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Underbody aerodynamics,defusers,canards...

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Old 06-25-2009, 10:06 PM
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Default Underbody aerodynamics,defusers,canards...

Interested in anything aerodynamic related. Personally more C5 oriented but, either platform would apply. Looking for pictures, insight, opinions, qustions, whatever. Looking at how to make the car smooth, and stable at speeds. Not cornering speeds so much, more along the lines of sheer high speed. The more homemade do it yourself stuff the better, as well as serious custom defussers, undertrays, etc.

I know some of you guys are really smart,...some of you don't always post. Well, if you've got some pointers on how to make a C5 go fast, say in a mile,...please, school me. Otherwise we're leaving it up to my imagination and some insight from friends.

Help a brother out,...let talk aero for straight line stability.

Wold a TIGER shark front bumper be effective? Does it need the chin spoiler to make it effective?

How about the world challenge front bumper? Obviously either would be primarly track used(atleast to have the front chin spoiler removable) because of ground clearence issues/resasons. My car is low, and it' not getting raised any time soon.

this?


The rear?


I think this would help for a little stability at high speeds,...without scrubbing off toomuch speed.












What about mirors? Are Corvette mirrors a burden to air low?
http://www.aprperformance.com/index....d=91&Itemid=51

Canards? Looks effective?


Also how about the 1/2 inch or 1 " strips that go along the roof ? From my understanding those are for should you loose control, and spin out at high velocity that the "L" channel strips would break up the smooth curves o the car and break the air smoothly going over it,...and therefore keep it stable, or still on the gound.

Frontal area? Do you tape off the intake ducts and leavemy front grill opening to cool/feed eveything? Or again, i the tiger shark my aero friendly? I'm willing to keep a street bumoer, and an event only bumper, should push come to shove.

Pretty much the idea here is to get a hugh horsepower C5 down the runway without blowing the tires off. I think C5's getmuch more loose traction wise then the newer C6 cars, o in my opinion, the C5 takes a little more muscle. The car also has coilovers, so it's rigid,...a cage and poly bushings are in the works,...so, the more stabiile I can make this thing, the safer the world would be.

Thanks for your help peoples...I appreciate it, as I think others will too if we can get some hardcore info/pics here.
Old 06-26-2009, 03:01 PM
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duck tape all your body gaps and and the such, foglights included
Old 06-27-2009, 01:23 PM
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Originally Posted by Tainted
duck tape all your body gaps and and the such, foglights included
Thanks,...was looking for something a little more scientific.
Old 06-28-2009, 12:20 AM
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Originally Posted by V-seriesTech
Thanks,...was looking for something a little more scientific.
It is. Tape is the best thing ever to happend to aerodynamics, the fastest way to cover a bodyline or an opening or wherever air can get trapped and slow you down.


Originally Posted by V-seriesTech
insight, opinions, qustions, whatever
I can provide some insight though.

The Coupe is better then the Z06 from the factory, the FRC body lines allows air to flutter around instead of flowing to the rear. Also the if it's a Z the ducts put more drag on the car and pose lift issues

One thing you'll have to look for is how to block ALL air in the front to make it flow AND still get air to cool the radiator/trans cooler/engines/lines and let the engine breathe.

If you want to go with aero pans, diffusers and all that remember you need to make the bottom as flat as possible, if there is an interruption of airflow from the front to back it wont work well.

The best pictures to look at would be race cars, mostly C5R's, notice how they're coupes, where the ducting is, what type of wing is on there etc.

Another insight would be to pick up some aero books




There's a bunch on amazon
Old 06-28-2009, 01:30 AM
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Very nice Tom. Info for the most part that I learned a while back but, very true and exact. Thank you for the time. I didnt think about aero books though,...so thats a great idea, and I will without a doubt check those out.

Thanks again
Old 06-30-2009, 12:34 PM
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I have a book (C5 Performance Projects) that says the body side moldings help aerodynamics. If you don't already have them, it would be easy enough to stick them on.

From the book:
"Some people like side spears and some don't. Ironically, after they were introduced, GM discovered that they actually aid the laminar side airflow."
Old 07-06-2009, 12:18 AM
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Get a wide body to force more air down.


It also helps to get a good rake and a front splitter to keep the out from underneath the car.

Old 07-06-2009, 12:46 AM
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almost always top speed and stability will be a tradeoff.

if you are looking for stability, downforce is your friend, and keeping turbulent air to an absolute minimum is also very important. downforce is only generated when drag is generated, which reduces top speed. however, if you find areas that are already producing high drag (usually by creating turbulent flow or stagnation points... such as the front bumper... bottom of the car... FOGLIGHTS and such) and replace those areas with devices that create downforce... you can both reduce drag and increase downforce simultaneously.

I'm not 100% sure, but the grooves on top of the car seem to be directional vortex generators... and destroy the aerodynamics of the car should it start moving sideways. they would do exactly like you say if that is the case... and prevent lift from being generated if the car were to turn sideways. should help keep it on the ground. downside... it creates more skin area and more drag. reducing top speed ever so slightly.



enough with my rambling. long story short:

if you want ultimate straight line stability... tie a parachute to the back of the car on a very long rope.

if you want ultimate speed... shape the car into a rocket-shape who's diameter is about 1/10 it's length, and fill it with rocket propellant.

anything that looks like it might act like a little parachute on the front of the car... cover it.
spray your car with a hose from the front... anywhere that the water leaves the surface of the car for any reason... that's an area you need to fix the flow over. if it doesn't flow very nicely without splashing... it's an area that's creating drag most likely. this works best if you have a high-speed laminar flow hose... or a wind tunnel... but we know that probably isn't the case, and so a garden hose can do the trick (no attachments)

a perfectly flat underbody tray will give you the greatest top speed... since you will have the least drag created.
an underbody tray that generates downforce will allow more stability. a tray that generates more downforce generates more drag... drag at the front of the car creates a car that is unstable at high speeds... explaining why they are almost always flat... and why the rear spoilers on say... F1 cars... or any othe race car... is larger than the front spoiler.

if you're looking for just enough stability at top speed in a straight line with no turning ability whatsoever...
generate just enough downforce up front (chin spoiler, perfectly shaped underbody tray, canards, etc...) to keep the front wheels on the ground while accelerating.
generate as much downforce/drag in the back as you need to be able to hit the brakes and slow down with all 4 wheels evenly (the faster you're going... the less of a rear spoiler/underbody tray combo you will need for this... incidentally)

now that i've done my rambling... i'm going to sleep. PM me if this doesn't make sense and you're interested. I'm sure it doesn't make sense... idk if you're interested. lol.
Old 07-06-2009, 12:49 AM
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Originally Posted by obi-1

From the book:
"Some people like side spears and some don't. Ironically, after they were introduced, GM discovered that they actually aid the laminar side airflow."
It's probably true. They look like they would help to allow the air to smoothly transition from the underside of the car, moving up to the sides.
Old 06-12-2010, 10:20 PM
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Default all you ever wanted on c5 aero

Go to sae.org and buy paper # 2002-01-3333. Costs about $20. Worth every penny. 10 hours of windtunnel data on a c5 with all possible combinations of aero mods every imagined. Probably $50-$100k of testing and engineering time. As stated above, add down force to the front and rear for stability will cost you drag. You need more horsepower to overcome the extra drag to achieve the same top speed (think $10k for turbos). Quite a viscious cycle. Short answer and most bang for the buck, remove your license plate mount, tape all the seams and fog light cutouts and rear brake ducts (not front or front side ducts though), lower the front 2 inches with front lower bolts ($25) (keep rear stock height) and remove the front underbody side plastic pieces. If you have the money ($500+shipping) buy a 3" splitter for the front. You drop about 30 pounds of drag, add about 250 pounds of front down force, and lose 90 pounds (bad) on the rear at 120 mph. If you really have the money, then add a huge rear wing with 12 degree angle, 1 inch wicker, and big endplates. Adds 55 pounds of drag, loses 25 pounds of front down force, and gains 120 pounds of rear down force in addition to the above combos. Wing with all above would give you 25 pounds more drag, 225 pounds of front down force, and 30 pounds extra rear down force at 120 mph above stock. Cost out the door would be around $2,500 without installation or paint. If you find the rear too loose still, then better tires or adding rear weight are the only non-exotic (aka expensive) choices you have available.
Old 06-14-2010, 04:26 PM
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Originally Posted by AxisOfOil
almost always top speed and stability will be a tradeoff.

if you are looking for stability, downforce is your friend, and keeping turbulent air to an absolute minimum is also very important. downforce is only generated when drag is generated, which reduces top speed. however, if you find areas that are already producing high drag (usually by creating turbulent flow or stagnation points... such as the front bumper... bottom of the car... FOGLIGHTS and such) and replace those areas with devices that create downforce... you can both reduce drag and increase downforce simultaneously.

I'm not 100% sure, but the grooves on top of the car seem to be directional vortex generators... and destroy the aerodynamics of the car should it start moving sideways. they would do exactly like you say if that is the case... and prevent lift from being generated if the car were to turn sideways. should help keep it on the ground. downside... it creates more skin area and more drag. reducing top speed ever so slightly.



enough with my rambling. long story short:

if you want ultimate straight line stability... tie a parachute to the back of the car on a very long rope.

if you want ultimate speed... shape the car into a rocket-shape who's diameter is about 1/10 it's length, and fill it with rocket propellant.

anything that looks like it might act like a little parachute on the front of the car... cover it.
spray your car with a hose from the front... anywhere that the water leaves the surface of the car for any reason... that's an area you need to fix the flow over. if it doesn't flow very nicely without splashing... it's an area that's creating drag most likely. this works best if you have a high-speed laminar flow hose... or a wind tunnel... but we know that probably isn't the case, and so a garden hose can do the trick (no attachments)

a perfectly flat underbody tray will give you the greatest top speed... since you will have the least drag created.
an underbody tray that generates downforce will allow more stability. a tray that generates more downforce generates more drag... drag at the front of the car creates a car that is unstable at high speeds... explaining why they are almost always flat... and why the rear spoilers on say... F1 cars... or any othe race car... is larger than the front spoiler.

if you're looking for just enough stability at top speed in a straight line with no turning ability whatsoever...
generate just enough downforce up front (chin spoiler, perfectly shaped underbody tray, canards, etc...) to keep the front wheels on the ground while accelerating.
generate as much downforce/drag in the back as you need to be able to hit the brakes and slow down with all 4 wheels evenly (the faster you're going... the less of a rear spoiler/underbody tray combo you will need for this... incidentally)

now that i've done my rambling... i'm going to sleep. PM me if this doesn't make sense and you're interested. I'm sure it doesn't make sense... idk if you're interested. lol.

Thanks for the info man. Been talking alot with a aeronautical engineer on this subject lately. Thank you for the info,...i'll probably PM you once I read this again lol. I appreciate it!!!


Originally Posted by engr
Go to sae.org and buy paper # 2002-01-3333. Costs about $20. Worth every penny. 10 hours of windtunnel data on a c5 with all possible combinations of aero mods every imagined. Probably $50-$100k of testing and engineering time. As stated above, add down force to the front and rear for stability will cost you drag. You need more horsepower to overcome the extra drag to achieve the same top speed (think $10k for turbos). Quite a viscious cycle. Short answer and most bang for the buck, remove your license plate mount, tape all the seams and fog light cutouts and rear brake ducts (not front or front side ducts though), lower the front 2 inches with front lower bolts ($25) (keep rear stock height) and remove the front underbody side plastic pieces. If you have the money ($500+shipping) buy a 3" splitter for the front. You drop about 30 pounds of drag, add about 250 pounds of front down force, and lose 90 pounds (bad) on the rear at 120 mph. If you really have the money, then add a huge rear wing with 12 degree angle, 1 inch wicker, and big endplates. Adds 55 pounds of drag, loses 25 pounds of front down force, and gains 120 pounds of rear down force in addition to the above combos. Wing with all above would give you 25 pounds more drag, 225 pounds of front down force, and 30 pounds extra rear down force at 120 mph above stock. Cost out the door would be around $2,500 without installation or paint. If you find the rear too loose still, then better tires or adding rear weight are the only non-exotic (aka expensive) choices you have available.

Wow,..more good info. Thank you both of you guys. Keep you posted on questions.




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