Last week I went to VIR and the A2 wind tunnel. Both are about 10 hours away from me, so I made it a twofer and hit them on the same trip. I couldn’t get two consecutive days at A2, so the wind tunnel testing was on a Monday and a Thursday, with VIR in between.
I’ll get around to sharing some of the data in the upcoming weeks, and follow up with another wind tunnel report. I’ve been talking to AJ Hartman about writing a book together, and I think I think this could take the place of the wind tunnel report, but we shall see.
Monday was slated as hatchback day, with my Veloster and Andrew Rivers’s CRZ. We also had some extra company, with Kaan from the Blind Apex podcast, Michael Jui from Wing-Logic, and Robertson Racing’s aerodynamicist Tim Miller.
Thursday was fastback day. AJ Hartman brought a customer’s C7 Corvette, Raul Iriarte brought his ST5 BRZ, and Pete Mink a Porsche 944. We also had a few more guests with fellow blogger TJ Lathrop from The Rising Edge, and aerodynamicist Ido Waksman, who used to work for Honda and Pratt Miller, but now has his own business called MAD Aerodynamics. AJ also brought along a couple employees, past and present, who hadn’t been to the wind tunnel before.
So it was a full house on both days, and sometimes chaotic. But with plenty of hands on deck, we had extra people to turn wrenches, fetch things, wool tuft the cars, and fabricate parts as needed. All of which is necessary because nothing goes exactly as it should.
I spend a lot of time organizing, building parts, figuring out the order in which to test things, and putting together spreadsheets. This mostly works out, but there’s always a fitment problem, or something you left at home. No plan survives contact with the enemy.
For example, Andrew’s S1223 foam-core wing didn’t make the test. During vacuum bagging the core shifted, and so he got a pretzel instead of a wing. Andrew ordered a Simon McBeath wing, but it wasn’t ready until the day after the wind tunnel test. I thought maybe we could use a new nylon wing from Adam Bao of Epsilon, which was coming hot off the presses from Asia… but it too was stuck in shipping.
In the end, I made up a set of temporary mounts for my 71″ MSHD wing, and I’m glad that worked out, because we got great data from his car.
Day one testing
After unloading 8 wings, 4 spoilers, a roof extension, tools, parts, raw materials, etc., the Veloster went first into the tunnel. The first four runs were canard size and edge height, the former being obvious, the latter less so.
Then I was onto wing mounts and locations. I started with basic mounts below the wing, then also used radiused fillets, which both reduced drag and increased downforce. I ended with reverse swan necks, which oddly increases drag, but also increased downforce a fair amount.
All of this testing was with a 71” Wing-Logic MSHD. I then tested endplate shapes, sizes, vents, etc., then set the wing aside so that I could do wing comparisons.
I swapped to a 64” version of the MSHD, so I could test it versus a 64” 9 Lives original wing. I tested both as single wings and dual wings, and the MSHD made more downforce, which resulted in higher efficiency for all angles and arrangements.
I’ll do a full write up on the MSHD performance soon, but to sum it up, it outperformed every other aluminum wing I’ve ever tested.
We then switched to Andrew’s CRZ, which put down some of the best numbers I’ve seen, with over 1.6 L/D ratio. This is pretty astonishing since he doesn’t have a splitter (but does have an undertray), and that he borrowed a wing which we riveted on just before the test.
He did some tests on canards, open/closed windows, and a wing sweep. All of this should be quite useful when he gets his new wing, which is of course different, but should give at least some point of reference.
All told I did 31 runs on my Veloster, and 8 on the CRZ, which brings me up to about 70 runs just on hatchbacks, over my various tests. I really should write a book on hatchback aero at some point.
And then I was off to VIR for what was supposed to be a couple days of instructing and driving.
A day at VIR
I was supposed to instruct for two days VIR, but we had more instructors than students and so I had nobody to teach. Which was fine for me, since this was my first time at VIR.
The first session was spoiled by my helmet being soaking wet because the Veloster A/C vent gets clogged easily, and then dumps water into the passenger footwell. I forgot about that, which is where my helmet and DE gear was.
But it was hot at VIR and my gear dried out quickly. I made the second session, which was a “how does Assetto Corsa match up with real life” experience, and it went well enough, except for the number of cars passing me. Everyone was on better tires and had more power, which made me the rolling chicane in the advanced group.
By the next session it was 130 degrees on the asphalt. My “cold” tire temps measured 117 with my pyrometer. I started to pick up the rhythm, but I was slowing too much for South Bend, T14, and Hog Pen.
I did one final session at the end of the days and managed a 2:20. I’m not particularly proud of that, it should have been a 2:14-15 based on the fact that VIR is a couple seconds faster than WGI.
Anyway, it was hot, three sessions wasn’t really enough for me to feel comfortable, my RS4s were toast, and whatever other excuses I can manage. The straights are too long for my tastes, but wow, it’s a fun track. VIR is every bit as good as people say it is.
Interlude: Pete’s 944
Getting back to the “no plan survives contact with the enemy” theme, let’s talk about Pete Mink’s Porsche 944 endurance racer. In this case the enemy was his neighbor’s son, who broke into Pete’s garage, stole his racecar, and took it for a joyride! I give the kid props for figuring out the kill switch, but teenagers these days don’t know how to use a manual transmission, so he money-shifted it, locked it up, and crashed into a ditch.
I found out about this midday Tuesday, while I was at VIR. Pete’s truck broke later that same day, and so he was well and truly fucked with no car, no truck, and much to do before the wind tunnel test on Thursday. Talk about kicking a man when he’s down.
So I did what any fellow racer would do and sacrificed a day at the track to help a brother in need. I left VIR at 6am the next morning, drove to Asheville, spent all day with Pete, and got back to my hotel in Mooresville some 14 hours later. A long day surely, but we got the aero installed, fetched his fixed truck, pushed the 944 into the trailer, and called it a day.
We didn’t get all of the aero transferred over to Pete’s backup car. The front was trashed, and so all the runs were done with no splitter or undertray. The backup car also didn’t have a transmission, so we had to push it in and out of the trailer, and so it was good that Pete is an ex-strongman competitor. He literally used to put on a harness and pull a semi truck from a standstill. This came in handy.
Back to the tunnel
Day two in the tunnel was hectic, with three cars to test. AJ Hartman went first because Raul and Pete were still in transit, but we had planned for that. His customer’s C7 put down some impressive numbers with the 14” chord wing and well developed splitter.
Then it was Pete’s turn, and we did a wing sweep with the new 9 Lives Evo wing. Since his car has no front aero, the balance is way off, but now Pete knows where to set the wing before it stalls.
We also made some DIY canards, using some of the knowledge from my Veloster testing. These worked really well, with almost no loss of rear downforce, and really good gains on the front. The surprising part was an efficiency of nearly 5:1, which you don’t generally see from canards.
Raul was next, and we did some of the coolest stuff on his car. Wing sweep and wing swap (PCI, 9LR, APR GTC200, Wing-Logic MSHD). We even did the 250 sq-in spoiler vs wing (swan neck this time) test for GLTC free points.
Raul got some great results out of splitter test, with both splitter angle and tunnels being evaluated.
I will say, the fastback shape of the BRZ makes it tricky to get the aero balance correct. The sleek shape means the rear has a ton of lift with no rear aero, but also makes a lot of downforce with a wing. And so the front/rear balance shifts more on this car than any other car I’ve seen.
You can’t just throw parts on a car like this and know what you’re getting, you have to test it. The car on the first turn, with a splitter and wing, had 0% front aero load distribution, but by the end of the test, was hitting the right numbers.
After that it was load up all the gear again, and drive the 10 hours back home, with a stop at Phil’s house to drop off the 9 Lives dual element I borrowed. I was back at Phil’s a couple days later to pick up some skateboard ramps his son Andy made. They generously gave these to me, and so thank you wind tunnel community, lets keep growing and sharing.
Occam's Racer 