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airflow
Airflowing through a car rather than around | |
For years aut designers have been designing cars in windtunnels, testing airflow around cars. I have thought up an idea, why not have the air flow through the car. The air would flow through ducts through the superstructure of the car, maybe even the substructure. I.e the chassis. I figured it would
be picked up at the front of the car and directed into ducts that flow through the car. I reckon one duct on each side of the car could form very oversized side-skirts like on the opel astra v-8 coupe' pictured here [see link --admin] almost exactly like that car. Also some air could be picked up along the side-skirts through scoops and such things. There also could be a scoop at the roof of the car to pick up additional airflow. The air would vent through the rear bumper with some sort of diffuser? But of course this car would only work in rear-wheel-drive applications.
Picture of an Opal concept vehicle
http://www.edmunds.....astra.r3-4.350.jpg
The author's link as a link. [phoenix, Oct 17 2004]
The drag equation
http://www.grc.nasa...irplane/drageq.html
[RayfordSteele, Oct 17 2004]
The Center for Creative Studies in Detroit
http://www.ccscad.e...timg.cfm?pageID=125
Yeah, it's in downtown Detroit, unfortunately. Look up Industrial Design, focusing on transportation design. [RayfordSteele, Oct 17 2004]
GM Precept
http://popularmecha..._80_mpg/index.phtml
Airflow control for lower Cd [NatLabgeek, Oct 17 2004]
[link]
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I think it would sound like a jet engine, too. All you're doing is making the car appear smaller head-on. Why not dispense with the skin and let the air flow around the ugly, exposed guts of the car? |
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The added design time and material would make cars heavier and pricier. the vastly increased surface area would create "hella friction" so the car wouldn't perform any better than a sensibly designed car. |
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True, but you can't safely pick up a sensibly designed car with a forklift, can you? |
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I still think it was a genius idea, because im 16 years old, and it would look wicked sweet (-:
HAHA i think its funny that all i think about is designing cars, whilst other people of my age are drinking and smoking things. |
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p.s. that car isnt a concept its a race car, just a new one, there were others of the same design except different colors, and a much more aggressive look. |
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I doubt the friction of the air moving inside ducts in a car would be that dramatic/heavy. Besides ever heard of a thing called carbon fibre? |
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Maybe I swallowed to much salt water surfing this morning, but I really don't see the advantage to this. All extra bodywork increases wetted area, the advantage is the improvement in handling gained by the additional downforce, and keeping brakes and intercoolers cooled by improving airflow across them. I think it would also be difficult to achieve and maintain laminar flow through/across scoops and ductwork. I have to admit, the Opel does look kinda nifty. |
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craig, it's not the weight of the material that matters the most in this problem. It's the fact that the air would be pushing against another surface in order to travel from the roof and down to the rear bumper. Each surface which blocks the natural flow of the air would cause friction and a drag effect. For the same reason, f1 cars are designed to be as much like an upturned wing as possible so that there is minimal surface for the air to hit, and what does hit undergoes a pressure differential to keep the thing on the ground.
Although, that opel does look rather nice... I wonder if Holden will bring it out here. (hmmmm) |
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Look at it this way: you can't shrink the outside without shrinking the inside, so in order to get these ducts, you'd need to make the outside bigger or make the inside smaller. Assuming you make the inside smaller in order to keep the frontal area the same, you've still massively increased the wetted area, and therefore increased the drag. |
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...But the "ducted" race car is faster, right? how can that be? The ducts serve a variety of purposes: |
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1:they direct air to the brakes, so that they don't overheat under extreme use. (ever watched a rally race at night?) |
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2: they manage airflow to produce downforce, so they can take turns faster. |
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The ducts produce a tremendous amount of drag, but these cars often have insanely powerful and fuel-hungry engines to make up for the extra drag. |
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So yes, the ducts definitely have a purpose, but drag reduction is not it. For downforce and cooling, I'd have to say baked. If all you're going for is looks, then by all means, go ahead! |
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Now hold on, there is an inkling of a concept here. Auto drag can be approximated by the amount of projected frontal area multiplied by the car's coefficient of friction. What your idea is trying to do is reduce the amount of frontal area, which is a worthy goal. However, the frictional forces generated by your ducts would probably result in more of a loss than a gain. |
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Reminds me of myself at 16. I had the same auto-styling dreams, but didn't have the right connections, until it was much too late. Wish I would've gone more into the auto styling world than the auto engineering world. |
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Craig, you want to get into the car design business? |
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You're in luck. Let me give you some future planning pointers, if this is what you really want to do, 'cause I found out this stuff long after I needed it, and I was screwed because of it. |
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Your best bet is to go to college in the geographic location that is most likely to have classes associated with the industry. In other words, get hooked up at the right school with the right connections early on. Local universities here in the Detroit area have many ties to the auto industry; take as much advantage of that as you can stand to handle. |
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Do whatever it takes in your high school years to get in to those colleges. Also, look for whatever programs they might offer to high school kids. |
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Check into the Center for Creative Studies in downtown Detroit. They specialize in industrial design-type classes. Google for them, and read up. There are probably a few others, but these guys are some of the heaviest hitters. |
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Take some manufacturing engineering classes. Load up on the math as well. Take some hands-on type of classes as well; something that'll shows that you have personal initiative. Bone up on your drawing skills, and learn to use a CAD system if you can find access to one. Don't waste your time with video games or even here that much. Get started on that as early as you can. |
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Don't go to a party school, and be prepared to work.
It's an extremely competitive position in the industry, because there are a lot of kids who want to be car stylists; it's a high-profile job, and they only take the very best. |
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Anything a design can do to avoid flow separation at the rear of the car (where most of the drag is) will have a profound affect on the drag. Look at the Precept link, they had the right idea.
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Another fuel stretcher is the shape of Precept's less-than-mainstream body. GM claims that its 0.16 coefficient of drag (Cd) saves 4 mpg. Those grille openings in the rear quarter panels and tail promote airflow through the engine compartment and create ideal flow over the rear of the car. GM rates the Precept with a Cd of one-half that of a standard midsize sedan. |
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You guys haven't had much exposure to the modern race car (Formula 1, CART, Pro Sports Car racing). The technology is called ground effects. There is literally twin tunnels through the car but in the form of venturis. As the air moves to the rear, the area which contains it expands forming low pressure which sucks the car to the road giving improved cornering capabilities. |
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