Why did you need a $42M Wind Tunnel?

Why did you need a $42M Wind Tunnel?
January 15, 2013 Greg Mark
In Aerodynamic Tuning

We were recently directed to a forum post, with a very good question about our testing at Windshear’s Wind Tunnel:

I’m not throwing off on the aeromotions part, hell I’d love to have it! But, did it really take a $42M, 180mph wind tunnel to make a completely flat piece of carbon with 2 generic looking end plates? The “motion” feature is awsome, but unless I’m missing something, the design of the wing doesn’t look very groundbreaking.

Edit: I looked at close ups and can now see that it’s not completely flat, but it still looks very basic to me.


Aero is a subtle art.

This is why the top F1 teams are able to do a few tricks and walk away from the competition (who are also very clever, driven, competitors). In our case, the top of the wing has a very gentle curve. But the magic happens on the bottom. Our wing runs the only “concave pressure recovery” system in racing. It looks like the big dipper, and is a very counterintuitive shape. But she works marvelously. Technically, it’s optimal. A recent development in aero was the ability to use an “optimal” pressure distribution, and then have the computer reverse-solve the actual shape. So, technically, the computer figured this one out.


Why is an Accurate Wind Tunnel So Important?

Mid-level performance airfoils are very robust to manufacturing defects. Think of an American V8 compared to an F1 engine. Small imbalances in piston weight don’t matter at 6,000 RPM, but they will blow your engine at 18,000 RPM. Aero is the same way. High performance airfoils are sensitive to small manufacturing defects, which is why most companies don’t use them. We went a different way. We used a high-performance foil, and then created a manufacturing process + tooling to produce extremely accurate, high-fidelity wings.


What did you Test in The Tunnel?

No two wings are exactly the same – there is a little variation in each shape. For example, when you glue the top and bottom halves together, there can be a 0.010″ variation in thickness of the trailing edge. In high-performance aero terms, this is HUGE. How much is acceptable? Well, we know exactly. We found out in the tunnel. Same the thing with the surface finish. We obsess over its smoothness. How much roughness is acceptable on that airfoil, we found out. The list goes on. The bottom line is that Aero is very complex. There are a huge number of factors that need to come together to get it right. This is why F1 is dominated by aero, and why they built $42M wind tunnels to develop exotic aero packages. I promise you, the 2D airfoil on the back of the Ferrari F1 car is one of the most advanced shapes, and best understood wings, ever made. It looks deceptively simple. But it’s not.