NASCAR Basics: Window Strips & Roof Flaps

An article at NASCAR.com explains how the new window strips are supposed to keep the Cup cars from going airborne at Daytona and Talladega...

"If you ride down the highway and you put your hand out the window and you hold your hand in the direction the car is traveling, there's not a lot of resistance," Darby said. "But turn your hand sidewise and it'll come back and slap you in the forehead. It's a very similar effect."

"If you picture the strip on the car, and you're going down the straightaway, it really doesn't have that much effect. But as the car starts to spin and the strip now sees the air pressure, it does two things. It slows the rotation of the car down, and as the air comes across it, it packs air on top of the trunk lid to help push the car back to the ground before it lifts."

And the reason why the trunk fin is on the left side of the window is also inherently logical.

"It's actually lined up with the left edge of the left roof flap," Darby said. "Because as the air hits that fin, part of what happens is that the airflow travels up to the flap. There's a misconception about the flap. A lot of people think that air pressure blows them open. It's quite the contrary.

"The flaps are contoured on the top and it works much like an airplane wing to where the airspeed that travels over the flap actually pulls it open. If we can put more air to the flap and accelerate where it goes across it, then it's going to open faster and stay up stronger. So part of the air helps deploy the flap and the rest of the air -- because the trunk lid is wide and you have more surface area to come across -- helps hold the car back down on the ground."

Even though the trunk fin seems to be the best solution for Daytona and Talladega at this point, Darby said the process is always evolving -- and more improvements may come from additional wind tunnel testing.

NASCAR Basics: The Tracks: Master List

As part of my NASCAR Basics series of posts, I'm writing a post about each of the tracks that hold Sprint Cup races. This will be an ongoing process throughout the 2008 season with a new post whenever NASCAR travels to a new track. Then I'll link to that post here, making a master list.

A note: These are loose categories of tracks. Some authoritative sources might have only four categories, combining tracks from one to two miles in length into one big "Intermediate" category. To me, it doesn't make much sense to compare longer, wider, higher speed tracks like Atlanta or Texas to tracks like Phoenix or Dover.

SUPERSPEEDWAYS (over two miles long)

Daytona International Speedway*
Pocono Raceway
Talladega Superspeedway*

* restrictor plate tracks

SPEEDWAYS (1.5 to two miles long)

Atlanta Motor Speedway
Auto Club Speedway (formerly California Speedway)
Charlotte Motor Speedway (formerly Lowe's Motor Speedway)
Homestead-Miami Speedway
Michigan International Speedway
Texas Motor Speedway

INTERMEDIATE TRACKS (one to 1.5 miles long)

Darlington Raceway
Kansas Speedway
Las Vegas Motor Speedway
New Hampshire Motor Speedway
Phoenix International Raceway

SHORT TRACKS (less than a mile long)

Bristol Motor Speedway
Dover International Speedway
Martinsville Speedway
Richmond International Raceway

ROAD COURSES

Infineon Raceway (formerly Sears Point Raceway)