Monthly Archives: July 2014

Tunnel Vision

Had a chance to do something over the weekend that was cool enough that I thought I’d share, since obviously it’s been a while since I’ve put anything up here.

Last year at the F1000 Pro Series race at Miller, Ryan made a contact with the owner of a new full-scale wind tunnel that opened up in Ogden, UT.

The tunnel is operated by Darko Technologies – http://www.darkotech.com/, and since they were interested in seeing some race cars in the tunnel, and obviously we were interested in data, we worked out the details and finally got the car out there this past weekend.

The tunnel is a fixed-floor, open circuit, full-scale tunnel, with maximum wind speed of 60(?) mph. The whole day ran smoothly, and the tech was helpful and friendly. 

We showed up in the morning, unloaded, and rolled the car right in the tunnel. We spent some time getting the tunnel configured for the car (load cells and such for the measurements), and then spent our time working through a test plan that Zebulon put together. Zebulon used a cool boundary-layer control technique to help mitigate the ill-effects of the fixed floor, and a few other tricks from tunnel work they’ve done before, so it was really handy having somebody there that knew their biz.

I have to say, it was an incredibly fun experience – and TOTALLY scratched the nerd/engineering itch! 

Each run was around 5 minutes long, as we would take 3 data points, each about 80 seconds apart, plus a few seconds to spin the fans up and down.


Ultimately we were able to answer the age-old question: “Does an F1000 generate enough downforce to drive upside down?”

The answer? No. Not even close. At least, not this one. But, it was surprisingly efficient in L/D – hats off to Jesse Brittsan/BRD’s bodywork on that one. Obviously rolling road and wheels would affect this number.

The data we gained was fascinating – effects of front and rear wing changes, beam wing angle changes, ride height changes, and tested a few of the aero whizzy bits to see what they did. In particular it was very interesting to see the relationship between the aero balance we typically run on track that feels “balanced” to me, versus the static weight distribution of the car – not exactly what I expected.

Most encouraging of all is that the data produced by the wind tunnel had outstanding correlation with the CFD that Zebulon has been doing as we sort through the car’s aero, which means we can continue to pursue the simulation avenue with a high degree of confidence. Zebulon’s plan is to mimic the conditions in the tunnel in CFD and validate the correlation as tightly as possible.

Also, as an aside, the driver was happy that the strong correlation between CFD and tunnel also means that his butt dyno is the largely accurate (and exquisite!) device that he’d hoped!

By the end the car had so much yarn on it it looked like I’d crashed into Hobby Lobby.

As a last step, purely for cool factor and extra validation, we did some smoke visualization to get a sense of airflow over the car, and in the underbody, which was also incredibly fun to do and see. The behavior of air around the front wing and front tires, and the resulting vortices is wild to watch. Encouragingly, the airflow we saw in smoke trails also matched up extremely well with what the CFD simulations have shown us, so a big nod to Zebulon on that one too. Never would have guessed what happens behind the front wing and front suspension.

Lots of data to go over and analyze now, to see what other conclusions we can draw from the numbers.

Incredibly fun experience to have, can’t wait to see what it gets us in terms of analyzing the car’s development and competitiveness. Not something that many of us at this level get to do, so I thought I’d share, and also to dangle the hook:

Darko and Zebulon’s hope is that others will think the value is there for visiting the Darko tunnel with their race cars, so maybe we’ll see more cars in the tunnel moving forward.

Contact Ryan at Zebulon MSC (www.zebulonmsc.com) to get a test plan set up, and they’ve arranged for discounted rates at the Darko Tech tunnel if you bring them with for engineering and consulting.

Overall, a true bucket-list day, still shaking my head at getting to do it