I want to start off by explaining that I am not an engineer, everything I know I learned from observation of the world around me, reading as much as I could without numbing my brain, watching bit pieces, and by being an adult child and playing. Some of what I write will require you to be a kid and play a little bit if you require demonstration. Finally, if you know more and see something that needs to be corrected or you have an alternate theory, feel free to talk to me. The more we all talk, the more we learn, the more excited we are about the subject.
Many of us remember a few years back when NASCAR came out with the “wing” which quickly failed and lead back to the spoiler. When the wing was on the car, we had cars getting airborne and they never told us why. To the best of my knowledge, nobody in the sport has explained the folly of the wing and the science behind it. This is going to get a little technical but I’ll try to keep it fun and interesting.
One of the first things we have to understand about the mysterious flying cars is aerodynamics. We have downforce that we hear about so much; we have lift that nobody wants to hear; we have drag that is the resistance behind the car; then this mysterious thing called side force which quite literally keeps the car going straight. All of these forces play a roll in flight and racing.
Sideforce and drag are fairly easy to explain. Side force is the amount of air pressure pushing on the side of a vehicle. If you have too much side force on one side of the car it wants to spin. In NASCAR on an oval you want a lot of side force on the right side of your vehicle. The reason for this is that as you turn left, the rear of the car wants to turn right. By applying air pressure to the right side it keeps the car in-line. This air is the difference between spinning in the corner and easily turning through it. The right rear has supports behind the sheet metal to transfer this force to the chassis of the car. Drag is best explained as air weight trapped behind the car. This air has mass and density. It creates a dead zone behind the rear bumper and the car tows this along.
Downforce is the pressure of the air pushing down on the car. As you are going down the road (in the passenger seat) roll down your window, put your hand out in the air flat with the tips of your fingers forward and your wrist as straight back as possible. Now lift your hand from behind the mirror… You will feel air on the top and bottom of your hand. Now, tip your fingers down slightly, you can feel the air on the top of your hand pushing down and your hand wants to plane down. This, is downforce. We like downforce, downforce adds weight to the car and make the tires contact the racing surface better. More pressure, more grip.
Now I want you to lift your fingertips up. Notice how you feel air pressure on the palm of your hand. This, is lift. The air is quite literally lifting your hand. Also, you’ll feel a light pulling sensation on the back of your hand, this is low pressure. When you have low pressure on top and high pressure (lift) on bottom, you achieve flight. The air will actually lift objects this way. That low pressure you feel is essentially drag. It’s turbulent air with a reduced mass/weight.
Put your hand back straight, angle your fingertips in towards the car. You again will feel air along the top and bottom of your hand, but also the outer edge. This is your side force. On the other side of your hand, by the thumb you will feel that low pressure and drag again.
Theres your quick lesson on aerodynamics that we will need for this all to make sense, everybody tracking? Good.
The “wing” which is essentially an elevated, bi-level spoiler was developed for 2 reasons. Number one, NASCAR wanted to appeal to a younger audience, an audience who customize their vehicles with big wings, an audience that is into car performance. Reason 2, it made great downforce for these new, taller, wider, brick shaped vehicles. As I said, we like downforce, it makes cars handle better, it helps put the horsepower to the ground, it helps the front tires steer.
Where did it go wrong? Like in our downforce experiment the leading edge, front, was angled down. It creates great downforce, science says this car should weigh a lot more at 200 mph than standing still.
The problem, as we know, came when these cars turned around. This now turned it into a tiny airplane wing. The leading edge was now higher than the trailing edge, this gave the car lift. Seeing that the car was decelerating, slowing down, this shouldn’t have been enough to lift the car up, surely the car was heavy enough to stay on the ground.
Well, you had multiple things that lead to this. You had a small wing creating lift but you also had a car angled on the banking of the track so the rear of the car was higher than the front. Since the splitter was dragging on the pavement and the rear of the car was well above the pavement, you now had 160-180 mph wind being channeled under the car. The more the rear end came around, the more it lifted the rear, the more lift was developed. The entire car become a giant wing!
Why didn’t side force keep the car in-line. As the rear end came around, surely there was enough air pressure on this big flat sides to push it back straight. The problem is that while the lower half of the car is straight the upper half taper toward the center of the car. That taper reduced the resistance at the top of the car, thus causing the bottom of the car to lift as there was more pressure at the bottom than at the top.
All this lift just multiplies, the car pivots on the splitter which was the final section of car touching the ground and these cars took off. The roof flaps were rendered totally useless. They work based solely upon air pressure, when there is reduced air pressure above them, they lift up because the air pressure in the cabin of the car is greater than on top of the flap. On the old car, the moment the car got sideways they would deploy, air would track over the decklid (trunk) then hit the flap which stood straight up. This applied downforce right in front of the flap and pushed the car back down.
Sadly, the wing, when turned around created a giant low pressure system behind it. All this drag would disturb the air, but wouldn’t allow sufficient flow to the roof flap to apply downforce. It was just a big mass of turbulent air that pushed the moving air away from the car. It’s biggest downfall was the fact that the “wing” made a perfect wing when spun around backwards. A Boeing 747 weighs 800,000 pounds and takes off at 180 mph. A stock car weighs 3,300 pounds. It doesn’t take much to get it airborne, especially when it’s only defense against that is rendered useless.
Many fans will note, this wasn’t the first wing in NASCAR. So why didn’t that wing on the 1969 Dodge Charger Daytona or the 1970 Plymouth Superbird and Charger Daytona meet the same fate? What was the difference? Those cars were said to be impossible to spin.
That wing had its pillars, the pedestals, to the outside of the car. These were tall and wide and generated a ton of side force. Also, as the rear of those cars turned the air channeled over the decklid which was wider and longer and had a concave shape. The decklid acted as a very small spoiler and allowed the dead air, the drag, the low pressure to pass through the giant window wing. The car was also far enough off the track to allow air to pass underneath without generating lift, the side skirts of the current cars made this impossible.
The giant window was achieved by making the top of that spoiler just a little higher than the roof of the car. You had downforce on top of the wing and on top of the decklid. The tiny wing of recent years, the spoiler was actually in the low pressure area behind the roof of the car. It was so close to the decklid that the low pressure couldn’t escape between the decklid and spoiler. The current decklid is also convex, so it creates a low pressure area on the trailing side of it.
All of these things lead to those stock cars taking flight. While in the past the wings seemed ridiculous, the manufacturers had found the sweet spot for their aerodynamic package. NASCAR, in its quest for a new audience and more fans and more money, rushed a flawed design through. The drivers that drove the old wing cars had vehicles that refused to spin out, the drivers that drove the new wing cars, had vehicles who wanted to break the surly bonds of Earth’s gravity. Those guys, the new guys, are some tough S.O.B.’s for controlling these bricks.
I doubt we will see another wing in NASCAR. Neither wing stayed for any extended period of time and the last time was a complete disaster that ended in fans being injured and cars flying when they should have been vacuum sealed to the track.
I hope this was informative, though out of date and a little late, I think we have to look to our past and understand it so that we can learn from it, become better by it, and ultimately develop enough to not make the same mistake again.
Thank you for reading, I welcome any and all reaction to this piece, I’ll see you from the box.