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      05-08-2019, 05:48 PM   #1
CTMP4me
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Custom mounts for Bimmerworld Ultralight GT Carbon wing

I picked this particular wing with the intention of running it just below the top of roofline and at a low angle of attack. Around 4 degrees AoA, it should produce both decent downforce and relatively little drag as compared to a smaller twisted wing like the APR GTC250 producing same downforce at much more aggressive AoA.

The wing is 66" wide, with uprights 41" apart - quite different from the typical APR GTC250 so using APR mounts was out of the question. Location of hatch mounting points was chosen with consideration to where the hatch can physically fit a 10"x2" base plate and to keep the uprights as vertical as possible.

The basic design idea was to have (1) a mounting point on the hatch that conforms to hatch's complex surface curve and spreads out the load over a large area and (2) a simple upright cut from flat 3/8" aluminum sheet that would bolt to the side of the base plate and to the wing's mount points above. The base plate that interfaces with hatch was machined from a block of aluminum. This iteration can benefit from making the solid uprights into a truss to lose weight, but overall, the mounts feel extremely solid under both vertical and side loads, even if they do look a bit prototype-y with mismatched hardware

Shoutout to inTgr8r and FDF Race Shop for the front aero package and aluminum splitter / tray / skid plate - they work very well in combination.

If you want the CAD files for getting your own pedestals / uprights machined, PM me.
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      05-09-2019, 02:53 PM   #2
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This is awesome and great to see a more aggressive option for racing purposes. Sending you a PM regarding the CAD file now.

Have you had this out testing yet? I would be curious if you need more front aero to balance the wing. With my APR GTC-250 and APR Splitter, anything over 4* AOA begins to make the car push too much.
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      05-09-2019, 07:16 PM   #3
Michael9218
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True AoA

One thing to consider is the AoA should be measured from the perspective of the airflow and not assuming it's parallel to the ground. I found this image a while back. IIRC, that airflow is about 5 degrees coming off that roof line and the higher you mount the wing the less angle to the airflow. So your true AoA where you have that mounted is really more like 9 degrees. Though it may look odd, to get 4 degrees, your wing would actually be pointing up. I have my wing set level to the ground.

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      05-09-2019, 11:34 PM   #4
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Quote:
Originally Posted by Michael9218 View Post
One thing to consider is the AoA should be measured from the perspective of the airflow and not assuming it's parallel to the ground. I found this image a while back. IIRC, that airflow is about 5 degrees coming off that roof line and the higher you mount the wing the less angle to the airflow. So your true AoA where you have that mounted is really more like 9 degrees. Though it may look odd, to get 4 degrees, your wing would actually be pointing up. I have my wing set level to the ground.

Accurate remark, this is what twisted / 3-D wings try to compensate for, to have a more even pressure distribution across the entire airfoil / same effective AoA across the span. The only economical way I can think of to get an airfoil like that is to start at OEM level i.e. Porsche GT3/GT2 RS wings that can be refined for a particular application because the development cost is spread over thousands of units.
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      05-09-2019, 11:45 PM   #5
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Quote:
Originally Posted by Azeka1 View Post
This is awesome and great to see a more aggressive option for racing purposes. Sending you a PM regarding the CAD file now.

Have you had this out testing yet? I would be curious if you need more front aero to balance the wing. With my APR GTC-250 and APR Splitter, anything over 4* AOA begins to make the car push too much.
I'll report back as soon as I can test at Mosport / CTMP in non-adverse weather. Anecdotally, friends running similarly aggressive wings on e46 M3's have had to just put up with relatively lower front grip and end up exploiting the greater rear traction by getting on throttle earlier. High speed understeer + low speed oversteer isn't exactly the worst of handling traits combinations
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