Reply to "Ground Effects"

This is funny. I write these topics and people read them, and there's no responses. So, I just keep developing different ideas and topics and people keep reading them, but don't respond. So, this tells me that you're interested, and so I'll keep developing the topics ideas. You can respond if you like though.... Sort of feels like I'm crazy and talking to myself, only like it's different from the homelsss people who yell at cars passing by, you folks are stopping to 'listen' to me talk to myself.... So here's the update:

I did a search "ground effects upgrade kit" and there's a bunch of manufacturers with 'upgrade kits' but not 'the right stuff' because all the available products are for 'show' with protruding externally visible body panels, spoilers, body widening or lower front spoiler stuff. Etc. That's of no interest to me. Let me discuss 'ground effects' theory a little more with you so you get an idea of what I'm doing, or, going to do... and why.

I've been watching Formula One, CART, IRL, and Le Mans, GTP, etc. for 20 years. Over that time, the TV commentators have had the opportunity to show under trays that came off the racing machinery and explain the theory of downforce a/k/a ground effects. Also, when the santioning bodies, like Formula One and Bernie Echelstein (sp?) make 'rules changes' every year to get the cars to slow down, the TV coverage gives nice explanantions and show graphics or side-by-side footage of changes to last year's cars and this year's cars.

Let me give you the bottom line first, so I don't lose your interest. I plan to bolt on some flat aluminum panels to the under side of my Pantera and do a 'side-by-side' comparison in a 'scientific' way. I'll attempt to do Vegas 2005 with a G-Tech Meter so I can download data for stock Pantera mode, with lateral (cornering) and forward (stopping) g-force measurements. I'm thinking basically 3 panels should do the job. Front panel covers the gap from the under side of my GTS spoiler to the back lip of the front valance. This smoothes out the air flow under that area and should produce more 'vacuum' or lower pressure from the rear of the radiator. The second panel is still in concept-debate mode, but it will either cover the entire center section of the under side of the car or just the tunnel housing the water tubes. I may have to have some small tabs or mounting brakets/bolts spot welded to make the attachment secure. The third under tray will go under the engine and transmission all the way back to the rear sway bar brackets mounting position (where those De Tomaso logos go with the nice aluminum sway bar mounts.

To get any measurable increase (Vegas 2006) in downforce, the car must be lowered. F-1 cars are about 0.5 to 1.0" off the ground. They used to have under trays with large indentations resembling airplane wings cross sectioned as if viewed from the inside of the airplane wing. The theory is simple. The airplane wing creates 'lift' and the opposite is true for ground effects where the air passes on the 'opposite side of the airplane wing'. The fast flowing air under the car expands into the cavity creating lower pressure, or down force. This worked so well on Formula One cars that they generated enough down force to be able to theoretically drive upside down at speeds over 100 mph. Is this making sense to you? So, the cars got really fast in the corners and they decided to eliminate the 'inverted wings' or indentations in the under trays to slow the cars down. Now Formula One mandates flat under trays. Why does this work? I think it's Bernouli's Law, but if you took a chemistry class in high school or college, maybe you remember a simple laboratory piece of equipment that you may have used in the lab experiment for the week. The device was a plastic tube that attached to the water faucet and had a small 90 degree tube fitting attached half way down. You attached the rubber 'suction hose' to the 90 degree fitting and turned the water on. As the water flow increased, the suction from the tube increased, and did the 'sublimation' experiment or whatever it was. It just worked to generate suction as it was intended to do, that's all I can tell you and that's all you need to know, i.e. enough science class for today. What it means is fast rushing air in a smooth flow will generate 90 degree suction, pulling the car and ground together. Ground Effects-101

This year's changes to F-1 cars mandate that the under trays extending towards the rear wheels have to come inboard more, to reduce the ground effects. The front wings are also required to be higher off the ground to reduce downforce or 'ground effects' and together they reduce downforce by 20% from last year. In pervious years F-1 rules chances also required raising the car higher off the ground to reduce ground effects. What this means to us is twofold. 1) the lower the car, the greater the downforce generated. 2) Flat bottom cars produce downforce and it's going to be pretty simple to design and install a three piece gound effects under tray kit for the Pantera. Thirdly, and implied is the greater the speed, the greater the downforce generated.

Downforce is a concept different than weight ('mass" is the scientific word). For example, if you're producing 500 pounds of downforce at 100 mph, going into a turn, this is a vector force that pulls the car downward only, not outward. Which is much different than 'weight' or 'mass' because the same car without ground effects and 500 pounds more of weight, will generate a vector force in a lateral direction, towards the outside radius of the turn. Weight of 500 pounds pulls the car that much more towards the outside of the turn, and the g-force meter would show a decrease in lateral g-loading on the car, and also on your body. An effective ground effects under tray would have the opposite effect on the readings of the g-force meter, the car would negotiate the turn faster and the g-forces on the car and your body would be higher. The car is safer to drive at higher sppeds around the corners, and the downforce also holds the car down, similar to weight, when it comes time to apply the brakes at high speed for the hairpin turn at the end of the straightaway. Weight creates inertia, whereas downforce creates grip without increasing inertia. Is this sort of making sense to you?

So the Pantera without ground effects will produce some turbulance of air rushing underneath the car at speed, causing lift. The Pantera with ground effects will produce airflow in a single direction, creating suction at a 90 degree angle to the direction of the airflow. The faster the airflow, the greater the ground effects downforce generated. The lower the car sits, the greater the downforce generated.

It's important to be able to apply the brakes or get response from the steering wheel at speeds over 100 mph, which these beasts can easily accomplish. This is what I call 'handling' and it's for functional purposes, and doesn't even have to be visible from the exterior. It's not for looks at all. And it can be done to any car.

So, I'm visualizing the rear Pantera under tray attaches to the frame, but extends further outboar toward the tires, with enough clearance of the lower A-arms, and the closer to the rear tire, the more downforce. This is going to have to be securely mounted and it will have to be about 3/16" thick aluminum for rigidity in this back under tray. There will still be plenty of air flow up through the openings in the wheel wells to feed the engine requirements and cool the headers and exhaust.

I'll get around to the other stuff that will make it go closer to 200 mph after I sort out these safety and handling issues first. That other 'stuff' is going to be a lot more expensive though, like horse power and transmission gear ratio modifications and/or a higher rpm-redline engine.

Class dismissed! Thanks for your interest in this subject. VFI