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The front under wing provides down force to the front of the car. The design shape looks to be very good, but there is some real issues from a aeronautical perspective.
There are 3 areas of concern;
1. The large square opening for the attached fasteners is disrupting the smooth air flow over the wing and causing turbulence and drag.
2. The large seam running the length of the wing between the front carbon fiber leading edge piece and the rear black plastic piece, can let air leak through.
3. The two large holes where some type of frame supports is protruding through the wing that is letting air leak through.
As with any wing, any imperfection or disruption to airflow in these critical areas can greatly reduce its performance.
I think a band-aid for these areas might be trying to seal them up with some clear mylar tape.
This would be a good experiment for someone that tracks the car a lot, they are more likely to be able to really tell if there is an increase in performance.
Attached are some pictures of the area of concern;
Are we sure this is a big issue? Wouldn't the airflow just pass over the openings and continue? I find it hard to believe that GM didn't CFD the wing design. I'm game to put some black duct tape over the cut outs for the fasteners but I bet the disruptance from the edge of the tape would be greater than the gain from covering the cut outs. There is a very real problem that the underwing can't extend back further but that's the reality of a street car.
So another issue for how effective this underwing works is the fact that it is on a "street car". When compared to a "race car", ground clearance necessitates higher ground clearance. I'm not an aerodynamics engineer, but it would seem the lower the chassis is to the ground, the more effective the underwing would work. Also and probably more important, as respect high speed corners or sweepers,where aero downforce is most important, like turn 12 at Road Atlanta, the car (like all street cars) has body lean, far more than a race/track car would have. As the inside corner raises (body lean), the air pressure will change dramatically rendering the underwing less effective - I would think much less effective.
Are we sure this is a big issue? Wouldn't the airflow just pass over the openings and continue? I find it hard to believe that GM didn't CFD the wing design. I'm game to put some black duct tape over the cut outs for the fasteners but I bet the disruptance from the edge of the tape would be greater than the gain from covering the cut outs. There is a very real problem that the underwing can't extend back further but that's the reality of a street car.
I do think it should help. I would try a thin clear tape, like packing tape that is 2" wide. You are correct that you don't want a thick tape as the edges can have a negitive effect.
Just look at the top surface of any high perforamce airplane wing as a example.
On a airplane wing, just a thin layer of frost is a no go, as it will kill the lift and induce excessive drag.
So another issue for how effective this underwing works is the fact that it is on a "street car". When compared to a "race car", ground clearance necessitates higher ground clearance. I'm not an aerodynamics engineer, but it would seem the lower the chassis is to the ground, the more effective the underwing would work. Also and probably more important, as respect high speed corners or sweepers,where aero downforce is most important, like turn 12 at Road Atlanta, the car (like all street cars) has body lean, far more than a race/track car would have. As the inside corner raises (body lean), the air pressure will change dramatically rendering the underwing less effective - I would think much less effective.
I agree. The lower the wing is to the ground the more effective it will work.
I do think it should help. I would try a thin clear tape, like packing tape that is 2" wide. You are correct that you don't want a thick tape as the edges can have a negitive effect.
Just look at the top surface of any high perforamce airplane wing as a example.
On a airplane wing, just a thin layer of frost is a no go, as it will kill the lift and induce excessive drag.
If the frost is smooth, it won't cause that much of a performance problem, but because it's difficult to gauge how smooth frost is, and because there have been some nasty accidents involving failing to deice, most pilots opt for removing all frost. I ferried an airplane once that had a fresh paint job that looked like it had been done outside in a dust storm, and, despite having wing surfaces that looked about as rough as 40 grit sandpaper, it flew ok.
The front under wing provides down force to the front of the car. The design shape looks to be very good, but there is some real issues from a aeronautical perspective.
There are 3 areas of concern;
1. The large square opening for the attached fasteners is disrupting the smooth air flow over the wing and causing turbulence and drag.
2. The large seam running the length of the wing between the front carbon fiber leading edge piece and the rear black plastic piece, can let air leak through.
3. The two large holes where some type of frame supports is protruding through the wing that is letting air leak through.
As with any wing, any imperfection or disruption to airflow in these critical areas can greatly reduce its performance.
I think a band-aid for these areas might be trying to seal them up with some clear mylar tape.
This would be a good experiment for someone that tracks the car a lot, they are more likely to be able to really tell if there is an increase in performance.
Attached are some pictures of the area of concern;
I saw you ref this in my thread and I didn't mean to ignore your thoughts as they do have merit, I just haven't had a chance to look closely enough at that yet. For street cars, yes it's negligible; however, for drag cars in 1320 and 2640, and road course racing, there is likely some merit to this. They do create "some" drag, but you'd have to be pretty competitive to have that matter in the grand scheme of things. I do agree though, that those could be taped off. I would like to see CFD as well on those vs. surface mounted (non-countersunk) bolts though because unless GM did this for clearance, there was less drag on this vs. them hanging off the bottom of the spoiler.
The front under wing provides down force to the front of the car. The design shape looks to be very good, but there is some real issues from a aeronautical perspective.
There are 3 areas of concern;
1. The large square opening for the attached fasteners is disrupting the smooth air flow over the wing and causing turbulence and drag.
2. The large seam running the length of the wing between the front carbon fiber leading edge piece and the rear black plastic piece, can let air leak through.
3. The two large holes where some type of frame supports is protruding through the wing that is letting air leak through.
As with any wing, any imperfection or disruption to airflow in these critical areas can greatly reduce its performance.
I think a band-aid for these areas might be trying to seal them up with some clear mylar tape.
This would be a good experiment for someone that tracks the car a lot, they are more likely to be able to really tell if there is an increase in performance.
Attached are some pictures of the area of concern;
On our recent builds we cut those supports and welded flat pieces to retain strength but get them out of the way a bit. Maybe a XPEL type wrap to cover the mounting screw points. Drop Spindles will bring it closer to the ground. A customer of ours that instructs recently drove a ZR1 at COTA with our drop spindles/sway bars and said that it was amazing (he's driven stock as well).
I don't think those exposed bolt holes will matter because as this isn't an airplane wing in the traditional sense. An airplane wing has no physical structure directly in front of it except air. The way an aero engineer explained it to me when dealing with cars is to imagine the car driving though an infinite amount of ping pong ***** in a tunnel 100' wide by 100' tall that goes on forever. The ping pong ***** would represent the air molecules. As you drive a car through the ping pong *****, the cars front leading edge of the bumper will push the ***** forward, upward, downwards and sideways, compressing them against other ***** in their way. The amount of ping pong ***** that actually go under the car are initially not stable and are unsettled but have been pushed forward and compressed against other ping pong *****. A traditional airplane wing makes contact with the ping pong ***** first so it is much easier to calculate what the air flow is predicted to do. On a Vette, there is a chance that the air flow doesn't even touch those exposed countersunk bolt openings as it bounces away and downward.....so it wouldn't really matter if they were "smooth" or not. Putting a Go Pro camera off to the side of the car and attaching some tufts of yarn will actually tell you what the air is doing in that spot of concern. You really don't know unless you do a physical test.
You've all probably driven on the highway at interstate speeds and your car runs into a plastic bag that is floating on the surface. Even if you aim dead straight for the plastic bag floating a foot or so off the surface of the highway, it never touches the front of your car...it usually moves slightly forward and then bounces over the car usually not even touching the windshield. If you do run over the bag, it often times can get hung up under the chassis right around the catalytic converters.....which unfortunately has happened to me a couple of times, what a mess.
Never underestimate the power of the ping pong ball, lol.
Ever heard of Mach tape? That would be the preferred tape. As for efficiency, I doubt that any of us would feel the difference (with or without the tape).
I saw you ref this in my thread and I didn't mean to ignore your thoughts as they do have merit, I just haven't had a chance to look closely enough at that yet. For street cars, yes it's negligible; however, for drag cars in 1320 and 2640, and road course racing, there is likely some merit to this. They do create "some" drag, but you'd have to be pretty competitive to have that matter in the grand scheme of things. I do agree though, that those could be taped off. I would like to see CFD as well on those vs. surface mounted (non-countersunk) bolts though because unless GM did this for clearance, there was less drag on this vs. them hanging off the bottom of the spoiler.
No problem.
I do think the benefit of taping it smooth will be the added downforce in the front. I agree only a skilled road course drive with time in this car will notice the change if any.
On our recent builds we cut those supports and welded flat pieces to retain strength but get them out of the way a bit. Maybe a XPEL type wrap to cover the mounting screw points. Drop Spindles will bring it closer to the ground. A customer of ours that instructs recently drove a ZR1 at COTA with our drop spindles/sway bars and said that it was amazing (he's driven stock as well).
I like the way you smooth out the bottom of the car, its got to help.
Based on what could be similar technology used on some race cars, those holes in the bottom of the under wing could be there to channel air into the engine bay. Depending on how air flows out of the engine bay, those holes may be helping reduce under body pressure. Note that the C6 Z06 has two vent holes just in front of the air dam to channel air onto the front brakes.
Based on what could be similar technology used on some race cars, those holes in the bottom of the under wing could be there to channel air into the engine bay. Depending on how air flows out of the engine bay, those holes may be helping reduce under body pressure. Note that the C6 Z06 has two vent holes just in front of the air dam to channel air onto the front brakes.
Back when the C6 Z06 was being released there was some GM press about the amount of time they spent on those brake cooling holes and the balance between getting effective cooling and sacrificing downforce because of the holes. I don't remember the number, but they quoted quite a few wind tunnel hours in the effort.
10-19-2018, 06:42 PM
Front underwing performance discussion
. A customer of ours that instructs recently drove a ZR1 at COTA with our drop spindles/sway bars and said that it was amazing (he's driven stock as well).
