Following a couple events in the rain, and visually analysing the residual dirt on the wing, I took a detour into evaluating rear wing performance. Of particular note was the slight flow detachment at the rear of the wing on the underside, and the high degree of turbulence around the upright attachment at the bottom of the wing.
To test wing attributes, I started with a very simple aerofoil design, which underwent some iterative improvements, to arrive at the design below. For testing purposes, the wing was 70" wide, with a 11.25" chord length. Overall, the design works relatively well. All testing below was conducted without the uprights or endplates, to evaluate the performance of the aerofoil itself.
For comparison purposes, the results were also compared to data available from two wing manufacturers, Nine Lives Racing and APR (specifically the GTC 300, which is what is current on the car).
The results generally compared well. The design was far less efficient than the Nine Lives Racing offering, but was able to produce far higher levels of downforce at steeper angles of attack; the NLR design lost efficiency fairly rapidly beyond 5 degrees (which produced 180 lbs of downforce). The APR GTC 300 was slightly more efficient, but also began to stall out after 10 degrees.
After testing the efficiency of the aerofoil, the wing assembly with simplistic bottom mounts was tested. The simple act of attaching .5" wide vertical elements to the underside of the wing reduced downforce by roughly 7%, and simultaneously increased drag roughly 7%. It's reasonable to conclude, given the very bulky attachment pieces on the aerofoil itself, the GTC 300 would fare considerably worse when measured with the mounts. And this is qualitatively supported when looking at the turbulent airflow around the mounts as evidenced by the dirt patterns on the wing and deck lid.
So, the big take-away here is the mounting system is critical. Optimally you'd mount from the top using a swan neck attachment. If that's not feasible, much care must be taken to optimize airflow around the mounts to prevent reduction in wing effectiveness.
Future testing of Corvette aero will incorporate this new wing design.