Miata Wind Tunnel Test Ideas

I wrote this post a while ago, and since then I made it back to the wind tunnel and tested a lot of things. Sadly, Falconet wasn’t ready for that trip, and so instead I took a Miata with the full 9 Lives Racing medium downforce kit. I was able to test everything that’s been modeled in CFD, and the entire 9LR catalog, as well as many other options, such as fastback, hood and fender vents, and various things to reduce drag and add downforce.

I’m going back to the A2 wind tunnel this summer and I’ll test a bunch of stuff on my Hayabusa-swapped Miata, Falconet. Wind tunnel testing is expensive, and it’s an 11-hour drive each way, so I need to be ultra prepared so that I’m not wasting time and money.

As part of that preparation, I want to know what other people are curious about. Do you have some parts to test? Send them to me and I’ll send them back when I’m done. Do you have some ideas you want to test, but can’t implement? Maybe I can cobble something together in time. Please drop me a comment at the bottom or use my contact form to email me, and I’ll do my best to test what’s important to the Miata community.

One of the benefits to wind tunnel testing is the parts don’t have to be race spec, they just need to survive a couple runs. So a lot of parts go on with the minimum number of fasteners and the maximum amount of duct tape. This allows me to do so a lot more fabricating and testing than would normally be possible.

Anyway, here are some things I’ll be testing.

Canards

I’ll be the first to admit I was wrong about canards, and so this is one area where I’ll be spending a lot of time money. Before I tested my Veloster N in the wind tunnel, I thought canards were poseur junk, but after finding out that changing the height by 8″ made a 700% increase in downforce, I realized I knew jack shit about canards.

I’ll test height to find out the optimal position on the lower canard. I’ll also test size, shape, angle, profile (blade vs airfoil), and end treatment (wicker sizes).

Splitter

On my Veloster I tested flat vs curved splitters and found massive gains (150% more downforce) using a splitter that curved upwards at the trailing edge. This is essentially that same thing as using splitter diffusers, but instead of diffusing air into the wheel wells, the air is diffused over the entire width of the car. So I’d like to test this vs a flat splitter with splitter diffusers.

I also added vortex strakes in front of the wheels and this reduced drag quite a bit, but because those strakes were only on one splitter, I didn’t do a proper A/B test. So I’ll test these again on the same diffuser to see how worthwhile that is.

I’ve seen some online conjecture on the drag from splitter rods, and it doesn’t make a lot of sense to me. I’ll double the number of splitter rods (they’ll be fake) and see what happens.

There’s already published data on splitter length, but I might test this if enough people are hungry for that data. Likewise splitter height has been tested and published (but not on a Miata). Just the same, it’s easy enough to put blocks under the tires and test changes to height and rake, and how that affects downforce and drag.

And I might get around to testing an airdam with an undertray and no splitter lip. I think I can get the undertray to make a lot of suction, even without a splitter lip. This test isn’t a high priority for me, because I’m not personally going to set up Falconet like this, but with enough community whining, this test could go higher up the list.

Underbody

When it comes to underbody aero on touring cars (especially Miatas), I’m a confirmed naysayer. But, just like it was with canards, I might find myself eating my own words after this test!

Some of the things I’ll be testing are a flat bottom, a partial flat bottom (trans tunnel exposed), barge boards, and at least one diffuser. Falconet uses a motorcycle transmission, and so that whole transmission tunnel is open. I’ll diffuse some air into that area and see what happens.

Vents

Al at Race Louvers has some of the best wind tunnel data on the web, and I see no reason to duplicate his efforts. But I have some ideas to get more extraction out of the wheel wells, and these haven’t been tested by him yet. I’ll also be testing a hood extractor vent, which is specific to Falconet, but the data may be interesting to others.

Wings

I’ve already tested and published wind tunnel data on five wings, four end plates, and Gurney flaps, but I have a few things still to test.

I have an oddball wing I made with a short 41″ wingspan with 16″ of chord. It seems absurd, but the additional chord was shown to be very efficient in previous testing, with a clear top-speed advantage. I want to try this as a single and dual element.

I’ll compare that wing to a Wing Logic, and that in turn to the industry standard 9 Lives Racing wing. Wing Logic appears to be a CH10, which has less camber and thickness than a Be 123-125 (which is about what the 9LR wing measures). If both wings were the same size and had the same Gurney flap, I’m fairly certain the 9LR would outperform Wing Logic. But this isn’t apples to apples, since the latter has more chord and a built-in Gurney flap. Anyway, interesting comparison.

I may also test my MSHD wing as a dual element. It’s designed as a 3D wing, but unlike many, the trailing edge is a single flat line across the span, and so I can add a second element pretty easily. And I kinda want to make a 2D MSHD, this one will be 63.5 x 11 with a built-in 1/2″ Gurney flap.

Tops

I tested the first version of my fastback at Watkins Glen, and I’d like to correlate the results from real-world track testing to wind tunnel testing. So I’ll bring an OEM roof and trunk with me and I may as well do one run without the top as well. I wish I still had a Chop Top, that would be worth testing again.

Open windows

Open windows add drag and reduce downforce, and so I’d like to test various things that may help. I’d like to test a wicker or vortex generator on the A pillar, smoothing airflow out the B pillar, using a longitudinal strake along the top of the window, and large NASCAR-style window nets (which are mostly fabric and not a lot of holes).

Mirrors and mirror stalks are another thing that might affect open windows, or downforce in general. By forcing air downwards, it’s possible to move air away from the windows (and wing). Conversely, moving air upwards may add downforce. And how would these trick mirrors compare to OEM mirrors or no mirrors at all? Gotta find out.

And you?

So that’s at least $4000 worth of testing and I haven’t started on your tests yet. What’s keeping you up at night?