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We designed and water jet cut that original wing mounting set-up very quickly, over the course of a few of days. The goal was to re-use these uprights with a 2D wing to be installed later that year, which never materialized. Because we had planned to use a 2D wing with these, and from my insistence, the APR 3D airfoil was mounted about 6 inches above the roof line - against the wishes of Ryan and Jason. At this height about half of the GTC-300 wing was doing nothing but generating drag.
Testing at both high and low speed tracks showed we were faster at max AoA on the APR wing: 12 degrees at the center
After we kept this GTC-300 wing on the car for a year, and after constant advice from aero folks, Jason and others, we eventually cut down these uprights by about half to lower the 3D wing element below the roofline. It seemed to work a
little better at this lower height - which is the opposite of what you normally want to do with an airfoil.
Moving this 3D airfoil lower actually helped, due to the curved center shape of the wing
Why is this rear wring shaped this way? Answer:
To meet certain class rules. This "3D" wing profile was made to help improve downforce when used in some racing classes on sedan-shaped cars that limited the mounting height of the wing element at 6" to 8" above the rear trunk lid height. This rule was made to limit rear downforce and slow cars down, so aero engineers came up with a way to trick these low mounted wings into producing more downforce at this low height by tilting
part of the airfoil element upwards by 10-15 degrees right behind the greenhouse (aka: the bubble of glass and steel above the shoulder line of a car that houses the passenger compartment).
I always look at the C5R, C6R and C7R Corvette race cars for some of the latest aero tricks - not ashamed to admit that!
So the center section of this type of wing is angled upwards compared to the outer edges, to grab more airflow coming down over the roof and following the rear window. It really only works well when mounted low, and should only be used
when class rules mandate a low wing mounting height. But this became so widespread in professional GT racing and looked so "high tech" that they caught on with racers who
didn't need to mount them low.
CFD data shown on GT2 classed Corvette C6R race car (at left) and a striated smoke wind tunnel picture on a 911 GT2 at right
I've even heard other racers try to tell me that this type of 3D wing is
better than a high mounted 2D wing. Which is wrong. Don't confuse popular solutions for another set of rules to mean that there isn't something better for your class. It is always worth looking at the "why" of a design.
Here is a chart of Drag (HP), downforce (pounds) and AoA for the 14" x 72" AJ Hartman Racing wing run through CFD software
You can see the CFD data on the GTC-300 airfoil at
this link. And remember to look at the same units - the APR data is shown with speed in MPH (SAE)
but force is shown in Newtons (metric), so you have to divide that Force data by 4 to see it pounds of force. The AJ Hartman wing just has better data, as you can see when comparing the two.
When to use a 2D vs 3D airfoil: http://www.aprperformance.com/index....sk=view&id=176
Even APR admits as such in the article above, and now that they make a 2D wing again they are pushing that design. And yes, we could have picked up a carbon APR wing, but when we were looking for one last summer they were having supply and manufacturing problems. Its no secret where their airfoils come from, and I would rather have a U.S. built carbon wing than one from an overseas factory. So we started looking at different wing manufacturers...
After a lot of phone calls, emails, investigations, spreadsheets, data investigations and personal inspection of various brands of U.S. made carbon fiber wings we honed in on two brands. The final decision was a close one but we picked the wing with the biggest span and chord available:
AJ Hartman Racing. Their 14" chord length (the front-to-back size of the wing) and the massive 72" max width were simply unmatched by anything in this category for anywhere near this cost.
The Fulcrum wings are super popular here in Texas and I see them used to great effect on ST, AI, and other race cars
This hand laid carbon fiber wing is molded by AJ at his shop in New Jersey. He installs the saddles (bonded and riveted) to the wing at your specified widths, trims the span to your specs and the final wing just looks amazing. They weigh 9 pounds, total, and his wings can support the weight of a full sized adult. You may not know the AJ Hartman Racing name now, but the original airfoil design and molds were purchased from Fulcrum Aeroworks, which was a company formerly based right here in Dallas/Ft. Worth.
The retail price for this AJH wing is only $1300, which is insanely low (this airfoil
easily compares to $2500-4000 U.S.-made wings), and now Vorshlag is their first ever dealer. AJ didn't yet have a wing mounting kit for the 2010-2014 Mustang trunk shape so we started designing one as soon as our first 14x72" AJH wing arrived.
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