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Old 11-22-2008, 12:27 PM   #51 (permalink)
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Quote:
Originally Posted by guudasitgets View Post
There might be vortece's rolling off the sides, you could curl some aluminium and straighten them out. Like cutting a toilet paper roll in quarters and tape them on the side supports facing inward
yeah, I thought of that on my way home, but I think it'll still do better than before. I may in the end wind up building a new wing, the adjustable part at least. with a custom very slight curve that will be reversable, as in I could flip it over and it would be shaped for really good aerodynamics, and then flip it and it would be shaped for really good downforce

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Old 03-06-2009, 01:54 AM   #52 (permalink)
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Quote:
Originally Posted by Daox View Post
This is a great question, and one I've been asking myself lately WRT the Paseo. Now, the Paseo's spoiler doesn't look like much. There is barely a gap between the trunk and the bottom of the spoiler (less than an inch). This leads me to believe it may help with aero. Also, I have noticed that on a rainy day the back windshield stays completely dry at highway speeds. I believe this is a good thing? None of my other cars stay as dry as the Paseo in rain. So, is it possible that the spoiler helps this (since it is downstream of the airflow)? I think I speak for most here in saying I don't want to rip off the spoiler (a big PITA from what I've heard) just to see that it does in fact help aero.



That spoiler probably does nothing at all for downforce, or the rear window, it should just smooth out the air as it goes over the back of the trunk, and not a good job of it, because it's so low. The reason i think you don't get wind on the rear window is because of where the turbulent air is sitting, if you have say a mini-van the turbulent air spins around and splatters the rear window, on your car i'd bet anything that the turbulent air (the big pocket that your car pulls along and holds the water spray from the rear wheels) is sitting behind the car, and not over the rear window, hence, not making it wet.

Quote:
Originally Posted by 3lr View Post
is your rear window more sloped than your other cars
or it there a possibility that the distance of the rear spoiler to the trunk lid is carefully determined like the boundry layer (usually the lenght of both wings combined) as it provides a cushion of air that has allowed many ocean flying, out of fuel, airplanes to "coast" for many miles and make a safe terra firma landing.
perhaps in your case it creates a venturi, creating a low pressure area in front of the spoiler thus allowing air to speed up as it flows down the rear window?
I'm kind of curious as to what you're on about.

Airplanes can coast for a long time because of aerodynamic advantages only when they're flying very low over the surface. To understand this you have to understand the airflow over the wing.

When the air flows over the wing on the top it moves towards the fusalage and on the bottom if tends to move away from the fusalage (this is because of high and low pressures)

So what you get as an affect is a big vortex spinning off of the tips of the wings, and a LOT of drag. When airplanes fly LOW over a surface it reduces these vortexes, and depending on a number of things, can help an airplane glide for an extended distance.



This effect has NOTHING to do with what's happening at the back of his peaso.

Also a low pressure area will NOT form at the beginning of a spoiler, a high pressure area will form at the beginning, and low at the back. Talking in terms of the aerodynamic effect of the spoiler though, excluding outside factors.
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Old 03-06-2009, 10:40 AM   #53 (permalink)
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Quote:
Originally Posted by tasdrouille View Post

Here's a good example of a working spoiler
I always liked that beetle wing myself. Justgoes to show that aero doesn't HAVE to look dweeby.

Also interesting is the link at the bottom of that page to an August 2004 Salon.com article about the VW. It's interesting to jump back 4.5 years and read an article describing the public's reaction to an aero modification and fuel efficiency. It is amazing how the general public's awareness of the importance of efficiency has changed in only four and a half years (I think $4.50/gallon gas got everyone's attention).

Beetle on the wing - Salon.com
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Old 05-08-2009, 11:09 AM   #54 (permalink)
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using wings for lift?

This is a totally newbie question from someone with no engineering knowledge - but curious about automobile aerodynamics.

Most of this great thread are eco-mods to 1) reduce drag, and 2) sometimes to increase downforce or wind-flow around the car.

Can a car use a wing or body-shape at higher speeds for LIFT to reduce the weight to improve fuel economy - or would the lift reduce traction and be a safety hazzard? Just curious why not have adjusting wing so at high driving speeds (70mph) your car is made a bit lighter (lift) and uses less fuel - or would this also produce drag. Perhaps adjustable wings could move to a lift position at high speeds, a neutral level slower or angle to increase down-force in rainy conditions? This prolly just shows my lack of knowledge of the physics of car aerodynamics at 70mph.


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Old 05-08-2009, 11:49 AM   #55 (permalink)
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Hello & welcome to EM!

The lift would be accompanied with more drag -- the lift can not be enough to offset the added drag, by definition. Also, lift is a bad thing for stability, so it should be avoided/minimized.

I'm glad you're thinking about the problem!
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Old 05-08-2009, 07:03 PM   #56 (permalink)
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Quote:
Originally Posted by MetroMPG View Post
I think the angle of the rear glass in #1 is too steep compared to the Pinto.

If the hatch angle is too great, and the separation point is the trailing edge of the roof, then the spoiler would be sitting in turbulent, detached flow:

So what is the best place and shape of a spoiler on the Golf? Just a basic roof line extension like they put on the Honda Hatches?
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Old 05-08-2009, 09:26 PM   #57 (permalink)
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Here is my factory spoiler/wing. Its nice and flat with an 8th of an inch gap across the front. The ends stick up a bit too much over the quarter panels for my liking but that I am stuck with. It also has a big opening in the back. Do you guys think I should fill the gap along the front edge where it meets the trunk and the rear cavity?



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Old 05-08-2009, 09:47 PM   #58 (permalink)
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I asked the local dealership for my car (a GM built local variant) about the aero benefits of fitting the optional aero body kit pack only to be told the effect is "aerodynamically neutral"
which meant there are no benefits or disadvantages to be had from fitting one.

At least they were honest about it !

Pete.
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Old 05-08-2009, 09:49 PM   #59 (permalink)
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Trip 323 ,
Welcome to the place and enjoy your stay.

Cheers , Pete.
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Old 05-08-2009, 09:54 PM   #60 (permalink)
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GM claims these cut outs by the lights dont affect aero either. Me personally.. I think they do but I dont have 4 college degrees and unlimited super computer resources like they do...

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