wing logic – Occam's Racer

Watkins Glen Test #1: Veloster N Spoiler and Wing

I plan on doing a few tests at Watkins Glen International this year, and this is the first of (I hope) several reports. WGI is 25 miles from my house, and I have a lot of opportunities for free track time with groups I instruct for (Chin, HoD, MT, NASA, PCA, SCDA). The Glen is convenient for testing, and the corner speeds are high, making it a good place to test aerodynamic downforce. But the straights are also quite long, and so drag matters a lot here.

However, as a testing venue, WGI is only so-so because it’s a popular track, and so there might be 40+ cars in your run group. It’s not just the traffic that’s the problem, but highly variable weather, and virtually no runoff. So it’s not uncommon to lose a session due to rain, fog, or because someone hits a wall. For this reason, I may need to use sector times and predicted laps in order to get good data.

But on April 13th we had decent weather and lots of space on track with Mass Tuning, and so I was able to test different things and get clean laps. But because I made aero changes each session, and was also playing taxi (guest rides), I wasn’t able to string together many hot laps, and so there are only three decent laps from each aero configuration.

Another reason for the lack of hot laps is it takes a full three laps to get my tires up to temperature. I start them at 27 front and 30 rear, and at the end of the session they are properly at 37 F and 36 R. But I lose a lot of time early in the session, braking and accelerating hard to get the temps up, while keeping corner speeds low. If I’m impatient and corner hard at less than 32 psi, the tires roll over and I cord the outer edge. I learned this the hard way last year, getting only about 1/3 of the life out of my tires.

In the future, I may start the tires at 30 psi, which should put the tires out of the danger zone after one lap. This would result in the front tires being 40-42 psi for most of the session, and while this won’t return the best lap times, I should be able to normalize the data better.

The long warm-up times are probably the result of not enough negative camber. In fact I never hear the tires working hard, they just make a low-frequency moaning sound, not the screeching howl I get out of my Miata on the same tires. The Veloster sits on lowering springs and has one set of camber bolts, and this maxes out the camber at -1.8 degrees. With offset bushings (or slotting) it’s possible to get -2.5 degrees, but any more than that and I risk blowing the OE struts. This is still a street car, and I’m not going to ruin it by turning it into a track car with coilovers, stiff sway bars, and solid bushings. Well, not yet anyway.

OE N wing 2:17.4

In the wind tunnel, the OE wing (or it could equally be called a spoiler) made 30.8 lbs of downforce at 100 mph. This cancelled out the rear lift on the base model hatchback, giving the car a slightly negative coefficient of lift. This is very rare in a street car. In my article Thinking in Aerodynamic Coefficients, I show that most cars have positive lift of around Cl 0.1-0.2. Cars that have zero lift or even some downforce are rare, and usually an exotic sportscar. But the Veloster N is one of those unicorns that has downforce straight from the factory.

The OE wing does a good job of stabilizing the rear of the car, and I felt none of the rear instability issues I felt when testing the car with the base model roof extension (meaning no wing). That was a test I ran at NYST, and the rear lift made the car twitchy under braking going into T1 and T5. But at WGI where I was 30 mph faster, the N wing felt stable under braking, and so the OE wing is definitely an improvement on the base model’s featureless roof extension.

The N wing also had the least drag, and posted the fastest top speed of 132 mph on the back straight. But the OEM wing also had the least downforce, and you can see this on the speed trace below, where I compare the OEM wing (red) to the same wing with a Gurney flap (blue). Note the difference in speed through the esses, it’s huge. But also note the vMins in each corner that I’ve circled. Not only are the vMins higher, they are shifted to the left, indicating that I’m backing up the corner better when the car has more rear downforce.

Red is OEM wing; Blue is the same wing with a Gurney flap.

Wicker kicker 2:16.4

I put a 1” tall Gurney flap (wicker) on the trailing edge of the N wing, and in the wind tunnel this made 114.7 lbs of rear downforce and 8.9 lbs of front downforce. The fact that this made front downforce means the wing is behaving more like a spoiler than a wing, and the combined 123.6 lbs of downforce is a lot more than I would have thought from adding a simple Gurney flap. When I add a Gurney flap to a wing I usually get 150-170% more downforce, not over 400% more! With an increase in downforce, there’s more drag, and 8.3 hp is lost at 100 mph.

But the extra grip through the esses is worth it, and by the time I get on the brakes for the bus stop, the max speeds are identical with or without the wicker. Around the rest of the lap, the modified OE wing has more grip, and the lap times are 1.1 seconds faster, lap after lap.

I uploaded a video of three consecutive laps, and I apologize in advance for the shitty audio. I use an original SmartyCam with an internal mic, and I can’t figure out how to make it less terrible. Anyway, I do a brace of identical 2:17.031 laps (down to the thousandth of a second!), on either side of a 2:16.415.

Three laps, turn the audio off.

S1223 54×11 wing 2:16.8

In the wind tunnel, my DIY Selig S1223 wing made 179.5 lbs of rear downforce at 100 mph, and 31.6 lbs of front lift. Wings are located higher and further rearward than spoilers, and so it’s normal for wings to lift the front end through leverage. As a practical matter, this is why people typically use a splitter and a wing together, but a spoiler can often be combined with a simple airdam, or just used on its own.

The wing’s total downforce of 147.9 lbs, divided by 45.3 lbs of drag force, returns a 3.27:1 L/D ratio, which is about the same as the OE wing, but not as good as with the Gurney flap. The drag amounts to 12 hp at 100 mph, and on the back straight of Watkins Glen, the wing is 2 mph slower than the other options.

One of the reasons the wing isn’t very efficient is because it has a span of only 54”. This is problematic for two reasons: first, wing-tip vortices have a detrimental effect on the wing’s overall performance, and so the greater the aspect ratio, the better the wing performs; second, most of the wing is in the silhouette of the hatchback roofline, and so very little of the wing is in clean air.

The reason the wing is 54” is because I wanted a cheap way to test a dual element wing, and bought a $35 extruded wing as the upper wing. The dual wing worked well at Pineview Run and NYST, setting the fastest laps (.8 seconds and 1.0 seconds faster than the single wing, respectively). But after seeing the initial results from the single wing at Watkins Glen, I didn’t even bother attaching the upper wing, as I’m sure the dual wing would have been the slowest.

Single wing has rather tall end plates, as they are used to hold a second wing element. I didn’t try the dual wing option at WGI.

Under most racing rules, wings are allowed to be body width, which in the case of the Veloster N would be 71.7”. I tested a 70” Wing Logic wing in the wind tunnel, and it made the same amount of total downforce as my 54” DIY wing, but with 44% of the drag. The resulting 7.4:1 L/D ratio shows how important it is to get the wing tips as far apart from each other as possible, into clean air, and away from the hatchback roofline. I may test this on track in the future.

Conclusions

Based on testing the single wing at Pineview Run (.7 seconds faster) and NYST (1.5 seconds), I felt for sure the S1223 single element wing was going to be worth 3 seconds at WGI. The fact that it was only worth about 1 second has me tail spinning into the D-K pit of despair. Let me think about why that may be….

One reason for the lack of performance may be the aero balance. As mentioned, the wing adds rear downforce with a lot of leverage, and so it was the only one that lifted the front. The result is the car may have too much rear aero bias, and not enough grip for turning in. Perhaps when I put a splitter on the car, I’ll see better results.

But note also that the aero balance was even worse at NYST and Pineview. The fastest rear aero on those tracks was the double wing, which I didn’t measure in the wind tunnel, but certainly has the most downforce and drag.

Another reason the wing underperformed could be the driver underperformed. I don’t believe I was cornering hard enough, and just barely edging into the performance envelope where aero is adding to what the tires alone can give. With more laps and coaching, we may see the driver perform better, and with that, the results may change.

Of course drag is a factor at Watkins Glen, and the 54” wing had the most drag. If I swapped to a 70” Wing Logic wing, I’d gain the equivalent of 6.7 hp (at 100 mph).

But as it sits now for both car and driver, the easiest and cheapest way to go faster in a Veloster N is to put a 1” Gurney flap on the OE wing. The performance of this modification was one of the biggest surprises in the wind tunnel, and it’s nice to see that reflected in real life, as well.

Three hot laps from each configuration went like this:

Config	Best lap	Average	Predicted
OEM wing	2:17.434	2:17.91	2:16.841
OE + wicker	2:16.415	2:16.83	2:15.783
54″ wing	2:16.795	2:17.02	2:16.284

While I have some work to do to get faster, I’m a consistent driver. Watkins Glen is a long 3.38 miles, but my lap times are usually within a couple-three tenths of the previous lap. That’s around a 0.3% difference, and probably similar to the noise you’d see in other variables that change throughout the day, such as air and track temperature, wind speed and direction, etc.

<brag>On a track that I have more laps on, like Pineview Run, I’m a metronome. Here’s six laps in a row with 0.372 seconds between all of them. If you throw out the fastest and slowest, I do four laps separated by 0.076 seconds.</brag>

I mention this not just so that I can thump my chest, but to throw some validity on track testing aero components. There are a lot of variables that change throughout the day, or even within a single track session. As those tolerances stack up, lap times can vary a lot. However, my driving is probably less of a factor than you might think, and I just want to point that out so I can deflect some of the “you’re driving like shit” comments. (Which are true, but at least I’m consistently driving like shit.)

Future tests

For Watkins Glen to be useful as an aero testing venue, I’ll need to fix my attitude, and turn my frown upside down. I’ve never gotten along well with this track, and I have to get to the point where I enjoy driving here. With some help from Gregg Vandivert (Omega 13 Coaching) and many more visits to the track, perhaps I can flip this script.

[sigh emoji] I hesitate to list the tests I want to do in the future, because the best laid plans of mice and men usually amount to the same dung heap of disappointment. But if things go as planned, I’ll test the following:

Driver mod – I’m curious to see how much time I can lose from professional coaching alone. In order to A/B test myself, I’ll need to use the same baseline setup and pray for days with similar weather.
Splitter – I didn’t use a splitter in any of these tests because I was matching the same setup I already tested at Pineview and NYST. But now that I’ve done those tests, I can put a splitter back on my car and see how this compares to the wind tunnel, and how getting more front aero load helps the overall balance. Naturally I’ll need to test the splitter at various heights and angles of attack, and so this could be a whole day of testing on its own.
Canards – I tested canards in the wind tunnel on two different occasions, and now it’s time to take the best results and see how they do in the real world.
OE wing modifications – The 1” wicker worked great on the OE wing, but I’ve only tried the one size. Next I should try 1/2” and 1.5” tall, and see what happens. Also, I believe that getting the OE wing a little higher may increase performance, and with that, I could also add some angle of attack. This should be as simple as installing a few shims beneath the wing.
Ducktail spoiler – I tested a DIY spoiler at Pineview and the results were similar to the single wing. But WGI has already proven to be quite different than other tracks, and so I should test this one.
Bigger wings – The wind tunnel already showed me how important wing span is, and so a 71.7” wing will be a lot more efficient. I’m building a big wing now, and shall test this for sure.
Active aero – I wrote an article on active aero, in which I did racing simulations at Watkins Glen. Now it’s time to put my money where my mouth is and do the same experiments in real life. The easiest active aero to fabricate would be a DRS spoiler, so I may start with that rather than jumping straight to a dual wing.
Diffuser – I tested a diffuser in the wind tunnel and it was pretty lousy, losing about as much front downforce as it made in the rear. But the A2 wind tunnel doesn’t have rollers for the wheels and so the effect of the underbody can’t be 100% trusted. So I should probably test the diffuser IRL and shoot myself up with another dose of disappointment.

vMins and driver performance

If you saw my previous post on vMins, you may wonder how well I performed on the vMin table. I put the OE wing on the Street table, and the modified wings on the Track side.

The red circles indicate my vMins with the OE wing, and you can see that I’m OK, but not great. My T7 may be a bit high, or more likely, all of my vMins can come closer to that level. However, when I add rear aero, I park it in the bus stop! I’m probably using the same braking marker, and then just over-slowing the car with the extra downforce and drag. I expected my vMins to be a lot worse than this, so I’m pleasantly surprised that I’m not driving like shit. And at least I know what to work on next time.

Gran Turismo nerds

I prepared for my Watkins Glen weekend by doing some laps in Gran Turismo 7. GT7 doesn’t have a Hyundai Veloster N in the game, so I’ve been using a Scirocco R. Now that I have data to refer to, I can modify the car to be as close as possible to the real world.

In the game I set the car weight to 3000 lbs and the horsepower to 244 (buy the lightweight modifier and add ballast weight and a power restrictor). This approximates the dry weight of my car (I have lighter wheels and the rear seats removed) and what my car puts out on the dyno (my engine is bone stock, not even a cold air intake). More importantly, this also gives me a realistic speed of 132 mph on the back straight. (I’m sure you could use a heavier car with more power, but this is just what I landed on.)

I also fitted the non-adjustable Sport suspension because I have lowering springs, and added the Sport brake pads (which do nothing in the game, but I’m trying to match the car IRL). I added a rear wing so that I can adjust the rear downforce from low (OE N spoiler) to high (single wing). GT7 doesn’t simulate aero accurately anyway, but I added no other downforce because I’m not using any. I use Comfort Soft tires, which puts the corner speeds in the right window for Hankook RS4s with painfully not enough negative camber.

If you have GT7, make a Scirocco R like this and play along. The PP value should be 492 with the wing maxed out. You can drop a comment here or contact me if you want to compare notes.

With the Scirocco R set up like this, I can click off low 2:14 laps regularly, and get the occasional 2:13 at WGI. That’s 3 seconds faster than I’m doing in the real world, which seems about right seeing as I can drive much harder in the game than IRL. As I get better in the real world, I expect the lap times to get closer to GT7. We shall see.

If you made it this far, thanks! If you’d like to support more content like this, hit the Buy Me a Coffee link. If you’d like the Veloster Wind Tunnel Report, it’s just $25 and goes through a ton of stuff you can do to make your car faster.

Wing Logic Dual Element

In the previous article, I mounted a Wing Logic wing to Steve Leo’s WRX. He’s been pretty happy with it, but I’ve been wondering about adding more rear downforce. An excess of rear downforce can make a car boring to drive, but it also improves braking, high-speed stability, and requires fewer corrections when you lose control. So while more rear downforce might ruin the aerodynamic balance, if the driver goes 2 seconds faster, let’s call that a better car.

If you want more downforce from a Wing Logic wing, you can increase the size of the Gurney flap by duct-taping down a piece of angle aluminum butted up against the built-in 1/4” Gurney flap. And with the larger wicker, you can add a little more wing angle. But you’ll soon hit a point of diminishing returns, and shortly after that, the wing will stall out. I haven’t run a full sweep on this wing, but I’ll guesstimate that a Gurney flap 1″ tall (very draggy) and an angle of attack around 11-12 degrees is the limit.

If you still need more downforce, the easiest way to do that is add a second element above the main wing, set somewhere between 25-35 degrees angle of attack (in relation to the main wing). Unlike the single wing, the double wing won’t stall because of the slot between the wings; Air shoots through the gap at great speed and this keeps air attached to the underside of the upper wing. Thus you can run more angle on the upper wing, which effectively increases both the chord and camber of the entire wing, without flow separation.

If you have a 9 Lives Racing wing, they can sell you a dual element wing for around $440 (with shipping). The kit includes the upper wing, plus adjustment brackets that go inside the standard end plate, plus little brackets that go in the Gurney flap slot. It’s a clever arrangement that’s easy to install and remove. I tested the double wing in a wind tunnel, and came away really impressed with how well it worked.

If you have a Wing Logic wing and you want a dual element, you’re shit out of luck. There isn’t a similar kit available, and I have yet to see anyone cobble something together. I wonder if the reason for that is because some people believe (incorrectly) that you can’t put a dual-element wing on top of a wing that has a Gurney flap? There was a recent discussion of this on the Professional Awesome Facebook group, and it seemed like most of the people said you should cut off the Gurney flap, or a dual wing won’t work with a Gurney flap on the lower wing, or that Gurney flaps only work on the top wing. That’s horseshit.

You can absolutely put a Gurney flap on the lower wing. Two research papers (James C Moss , and later F.M. Catalano and G. L. Brand) concluded that adding a Gurney flap to the main (bottom) element of a dual-element wing added downforce and improved L/D ratio. By fiddling with the Gurney flap height, overlap, and gap, they increased lift by 12% and increased L/D ratio by 40%.

But before you go adding a Gurney flap to your double wing, you should know that the authors only got those results after tons of experimentation. The height of the Gurney flap, the distance (gap) between the wings, and the overlap between the wings all need to be set correctly to get the most out of it. Knowing all of this, if you’re going to put an upper element on a Wing Logic wing (or any wing with a Gurney flap), you’ll need to be able to adjust the upper wing’s X-Y-Z coordinates for angle, gap, and overlap.

If this is all too much work for you, go and buy a 9 Lives Racing Big Wang and add The Deuce double element kit. It’s already set up with the right overlap and gap, and is simple to adjust for angle. The performance is excellent, and you will not be disappointed. Tell Johnny I said hi.

But if you’re a DIY-or-die kind of person (ahem, guilty), or you have more time than money, then maybe putting together your own dual wing how you want to spend a day. If that’s the case, read on and I’ll walk you through how I made a dual element for a Wing Logic.

Assembling the upper wing

I make wings rather than buy them, mostly so that I can experiment with different shaped airfoils and construction methods. My S1223 is a torsion box, and my MSHD is a foam core with fiberglass. But neither of those construction methods works great for a wing with a much smaller chord and less thickness. So rather than build one from scratch, I bought a couple cheap extruded aluminum wings on Amazon for $35 each. You can sometimes find them cheaper, and my friend Bill Fischer of Garage Heroes in Training once bought one of these wings and got a box of 10 for the same price.

Cheap extruded wing from Amazon, eBay, etc.

I’m not exactly sure what the airfoil is, but it looks a bit like a Wortmann FX 72-MS-150A. With a cL of 1.8, this is decent, but not what I’d call an ultra-high lift wing. According to my Car Wing Comparisons article, the airfoil outperforms the NASCAR used for in their Car of Tomorrow for a hot second.

Airfoil Tools is a great place to research wings.

These cheap extruded aluminum wings are strong and light. They have two internal semi-circular spars that run the length of the wing, and provide a lot of stiffness. These supports are also tapped with M8 threads and do double duty fastening the end plates. While I might wish for a different shaped airfoil, the entire design is lightweight, sturdy, and inexpensive.

The wing has a 4.7” chord, which is larger than the upper element 9 Lives Racing uses. A rule of thumb is that the upper element should be about 30-40% the chord of the total wing (combined chord of main and second element), and this second element comes in at 32% of the combined 14.7”, and that’s right in the ballpark.

The longest of these cheapo wings I’ve found is 135cm (53.3”), and so if you want a bigger wing than that, you’re going to have to figure out a way to join them together. Welding is the obvious solution, but I didn’t want to rely on skin strength alone, I wanted to add an internal support as well.

I cut threads into one of the wing holes and installed a M8 stud, bottoming it out on the threads. Then I tapped the same hole on the other wing. I sandwiched a little bracket between them, which will be used to hold up the center of the wing, and then twisted them upon each other, essentially threading the two wings together.

I took the wing to a local fabrication shop and they charged me their hourly minimum of $80 to weld it up. So that’s $150 for the upper wing, all in. I’m sure the welding could be done cheaper, especially if I was doing several wings at the same time.

Welded all the way around, and pivoting on the center support.

Double wing end plates

To mount the upper wing to the lower, I’d need to make new larger end plates that hold the ends of the upper wing. The top wing also needs to be able to adjust for angle, gap, and overlap, and because it fits inside the end plate, it’s kind of an end plate within an end plate situation. I made the inner plates from 9mm plywood because I needed to countersink the 8mm hardware into the ends. If I used 12 gauge aluminum, the bolt heads would stick up proud and keep the wing from changing angle.

Maximum angle for a second element is typically around 40 degrees, measured from the bottom element. But at this angle, the upper wing risks flow separation. A safer bet is to set the upper wing to 35 degrees, which should provide nearly the same downforce as the maximum angle of attack. I traced all this out on the end plate (a No Parking street sign, per my usual $1-per-pound source at the metal recycler).

I always lay out the chord line parallel to the upper edge of the end plate, this makes it easy to set the angle of the wing. I’m also mocking up the position of the upper wing.

I first made the maximum downforce 35-degree setting, and to this I added a low-drag setting of 25 degrees. I don’t see needing any more adjustment than that, because I can always rake the entire wing to adjust between the high- and low-downforce settings. If I want less downforce, I’ll just remove the upper wing and run it as a single. From there I can tune wing angle and Gurney flap height as I would any other single element wing.

Upper wing pivots inside of end plate. You can see the forward hole, which increases overlap and gap. The gaps are larger than you’d have normally, because of the Gurney flap.

The completed double wing weighs 22.8 lbs total, and so the upper wing added only 6.2 lbs, including all of the things required to mount it. That’s pretty light, and it feels quite sturdy. Eventually I’ll lighten the main wing by milling out slots and wrapping it with carbon fiber. But more on that DIY project when I’ve liberated the wing from Steve.

Data?

This section is supposed to be filled with A/B testing data, including vital details about the ideal gap height for a dual-element wing that has a 1/4” Gurney flap on the bottom wing…. but instead it’s filled with a pissy rant.

Steve and I had a full test day planned, which involved him setting a few laps and then coming into the hot pits, where I could quickly change the main and upper wing angle, gap height, and swap between single vs dual wing. But despite an entire day at Watkins Glen, we got shit all of nothing. The problem is the same as the first time I did aero testing… Watkins Glen.

The weather is always variable, and the first session was wet and made data irrelevant. In the second session, a McLaren (620R?) dumped it’s coolant and oil on the first lap. This sent four cars into the T11 wall, and the cleanup crew onto the track for a lengthy stint. In the third session, again on the first flying lap, a Corvette stacked itself in Turn 2, requiring a full session of cleanup. And in the fourth and final run of the day, a BMW M2CS decided to get some new baby-blue racing stripes in T10. In the end, I don’t think the Advanced/Instructors run group got more than 15 minutes of track time the whole day.

Now this is the same run group I would have been in if I chose to drive that day. The two people I was with (Steve and Gregg) were the first two cars through the oil. Steve was going slowly because the McLaren directly in front was misting oil on his windshield. Gregg went through at speed and saved it like a hero. But he has a ton of experience at WGI and has proven many times over that he can save a spin.

Gregg saves it and avoids the wall. The next four cars don’t.

Well, if I was out there, I would have certainly been passing both of them in the session, which would have made me the first car through the oil. Dodged a bullet right there, I did! (I’m kidding about passing them; I drive like a grandma on this track.)

And this is why I seldom drive Watkins Glen, even for free. There are so many other tracks that have runoff, sand traps, and slower speeds, and are much safer as a result. Where I find enjoyment is pushing the car to the limit, and I’m not going to do that here, it just doesn’t make sense, financial or otherwise. My understanding is that some track day insurance companies will no longer cover cars at Watkins Glen, and I can’t blame them for that.

But I also understand that many of you like the combination of high speed and steel walls; you feel it gives you focus or commitment or whatever. Good for you. But the reason i have no data or wing gap information is because someone else also felt that way, and lost their focus or commitment or whatever.

Mounting a Wing Logic wing on a Subaru WRX STi

Wing Logic makes a satisfactory wing at a great price. It doesn’t come set up for any particular car, and so you will need to do some DIY fabrication. You’ll have to figure out things like how to mount the wing securely in the correct location, and then you’ll need to drill the bottom mounts for a range of useful angles, and then weld the bottom mounts to the wing.

It takes some patience and know-how to figure it all out, and if I’m being honest, 90% of people will cock it up and do a sub-optimal job, losing some of the wing’s performance in the process. If you buy a ready-made kit from 9 Lives Racing, AJ Hartman Aero, and other reputable companies, you’ll get an easier install and better performance straight out of the box.

But if you know what you’re doing, a DIY wing like Wing Logic or 9 Lives Racing’s new Express kits, can save you some money. Or if you have a car that doesn’t have a ready-made kit available, then a DIY solution is the only game in town.

I tested a Wing Logic wing in the wind tunnel vs the industry standard 9 Lives Racing Big Wang (Wing Logic versus 9 Lives Racing), and found the performance was similar. Wing Logic’s wing has less camber, and so it makes less downforce for a given area, but it’s a physically larger wing (9.2” vs 10”), and so the performance ends up being quite close. 9 Lives has the edge in weight and performance, and so if you’re racing in a series that limits the total wing area (GLTC, SCCA TT Nats, etc), or if you care about two pounds (high up, at the polar end of the car), then 9 Lives is a better choice. For the track rat or hard-park poseur, it’s a wash. I have plans to radically lighten the wing by milling it out into a skeleton, and then wrapping with carbon fiber, but that experiment will have to wait until the end of the track season, because I no longer have it.

Steve Leo is making a foam composite dual element, and while that process takes place (for fucking forever) I loaned him my 65” Wing Logic for his Subaru WRX STi. He didn’t have any wing mounts for it, but he had a spare trunk, and I said bring it over and I’ll figure something out.

Because I had already tested this wing on a Miata, the wing has brackets welded 41” apart. Ergo, I’d need to put the same spacing on the Subaru trunk. As luck would have it, that put the wing mounts right on top of the hinges, which is a sturdy area with some extra thickness and support in the metal frame. Also as luck would have it, the hardware would now be in the way, and I’d have to work out how to allow the trunk to close.

But first things first, to place the wings on the surface of the trunk, such that the wing is braced against side to side movement. I went to the Lowe’s racing department and bought a couple feet of 1” angle aluminum. I cut this into four pieces to make brackets, and sandwiched the Miata wing stands between them.

But I couldn’t put bolts through the top of the trunk and nuts on the bottom, as the nuts would be in the trunk gutter – this would cause interference and keep the trunk from closing. So I installed the hardware upside down, with countersunk 6mm bolts going through the underside and nylock nuts on top. It’s maybe a little less attractive, but this was the only way I got it to work.

Countersunk bolts of differing lengths install from the bottom.

It took a bit of head scratching, but I figured out how to install all 12 bolts from underneath. It took bolts of different lengths, which I’ve noted in the previous images in case you want to give it a go. It all came out surprisingly sturdy, and probably more rigid than you’d see on most cars. You can grab the wing and shake the car side to side, and the wing mounts don’t move.

Angle aluminum brackets on the trunk hold the wing stands in place. It’s very rigid.

The only thing I wasn’t terribly happy with is that the wing is too far forward. The rule of thumb is to overlap the trunk by 1/4 of the chord. So on this 10” wing, 2.5” should overlap the trunk, and 7.5” should be over the bumper.

How important is that? Well, I tested a Civic coupe in the wind tunnel, and moving the wing from on top of the trunk to the ideal rearward position resulted in less drag and more downforce. Usually you get one at the expense of the other, but this was a win-win. I would have liked to do that for Steve, but I didn’t have any more aluminum stock to make another set of wing stands, and he needed this done ASAP.

We got super lucky with the setback distance, any closer and the wing would hit the roof when the trunk was fully opened. I’ll take that as a win and optimize the wing stands at some later date.

By a stroke of luck, the trunk can open fully and the wing doesn’t hit anything.

Data?

Steve reports that the wing is working really well, but through some bad luck, we have had the devil of a time getting comparative A/B data. He’s used the wing at Watkins Glen, Lime Rock, NYST, and Pineview Run, and while we have data from those events, it’s not the kind of back-to-back data that tells a compelling story.

By the seat of the pants, the Wing Logic setup works better than the VSC rally wing he had on there previously. But the Wing Logic single wing doesn’t work quite as well as the Wing Logic dual element he tried this week. Wait, what?! Dual-fucking-element Wing Logic? You can read about that in the next post.

Wing Logic vs 9 Lives Racing

The availability of inexpensive extruded aluminum wings has changed motorsports. Ten years ago it was rare to see a wing on a budget endurance racer or HPDE car. Now they are everywhere. A lot of the credit (blame?) goes to Johnny Cichowski of 9 Lives Racing, who sells an inexpensive extruded aluminum wing that sets the standard for the industry.

When you have a winning formula, people copy you. That’s the nature of business. That’s also the nature of racing. And so it’s no surprise that someone else has created a similar product.

This new extruded aluminum wing comes from Michael Jui of Wing Logic. He got wind that I was going to a wind tunnel, and asked if I would test his product. Of course I said yes, because I want that data, and I think the racing community as a whole would like that as well. So let’s take a look at this new wing in as much detail as I can, and compare it to the 9 Lives Racing Big Wang.

Wing Logic’s chord measures about 9.8”, while the 9LR wing is 9.2” across the top. So, the Big Wang is actually the smaller wing.

The wingspans are slightly different, as Wing Logic’s comes in standard lengths of 60″, 65”, 70″ and 72″. 9 Lives makes their wings to fit certain models, but you can also order a custom length. This is important because most racing rules limit wings to body width, and so if you have a Miata, you need to trim an inch off the 65″ Wing Logic, and re-tap the holes on one side. I didn’t do that for this test, so Wing Logic has a slight advantage, with 1″ more wingspan.

The construction of the wings are pretty similar, but Wing Logic has some extra internal thickness in a couple places, and while 9 Lives uses 5mm hardware for the end plates, Wing Logic uses 6mm. The Wing Logic end plates are 3mm, which is thicker than I’ve seen anywhere. All of this adds up to a wing that is sturdier, but heavier. A 65” Wing Logic fully set up with end plates and welded bottom mounts weighed 16.6 lbs. A 9 Lives 64” wing dressed the same weighed 14.6 lbs.

The shape of the wings are similar, but not the same. Anyone who says Wing Logic copied the 9 Lives Racing shape is simply wrong. As near as I can tell, Wing Logic is using a CH10 (Chuch Hollinger CH 10-48-13), which is a low Reynolds high-lift aviation airfoil, while the 9 Lives Racing wing was designed as a motorsports wing from the start.

If you measured Wing Logic in Benzing coordinates it’s a Be 133-105, while 9 Lives measures Be 123-125. That means the position of maximum thickness and maximum camber are the same in both wings, and that’s why they look similar. But Wing Logic’s is thicker and 9 Lives has more camber.

If you want to dive deep on that topic, I wrote an article on Car Wing Comparisons. Of all the wings I investigated, the most efficient was the CH10. But that is based on free stream efficiency, which means that the wing is not on a car, but just suspended in the air.

Cars are large and aerodynamically inefficient compared to wings, and when you put a wing on a car, the drag doesn’t go up that much, but the downforce does. So you usually get the best vehicle efficiency by choosing a wing that has the most downforce, not by choosing a wing for its efficiency or low drag.

Enough preamble, how do the wings compare in the wind tunnel?

Wind tunnel testing

I use the A2 wind tunnel, because for people like me, it’s the only game in town. I’ve tried to get into other wind tunnels, and either I’m not allowed, or it’s prohibitively expensive. The Aerodyne wind tunnel next door has a rolling floor, and I’d like to try it, even if it’s 4x the cost. But the rollers are designed for NASCAR, so unless I bring a car with a 109″ ish wheelbase (Miatas are 90″), I’m shit out of luck.

A2 doesn’t have a rolling floor, and so the effect of the tires rolling on the ground can’t be measured. This is significant for underbody testing, but you can measure things on the front of the car and over the body with acceptable accuracy.

There’s a lot of online conjecture by people who have never been to A2, that the small size of the wind tunnel, and the proximity of the walls, contributes highly to a blockage rate (or ratio?) that makes this wind tunnel results inaccurate. However, the walls in the tunnel are designed to reduce the blockage, by being curved rather than flat. And I’m also not after 100% accuracy, I’m looking for deltas – the difference between this or that. Did this wing have more or less drag than the previous wing? Did it produce more or less downforce? These things can be measured with accuracy at A2.

For the wind tunnel testing, I wanted to to use a car that already had CFD done on it, so I borrowed Phil Sproger’s car. His NA Miata has a 9 Lives Racing medium aero kit, and we set the ride height so that it would be as close as possible to the specifications that Morlind Engineering used when they ran CFD for 9 Lives Racing. (AJ Hartman and I did 42 runs on this car, baselining the car vs CFD, and then testing wings, spoilers, fastbacks, and many other ideas for drag and downforce. You’ll be able to read about that in a future report.)

We tested a 65″ Wing Logic back to back with a 64″ Nine Lives. Wing Logic has a built-in 1/4″ Gurney flap, and 9 Lives Racing has a slot for Gurney flaps of various heights, and we used a 1/2” Gurney. But because the slot is slightly recessed, this is more like 3/8”. So while one wing was slightly larger, the other had a slightly taller wicker, and it should be a fair fight.

Wing Logic – notice the smaller end plates.

I also threw in a strange DIY wing I made to see how it compares. It measures 41″x16″, and looks like an old-school F1 wing. The low-aspect ratio would not work in its favor, however the extra chord should make the wing slightly more efficient by having a higher Reynolds number.

Let’s see how they measured up at 100 mph, using the following fields:

Front downforce – This is a negative number, which you can think of as lift. When you add rear downforce (or drag), it lifts the front of the car through leverage, like a see-saw.
Rear downforce – This is the wing’s job, and varies with wing angle, Gurney flap height, and many other variables.
Total downforce – Front lift and rear downforce combined.
Drag – The number of pounds of drag the wing adds. This is a pretty meaningless number on its own, but is used to calculate the L/D ratio.
HP – An easier way of thinking about drag is how much horsepower it consumes.
L/D ratio – This is also known as aerodynamic efficiency, and is usually a good way of determining which part is better on the car. Note that the numbers in this table are not the bullshit free-stream efficiency you see in CFD, but the actual returned efficiency as run on the car.

Three wings compared at zero and 5 degrees.

As you can see from the data, at zero degrees angle of attack, Wing Logic, 9 Lives Racing, and my DIY wing are all better than a 10:1 L/D ratio. At this setting, the Big Wang makes the most downforce, and is thus the most efficient by about 5%.

When I set the wings to 5 degrees, Wing Logic and 9 Lives are identical in terms of aero efficiency. The Big Wang makes slightly more downforce, but the bigger wing makes less drag, and they are effectively the same at this setting. This is also about the maximum angle you can set, because air is coming down the roof at 5-7 degrees, and so if you use more angle than this, the center of the wing stalls, which adds drag and reduces downforce.

As a side note, my chunky DIY wing was similar to the other wings at zero degrees, by virtue of less drag. I should have tested it at the same 5 degrees as the others, because it was stalling at 7 degrees. It’s definitely the worst wing here, but not by a lot. On the plus side, it weighed on average 6 lbs less than the aluminum wings, and it cost me $30 in materials!

To get back to the actual contenders here, the two aluminum wings performed the same at 5 degrees AoA, but that isn’t the whole story, because the Big Wang is dimensionally the smallest. If you are racing in a class that limits total wing area (GLTC 500 square inch wings, for example), then the 9 Lives wing will give you about an 8% advantage over Wing Logic. It’s not a huge difference, but in a rule set that limits wing area , I’d take the Big Wang.

The full results of the wind tunnel testing are in my Miata Wind Tunnel Report, where I go into not only wings, but different tops, front end options (canards, hood and fender vents, splitter adornments, etc. You can purchase the report here by clicking the button, and you’ll get a link where you can download it.

Purchase Miata Wind Tunnel Report

If you don’t want to invest in the wind tunnel report, but you want to support this kind of investigative content, Buy Me a Coffee. It takes 15 coffees ($5 each) to pay for one run in the wind tunnel. That doesn’t count the many hours of preparation, towing 11 hours each way, gas, hotel, and other expenses I accrue on the way. Your support makes it possible for me to do community-driven wind tunnel testing. Thanks!

CFD vs wind tunnel

Both 9 Lives Racing and Wing Logic publish CFD results of their wings, and I thought it would be illuminating to see how accurate those are compared to the A2 wind tunnel. Wing Logic use Kyle Forster to do their CFD, and he used a 70” wing on a Mustang rather than a 65” wing on a Miata, so it’s not a direct comparison. Kyle used the same CFD settings as he did for AJ’s wings, which have generally landed within about 3% on loads in the same tunnel with matching cars/positions etc, so A2 correlation should be OK for this data.

Note that the reference area for the Miata is 1.67 meters squared (18 square feet), while in the CFD, it’s set at 1 meter squared. Ergo, I need to multiply the CFD numbers by 1.67 so that they match the wind tunnel data. When I do that, you can see, the wind tunnel returns similar downforce as the CFD, but drag is higher in the simulation.

Wing Logic wind tunnel (65″ Miata) vs CFD (70″ Mustang)

Is this a big problem? Not really. After testing the same wing on a Veloster N, an 8th Gen Civic coupe, a Miata, and a Supra, I can tell you that the shape of the car has a greater impact on a wing’s performance than any CFD error. On a hatchback, I’ve seen a 3.5:1 L/D and on a coupe up to 24.5:1. In the end, the main difference between CFD and wind tunnel results isn’t computer vs real world, it’s the shape of the car. A Miata ain’t a Mustang, and that’s likely where most of the differences lie between the Wing Logic CFD and wind tunnel data.

9 Lives Racing also publishes CFD using a 64″ wing on a Miata, and that’s exactly what we brought to the tunnel. So we can get an apples to apples comparison on this wing for shiz. But 9 Lives doesn’t publish coefficients, they only give us drag and downforce. Still, it’s enough to work from.

9 Lives Racing wind tunnel vs CFD at 100 mph.

Comparing the wind tunnel results to CFD, the computer predicted both less drag and less downforce than we got in the wind tunnel. The fact that the CFD was off by 33% in downforce points to some kind of problem with that model.

I base that on another nugget Kyle dropped on me which is that as a general rule of thumb, if CFD is off by <20% it could be correlation, <30% it’s setup differences, >30% something has gone wrong with the output numbers at some point or the CFD is extremely broken. So I’m not sure what’s going on with the 9 Lives / Morlind Engineering CFD, but it’s not matching real-world values very closely. When we tested the whole car (not just the wing), the drag was also off by a lot (as in .4 vs .6).

70″ Wing Logic, end plates, 3/4″ Gurney

I was also able to test a 70″ Wing Logic on my Hyundai Veloster N, which allowed me to compare the effect of wingspan on a hatchback. Last year I tested a 55″ Big Wang on my Veloster, and since Wing Logic and 9 Lives are pretty similar, I can get find out how much I was giving up with a shorter wingspan.

I also wanted to try 12″ square end plates to see if the smaller end plates were giving up some performance. And since Wing Logic has a built-in Gurney flap, I also wanted to see what would happen if I butted up a 3/4″ Gurney flap against that. (If you’re wondering what a 1/2″ Gurney would do, you can just average the numbers).

Comparing the 70″ Wing Logic to 55″ 9 Lives is absolutely not fair, so think of this only as a comparison of wingspan. The longer wing made 10 lbs less downforce (what in the actual fuck?), but had a lot less drag. The end result is a much better L/D ratio of 7.4:1 for the longer wing compared to about 3:1 for the shorter wing.

Now this is flatly absurd, because according to Kyle, an increase of 100mm span is worth about 7% load on the same car, so an increase in 15″ span (375 mm) should be an increase of 26% difference in load, not a decrease of almost 7%. I’m not sure what’s going on here, as the wing was in a similar position, and on the same car.

Changing the smaller end plates for 12″ square end plates added 7.2 lbs of downforce, but also used an additional 1.1 hp in drag. The change in parts returns a L/D ratio of 1.3:1, which means the smaller end plates would be faster anywhere but an autocross course.

Adding a 3/4″ Gurney flap added 48.1 lbs of downforce for 21.4 lbs of drag, which works out to a 2.25 L/D ratio. If you need more rear downforce, adding the larger wicker would be worthwhile on just about any track that isn’t a high speed oval.

Conclusions

Comparing the two wings, my main gripe is that Wing Logic’s wing is 2 pounds heavier than a 9 Lives wing of the same length. That’s not a lot of weight, but the location of the weight, high up and at the polar end of the car, isn’t helpful. As previously stated, in a racing class that limits the wing size to a certain amount of total area, 9 Lives has a slight advantage.

Those negatives aside, Wing Logic has a fine product that is well constructed and performs similarly to the Big Wang. At $349-399 with free shipping, Wing Logic’s wing is a downright bargain.