeping Racecars on the Racetrack

Ryan Newman escaped NASCAR sanctions for his comments immediately after being discharged from the infield care center at Talladega.

“They can build safer racecars, they can build safer walls, but they can’t get their heads out of their asses far enough to keep them on the race track and that’s pretty disappointing, and I wanted to make sure I get that point across,” he said. “You all can figure out who ‘they’ is.”

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A Quick Post on Why Cars Go Airborne

A quick post for my friend, @TheOrangeCone that I’ll expand on later (I have theater tickets tonight!)

@TheOrangeCone asked why Kurt Busch went airborne in the Talladega crash. The answer is the same for all the cars that end up in the air: when a car rotates (so that its side or its back is leading instead of its front), it looks an awful lot like an airplane wing — a shape that is optimized to generate lift.

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Brief Thoughts on the Nationwide Accident at Daytona

We’ve been painting the house. I was straining to hear EPSN’s commentary over the swoosh-swish of the paint roller as the race came to a close – but it was all too easy to hear the change the tone of Allen Bestwick’s voice. We heard it recently from Marty Reid in Vegas. I remember the first-hand feeling sitting about 50 yards from Michael McDowell’s wreck during qualifying at Texas. A track full of race fans – all quiet – is one of the worst sounds in all of sports.

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Why 200 mph Laps at Michigan are not like 200-mph Laps at Daytona or Talladega

That fact that people are even talking about restrictor plates for Cup racing at Michigan International Speedway indicates a lack of understanding of the issues that give rise to concerns about cars getting airborne.

I touched on the difference between average and instantaneous quantities last week with the pit road speeding issue at Pocono. Instantaneous speed is the speed you are going at some particular instant. A radar gun measures instantaneous speed.

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