WIng Math

[Jack B]

As we all know the rear spoiler provides down force. The combination of the front/rear aero options reportedly (I think) give us 200 lbs of down force at 100 mph.

That is the vertical component of the total force. What is the horizontal component for this set up. In other words, what is the conversion to a hp loss for the factory aero option at 100 mph - it sure looks nice.

Any vendors or road racers know.

[City]

That hurt my brain. I fear the answer will be more painful. Good question nonetheless.

[FLATOUT]

Watch my freeway pulls in my Stock 2008 ACR against Nineballs stock 2013 and you will get a good idea of the combined effect of the Gen IV ACR areo (obviously much higher than then 200lbs the TA aero creates) and the difference in trans gearing in 4th between an 08 and 13 car.

Basically it looks like my ACR loses about 50rwhp in forth and it only compounds the faster we go (in a straight line). That being said I wouldn't have it any other way in the twisties ;)

Nineball has since added the Gen V factory aero but I have added about 60rwhp and 65ftlbs of torque so the comparison would be difficult at this point.

[VENOM V]

Excellent question, I'm sure the factory engineers have this info. I have an APR GT-250 wing that is being installed on my Camaro, and APR publishes L/D (Lift/Drag) ratios and charts on their website. L refers to negative lift, which is downforce. Here's what my Camaro wing's performance is:

At a 10-degree AOA (angle of attack):

SPEED DOWNFORCE DRAG L/D Ratio (Efficiency)
080 mph 130 Lb 19 Lb 6.7
120 mph 301 Lb 50 Lb 6.1
150 mph 470 Lb 66 Lb 5.9
160 mph 540 Lb 71 Lb 5.9

One thing I've noticed is that on road courses, even underpowered cars like S2000s and Civics with big wings can sometimes beat a Viper, with good drivers in all cars. So with a relatively efficient wing design, the penalty of drag is outweighed by the benefit of downforce. These wings are tunable, there's a sweet spot.

I think I read that the top speed of a Gen V Viper with carbon aero drops from 206 MPH to around 186 MPH, if memory serves. I don't recall the exact speed. But on a road course, I'll glady take the carbon aero package.

[Martin]

Complicated thing to answer - and there are two major components of drag. One is induced drag (which is induced by the lift and varies according to the direction of the lift with respect to the freestream air and relative airflow), and one is parasitic drag (usually very small at subsonic speeds and is the "skin drag").

In short, the induced drag can be calculated by drawing a triangle of the three forces on the wing. There's the lift that's purely vertical (actual lift), the lift that's perpendicular to effective relative airflow (rule of thumb, about half way between freestream airflow and the chord angle of the wing), and then when you draw a right triangle to connect those two components of lift, the rearward facing component is the induced drag.

I know - it hurts my brain to think about it, too, and I probably have half of that wrong now that it's been 20+ years since I actually did that stuff for a living....

[NI-KA]

All sounds very trigonometric to me!

Common install some sensors on the beast at answer the question empirically. :)

[Martin]

Or, even more fun - take the wing off, record maximum speed in two directions, then put wing back on and repeat. Pretty easy to figure out how much power it took to generate that downforce, and much more fun in the process. Of course, drag goes up at the square of velocity, so would have to figure that in according to the acceleration curve, but it should work out after a few data runs. Give me a few beers in the Nevada desert and I'll demonstrate.

[ViperGeorge]

Excellent question, I'm sure the factory engineers have this info. I have an APR GT-250 wing that is being installed on my Camaro, and APR publishes L/D (Lift/Drag) ratios and charts on their website. L refers to negative lift, which is downforce. Here's what my Camaro wing's performance is:

At a 10-degree AOA (angle of attack):

SPEED DOWNFORCE DRAG L/D Ratio (Efficiency)


080 mph 130 Lb 19 Lb 6.7
120 mph 301 Lb 50 Lb 6.1
150 mph 470 Lb 66 Lb 5.9
160 mph 540 Lb 71 Lb 5.9

One thing I've noticed is that on road courses, even underpowered cars like S2000s and Civics with big wings can sometimes beat a Viper, with good drivers in all cars. So with a relatively efficient wing design, the penalty of drag is outweighed by the benefit of downforce. These wings are tunable, there's a sweet spot.

I think I read that the top speed of a Gen V Viper with carbon aero drops from 206 MPH to around 186 MPH, if memory serves. I don't recall the exact speed. But on a road course, I'll glady take the carbon aero package.

An SRT engineer just told me that the top speed in the Viper is 206 mph. With the aero kit top speed drops to 193 mph.

[Viper Girl]

I wonder if these type of spagetti renderings are out for the Gen V? It would be really cool to see especially with the new hood.

http://i1127.photobucket.com/albums/l631/socalgirlz/spaghet1front.jpg (http://s1127.photobucket.com/user/socalgirlz/media/spaghet1front.jpg.html)

http://i1127.photobucket.com/albums/l631/socalgirlz/spaghet2back.jpg (http://s1127.photobucket.com/user/socalgirlz/media/spaghet2back.jpg.html)

[City]

Those are cool regardless! But I'm thinking capellini.

[VYPR BYT]

I wonder if these type of spagetti renderings are out for the Gen V? It would be really cool to see especially with the new hood.

http://i1127.photobucket.com/albums/l631/socalgirlz/spaghet1front.jpg (http://s1127.photobucket.com/user/socalgirlz/media/spaghet1front.jpg.html)

http://i1127.photobucket.com/albums/l631/socalgirlz/spaghet2back.jpg (http://s1127.photobucket.com/user/socalgirlz/media/spaghet2back.jpg.html)

I got your back ;-)

http://i1121.photobucket.com/albums/l514/VYPR_BYT_94/genVcfdimage.png (http://s1121.photobucket.com/user/VYPR_BYT_94/media/genVcfdimage.png.html)

[Jack B]

What do you think it would cost in 1/4 mile et.

[Viper Girl]

Wow Nice!

[FLATOUT]

What do you think it would cost in 1/4 mile et.

Depends on final trap speed. I would think maybe a 1/2 a tenth on the Gen V because the Aero doesn't create that much down force. So see what it creates at 127mph and go from there.

I know the Gen IV ACR's it hurt their traps by about 2 mph over the coupes. When I finally get out to the drag strip I will make a few passes with the rear wing on and a couple with it off.

[The_Greg]

I got your back ;-)

http://i1121.photobucket.com/albums/l514/VYPR_BYT_94/genVcfdimage.png (http://s1121.photobucket.com/user/VYPR_BYT_94/media/genVcfdimage.png.html)

Wow, those are some serious vortices.

[Jack B]

That would be very interesting to see the side-by-side MPH



Depends on final trap speed. I would think maybe a 1/2 a tenth on the Gen V because the Aero doesn't create that much down force. So see what it creates at 127mph and go from there.

I know the Gen IV ACR's it hurt their traps by about 2 mph over the coupes. When I finally get out to the drag strip I will make a few passes with the rear wing on and a couple with it off.

[slitherv10]

Depends on final trap speed. I would think maybe a 1/2 a tenth on the Gen V because the Aero doesn't create that much down force. So see what it creates at 127mph and go from there.

I know the Gen IV ACR's it hurt their traps by about 2 mph over the coupes. When I finally get out to the drag strip I will make a few passes with the rear wing on and a couple with it off.

Wouldn't that be hard to render as each run would never be identical and mere differences in launch reaction, shift, wheel spin etc..would make it difficult to pin point as the difference would be too slight to tell?

[ACRucrazy]

I have read others state 3mph at the big end of the 1320 with the ACR aero removed.

No first hand experience however.

[Jack B]

Mph will be very close if the ambient temps and car temps are similar, ET could be wide ranging. If you get a mph diff, you could calculate hp diff, then, calculate reduced ET. You would need a couple runs for each configuration. Most of the restrictive horizontal force is going to be from 100 MPH to approx 128 MPH, that is only about 3-4 seconds.



Wouldn't that be hard to render as each run would never be identical and mere differences in launch reaction, shift, wheel spin etc..would make it difficult to pin point as the difference would be too slight to tell?

[Sundiego]

Or, even more fun - take the wing off, record maximum speed in two directions, then put wing back on and repeat. Pretty easy to figure out how much power it took to generate that downforce, and much more fun in the process. Of course, drag goes up at the square of velocity, so would have to figure that in according to the acceleration curve, but it should work out after a few data runs. Give me a few beers in the Nevada desert and I'll demonstrate.

Taking off part of an Aero package doesn't end well at speed. You have a planted front end, and a loose back end. Probably fine, until you hit the brakes. When you brake from a speed like that, you brake hard. The nose dives, and plants more weight forward. The back end can easily step out and around.

[Newport Viper]

http://i1.ytimg.com/vi/qI_IZOeeKjY/hqdefault.jpg

http://www.drivesrt.com/news/wp-content/uploads/2013/06/GTS-R-Aero1.jpg

http://speed-tech.zorly.com/pictures/viper-more/2013-srt-viper-wind-tunnel.jpg

http://farm8.staticflickr.com/7054/6966602092_95f0787f14_b.jpg

http://s1.dmcdn.net/APkqB/526x297-eXb.jpg