| ghschirtz | 05-10-2006 12:28 AM |
Rear Wing Effectiveness
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I am going to CA Speedway in a couple of weeks. I have the OEM WRX (low) wing on my Sub. I have had the car out to 130 and it seemed very stable. However, does anyone have any data about this wing and how effective it may or may not be?
Proably not enough time to do anything about it but I would like to know if it contributes to rear end lift, or cancels it out. If the rear end is going to get light I hope someone can tell me.
George
Proably not enough time to do anything about it but I would like to know if it contributes to rear end lift, or cancels it out. If the rear end is going to get light I hope someone can tell me.
George
| buster | 05-10-2006 12:31 AM |
I drove a track day and a lots of autoX with and without the stock WRX wing, I can't tell any difference. If you are talking about 130mph, there might be a negligable gain to have it but not much.
In Ontario I was driving 130-160km/hr on the highways regualrly and didn't notice any difference
In Ontario I was driving 130-160km/hr on the highways regualrly and didn't notice any difference
| TypeR | 05-10-2006 12:51 AM |
When I ran with a CF trunk it felt like the back was floating in comparison to the stock trunk/wing. I'd hang on to it if I were you. 80lbs of downforce is a lot when you have to get on the brakes hard from 130 mph+.
| stifry | 05-10-2006 01:06 AM |
I didn't notice any difference either. My stock STI trunk and wing were removed and replaced with a CF trunk. I probably saved 50 or 60 lbs. I have had it up to 145mph without any problems. Honestly, the STI wing doesn't look like it was designed with any angle for downforce. I have read that a race wing can add like 50-100lbs of downforce at those speeds. I'm going to install an aluminum APR race wing before my next event to see how that feels. Those world challenge GT cars must have wings for a reason, right?
Take what TypeR says with a grain of salt. He drives a spec miata now :p
Take what TypeR says with a grain of salt. He drives a spec miata now :p
| Impreza01 | 05-10-2006 02:43 AM |
[QUOTE=stifry]I didn't notice any difference either. My stock STI trunk and wing were removed and replaced with a CF trunk. I probably saved 50 or 60 lbs. I have had it up to 145mph without any problems. Honestly, the STI wing doesn't look like it was designed with any angle for downforce. I have read that a race wing can add like 50-100lbs of downforce at those speeds. I'm going to install an aluminum APR race wing before my next event to see how that feels. Those world challenge GT cars must have wings for a reason, right?
Take what TypeR says with a grain of salt. He drives a spec miata now :p[/QUOTE]
The STi wing wasn't designed for high loads of downforce, more aiming towards zero lift. As for the low wing, I know there was a thread before where someone wind-tunneled it and it provided some downforce at speed (it was to the degree a semi or pro would feel; it wasn't high at all). I know the Group N Imprezas for the Production Car WRC in 2004 (WRX STi Spec C WR Limitied) had the low wing too.
Take what TypeR says with a grain of salt. He drives a spec miata now :p[/QUOTE]
The STi wing wasn't designed for high loads of downforce, more aiming towards zero lift. As for the low wing, I know there was a thread before where someone wind-tunneled it and it provided some downforce at speed (it was to the degree a semi or pro would feel; it wasn't high at all). I know the Group N Imprezas for the Production Car WRC in 2004 (WRX STi Spec C WR Limitied) had the low wing too.
| pio!pio! | 05-10-2006 04:17 AM |
to all those that say they haven't noticed a difference:
If you say you've been at high speeds on the highway and havne't noticed a difference, it's because you aren't cornering hard enough...try taking a high speed corner at high speeds (enough to get the tires to start screeching slightly) w/ and w/o the wing and w/ the wing should feel more stable or be faster
If you say you've been at high speeds on the highway and havne't noticed a difference, it's because you aren't cornering hard enough...try taking a high speed corner at high speeds (enough to get the tires to start screeching slightly) w/ and w/o the wing and w/ the wing should feel more stable or be faster
| ghschirtz | 05-10-2006 11:12 AM |
It sounds like there is benefit to having the wing. Right now I don't want the rear end floating, as pio!pio! and Type R are saying. And if the low wing is good enough for WRC, I suspect it has to have some value. Downforce, as in other venues of racing, is not the same concern I have. I have spun Formula Fords by decelerating too quickly through turns-they are very sensitive to load transfer. I was braking hard from 115-125 in the Sub at Laguna Seca and Willow Springs without issues or Bad Feelings with the low wing so I will keep it and just be a little gentle at first. Prodrive wing, maybe later...
To generate real downforce I would need a front splitter and likely a high wing, Gurney flaps, the lot, and lower the car to reduce airflow underneath in preference to running it over surfaces that promote downforce. That is what the GT cars do, and it works. Making a production car into Chapman's inverted wing (as in F1) simply is not on. Not my goal right now.
Many thanks to all. Be safe out there!
George
To generate real downforce I would need a front splitter and likely a high wing, Gurney flaps, the lot, and lower the car to reduce airflow underneath in preference to running it over surfaces that promote downforce. That is what the GT cars do, and it works. Making a production car into Chapman's inverted wing (as in F1) simply is not on. Not my goal right now.
Many thanks to all. Be safe out there!
George
| zoomfactor | 05-10-2006 02:29 PM |
Well, is the issue increasing downforce or reducing lift? or a combination of both?
Reduce some of the air going under the car (vs over the car) and you will impact some of the lift that occurs at high speed - this may not be the same as creating downforce.
Reduce some of the air going under the car (vs over the car) and you will impact some of the lift that occurs at high speed - this may not be the same as creating downforce.
| goto_racing | 05-10-2006 03:33 PM |
[QUOTE=zoomfactor]Well, is the issue increasing downforce or reducing lift? or a combination of both?
Reduce some of the air going under the car (vs over the car) and you will impact some of the lift that occurs at high speed - this may not be the same as creating downforce.[/QUOTE]
It's all the same to the tires: more normal force to corner with.
we have an accelarometer in our legacy. Peak cornering at A1GP was about 1.92g. At GrandAm, minus our splitter and Cusco wing, we only measured a peak of 1.7g.
Please note that the tire are different for the series as well, but between the butt dyno and the data, it seems like our aero made more than a casual difference.
Chris Lock
Reduce some of the air going under the car (vs over the car) and you will impact some of the lift that occurs at high speed - this may not be the same as creating downforce.[/QUOTE]
It's all the same to the tires: more normal force to corner with.
we have an accelarometer in our legacy. Peak cornering at A1GP was about 1.92g. At GrandAm, minus our splitter and Cusco wing, we only measured a peak of 1.7g.
Please note that the tire are different for the series as well, but between the butt dyno and the data, it seems like our aero made more than a casual difference.
Chris Lock
| solo-x | 05-10-2006 03:42 PM |
wow, that legacy must be a rocket. it's pulling more g's then a formula ford does on the soft compound hoosier slicks!
| goto_racing | 05-10-2006 04:10 PM |
[QUOTE=solo-x]wow, that legacy must be a rocket. it's pulling more g's then a formula ford does on the soft compound hoosier slicks![/QUOTE]
Take those numbers witha grain of salt. Those are peak, and probably happened for brief moments only on high speed, on camber sections of track. Not flat.
I think a FFord skippy car can pull 2.5 on that track.
Chris Lock
Take those numbers witha grain of salt. Those are peak, and probably happened for brief moments only on high speed, on camber sections of track. Not flat.
I think a FFord skippy car can pull 2.5 on that track.
Chris Lock
| MPME | 05-10-2006 04:25 PM |
The WRX trunk "spolier" is simply there to prevent lift, and in doing so, reduce drag.
The STI 'wing,' does work as an actual wing, but the profile and chord aren't designed to make gobs of downforce.
The tall profile of the wing and stubby chord tell you the downforce it makes was meant to be most impactful and efficient at lower speeds. If it was meant to be more effective at higher speeds, it'd be a lower profile with a deeper chord.
It also serves to reduce lift by detaching the air passing over the rear window at a higher point than the WRX lip, thereby also reducing drag, but being a wing, it creates a degree of of its own drag by nature.
As most street cars have little or no downforce, even a mild attempt at adding some with the stock STI wing helps.
I know this is all basic aero 101 stuff most people already know...
The STI 'wing,' does work as an actual wing, but the profile and chord aren't designed to make gobs of downforce.
The tall profile of the wing and stubby chord tell you the downforce it makes was meant to be most impactful and efficient at lower speeds. If it was meant to be more effective at higher speeds, it'd be a lower profile with a deeper chord.
It also serves to reduce lift by detaching the air passing over the rear window at a higher point than the WRX lip, thereby also reducing drag, but being a wing, it creates a degree of of its own drag by nature.
As most street cars have little or no downforce, even a mild attempt at adding some with the stock STI wing helps.
I know this is all basic aero 101 stuff most people already know...
| shemoves | 05-10-2006 04:30 PM |
I've read a couple mag articles that 'measured' the downforce to be 50 lbs. @ 100 mph. On a 3000+ lb car it is insignificant. So ya know, the downforce is not created by the AoA (angle of attack...though there seems to be a bit), it is an upside down wing (that's why the top is flat and the bottom is curved...*kinda* like a tear drop cut in half).
The high-speed straight line stability is much more likely caused by the vertical slats...they act like rudders.
For reference, F1 cars produce four times the vehicle's weight in downforce...thousands of pounds...and is greatly affected by the speed of the car.
The STi wing is basically dead weight at anything below fast highway speeds. And even at high speeds, does not do much. Compare it with the WRC wing...notice what is different about it (vertical slats). The WRC wing also sits further back so that the air actually has a chance to get down the rear-window. Also, notice what they did in '06 to reduce rear lift on the WRX car...secondary wing (which you don't have) to help get that freakin air get down to the wing and under-carriage aero (<-- this is where the big differences are made for high-speed anti-lift). Furthermore, look at how high actual race car wings sit...passenger cabin blocks air again.
If you watch videos of cars 'taking off,' you can almost see the car getting pushed up from the bottom. Once you get some wind going under there, and the car starts to lift, there is a catostrophic cycle that occurs...as the air lifts the car more, the bottom of the car gets higher, enabling more air to get underneath, lifting higher, even more lift...
My point is this...the stock STi wing is not that big of a deal until you get going REALLY fast, and even then isn't that much. Keep your WRX wing on there, be safe, and just have some fun.
Perhaps some more competitive race teams could back me up or give a good slap upside the noggin on this though.
The high-speed straight line stability is much more likely caused by the vertical slats...they act like rudders.
For reference, F1 cars produce four times the vehicle's weight in downforce...thousands of pounds...and is greatly affected by the speed of the car.
The STi wing is basically dead weight at anything below fast highway speeds. And even at high speeds, does not do much. Compare it with the WRC wing...notice what is different about it (vertical slats). The WRC wing also sits further back so that the air actually has a chance to get down the rear-window. Also, notice what they did in '06 to reduce rear lift on the WRX car...secondary wing (which you don't have) to help get that freakin air get down to the wing and under-carriage aero (<-- this is where the big differences are made for high-speed anti-lift). Furthermore, look at how high actual race car wings sit...passenger cabin blocks air again.
If you watch videos of cars 'taking off,' you can almost see the car getting pushed up from the bottom. Once you get some wind going under there, and the car starts to lift, there is a catostrophic cycle that occurs...as the air lifts the car more, the bottom of the car gets higher, enabling more air to get underneath, lifting higher, even more lift...
My point is this...the stock STi wing is not that big of a deal until you get going REALLY fast, and even then isn't that much. Keep your WRX wing on there, be safe, and just have some fun.
Perhaps some more competitive race teams could back me up or give a good slap upside the noggin on this though.
| MPME | 05-10-2006 04:43 PM |
[I]QUOTE=shemoves I've read a couple mag articles that 'measured' the downforce to be 50 lbs. @ 100 mph. On a 3000+ lb car it is insignificant. So ya know, the downforce is not created by the AoA (angle of attack...though there seems to be a bit), it is an upside down wing (that's why the top is flat and the bottom is curved...*kinda* like a tear drop cut in half). [/I]
No. 50lbs of downforce on a 3000lb car, compared to no downforce, is an improvment, and is noticeable by a skilled driver.
[I]The high-speed straight line stability is much more likely caused by the vertical slats...they act like rudders. [/I]
No. End plates (what you call 'vertical slats') minimize drag and improve downforce. Without them, air spills off the ends of a wing, causing nasty drag--downforce is also lost as a result. They do not act like rudders.
[I]For reference, F1 cars produce four times the vehicle's weight in downforce...thousands of pounds...and is directly related to the speed of the car.[/I]
Bad comparison. An F1 car is a machine of pure aero design. A $30K car will have its body designed to look good while achieving the best coefficient of drag--that's a big area for fuel consumption gains to be made.
[I]The STi wing is basically dead weight at anything below fast highway speeds. And even at high speeds, does not do much. Compare it with the WRC wing...notice what is different about it (vertical slats). Also, notice what they did in '06 to reduce rear lift...secondary wing (which you don't have) and under-carriage aero (<-- this is where the big differences are made for high-speed anti-lift). [/I]
Vertical slats? Anit-lift? I don't want to be mean, but as you don't know even the most basic of aerodynamic terms, maybe trying to give valued feedback to the original poster isn't such a good idea.
[I]My point is this...the stock STi wing is not that big of a deal until you get going REALLY fast, and even then isn't that much.[/I]
Oh, forget it.
No. 50lbs of downforce on a 3000lb car, compared to no downforce, is an improvment, and is noticeable by a skilled driver.
[I]The high-speed straight line stability is much more likely caused by the vertical slats...they act like rudders. [/I]
No. End plates (what you call 'vertical slats') minimize drag and improve downforce. Without them, air spills off the ends of a wing, causing nasty drag--downforce is also lost as a result. They do not act like rudders.
[I]For reference, F1 cars produce four times the vehicle's weight in downforce...thousands of pounds...and is directly related to the speed of the car.[/I]
Bad comparison. An F1 car is a machine of pure aero design. A $30K car will have its body designed to look good while achieving the best coefficient of drag--that's a big area for fuel consumption gains to be made.
[I]The STi wing is basically dead weight at anything below fast highway speeds. And even at high speeds, does not do much. Compare it with the WRC wing...notice what is different about it (vertical slats). Also, notice what they did in '06 to reduce rear lift...secondary wing (which you don't have) and under-carriage aero (<-- this is where the big differences are made for high-speed anti-lift). [/I]
Vertical slats? Anit-lift? I don't want to be mean, but as you don't know even the most basic of aerodynamic terms, maybe trying to give valued feedback to the original poster isn't such a good idea.
[I]My point is this...the stock STi wing is not that big of a deal until you get going REALLY fast, and even then isn't that much.[/I]
Oh, forget it.
| silentbob343 | 05-10-2006 04:59 PM |
He is talking about the later STi WRC wing that had vertical slats within the wing. I can't recall the year they were introduced.
| shemoves | 05-10-2006 05:00 PM |
MPME does know what he is talking about so listen to him. Perhaps you can educate me though. I could understand how a vertical slat can reduce drag by reducing turbulence within the wing but not increase downforce...well, perhaps it is one of those 'one thing leads to another kind of deals'. Reduced turbulence=Reduced drag=better airflow over actual lift reduction parts=profit! Do they act like vortex generators?
The F1 reference was for comparison, although an extreme one at that.
Edited to make sense :rolleyes:
The F1 reference was for comparison, although an extreme one at that.
Edited to make sense :rolleyes:
| Mykl | 05-10-2006 06:05 PM |
I would like to drive my car without a wing just to see if I notice the difference. A WRX driving friend of mine swapped trunks with an STi owner and he said that the difference was so obvious that he didn't really have to try to notice. He says it simply felt more stable at speed.
I don't know anything about aerodynamics so that's all I can offer to the conversation.
I don't know anything about aerodynamics so that's all I can offer to the conversation.
| Joel Gat, 1.8L | 05-10-2006 07:21 PM |
Hello,
[QUOTE=MPME]The tall profile of the wing and stubby chord tell you the downforce it makes was meant to be most impactful and efficient at lower speeds. If it was meant to be more effective at higher speeds, it'd be a lower profile with a deeper chord.[/quote]
Or it could simply mean that the more efficient, short chord design, was chosen to reduce drag and improve fuel economy, relative to the longer chord design.
I agree with you that their goal was perhaps better efficiency at lower speed since the end-plate / winglet could serve to function simply to reduce induced drag. Induced drag is inversely proportional to speed, so doing this would help reduce drag most at low speeds.
Joel
[QUOTE=MPME]The tall profile of the wing and stubby chord tell you the downforce it makes was meant to be most impactful and efficient at lower speeds. If it was meant to be more effective at higher speeds, it'd be a lower profile with a deeper chord.[/quote]
Or it could simply mean that the more efficient, short chord design, was chosen to reduce drag and improve fuel economy, relative to the longer chord design.
I agree with you that their goal was perhaps better efficiency at lower speed since the end-plate / winglet could serve to function simply to reduce induced drag. Induced drag is inversely proportional to speed, so doing this would help reduce drag most at low speeds.
Joel
| GarySheehan | 05-10-2006 08:32 PM |
When we first started racing the WRX in USTCC, we didn't have a rear wing. Although the car's tendency was to understeer pretty much everywhere, I noticed that in the higher speed corners (80mph+), the rear of the car felt light and became unstable, causing significant oversteer.
If the stock wing makes 50 lbs of downforce at 100mph, that's significantly better than the LIFT the shape of the car generates without the wing.
Gary
#99 ESX Subaru STi
World Challenge GT
If the stock wing makes 50 lbs of downforce at 100mph, that's significantly better than the LIFT the shape of the car generates without the wing.
Gary
#99 ESX Subaru STi
World Challenge GT
| silver04rs | 05-10-2006 10:53 PM |
[QUOTE=GarySheehan]
If the stock wing makes 50 lbs of downforce at 100mph, that's significantly better than the LIFT the shape of the car generates without the wing.
Gary
#99 ESX Subaru STi
World Challenge GT[/QUOTE]
+1
Travis
If the stock wing makes 50 lbs of downforce at 100mph, that's significantly better than the LIFT the shape of the car generates without the wing.
Gary
#99 ESX Subaru STi
World Challenge GT[/QUOTE]
+1
Travis
| ghschirtz | 05-10-2006 11:14 PM |
Gentlemen,
Your comments are appreciated. I will keep the wing, obviously. As I said about F1, making a Sub an "inverted wing" is not on. It can be improved, but the basics simply aren't there to even try. The point, however, is clear. You need to make air your friend, recognizing that increased downforce often means more drag.
The "blowover" event, somewhat common in unlimited hydroplane boats and experienced by Mercedes at Le Mans twice some years ago, is really ugly. NASCAR has a self-deploying roof spoiler to try to prevent such flights, or had. I may not be current. My little stock motor is unlikely to get things to that level. I did compute that .8g lateral acceleration equates to about 218 mph on the front straight if you follow the centerline of CAS, without adjusting for banking. The notation by that computation says, "Not attainable at this session". Never give an inch, my friends.
Cheers and long life,
George
Your comments are appreciated. I will keep the wing, obviously. As I said about F1, making a Sub an "inverted wing" is not on. It can be improved, but the basics simply aren't there to even try. The point, however, is clear. You need to make air your friend, recognizing that increased downforce often means more drag.
The "blowover" event, somewhat common in unlimited hydroplane boats and experienced by Mercedes at Le Mans twice some years ago, is really ugly. NASCAR has a self-deploying roof spoiler to try to prevent such flights, or had. I may not be current. My little stock motor is unlikely to get things to that level. I did compute that .8g lateral acceleration equates to about 218 mph on the front straight if you follow the centerline of CAS, without adjusting for banking. The notation by that computation says, "Not attainable at this session". Never give an inch, my friends.
Cheers and long life,
George
| buster | 05-10-2006 11:37 PM |
[QUOTE=pio!pio!]to all those that say they haven't noticed a difference:
If you say you've been at high speeds on the highway and havne't noticed a difference, it's because you aren't cornering hard enough...try taking a high speed corner at high speeds (enough to get the tires to start screeching slightly) w/ and w/o the wing and w/ the wing should feel more stable or be faster[/QUOTE]
I guess the autoX and track days don't count... :rolleyes:
If you say you've been at high speeds on the highway and havne't noticed a difference, it's because you aren't cornering hard enough...try taking a high speed corner at high speeds (enough to get the tires to start screeching slightly) w/ and w/o the wing and w/ the wing should feel more stable or be faster[/QUOTE]
I guess the autoX and track days don't count... :rolleyes:
| merlot | 05-11-2006 09:13 AM |
[QUOTE=buster]I guess the autoX and track days don't count... :rolleyes:[/QUOTE]
Since when is autox high-speed? :rolleyes:
Since when is autox high-speed? :rolleyes:
| Chiketkd | 05-11-2006 09:23 AM |
[QUOTE=MSD]Since when is autox high-speed? :rolleyes:[/QUOTE]
+1 Inorder to keep SCCA classing fair, speeds on autoX courses are designed to be lower than 65mph. If speeds reach any higher at a Provisional or National event, you can protest and have the results thrown out. It's already happened once in the 2006 season.
+1 Inorder to keep SCCA classing fair, speeds on autoX courses are designed to be lower than 65mph. If speeds reach any higher at a Provisional or National event, you can protest and have the results thrown out. It's already happened once in the 2006 season.
| Chiketkd | 05-11-2006 09:27 AM |
[QUOTE=Impreza01]As for the low wing, I know there was a thread before where someone wind-tunneled it and it provided some downforce at speed (it was to the degree a semi or pro would feel; it wasn't high at all). I know the Group N Imprezas for the Production Car WRC in 2004 (WRX STi Spec C WR Limitied) had the low wing too.[/QUOTE]
I was watching the Impreza vs Evo Best Motoring vid the other day and saw that the JDM Spec C STI came with the low wing. I'm would love to get my hands on an English verison of the brochure for that car to see if Subaru mentions anything about the downforce produced by the low wing.
I was watching the Impreza vs Evo Best Motoring vid the other day and saw that the JDM Spec C STI came with the low wing. I'm would love to get my hands on an English verison of the brochure for that car to see if Subaru mentions anything about the downforce produced by the low wing.
| boxered | 05-11-2006 09:34 AM |
Remember during the WRC last year? Solberg over corrected, hit a ditch, and lost the wing. He was able to continue and the lack of the rear wing made a large impact on his following times. He was basically doing huge drifts through sweepers and while he admitted it was fun, it wasn't very effective.
Granted it was hte WRC wing, gravel, etc, etc. but if I'm doing high speed sweepers in the mountains of NC, I'll take all the control factors I can.
Granted it was hte WRC wing, gravel, etc, etc. but if I'm doing high speed sweepers in the mountains of NC, I'll take all the control factors I can.
| Firestarter1973 | 05-11-2006 09:38 AM |
The STI wing produces 50 lbs of downforce at 100 mph, thats straight from Subaru. With the new vane spoiler I don't know how much it makes now though.
| gargleblaster | 05-11-2006 09:48 AM |
[QUOTE=boxered]if I'm doing high speed sweepers in the mountains of NC, I'll take all the control factors I can.[/QUOTE]+1, but replace NC with CO. :D
| Type1 | 05-11-2006 10:11 AM |
With that post above about the WRC wing keep in mind while the STi fwing may produce 50lbs of downforce it is in no way shape or form the same as the STi rally wing. First off it doesnt have all the splitters in it and its not extended far enough.
Now people argue that the previous wings didnt have the splitters, thats true but they werent unstable like the ones that come with out car.
There was a thread about 15 million pages long about this discussion. Basically the STi wing generates the downforce but its actually the lower section and not the big push cart top section. Why? Its far to flimsy and unstable. I traded in my wrx wing for it and know from experience. Even the slightest dip or bump in the road at 70 mph will make the top portion shake and bend like crazy.
The real STi rally wing sits father back on the trunk as to catch more off the airflow and has the lateral splitters to keep the car going straight while in jumps. If you do a search on google about the current STi wing youll see it all.
Good luck, your bette off sticking with your wrx wing and adding the risers.
I rally alot but I dont think I go fast enough to notice the switch from my wrx to STi wing, if anything the sheer weight of the wing is what helped the downforce.
Good luck with your decision.
IMO, it just looks better..hehe
[IMG]http://i2.photobucket.com/albums/y7/lennardlector/1LECTOR-R3-015-6.jpg[/IMG]
[IMG]http://i2.photobucket.com/albums/y7/lennardlector/22.jpg[/IMG]
[IMG]http://i2.photobucket.com/albums/y7/lennardlector/012106SD1strallyx02.jpg[/IMG]
Now people argue that the previous wings didnt have the splitters, thats true but they werent unstable like the ones that come with out car.
There was a thread about 15 million pages long about this discussion. Basically the STi wing generates the downforce but its actually the lower section and not the big push cart top section. Why? Its far to flimsy and unstable. I traded in my wrx wing for it and know from experience. Even the slightest dip or bump in the road at 70 mph will make the top portion shake and bend like crazy.
The real STi rally wing sits father back on the trunk as to catch more off the airflow and has the lateral splitters to keep the car going straight while in jumps. If you do a search on google about the current STi wing youll see it all.
Good luck, your bette off sticking with your wrx wing and adding the risers.
I rally alot but I dont think I go fast enough to notice the switch from my wrx to STi wing, if anything the sheer weight of the wing is what helped the downforce.
Good luck with your decision.
IMO, it just looks better..hehe
[IMG]http://i2.photobucket.com/albums/y7/lennardlector/1LECTOR-R3-015-6.jpg[/IMG]
[IMG]http://i2.photobucket.com/albums/y7/lennardlector/22.jpg[/IMG]
[IMG]http://i2.photobucket.com/albums/y7/lennardlector/012106SD1strallyx02.jpg[/IMG]
| BlackSnake | 05-11-2006 10:15 AM |
Anyone know if the WRX wing Creates any downforce? Like a Nice 2lbs? :lol:
| maxQ | 05-11-2006 11:11 AM |
[QUOTE=Type1]
There was a thread about 15 million pages long about this discussion. Basically the STi wing generates the downforce but its actually the lower section and not the big push cart top section. Why? Its far to flimsy and unstable. I traded in my wrx wing for it and know from experience. Even the slightest dip or bump in the road at 70 mph will make the top portion shake and bend like crazy.[/quote]
So what? Watch the wingtip of a transport wing sometime. It bounces around quite a bit as well. The vibration of the wing affects the downforce slightly but it's insignificant. Laws of physics can handle unsteady flow.
[quote]
The real STi rally wing sits father back on the trunk as to catch more off the airflow and has the lateral splitters to keep the car going straight while in jumps. If you do a search on google about the current STi wing youll see it all.[/quote]
The other, more important reason the wing is set back is because it increases the moment of the downforce.
There was a thread about 15 million pages long about this discussion. Basically the STi wing generates the downforce but its actually the lower section and not the big push cart top section. Why? Its far to flimsy and unstable. I traded in my wrx wing for it and know from experience. Even the slightest dip or bump in the road at 70 mph will make the top portion shake and bend like crazy.[/quote]
So what? Watch the wingtip of a transport wing sometime. It bounces around quite a bit as well. The vibration of the wing affects the downforce slightly but it's insignificant. Laws of physics can handle unsteady flow.
[quote]
The real STi rally wing sits father back on the trunk as to catch more off the airflow and has the lateral splitters to keep the car going straight while in jumps. If you do a search on google about the current STi wing youll see it all.[/quote]
The other, more important reason the wing is set back is because it increases the moment of the downforce.
| buster | 05-11-2006 11:22 AM |
[QUOTE=MSD]Since when is autox high-speed? :rolleyes:[/QUOTE]
Right and trackdays aren't. I was also talking about cornering...not all raw speed.
Right and trackdays aren't. I was also talking about cornering...not all raw speed.
| drees | 05-11-2006 12:11 PM |
[QUOTE=Type1]The real STi rally wing sits father back on the trunk as to catch more off the airflow and has the lateral splitters to keep the car going straight while in jumps.[/QUOTE]The "lateral splitters" (I think you mean vertical, not lateral) do little to keep the car straight while in jumps. They are there to improve the function of the wing (improve downforce) while going sideways which a rally car does plenty of. When you drag the wing sideways through the air the downforce generated by it is significantly compromised. Adding the vertical splitters forces the air to pass front to back over the wing increasing downforce when going sideways.
[img]http://www.swrt.com/img_gallery/785709112.jpg[/img][img]http://www.swrt.com/img_gallery/148305839.jpg[/img]
(Images from [url=http://www.swrt.com/gallery/gallery.html]SWRT's gallery[/url])
You can see also how much more of a wing the real rally car has compared to the nearly flat STI wing.
[QUOTE=Type1]Basically the STi wing generates the downforce but its actually the lower section and not the big push cart top section.[/quote]The top portion of the wing does more than you think due to the direction of the air coming off the roof of the car. It is certainly more effective than the portion sitting on the trunk which gets nearly no airflow. Some string taped onto the wing and a someone following with a camera should quickly show how much more air flows over the top than the bottom of the STI wing.
[img]http://us1.webpublications.com.au/static/images/articles/i10/1071_2lo.jpg[/img]
(Image from [url=http://autospeed.drive.com.au/cms/A_1071/article.html]Autospeed Aero Testing - Part 4[/url])
Not an Impreza, but it's the same basic body shape and shows how little air reaches the trunk lid, while where the top portion of the STI wing would sit in very clean air.
[img]http://www.swrt.com/img_gallery/785709112.jpg[/img][img]http://www.swrt.com/img_gallery/148305839.jpg[/img]
(Images from [url=http://www.swrt.com/gallery/gallery.html]SWRT's gallery[/url])
You can see also how much more of a wing the real rally car has compared to the nearly flat STI wing.
[QUOTE=Type1]Basically the STi wing generates the downforce but its actually the lower section and not the big push cart top section.[/quote]The top portion of the wing does more than you think due to the direction of the air coming off the roof of the car. It is certainly more effective than the portion sitting on the trunk which gets nearly no airflow. Some string taped onto the wing and a someone following with a camera should quickly show how much more air flows over the top than the bottom of the STI wing.
[img]http://us1.webpublications.com.au/static/images/articles/i10/1071_2lo.jpg[/img]
(Image from [url=http://autospeed.drive.com.au/cms/A_1071/article.html]Autospeed Aero Testing - Part 4[/url])
Not an Impreza, but it's the same basic body shape and shows how little air reaches the trunk lid, while where the top portion of the STI wing would sit in very clean air.
| gargleblaster | 05-11-2006 12:15 PM |
[QUOTE=Type1]Basically the STi wing generates the downforce but its actually the lower section and not the big push cart top section. Why? Its far to flimsy and unstable. I traded in my wrx wing for it and know from experience. Even the slightest dip or bump in the road at 70 mph will make the top portion shake and bend like crazy.[/QUOTE]So when the wings on a commerical airliner flex up and down, there is no lift and the plane is going to crash?
Have you watched any F1 coverage this season and all the ruckus caused by Ferrari's moving aero surfaces? Movement of the upper wing does not mean it's not providing downforce or negating lift. It simply means it's being flexed by the turbulent air coming off the roof of the car. It's certainly not as effective as the WRC wing, but to say it's ineffective isn't exactly accurate.
Have you watched any F1 coverage this season and all the ruckus caused by Ferrari's moving aero surfaces? Movement of the upper wing does not mean it's not providing downforce or negating lift. It simply means it's being flexed by the turbulent air coming off the roof of the car. It's certainly not as effective as the WRC wing, but to say it's ineffective isn't exactly accurate.
| ghschirtz | 05-11-2006 03:24 PM |
I expect the trunk WRX wing is acting more like a flat plate than a wing. The pic of the Mercedes, if it had a plate on the rear, would indicate some airflow pushed upward, I suspect, and that cancels out some lift that otherwise would occur.
Remember when the Audi TT first came out, and then a lip on the rear was added as a standard thing? Too many loops at high speed. It needed something to cancel out some of the lift, for it was just a little too edgy when asked to change direction at speed.
Wing movement might momentarily change the aero benefit, but cancellation would require removal. All aricraft wings flex a little in flight. Old story about Ted Hoover pulling 9g's (he says-probably more like 7) in a P-51 over Europe. The airplane did not come apart but he landed with much more dihedral than when he took off. So the wings flexed and yielded, but he still held the turn.
George
Remember when the Audi TT first came out, and then a lip on the rear was added as a standard thing? Too many loops at high speed. It needed something to cancel out some of the lift, for it was just a little too edgy when asked to change direction at speed.
Wing movement might momentarily change the aero benefit, but cancellation would require removal. All aricraft wings flex a little in flight. Old story about Ted Hoover pulling 9g's (he says-probably more like 7) in a P-51 over Europe. The airplane did not come apart but he landed with much more dihedral than when he took off. So the wings flexed and yielded, but he still held the turn.
George
| MPME | 05-11-2006 03:32 PM |
I've never understood where the belief that something shaped in the form of a wing, be it an OE piece or aftermarket piece, doesn't function as a wing.
It isn't there to act as a flat plate. It's a wing. Maybe not an impressive wing, but a wing nonetheless.
That it's made from a plasticky material doesn't negate its function as a wing. That it vibrates doesn't negate the fact that it's a wing.
Does it have to be made out of carbon, and attached to a Ferrari for people to then believe it works? Does the wing on an Evo work, but not the wing on an STI?
It isn't there to act as a flat plate. It's a wing. Maybe not an impressive wing, but a wing nonetheless.
That it's made from a plasticky material doesn't negate its function as a wing. That it vibrates doesn't negate the fact that it's a wing.
Does it have to be made out of carbon, and attached to a Ferrari for people to then believe it works? Does the wing on an Evo work, but not the wing on an STI?
| BlackSnake | 05-11-2006 03:44 PM |
What about the roof Vain on the 06 sti's, I remember seeing somthing how it Actually does improve the downforce. Can Anyone comment on that?
| Impreza01 | 05-11-2006 03:46 PM |
[QUOTE=MPME]I've never understood where the belief that something shaped in the form of a wing, be it an OE piece or aftermarket piece, doesn't function as a wing.
It isn't there to act as a flat plate. It's a wing. Maybe not an impressive wing, but a wing nonetheless.
That it's made from a plasticky material doesn't negate its function as a wing. That it vibrates doesn't negate the fact that it's a wing.
Does it have to be made out of carbon, and attached to a Ferrari for people to then believe it works? Does the wing on an Evo work, but not the wing on an STI?[/QUOTE]
Seriously, people learn some fluid mechanics or aerodynamics before making conjectures...
It isn't there to act as a flat plate. It's a wing. Maybe not an impressive wing, but a wing nonetheless.
That it's made from a plasticky material doesn't negate its function as a wing. That it vibrates doesn't negate the fact that it's a wing.
Does it have to be made out of carbon, and attached to a Ferrari for people to then believe it works? Does the wing on an Evo work, but not the wing on an STI?[/QUOTE]
Seriously, people learn some fluid mechanics or aerodynamics before making conjectures...
| BlackSnake | 05-11-2006 04:34 PM |
Nevermind.... Found what I was looking for. :)
[QUOTE=VIRULENT]Sort of found what I was looking for in this brochure from Subaru
Australia which explains what several of you have posted and
gives an image to support it, even though it�s a hella low rez one!
[IMG]http://img.photobucket.com/albums/v310/deterioration/NASIOC/06aero.jpg[/IMG]
[SIZE=2]Aerodynamics The MY06 Impreza STI features a completely revised aerodynamic
package compared to the previous MY05 model. Additions include a WRC look front
bumper which generates frontal downforce, also front corner spoilers and grilles.
These components provide air extraction from the area behind the front bumper,
and improve the airflow down the side of the car. The new roof vane combines
with the rear diffuser and boot spoiler dramatically improves the aerodynamics
for improved stability and handling. The roof vane catches the airflow from the
roof and directs it to the rear spoiler thereby enhancing its performance. The
rear diffuser smooths the airflow under the car helping to create a smooth
airflow on exit. The co-efficient of lift (CL) performance has improved from
minus 0.045 to minus 0.075. (Greater down force) which is a 67%
improvement on the MY05 model[/SIZE]
[URL=http://subaru.com.au/downloads/6DB712A5-6FE8-4B46-B7C2-2D09F1192CDD.pdf]Impreza Technical Description MY06[/URL]
Download our full 36 page technical description of
the Subaru Impreza. This pdf document is 1,375KB.
[SIZE=1][Right Click : Save As][/SIZE]
:cool:[/QUOTE]
[QUOTE=VIRULENT]Sort of found what I was looking for in this brochure from Subaru
Australia which explains what several of you have posted and
gives an image to support it, even though it�s a hella low rez one!
[IMG]http://img.photobucket.com/albums/v310/deterioration/NASIOC/06aero.jpg[/IMG]
[SIZE=2]Aerodynamics The MY06 Impreza STI features a completely revised aerodynamic
package compared to the previous MY05 model. Additions include a WRC look front
bumper which generates frontal downforce, also front corner spoilers and grilles.
These components provide air extraction from the area behind the front bumper,
and improve the airflow down the side of the car. The new roof vane combines
with the rear diffuser and boot spoiler dramatically improves the aerodynamics
for improved stability and handling. The roof vane catches the airflow from the
roof and directs it to the rear spoiler thereby enhancing its performance. The
rear diffuser smooths the airflow under the car helping to create a smooth
airflow on exit. The co-efficient of lift (CL) performance has improved from
minus 0.045 to minus 0.075. (Greater down force) which is a 67%
improvement on the MY05 model[/SIZE]
[URL=http://subaru.com.au/downloads/6DB712A5-6FE8-4B46-B7C2-2D09F1192CDD.pdf]Impreza Technical Description MY06[/URL]
Download our full 36 page technical description of
the Subaru Impreza. This pdf document is 1,375KB.
[SIZE=1][Right Click : Save As][/SIZE]
:cool:[/QUOTE]
| ghschirtz | 05-11-2006 05:18 PM |
[QUOTE=MPME]I've never understood where the belief that something shaped in the form of a wing, be it an OE piece or aftermarket piece, doesn't function as a wing.
It isn't there to act as a flat plate. It's a wing. Maybe not an impressive wing, but a wing nonetheless.
That it's made from a plasticky material doesn't negate its function as a wing. That it vibrates doesn't negate the fact that it's a wing.
Does it have to be made out of carbon, and attached to a Ferrari for people to then believe it works? Does the wing on an Evo work, but not the wing on an STI?[/QUOTE]
Agreed that it doesn't mater what a wing is made of. What makes a wing act as a wing is differential airflow, faster on one side, that creates a vacuum and hence lift on the side with a higher flow rate.
The difference between a flat plate and a wing can be thought of as this:
NASCAR, early Can-Am cars, the Cobra Daytona coupe, all have (had) flat spoilers on the back that act as plates, directing airflow upward and canceling out lift at the rear end. A wing needs differential airflow over the top and bottom to exert force.
Looking at the WRX (not STi) wing on my 02, I suspect there might not be much flow under the wing, enough to promote "wing" downforce by being faster than the flow over the top of the wing. Look at the Mercedes pic again. The area toward the end of the trunk has relatively slow and turburlent airflow. This kind of airflow is less likely to go under the WRX wing at a higher rate than the air over the top of the wing, so that you can get the negative lift a wing is intended to produce.
However, the angled upper surface of the wing will tend to shove air upward, which creates a down force vector cancelling the normal lift at the rear experienced by this nominal body shape. The net result for the system is cancellation of lift/downforce generation. Except for induced drag differences, the result is the same.
As race cars evolved, the idea of generating the same downforce with a wing instead of a plate came to pass. F1 cars, and the Chapparal 2F Can-Am car, put wings up on stilts, with varying success. Finally, Colin Chapman made the whole of the F1 car an inverted wing. Jiim Hall went the other way with the "sucker" Chapparal, with great effect.
Good pics re the 06 STi. Very explanatory.
Not all wings are created equal. What made the P-51 of WWII such a superior escort fighter was the use of a laminar flow wing, which had less induced drag than other designs, hence the airplane could go farther faster on the same or less fuel and horsepower. Huge strides were made in the later 40's in aircraft design, and it wasn't just the introduction of the jet engine that increased performance.
George
It isn't there to act as a flat plate. It's a wing. Maybe not an impressive wing, but a wing nonetheless.
That it's made from a plasticky material doesn't negate its function as a wing. That it vibrates doesn't negate the fact that it's a wing.
Does it have to be made out of carbon, and attached to a Ferrari for people to then believe it works? Does the wing on an Evo work, but not the wing on an STI?[/QUOTE]
Agreed that it doesn't mater what a wing is made of. What makes a wing act as a wing is differential airflow, faster on one side, that creates a vacuum and hence lift on the side with a higher flow rate.
The difference between a flat plate and a wing can be thought of as this:
NASCAR, early Can-Am cars, the Cobra Daytona coupe, all have (had) flat spoilers on the back that act as plates, directing airflow upward and canceling out lift at the rear end. A wing needs differential airflow over the top and bottom to exert force.
Looking at the WRX (not STi) wing on my 02, I suspect there might not be much flow under the wing, enough to promote "wing" downforce by being faster than the flow over the top of the wing. Look at the Mercedes pic again. The area toward the end of the trunk has relatively slow and turburlent airflow. This kind of airflow is less likely to go under the WRX wing at a higher rate than the air over the top of the wing, so that you can get the negative lift a wing is intended to produce.
However, the angled upper surface of the wing will tend to shove air upward, which creates a down force vector cancelling the normal lift at the rear experienced by this nominal body shape. The net result for the system is cancellation of lift/downforce generation. Except for induced drag differences, the result is the same.
As race cars evolved, the idea of generating the same downforce with a wing instead of a plate came to pass. F1 cars, and the Chapparal 2F Can-Am car, put wings up on stilts, with varying success. Finally, Colin Chapman made the whole of the F1 car an inverted wing. Jiim Hall went the other way with the "sucker" Chapparal, with great effect.
Good pics re the 06 STi. Very explanatory.
Not all wings are created equal. What made the P-51 of WWII such a superior escort fighter was the use of a laminar flow wing, which had less induced drag than other designs, hence the airplane could go farther faster on the same or less fuel and horsepower. Huge strides were made in the later 40's in aircraft design, and it wasn't just the introduction of the jet engine that increased performance.
George
| T-boner | 05-11-2006 07:38 PM |
Didn't I also read that the stock STi wing generated 120 lb. of downforce at 150 MPH? Or is that a figment of my hallucination?
| Impreza01 | 05-11-2006 08:44 PM |
Ahaha, sorry for the quick off-topic, but I just found this video funny in connection to this thread:
[url]http://www.tooshocking.com/index.php?ns=view_vid&id=980[/url]
[url]http://www.tooshocking.com/index.php?ns=view_vid&id=980[/url]
| MPME | 05-11-2006 10:31 PM |
[QUOTE=ghschirtz]Agreed that it doesn't mater what a wing is made of. What makes a wing act as a wing is differential airflow, faster on one side, that creates a vacuum and hence lift on the side with a higher flow rate.
The difference between a flat plate and a wing can be thought of as this:
NASCAR, early Can-Am cars, the Cobra Daytona coupe, all have (had) flat spoilers on the back that act as plates, directing airflow upward and canceling out lift at the rear end. A wing needs differential airflow over the top and bottom to exert force.
Looking at the WRX (not STi) wing on my 02, I suspect there might not be much flow under the wing, enough to promote "wing" downforce by being faster than the flow over the top of the wing. Look at the Mercedes pic again. The area toward the end of the trunk has relatively slow and turburlent airflow. This kind of airflow is less likely to go under the WRX wing at a higher rate than the air over the top of the wing, so that you can get the negative lift a wing is intended to produce.
However, the angled upper surface of the wing will tend to shove air upward, which creates a down force vector cancelling the normal lift at the rear experienced by this nominal body shape. The net result for the system is cancellation of lift/downforce generation. Except for induced drag differences, the result is the same.
As race cars evolved, the idea of generating the same downforce with a wing instead of a plate came to pass. F1 cars, and the Chapparal 2F Can-Am car, put wings up on stilts, with varying success. Finally, Colin Chapman made the whole of the F1 car an inverted wing. Jiim Hall went the other way with the "sucker" Chapparal, with great effect.
Good pics re the 06 STi. Very explanatory.
Not all wings are created equal. What made the P-51 of WWII such a superior escort fighter was the use of a laminar flow wing, which had less induced drag than other designs, hence the airplane could go farther faster on the same or less fuel and horsepower. Huge strides were made in the later 40's in aircraft design, and it wasn't just the introduction of the jet engine that increased performance.
George[/QUOTE]
Yeah, my point was that aflat plate, turned at a 75deg angle, is a massive spoiler that serves to provide downforce not by use of a winged profile, but by smashing air into a blunt surface, and that force then being transmtted downwards through the body onto the chassis/tires.
The air, as it naturally travels, might not want to go under your '02 wing faster than the air going over the top of the wing, but thanks to good ole' Monsier Bernoulli, we know that becuase of the wing profile, the air that does travel beneath a wing is forced to accelerate faster than the air on top in order to catch up to that top flow.
Air, like any fluid, hates to be displaced, so with the longer path of the wing's underside curvature, the acceleration to catch up, and resulting low pressure is where the downforce comes from.
It also cleans up the turbulent air that without the wing, would have the turbulence eddying as shown on the Mercedes.
As for the 60's flat plate thing, it made so much drag, and was so inneficient, they moved away from it once winged technology was applied to a racecar. Keep in mind that Jim Hall, one of my hero's, BTW, pioneered the wing in racing, and went away from the 'flat plate' mentod ASAP.
The only place we see it in 'modern' times is in the ever-so 'modern' NASCAR series. 'Nuff said.
The difference between a flat plate and a wing can be thought of as this:
NASCAR, early Can-Am cars, the Cobra Daytona coupe, all have (had) flat spoilers on the back that act as plates, directing airflow upward and canceling out lift at the rear end. A wing needs differential airflow over the top and bottom to exert force.
Looking at the WRX (not STi) wing on my 02, I suspect there might not be much flow under the wing, enough to promote "wing" downforce by being faster than the flow over the top of the wing. Look at the Mercedes pic again. The area toward the end of the trunk has relatively slow and turburlent airflow. This kind of airflow is less likely to go under the WRX wing at a higher rate than the air over the top of the wing, so that you can get the negative lift a wing is intended to produce.
However, the angled upper surface of the wing will tend to shove air upward, which creates a down force vector cancelling the normal lift at the rear experienced by this nominal body shape. The net result for the system is cancellation of lift/downforce generation. Except for induced drag differences, the result is the same.
As race cars evolved, the idea of generating the same downforce with a wing instead of a plate came to pass. F1 cars, and the Chapparal 2F Can-Am car, put wings up on stilts, with varying success. Finally, Colin Chapman made the whole of the F1 car an inverted wing. Jiim Hall went the other way with the "sucker" Chapparal, with great effect.
Good pics re the 06 STi. Very explanatory.
Not all wings are created equal. What made the P-51 of WWII such a superior escort fighter was the use of a laminar flow wing, which had less induced drag than other designs, hence the airplane could go farther faster on the same or less fuel and horsepower. Huge strides were made in the later 40's in aircraft design, and it wasn't just the introduction of the jet engine that increased performance.
George[/QUOTE]
Yeah, my point was that aflat plate, turned at a 75deg angle, is a massive spoiler that serves to provide downforce not by use of a winged profile, but by smashing air into a blunt surface, and that force then being transmtted downwards through the body onto the chassis/tires.
The air, as it naturally travels, might not want to go under your '02 wing faster than the air going over the top of the wing, but thanks to good ole' Monsier Bernoulli, we know that becuase of the wing profile, the air that does travel beneath a wing is forced to accelerate faster than the air on top in order to catch up to that top flow.
Air, like any fluid, hates to be displaced, so with the longer path of the wing's underside curvature, the acceleration to catch up, and resulting low pressure is where the downforce comes from.
It also cleans up the turbulent air that without the wing, would have the turbulence eddying as shown on the Mercedes.
As for the 60's flat plate thing, it made so much drag, and was so inneficient, they moved away from it once winged technology was applied to a racecar. Keep in mind that Jim Hall, one of my hero's, BTW, pioneered the wing in racing, and went away from the 'flat plate' mentod ASAP.
The only place we see it in 'modern' times is in the ever-so 'modern' NASCAR series. 'Nuff said.
| ghschirtz | 05-11-2006 11:03 PM |
[QUOTE=Impreza01]Ahaha, sorry for the quick off-topic, but I just found this video funny in connection to this thread:
[url]http://www.tooshocking.com/index.php?ns=view_vid&id=980[/url][/QUOTE]
I never trusted the 2CV. Now I know...LOL!
[url]http://www.tooshocking.com/index.php?ns=view_vid&id=980[/url][/QUOTE]
I never trusted the 2CV. Now I know...LOL!
| ghschirtz | 05-11-2006 11:10 PM |
Yah, Hall was a pioneer all the way on using airflow the right way.
Part of the Porsche advantage in the Can-Am, after they hired Donohue and Penske to run the team, was McLaren's mistake in integrating a front wing into the 8F design, while Donohue and cadre carved stuff off the front to take as much over the car as possible, with a short shovel nose and low splitter.
I see your point that high flow over the top may pull flow over the curved underside of the wing, making it work. I might get some yarn and see if the flow appears to go that way...
George
Part of the Porsche advantage in the Can-Am, after they hired Donohue and Penske to run the team, was McLaren's mistake in integrating a front wing into the 8F design, while Donohue and cadre carved stuff off the front to take as much over the car as possible, with a short shovel nose and low splitter.
I see your point that high flow over the top may pull flow over the curved underside of the wing, making it work. I might get some yarn and see if the flow appears to go that way...
George
| Millencolin! | 05-11-2006 11:25 PM |
In a old Sport compact Car edition I have, they test drive the Evo XIII and the Evo XIII rs on a track. One of the turns was a high speed left (if I remember correctly) And they said that the evo rs couldn't hold its line as well as the baseline evo because it lacked a rear wing.
My basic opinion: You don't need a wing for street its just not worth the extra lbs, I'd only install a wing if I were going to be spending a lot of time at the track or building a dedicated racer.
My basic opinion: You don't need a wing for street its just not worth the extra lbs, I'd only install a wing if I were going to be spending a lot of time at the track or building a dedicated racer.
| MPME | 05-11-2006 11:27 PM |
[QUOTE=ghschirtz]Yah, Hall was a pioneer all the way on using airflow the right way.
Part of the Porsche advantage in the Can-Am, after they hired Donohue and Penske to run the team, was McLaren's mistake in integrating a front wing into the 8F design, while Donohue and cadre carved stuff off the front to take as much over the car as possible, with a short shovel nose and low splitter.
I see your point that high flow over the top may pull flow over the curved underside of the wing, making it work. I might get some yarn and see if the flow appears to go that way...
George[/QUOTE]
George--just be sure it's JDM yarn. Very imprtant detail.
Part of the Porsche advantage in the Can-Am, after they hired Donohue and Penske to run the team, was McLaren's mistake in integrating a front wing into the 8F design, while Donohue and cadre carved stuff off the front to take as much over the car as possible, with a short shovel nose and low splitter.
I see your point that high flow over the top may pull flow over the curved underside of the wing, making it work. I might get some yarn and see if the flow appears to go that way...
George[/QUOTE]
George--just be sure it's JDM yarn. Very imprtant detail.
| ghschirtz | 05-12-2006 12:27 PM |
MPME,
Darn, I almost put Chinese yarn on there, but I am saved!
I think I will do this, however. I can see most of the wing through the rear mirror, and with tape on the leading edge, place streamers below and above. If they go parallel and back, we will have flow on both sides and lift. Will report back.
George
Darn, I almost put Chinese yarn on there, but I am saved!
I think I will do this, however. I can see most of the wing through the rear mirror, and with tape on the leading edge, place streamers below and above. If they go parallel and back, we will have flow on both sides and lift. Will report back.
George
| CarbineReloaded | 05-14-2006 03:52 AM |
fuel for the fire..... sti wing vs "limited" lip on the rear end.
Will the limited spoiler make a difference vs wingless? Will it be noticeable? Will my dog fart again?
Will the limited spoiler make a difference vs wingless? Will it be noticeable? Will my dog fart again?
| ghschirtz | 05-14-2006 01:56 PM |
Testing is completed.
I taped string on the leading edge of the wing so that part was underneath and part on top.
At about 70 mph, I had airflow under the wing and over it. At lower speeds, airflow under the wing moved to the center and ultimately ceased.
The conclusion is that the wing is acting like a wing. I will get a tape to measure the upper surface and underside, but by eyeball measure, it looks like air has to travel farther on the underside, so the wing should be generating lift, downforce in this case.
At the speeds I expect to achieve, the wing will be valuable. Carbine, I think the answer is the WRX wing will make a difference, probably noticeable, and your dog will fart again.
Cheers,
George
I taped string on the leading edge of the wing so that part was underneath and part on top.
At about 70 mph, I had airflow under the wing and over it. At lower speeds, airflow under the wing moved to the center and ultimately ceased.
The conclusion is that the wing is acting like a wing. I will get a tape to measure the upper surface and underside, but by eyeball measure, it looks like air has to travel farther on the underside, so the wing should be generating lift, downforce in this case.
At the speeds I expect to achieve, the wing will be valuable. Carbine, I think the answer is the WRX wing will make a difference, probably noticeable, and your dog will fart again.
Cheers,
George
| richde | 05-14-2006 02:33 PM |
[QUOTE=shemoves]MPME does know what he is talking about so listen to him. Perhaps you can educate me though. I could understand how a vertical slat can reduce drag by reducing turbulence within the wing but not increase downforce...well, perhaps it is one of those 'one thing leads to another kind of deals'. Reduced turbulence=Reduced drag=better airflow over actual lift reduction parts=profit! Do they act like vortex generators?
The F1 reference was for comparison, although an extreme one at that.
Edited to make sense :rolleyes:[/QUOTE]
The vertical slats "capture" the pressure differential between the top and bottom of the wing, this presssure differential is what causes lift/downforce, without an endplate to the wing, the pressure differential "rolls" off the end of the wing. You can see this on a large airplane without winglets, on takeoff on humid days you can see the wingtip vorticies, which is the meeting of the high pressure zone underneath the wing and the low pressure zone on top and while I'm no aerodynamicist, they say it's a bad thing and is inefficient. Like a winglet on an airplane, but to a larger degree.
The F1 reference was for comparison, although an extreme one at that.
Edited to make sense :rolleyes:[/QUOTE]
The vertical slats "capture" the pressure differential between the top and bottom of the wing, this presssure differential is what causes lift/downforce, without an endplate to the wing, the pressure differential "rolls" off the end of the wing. You can see this on a large airplane without winglets, on takeoff on humid days you can see the wingtip vorticies, which is the meeting of the high pressure zone underneath the wing and the low pressure zone on top and while I'm no aerodynamicist, they say it's a bad thing and is inefficient. Like a winglet on an airplane, but to a larger degree.
| ghschirtz | 05-14-2006 05:15 PM |
^Richde is right. The winglets on airplanes help control the vortici and smooth airflow, so the aircraaft gets more benefit from the entire wing, and thus more range. The endplates on wings on cars do what he is saying, so that the whole of the wing is working for you, not just part of it.
I measured the wing on my Sub, and the air is traveling farther on the underside. Reconfirmed flow findings at speed, to 100mph. The strings start to straighten out in the center of the wing at about 45mph and by 80 have all got in the game. At 100, the flow seems more stable than at 80, but hard to tell.
CAS, here I come...
I measured the wing on my Sub, and the air is traveling farther on the underside. Reconfirmed flow findings at speed, to 100mph. The strings start to straighten out in the center of the wing at about 45mph and by 80 have all got in the game. At 100, the flow seems more stable than at 80, but hard to tell.
CAS, here I come...
| nhluhr | 05-15-2006 06:44 AM |
[QUOTE=gargleblaster]So when the wings on a commerical airliner flex up and down, there is no lift and the plane is going to crash?[/QUOTE]I was gonna post the same thing! The bouncy wiggling of the STi wing has 0 impact on the downforce it generates.
| maxQ | 05-15-2006 12:49 PM |
[QUOTE=richde] Like a winglet on an airplane, but to a larger degree.[/QUOTE]
Actually, the winglets you see on commercial airplanes do little to dissipate the wingtip vortex (the pressure spillage) but are actually designed to use the vortex to develop a little bit of thrust.
Actually, the winglets you see on commercial airplanes do little to dissipate the wingtip vortex (the pressure spillage) but are actually designed to use the vortex to develop a little bit of thrust.
| Joel Gat, 1.8L | 05-15-2006 03:55 PM |
[QUOTE=maxQ]Actually, the winglets you see on commercial airplanes do little to dissipate the wingtip vortex (the pressure spillage) but are actually designed to use the vortex to develop a little bit of thrust.[/QUOTE]
Hello,
That is incorrect. They definitely reduce the size of the vortex, but then also are used to develop a little thrust...
Joel
Hello,
That is incorrect. They definitely reduce the size of the vortex, but then also are used to develop a little thrust...
Joel
| racerjon1 | 05-15-2006 04:08 PM |
Last year before testing for One Lap of America, Luke tested his STi with and without wing.. he was much happier with the wing on the car in the higher speed corners. (90mph+)
Jon K
Jon K
| SlideWRX | 05-15-2006 04:16 PM |
Well I'm coming in late to the subject, but I may be able to confuse/clarify some stuff:
The spoiler on the WRX is there to re-attach laminar airflow, to reduce lift. By default, most streetcars have a certain amount of lift they produce (which is an exponential function of speed, IIRC). even the relatively brick shaped WRX produces lift. It produces it from the eddies that form on the trailing side of the car; the rear window & trunk mostly. the eddies area low pressure area versus the pressure underneath the car.
One way to keep eddies from forming as much is to keep smooth airflow over the rear of the car. The spoiler the WRX has helps the airflow re-attach to a surface at the bottom and stay relatively smooth. So the WRX spoiler by itself doesn't produce downforce, so much as eliminate some lift. It's almost just filling in the area where eddies could form, but because the currents didn't form the air generally stays 'pulled' down to the spoiler for more of the speedrange. The irony is that this is also a lower drag condition, so slightly better fuel economy. The turbulent eddy currents are a high drag & lift generating condition.
[img]http://us1.webpublications.com.au/static/images/articles/i10/1071_2lo.jpg[/img]
As for the STi wing, it still has a spoiler on it similar to the WRX spoiler, just smaller. Coincidentally this spoiler helps the actual wing on the STi by keeping the turbulent eddy currents smaller (just like the WRX one), so more smooth air flows over the wing to produce downforce. The downforce from the wing cancels out some of the lift produced by the rear window.
I'm guessing that even with the extra 'wing' added to the 2006, that there's still some turbulence, but it's probably a LOT less than previous years.
The spoiler on the WRX is there to re-attach laminar airflow, to reduce lift. By default, most streetcars have a certain amount of lift they produce (which is an exponential function of speed, IIRC). even the relatively brick shaped WRX produces lift. It produces it from the eddies that form on the trailing side of the car; the rear window & trunk mostly. the eddies area low pressure area versus the pressure underneath the car.
One way to keep eddies from forming as much is to keep smooth airflow over the rear of the car. The spoiler the WRX has helps the airflow re-attach to a surface at the bottom and stay relatively smooth. So the WRX spoiler by itself doesn't produce downforce, so much as eliminate some lift. It's almost just filling in the area where eddies could form, but because the currents didn't form the air generally stays 'pulled' down to the spoiler for more of the speedrange. The irony is that this is also a lower drag condition, so slightly better fuel economy. The turbulent eddy currents are a high drag & lift generating condition.
[img]http://us1.webpublications.com.au/static/images/articles/i10/1071_2lo.jpg[/img]
As for the STi wing, it still has a spoiler on it similar to the WRX spoiler, just smaller. Coincidentally this spoiler helps the actual wing on the STi by keeping the turbulent eddy currents smaller (just like the WRX one), so more smooth air flows over the wing to produce downforce. The downforce from the wing cancels out some of the lift produced by the rear window.
I'm guessing that even with the extra 'wing' added to the 2006, that there's still some turbulence, but it's probably a LOT less than previous years.
| maxQ | 05-15-2006 04:39 PM |
[QUOTE=Joel Gat, 1.8L]Hello,
That is incorrect. They definitely reduce the size of the vortex, but then also are used to develop a little thrust...
Joel[/QUOTE]
Let me be more clear then.... if you build two wings, one with the aforementioned winglet and one with the winglet turned flat and added onto the tip of the existing wing, the second design will have a lower induced drag than the wing with a winglet. Therefore winglets do not reduce drag compared to an equivalent sized wing.
If you compare a non-winglet wing with the same wing with an added winglet, then you will notice a reduction in induced drag but you're not comparing apples to apples.
Satisified, Mr. Joelander?
That is incorrect. They definitely reduce the size of the vortex, but then also are used to develop a little thrust...
Joel[/QUOTE]
Let me be more clear then.... if you build two wings, one with the aforementioned winglet and one with the winglet turned flat and added onto the tip of the existing wing, the second design will have a lower induced drag than the wing with a winglet. Therefore winglets do not reduce drag compared to an equivalent sized wing.
If you compare a non-winglet wing with the same wing with an added winglet, then you will notice a reduction in induced drag but you're not comparing apples to apples.
Satisified, Mr. Joelander?
| FromageTheDog | 05-15-2006 05:00 PM |
[QUOTE=MPME]Yeah, my point was that aflat plate, turned at a 75deg angle, is a massive spoiler that serves to provide downforce not by use of a winged profile, but by smashing air into a blunt surface, and that force then being transmtted downwards through the body onto the chassis/tires.[/QUOTE]
This belief is more a legacy of folks not understanding why spoilers worked, except that they did. What really happens is that a spoiler effectively acts like a split flap, "spoiling" the flow over the vehicle that would have otherwise generated a lifting force. The resultant change in pressure distribution causes a net loss of lift about the vehicles' center of lift (where that really is is anyone's guess, but roughly 50% along the length of the vehicle is probably about right).
In other words, while a spoiler probably has a non-negligible contribution to tail-end downforce from simple momentum transfer, the real benefit comes from this overall reduction of lift.
- Fromage (wearing his aero engineer hat)
This belief is more a legacy of folks not understanding why spoilers worked, except that they did. What really happens is that a spoiler effectively acts like a split flap, "spoiling" the flow over the vehicle that would have otherwise generated a lifting force. The resultant change in pressure distribution causes a net loss of lift about the vehicles' center of lift (where that really is is anyone's guess, but roughly 50% along the length of the vehicle is probably about right).
In other words, while a spoiler probably has a non-negligible contribution to tail-end downforce from simple momentum transfer, the real benefit comes from this overall reduction of lift.
- Fromage (wearing his aero engineer hat)
| Joel Gat, 1.8L | 05-15-2006 05:18 PM |
Hello,
[QUOTE=maxQ]Let me be more clear then.... if you build two wings, one with the aforementioned winglet and one with the winglet turned flat and added onto the tip of the existing wing, the second design will have a lower induced drag than the wing with a winglet. Therefore winglets do not reduce drag compared to an equivalent sized wing.
If you compare a non-winglet wing with the same wing with an added winglet, then you will notice a reduction in induced drag but you're not comparing apples to apples.
Satisified, Mr. Joelander?[/QUOTE]
Yep. Except when you're talking about a car, the overall outside-to-outside dimensions don't change (usually within the bounds of the car sheetmetal) - so you "get" to use an effectively longer wing when you use "winglet" type ends.
Joel
[QUOTE=maxQ]Let me be more clear then.... if you build two wings, one with the aforementioned winglet and one with the winglet turned flat and added onto the tip of the existing wing, the second design will have a lower induced drag than the wing with a winglet. Therefore winglets do not reduce drag compared to an equivalent sized wing.
If you compare a non-winglet wing with the same wing with an added winglet, then you will notice a reduction in induced drag but you're not comparing apples to apples.
Satisified, Mr. Joelander?[/QUOTE]
Yep. Except when you're talking about a car, the overall outside-to-outside dimensions don't change (usually within the bounds of the car sheetmetal) - so you "get" to use an effectively longer wing when you use "winglet" type ends.
Joel
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