RE GT2 Wing - pics
12-30-04, 01:19 AM
#51
1993 RX7 R1
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Originally Posted by damian
too aggressive angle of attack on the old wing making more downforce but a lot more drag
Just an FYI, generally speaking, most wings stall at an angle of attack greater than 14-15 degrees.
12-30-04, 10:23 AM
#54
The only other way I know of is with some sort of CFD package. I've tried to find one that I could figure out how to use but I've been unsucessful so far. (I'm not an aerospace engineer, but I've did take some college classes) You'd also need some sort of CAD/object file for the wing itself. You might be able to get that from the manufacturer or you could make it yourself with a 3d object scanner.
At that point it would be useful to have a 3d model of the entire car, since for a wing like D's new one, there's a pretty complex (3 main parts plus transitions) airfoil and the airflow itself isn't going to be perpendicular to the car.
Like someone else said, the MS-GTC wing is a much simpler design. There's one consistent airfoil on a simple forward swept arc. I'm going to get a contour gauge and see if I can cross reference it with some standard NACA profile. You're right, it shouldn't be too hard to figure out the downforce for various angles of attack, if you assume clean air hits it. Figuring it out for air actually flowing over the car would require windtunnel testing or the same CFD work from above.
At that point it would be useful to have a 3d model of the entire car, since for a wing like D's new one, there's a pretty complex (3 main parts plus transitions) airfoil and the airflow itself isn't going to be perpendicular to the car.
Like someone else said, the MS-GTC wing is a much simpler design. There's one consistent airfoil on a simple forward swept arc. I'm going to get a contour gauge and see if I can cross reference it with some standard NACA profile. You're right, it shouldn't be too hard to figure out the downforce for various angles of attack, if you assume clean air hits it. Figuring it out for air actually flowing over the car would require windtunnel testing or the same CFD work from above.
Originally Posted by afterburn27
I don't know of a way to measure the downforce without a wind tunnel... maybe you could somehow measure the ride height at different speeds. Then you could use that data with the known spring rates to calculate the forces pushing the car down. Lots of variables in that situation though...
If the wing used a NACA airfoil profile and it was constant down the length of the wing, it would be fairly simple to calculate the downforce created at different speeds.
If the wing used a NACA airfoil profile and it was constant down the length of the wing, it would be fairly simple to calculate the downforce created at different speeds.
12-31-04, 04:42 AM
#56
_________________________
Damian, the new wing looks great!
You said at BIR you can reach speeds up to 160.... have you made any plans to install a full rollcage? Perhaps you already have one.... just going by this recent photo I saw of you in your track car.
Best of luck to you, in 2005
Oliver
You said at BIR you can reach speeds up to 160.... have you made any plans to install a full rollcage? Perhaps you already have one.... just going by this recent photo I saw of you in your track car.
Best of luck to you, in 2005
Oliver
12-31-04, 10:35 AM
#57
yep, at the end of straight at BIR, before turn one I am at 160 +- and go through the turn at 140+
on the cage, the car came with a kirk 4 point roll bar mounted, so I have some safety in that...however I did have a plans to strip the entire car down and have a full cage welded in...but ran out of the 2 things that always limit a project.....time...... and money. :-)
and thats not so recent of a pic :-) here is a more recent pic:
on the cage, the car came with a kirk 4 point roll bar mounted, so I have some safety in that...however I did have a plans to strip the entire car down and have a full cage welded in...but ran out of the 2 things that always limit a project.....time...... and money. :-)
and thats not so recent of a pic :-) here is a more recent pic:
Last edited by damian; 12-31-04 at 10:40 AM.
12-31-04, 01:32 PM
#58
Originally Posted by damian
yep, at the end of straight at BIR, before turn one I am at 160 +- and go through the turn at 140+
For those who didn't see the video, Damian but a "graphic tach" so to speak on the video screen, so you could see the speeds he was at, even though you couldn't see the instrument cluster. I showed that to my folks... their jaws DROPPED lol. Taking a turn at 140...LOL
on the cage, the car came with a kirk 4 point roll bar mounted, so I have some safety in that...however I did have a plans to strip the entire car down and have a full cage welded in...but ran out of the 2 things that always limit a project.....time...... and money. :-)
On that note, no tracks require full cages, do they? Just roll bars meeting various specifications, right?
12-31-04, 03:09 PM
#59
>>On that note, no tracks require full cages, do they? Just roll bars meeting various specifications, right?
its not the track as much as it is the club you run with, some clubs only require roll bars on convertable cars, .... most clubs that do full on w-2-w racing require full certified roll cages
its not the track as much as it is the club you run with, some clubs only require roll bars on convertable cars, .... most clubs that do full on w-2-w racing require full certified roll cages
01-01-05, 12:57 PM
#61
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hi guys.....just lurking a little and enjoying a little nostalgia regarding my old car 
a couple thoughts regarding the aerodynamics discussions. now that i race cars with full aero, i've learned a ton about it over the last couple years.
1. NACA airfoil data is always the start of a good wing design. however, the limitations are that the data is developed with an isolated high aspect ratio wing without any interactions. as soon as you put in struts, local bodywork, etc, things change dramatically.
2. the hump in Damian's new wing may have an aerodynamic basis....BUT my guess is that they are trying to get as much of the wing as possible down against the bodywork and still be able to see out the back. the old wing blocked rear view quite effectively. brad constructed some taller struts for his car the fixed this, but my guess is that downforce may have suffered and drag increased. the reason you want the wing down low is that if it is correctly designed, the downforce generated is increased by interactions with the bodywork, venturis, etc. additionally drag is reduced. i know it goes against the concept of "get the wing into clean air"....but wind tunnel testing in F1 and ALMS doesn't lie.
3. having said that it's very difficult to verify this stuff without wind tunnel testing. someone mentioned CFD (computational fluid dynamics), but at present, even the brightest race car engineers rarely rely on the data from those methods. it's just too complex, requires mega computers, and is fraught with inaccuracy.
4. so what do us mortals do? data acquistion systems is our only way. specifically, for downforce measurement, we extrapolate from ride height data.... a simple shock potentiometer and a straight section of track. basically, given unchanged suspension settings and weight, ride height goes down as downforce goes up. you can generate pretty decent downforce vs speed graphs for the front and back of the car. a side benefit of DA systems is that all your screw ups and bad habits are easily discoverable. car set up and driving techniques are much more easily accomplished when you have data to back up changes.
5. my thought is that the new wing may or may not improve the car. if the downforce increases, but the drag goes up with it, lap times may not improve or may get worse (especially on the high speed tracks). as a general rule on the sports racers, we try to minimize drag on the bigger faster tracks, and try to maximize downforce on the shorter more "technical" tracks. but we also have the luxury of changing final drive ratios at will, etc.
6. if nothing else the wing looks kick ***......so there's always that!!
damian, car's looking great....can't wait for you to bring it back out west for a little california track tour
happy new year everyone!!
fabian
a couple thoughts regarding the aerodynamics discussions. now that i race cars with full aero, i've learned a ton about it over the last couple years.
1. NACA airfoil data is always the start of a good wing design. however, the limitations are that the data is developed with an isolated high aspect ratio wing without any interactions. as soon as you put in struts, local bodywork, etc, things change dramatically.
2. the hump in Damian's new wing may have an aerodynamic basis....BUT my guess is that they are trying to get as much of the wing as possible down against the bodywork and still be able to see out the back. the old wing blocked rear view quite effectively. brad constructed some taller struts for his car the fixed this, but my guess is that downforce may have suffered and drag increased. the reason you want the wing down low is that if it is correctly designed, the downforce generated is increased by interactions with the bodywork, venturis, etc. additionally drag is reduced. i know it goes against the concept of "get the wing into clean air"....but wind tunnel testing in F1 and ALMS doesn't lie.
3. having said that it's very difficult to verify this stuff without wind tunnel testing. someone mentioned CFD (computational fluid dynamics), but at present, even the brightest race car engineers rarely rely on the data from those methods. it's just too complex, requires mega computers, and is fraught with inaccuracy.
4. so what do us mortals do? data acquistion systems is our only way. specifically, for downforce measurement, we extrapolate from ride height data.... a simple shock potentiometer and a straight section of track. basically, given unchanged suspension settings and weight, ride height goes down as downforce goes up. you can generate pretty decent downforce vs speed graphs for the front and back of the car. a side benefit of DA systems is that all your screw ups and bad habits are easily discoverable. car set up and driving techniques are much more easily accomplished when you have data to back up changes.
5. my thought is that the new wing may or may not improve the car. if the downforce increases, but the drag goes up with it, lap times may not improve or may get worse (especially on the high speed tracks). as a general rule on the sports racers, we try to minimize drag on the bigger faster tracks, and try to maximize downforce on the shorter more "technical" tracks. but we also have the luxury of changing final drive ratios at will, etc.
6. if nothing else the wing looks kick ***......so there's always that!!
damian, car's looking great....can't wait for you to bring it back out west for a little california track tour
happy new year everyone!!
fabian
01-01-05, 09:45 PM
#62
hey Fabian, good to hear from you,
i always value your opinion, thanks for the notes. My take on the 'hump' is that it is done to maximine the airflow to the wing when it comes over the cabin of the car, in other words, the cabin causes the air to hit the part of the wing right behind the cabin at a slighly different angle, so that part of teh wing is 'tilted' to maximize that airflow, as apposed to the 'normal' airflow on the sides of the car/cabin.
PS
email me an update on your race car!!! :-)
i always value your opinion, thanks for the notes. My take on the 'hump' is that it is done to maximine the airflow to the wing when it comes over the cabin of the car, in other words, the cabin causes the air to hit the part of the wing right behind the cabin at a slighly different angle, so that part of teh wing is 'tilted' to maximize that airflow, as apposed to the 'normal' airflow on the sides of the car/cabin.
PS
email me an update on your race car!!! :-)
01-02-05, 04:46 PM
#64
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The RE car also has 1000$ worth of other aero on it (ground effects, fenders, front spoiler, etc.)
If they wind tunneled this, they did it with the entire car.
If they wind tunneled this, they did it with the entire car.
01-03-05, 01:07 AM
#65
Originally Posted by clayne
The RE car also has 1000$ worth of other aero on it (ground effects, fenders, front spoiler, etc.)
If they wind tunneled this, they did it with the entire car.
If they wind tunneled this, they did it with the entire car.
Fender and quarter panel exit vents:
A pic of their diffuser...
01-03-05, 01:36 AM
#68
NP Damian. There are a bunch more here (55 more pics, 45 or so of which are of the RE car hehe): http://www.villagephotos.com/pubbrow...der_id=1150322
01-03-05, 09:15 PM
#72
Originally Posted by clayne
Why did I write 1000$ worth of other aero?
If anything I meant 10,000$ worth. Sorry.
If anything I meant 10,000$ worth. Sorry.
Time to save these RE pics to HD. 
