Spoiler vs Wing (Drag)
06-17-2008, 09:47 AM
#1
Drifting
Thread Starter
Spoiler vs Wing (Drag)
I am running a 4"-5" adjustable lexan spoiler and feel like I am losing some speed on straightaways due to the added drag 
...with that said...
How much more drag does a 4"-5" spoiler have compared to a 67" wing?
What does that equate to in MPH on a long straight?
Also, as a side, I noticed that the APR wings do not mount the the frame and only use the fiberglass body as the holding point...I thought this was a no no, and could lead to the wing breaking off at very high speeds (150+)???
Thx
...with that said...How much more drag does a 4"-5" spoiler have compared to a 67" wing?
What does that equate to in MPH on a long straight?
Also, as a side, I noticed that the APR wings do not mount the the frame and only use the fiberglass body as the holding point...I thought this was a no no, and could lead to the wing breaking off at very high speeds (150+)???
Thx
06-17-2008, 12:20 PM
#2
Safety Car
Member Since: May 2006
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St. Jude Donor '08
I am running a 4"-5" adjustable lexan spoiler and feel like I am losing some speed on straightaways due to the added drag ...with that said...
How much more drag does a 4"-5" spoiler have compared to a 67" wing?
What does that equate to in MPH on a long straight?
Also, as a side, I noticed that the APR wings do not mount the the frame and only use the fiberglass body as the holding point...I thought this was a no no, and could lead to the wing breaking off at very high speeds (150+)???
Thx
...with that said...How much more drag does a 4"-5" spoiler have compared to a 67" wing?
What does that equate to in MPH on a long straight?
Also, as a side, I noticed that the APR wings do not mount the the frame and only use the fiberglass body as the holding point...I thought this was a no no, and could lead to the wing breaking off at very high speeds (150+)???
Thx
Would need more info to answer your question. Do you have a picture? How steep is the angle?
All aerodynamic devices create some drag. The goal is to achieve the best trade-off possible between increased downforce and drag.
On tracks with long straights you probably want to go with less downforce (and hence drag) than at a track with more turns.
06-17-2008, 12:47 PM
#3
Melting Slicks
A friend had a wing mounted to the trunk lid on his C5 Z06. During the last ORR the wing broke the lid - pulled out in the front. I'm surprised it stayed on as he was in the 140 or 145 mph class so he was haulin'.
06-17-2008, 01:04 PM
#4
Le Mans Master
Member Since: Feb 2000
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Any decent wing is much more efficient that a spoiler in terms of downforce/drag. In addition, any decent wing cannot be mounted on just the fiberglass trunk lid, because at 140MPH it should be generating more downforce than the weight of a iron small block Chevy engine and I don't think anyone would want that much weight on a couple of little pads on the deck lid.
06-17-2008, 01:14 PM
#5
Le Mans Master
This will actually require testing or data from someone else's test with the same kind of car. Some cars can actually see a reduction in drag with a small spoiler (like 1" tall) but yours is most likely producing some drag. It is possible that a wing will create more total vehicle drag due to the wake effect of the car without a rear spoiler. Wing placement and angle of attack is critical and can only be determined with testing. The same goes for spoiler height and angle. I'm sorry there isn't an easy answer but aero interactions are rather complex and even the most experienced guys will be surprised on occasion. You could start by optimizing your current setup by at least doing some coastdown testing.
06-17-2008, 01:26 PM
#6
Le Mans Master
This all depends on your goal.
Losing a few MPH on a straight-a-way may not be such a huge price to pay depending on the track itself.
If you are running an overall tight technical slower track than less downforce may be acceptable.
You have two ways to make the car stick to the ground, mechanical grip and aero grip.
Take a 14-turn layout for example:
If you lose 0.2 seconds on a straight-a-way but can gain 0.1 seconds in each ensuing turn because of good aero grip, that's a great trade off for top end speed. That would give you a full second faster per lap.
Everyone gets excited about top speed on the straight-a-way, but the battle is won in braking and turning.
Do you have a pic of your set up?
Mike
06-17-2008, 01:52 PM
#7
Drifting
Thread Starter
Pics are here...
http://www.skyhighway.com/~bfpix4/IMG_1842.JPG
http://www.skyhighway.com/~bfpix4/IMG_1840.JPG
http://www.skyhighway.com/~bfpix4/IMG_1838.JPG
http://www.skyhighway.com/~bfpix4/IMG_1837.JPG
Its about 4 1/2" tall and is currently set at 45".
I am completely aware that there are trade offs in everything and that if time gained somewhere is less than time lost in other places, then the overall effect is negative.
I have spoken to race shops who used to run spoilers and changed to wings, and said they picked up 4-5 mph on the straightaways.
I definitely do not need the total amount of downforce that a 67" wing is capable of producing, but if that wing can reduce drag (relative to my current spoiler), while providing equal downforce, than I am only likely to benefit from it.
So back to my original question, how much drag is a 67" wing producing vs a 5" spoiler (both angled to exert equal downforce)? and how does this difference in drag equate to mph?
Hope my question makes sense...
http://www.skyhighway.com/~bfpix4/IMG_1842.JPG
http://www.skyhighway.com/~bfpix4/IMG_1840.JPG
http://www.skyhighway.com/~bfpix4/IMG_1838.JPG
http://www.skyhighway.com/~bfpix4/IMG_1837.JPG
Its about 4 1/2" tall and is currently set at 45".
I am completely aware that there are trade offs in everything and that if time gained somewhere is less than time lost in other places, then the overall effect is negative.
I have spoken to race shops who used to run spoilers and changed to wings, and said they picked up 4-5 mph on the straightaways.
I definitely do not need the total amount of downforce that a 67" wing is capable of producing, but if that wing can reduce drag (relative to my current spoiler), while providing equal downforce, than I am only likely to benefit from it.
So back to my original question, how much drag is a 67" wing producing vs a 5" spoiler (both angled to exert equal downforce)? and how does this difference in drag equate to mph?
Hope my question makes sense...
06-17-2008, 02:42 PM
#8
Race Director
$11 and you can answer all your questions very scientifically.
Aerodynamic Test and Development of the Corvette C5 for Showroom Stock Racing
Thanks to the "Golden Eagle" for pointing me towrd this gem...
Aerodynamic Test and Development of the Corvette C5 for Showroom Stock Racing
Thanks to the "Golden Eagle" for pointing me towrd this gem...
Last edited by RC45; 06-17-2008 at 02:50 PM.
06-17-2008, 03:01 PM
#9
Melting Slicks
Good little site discussing aerodynamics
http://www.gmecca.com/byorc/dtipsaerodynamics.html
I read where adding a small spoiler on the rear of the car - about 1" tall - creates downforce with little added drag.
http://www.gmecca.com/byorc/dtipsaerodynamics.html
I read where adding a small spoiler on the rear of the car - about 1" tall - creates downforce with little added drag.
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kelp (07-08-2021)
06-17-2008, 03:10 PM
#10
Le Mans Master
That SAE report would certainly be a good start but you would still need a configuration comparing a spoiler to the wing. The bottom line is that a wing and a spoiler interact differently with the top of the car to alter the pressure and flow on the bottom of the car and only testing will tell you which will generate less total vehicle drag. throwit, was it a Corvette that the race shop was running? Was it an FRC or a coupe? That will make a difference. Also, what other devices were they running (front splitter, rear diffuser, etc)? As I said, the interactions are complicated.
06-17-2008, 03:20 PM
#11
Drifting
Thread Starter
That SAE report would certainly be a good start but you would still need a configuration comparing a spoiler to the wing. The bottom line is that a wing and a spoiler interact differently with the top of the car to alter the pressure and flow on the bottom of the car and only testing will tell you which will generate less total vehicle drag. throwit, was it a Corvette that the race shop was running? Was it an FRC or a coupe? That will make a difference. Also, what other devices were they running (front splitter, rear diffuser, etc)? As I said, the interactions are complicated.
Yes they were running corvettes...one of my sources was LG with their old trans am car.
http://lgmotorsports.com/gallery/dis...?album=7&pos=1
I used to have a 1" spoiler (the mid america one...still have it btw) and didnt notice any downforce what so ever. I feel a significant difference with my current spoiler, but fear that I am actually going slower due to drag than i would with a wing. Also, there must be a reason why all the pro teams use wings and not spoilers...
I know that nascars use spoilers, but I think thats because they have to, not because its whats best...
Last edited by throwit; 06-17-2008 at 03:25 PM.
06-17-2008, 03:32 PM
#12
Race Director
That SAE report would certainly be a good start but you would still need a configuration comparing a spoiler to the wing. The bottom line is that a wing and a spoiler interact differently with the top of the car to alter the pressure and flow on the bottom of the car and only testing will tell you which will generate less total vehicle drag. throwit, was it a Corvette that the race shop was running? Was it an FRC or a coupe? That will make a difference. Also, what other devices were they running (front splitter, rear diffuser, etc)? As I said, the interactions are complicated.
It is pretty much the only publicly available documented wind tunnel tested aerodynamic testing done on the C5 Z that names and describes the parts used - and that are still available for purchase (from Kerry Hitt in Florida).
This is one little gem that nobody can afford to not read.
Last edited by RC45; 06-17-2008 at 03:36 PM.
06-17-2008, 04:11 PM
#13
Safety Car
Member Since: May 2006
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St. Jude Donor '08
Unfortunately, I do not have a true means of testing drag vs downforce, so I was hoping others who may have experience with both a wing and spoiler would chime in.
Yes they were running corvettes...one of my sources was LG with their old trans am car.
http://lgmotorsports.com/gallery/dis...?album=7&pos=1
I used to have a 1" spoiler (the mid america one...still have it btw) and didnt notice any downforce what so ever. I feel a significant difference with my current spoiler, but fear that I am actually going slower due to drag than i would with a wing. Also, there must be a reason why all the pro teams use wings and not spoilers...
I know that nascars use spoilers, but I think thats because they have to, not because its whats best...
Yes they were running corvettes...one of my sources was LG with their old trans am car.
http://lgmotorsports.com/gallery/dis...?album=7&pos=1
I used to have a 1" spoiler (the mid america one...still have it btw) and didnt notice any downforce what so ever. I feel a significant difference with my current spoiler, but fear that I am actually going slower due to drag than i would with a wing. Also, there must be a reason why all the pro teams use wings and not spoilers...
I know that nascars use spoilers, but I think thats because they have to, not because its whats best...
If you go with a wing just make sure you don't get too carried away and create an aerodyamic in balance between the front and rear.
Agree with what Short-throw said. It's about lap times not top speed.
06-17-2008, 04:44 PM
#15
Le Mans Master
RC45, that sounds like a pretty complete report. The description didn't mention a spoiler so that is very cool that it is included. throwit, I would still caution against direct comparisons as to drag and downforce to your car without being in a very similar configuration. It should be good for showing trends, however.
06-17-2008, 05:13 PM
#16
Race Director
RC45, that sounds like a pretty complete report. The description didn't mention a spoiler so that is very cool that it is included. throwit, I would still caution against direct comparisons as to drag and downforce to your car without being in a very similar configuration. It should be good for showing trends, however.
When the Corvette C5 started racing in 1999 the goal was tp keep the car as close to production as possible. A typical 1999 Corvette C5 racecar is shown in Figure 1.
As time evolved, the S.C.C.A. rules allowed for aerodynamic modifications such as rear wings and front fascias with splitters. In an effort to maintain stock appearance, a package was developed that included a front fascia with short splitter, a 10cm rear spoiler on the deck, and rocker panel aerodynamic skirts. This package proved adequate through the 2000 season and is shown in Figure 2.
The 2001 season included a new spec tire, which was only available in the 295/35-18 size, and did not offer the 335/35-18 rear tire the Corvette needed to be competitive. In an effort to compensate for the lack of rear tire size, the sanctioning body approved the use of a rear wing for the 2001 race season. The race teams developed the rear wing shown in Figure 3 based on, on-track performance.
Even with the addition of a rear wing, the performance disparity due to the smaller sized rear tire was still overwhelming, and merited this aerodynamic development program.
As time evolved, the S.C.C.A. rules allowed for aerodynamic modifications such as rear wings and front fascias with splitters. In an effort to maintain stock appearance, a package was developed that included a front fascia with short splitter, a 10cm rear spoiler on the deck, and rocker panel aerodynamic skirts. This package proved adequate through the 2000 season and is shown in Figure 2.
The 2001 season included a new spec tire, which was only available in the 295/35-18 size, and did not offer the 335/35-18 rear tire the Corvette needed to be competitive. In an effort to compensate for the lack of rear tire size, the sanctioning body approved the use of a rear wing for the 2001 race season. The race teams developed the rear wing shown in Figure 3 based on, on-track performance.
Even with the addition of a rear wing, the performance disparity due to the smaller sized rear tire was still overwhelming, and merited this aerodynamic development program.
06-17-2008, 05:14 PM
#17
Le Mans Master
I just found this photo where they are running a small spoiler with a wing. Interesting, I wounder how well it worked.
Also, check it out... it's David Farmer.
Also, check it out... it's David Farmer.
06-17-2008, 05:19 PM
#18
Race Director
Guess what, in that last picture of my car, the wing WAS BOLTED TO THE DECK LID! Held up great until I hit the wall backward (thanks to getting hammered by another car). It was a temporary arrangement anyway, but it did work for a while.
A note I haven't seen mentioned. Spoilers tend to stack air on the entire rear half of the car, and add downforce to the entire car. A wing will apply downforce directly to where it is mounted, usually behind the rear axle, and will increase rear and often take away front downforce.
Anyway, if you want overal stability, a spoiler can help. If you really need to plant the rear end, a wing is the way to go. However, to take advantage of a wing, you need a real splitter on the front or the nose will be light.
A note I haven't seen mentioned. Spoilers tend to stack air on the entire rear half of the car, and add downforce to the entire car. A wing will apply downforce directly to where it is mounted, usually behind the rear axle, and will increase rear and often take away front downforce.
Anyway, if you want overal stability, a spoiler can help. If you really need to plant the rear end, a wing is the way to go. However, to take advantage of a wing, you need a real splitter on the front or the nose will be light.
06-17-2008, 05:58 PM
#20
Instructor
Actually you can use both. The spoiler hides within about a 10-14 degree angle of divergence off the frontal area of the greenhouse. That means you can use it to put more pressure on the rear deck without extra drag....sometimes it even decreases drag. Putting a wing above the greenhouse frontal area is a very efficient way to add significant downforce as well. Plan on taking a visit to the aerodyn2 windtunnel. Until you really get a chance to go and test....you'll never really know what's going on. Some of the things that look prefectly reasonable to do can actually increase lift. Every car model behaves different than others.
