AJ Hartman Aero - 18+ Canards

[Flyhalf]

You could probably just fab some detachable panels to close off one or both front diffuser sets?

I could. But it wont be precise. Also I need a spare anyway

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[TeeLew]

Right now the ROMA splitter.is.producing a shit tona of DF meaning high angle rear wing. Not ideal in high speed track such willow springs.

And why would you not *want* a shit-ton of downforce at Big Willow? Are you having trouble controlling it or is it just the issue of drag?

 

[TeeLew]

You could probably just fab some detachable panels to close off one or both front diffuser sets?

^^^Yep.

 

[Flyhalf]

And why would you not *want* a shit-ton of downforce at Big Willow? Are you having trouble controlling it or is it just the issue of drag?

Drag. At 147mph in t8 you already have a lot.of DF cause the higher speed. So you don't want 100lbs of drag.

 

[TeeLew]

Drag. At 147mph in t8 you already have a lot.of DF cause the higher speed. So you don't want 100lbs of drag.

I bet you a dollar to a donut that it's faster with the wing in it, regardless of the drag (assuming you've got a decent balance with both setups). Don't get too worried about straights at Big Willow, because you spend so much time at high speed and high lat G that I've never found a high trap speed number to correlate all that well with a fast lap time.

It's been a minute since I ran a GT car there, but we would always go faster if we added downforce. That car was the real deal, not Lemons car or something. For GT cars with good power (you've got that, LOL!), Daytona is the only track I'm aware of in North America where you go faster with less downforce, but that's because so much of your high-speed time is not cornering and the cornering time is mostly not high-speed. Even Indy is a bit of a wash, lap time is similar high and low downforce, but you're a lot racier tactically if you trim.

By all means, though, take that all with a dash of salt. It's just been a general observation.

 

[Flyhalf]

Well i was there with the AJ wing at 3deg and gurney flap which generates about 500lbs at 120
The splitter was the "old" one with 2 smaller prof awesome tunnels at 2.75"from the ground
I was able to sustain 147mph in t8 closing at 1:23. Which was 3 sec faster than previous one. The car was glued. (did u watch the video?)
The new splitter gets balanced at Sonoma with a 7deg wing angle.+ Gurney
At that angle we are around 70-80Hp loss.

Like you were saying I'm looking for balance. Car was balanced.
At Daytona i would have been 3sec slower with a 7deg wing

 

[TeeLew]

<Tons of aero experience>

This is a little off topic, but I've only autocrossed my car to this point, so I haven't addressed anything aero besides a 350-style spoiler and that was just for looks.

Anyway, what would you recommend for a reasonable aero balance with basically stock aero? AJ's splitter is great, but I'm not considering that level of commitment for a play-day. Having said that, would it be a bonus to grab a PP2 splitter lash up off Ebay or maybe make a plywood arts & crafts project? Obviously, it needs to be mounted appropriately as opposed to the included chewing gum and safety wire.

I just don't have a good feel for the stock aero balance and thought you might be able to add some insight concerning the easy stuff.

TIA

 

[PaddyPrix]

I just don't have a good feel for the stock aero balance and thought you might be able to add some insight concerning the easy stuff.

I'm obviously not Alessandro, but in short, you'd be amazed at how well a simple splitter made from wood would do you, it certainly woke my car up big-time. I'm sure an expert will come pick my arguments apart, but while the rear needs some CFD to figure out vortices and boundary layers, for the most part, the front is laminar, or non-turbulent air that's semi dependable.

Assuming you use something strong enough like Alumalite, or hell, 15/32" Birch, you should be able to do 300, 400, maybe even 500+ if designed it well enough. That's where things get fun with how you're going to attach it to the car (read: not the bumper) and the airdam/fence, which if done right, prevents air from getting through and out back, but into your intake, radiator, and various coolers and whatnot.

You can get well fancier with canards, deflectors, even fenders, but having a splitter does an awful lot, then you have to test, and test... and test. It's not very much fun out here in the desert where a 4 session HPDE day will typically only have two similar sessions with the same air and track temps, but the challenge is driving it the same and varying turns you've identified by 10-20mph, instead of like the 160mph that some of the charts go to.

 

[tosha]

so I have a somewhat related question about the splitters - I'm looking to add a FP spoiler with gurney flap (the one that comes on Mach1 HP and GT500). this option seems to be the best as far as function without going full massive wing route. I have a set of racelouvers in the hood, which should create some downforce for the front. with that in mind, what would be my best option for splitter to balance out the back spoiler? I'm not looking to start fabricating my own yet, and hoping that there should be some descent options available for purchase. the car is also my daily, and it's already scratching the bottom here and there, so something more civil would be preferrable. I have space and means to mount/unmount the splitter for track days as long as I don't need to take the whole facia off every time.

couple options I'm looking at are 1) FP splitter from PP2 package 2) APR Performance splitter for 2018+. thoughts on these? anything else I should look at?

oh, almost forgot about the problem statement - after adding the racelouvers, I'm getting a feeling that the rear end gets "light" at speeds roughly over 100-120, especially in high-speed heavy braking zones. it creates this floaty feeling, which was there before but it seems that now it's more pronounced. I don't wear brown pants to track events, so some more stability is definitely welcome.

 

[TeeLew]

Assuming you use something strong enough like Alumalite, or hell, 15/32" Birch, you should be able to do 300, 400, maybe even 500+ if designed it well enough. That's where things get fun with how you're going to attach it to the car (read: not the bumper) and the airdam/fence, which if done right, prevents air from getting through and out back, but into your intake, radiator, and various coolers and whatnot.
charts go to.

You're reading my mind. I was thinking birch sheet with a layer of S-glass on top and bottom. I might locate it with the stock splitter, but the idea is to support it properly off the chassis.

Do you think one of those cheap-o PP2 splitters off of Ebay would make a good template?

 

[Flyhalf]

This is a little off topic, but I've only autocrossed my car to this point, so I haven't addressed anything aero besides a 350-style spoiler and that was just for looks.

Anyway, what would you recommend for a reasonable aero balance with basically stock aero? AJ's splitter is great, but I'm not considering that level of commitment for a play-day. Having said that, would it be a bonus to grab a PP2 splitter lash up off Ebay or maybe make a plywood arts & crafts project? Obviously, it needs to be mounted appropriately as opposed to the included chewing gum and safety wire.

I just don't have a good feel for the stock aero balance and thought you might be able to add some insight concerning the easy stuff.

TIA

Sorry man for the late response.been crazy at work.
The MOST IMPORTANT thing as always is balance.
Most of the wings have CFD done so is kind of easier to know the DF produced. For The splitter we have "some idea" but nothing in stone.
Splitter performance comes from 4 main factors.
1. Size.
2. Height from the ground.
3. Front diffuser.
4. Shape

1. Size matters. Lol. How much lip you want depends on you and the competition rules u do. Usually between 4 and 6 inches is a great target
2. One of the key factor. ~3" from the ground is the 'magic number' here. More and the effectiveness of the splitter is reduced .less and u destroy it every time you brake (if u dont have enough springs)
3. This can multiple downforce.
4. Shape is more about how far back you want to go with splitter and what about the side part where you will have side plates canards and tire deflector.

NUMBERS.
a only blade splitter is about 150-200lbs DF @100mph (from now on DF is always referred at 100mph)
Side plates and deflectors can add another 50-70lbs (but increase drag too) . Canards about 20-30but more important canards help reducing drag and improve overall aero performance.
Front Diffuser well...we can discuss years here. 2 pairs of AJ diffusers can double the DF(SEE PICS)

wings.
AJ WINGS are master pieces. fulcrum 14 is an excellent piece can sustain and balance a splitter from a flat blade to a more complex front diffuser blade. (Just changing the Angle of Attack)
APR 250 is a nice "base" wing that produces leff DF and less drag. It is good to balance a blade only solution but cannot balance a bigger splitter.
So if you plan to ..evolve your splitter you need to consider it.

Materials.
As patrick mentioned there are many options.
1. Plywood burch. I made one in 1/2 inch thickness. He is cheap so less thick . Heavier but less brackets required to hold it in one piece.
2.alumalite or PROLITE 10mm .this is my current one. Requires many reinforcements with brackets .
3. carbon fiber. Cool and string but expensive. Especially if you smash it lol.

Last. All my splitters can be removed with quick release connectors from Prof Awesome. This allows u to use the car for street duty without having a splitter hitting every bump of the highway .

Hope this help

 

[TeeLew]

?oh, almost forgot about the problem statement - after adding the racelouvers, I'm getting a feeling that the rear end gets "light" at speeds roughly over 100-120, especially in high-speed heavy braking zones. it creates this floaty feeling, which was there before but it seems that now it's more pronounced. I don't wear brown pants to track events, so some more stability is definitely welcome.

You need more rear spoiler. I've considered getting a spare decklid to run a stockcar-type spoiler. They might not be as sexy as a wing, but they're damned effective, not as draggy as you might suspect and that feeling in the rear will go away. I think Strengthrehab(?) has a 10" (max legal) spoiler when he runs CAM-C and I don't see him taking it back off.

Even if it's only 4-6" tall, you'll feel the difference.

 

[Flyhalf]

You're reading my mind. I was thinking birch sheet with a layer of S-glass on top and bottom. I might locate it with the stock splitter, but the idea is to support it properly off the chassis.

Do you think one of those cheap-o PP2 splitters off of Ebay would make a good template?

Pp2 adds 16lbs of DF to make a template is super easy. Put a 4x8 sheet under the car. And trace it witha block of wood and a sharpie

 

[tosha]

You need more rear spoiler. I've considered getting a spare decklid to run a stockcar-type spoiler. They might not be as sexy as a wing, but they're damned effective, not as draggy as you might suspect and that feeling in the rear will go away. I think Strengthrehab(?) has a 10" (max legal) spoiler when he runs CAM-C and I don't see him taking it back off.

Even if it's only 4-6" tall, you'll feel the difference.

Are you saying that FP spoiler with gurney flap won't make enough difference? What else do we have that you would recommend? APR 250 wing is out of budget at the regular price, let alone AJ stuff. I was thinking about spare decklid option as well, in fact I went down that route with the hood to cut for racelouvers. Also thought I would swap them for the events, but I'm too lazy and ended up driving with it all the time. I fabbed my own rain trays that I can take on and off relatively quickly. I'm afraid same would happen with the decklid

For the reference, I have stock PP1 "spoiler" at the moment, which doesn't do much aside from flapping like crazy and trying to take off and fly away on back straights. I'm also not looking to compete or chase record lap times. Would a FP spoiler be a waste of money or will it give enough improvement over what I have now for my goals and problem?

 

[TeeLew]

I *really* hate to go too far out on a limb on aero stuff, because it can be so counter-intuitive at times, but here goes, and take with the appropriate dash of salt.

I think all the Ford supplied options are produced with fuel mileage and styling in mind as much as anything else. The 16600-FP wing is not nearly as effective as it could be, specifically because it has vents to evacuate the high pressure off the decklid. That's what you want! Why would we vent that air? Well, you'd vent it because the mpg hit is too much. I think that spoiler/wing looks a whole lot more aggressive from a side view than it does to the air that actually encounters it.

I'm using the GT350 spoiler that is actually kind-of a spoiler. I like its looks, but it's also formed in a way which is meant to disturb the air as little as possible. It's much more of a ramp than a dam and the outer edges are rolled to dump as much air as possible. I was just looking at the flow lines from a rain/sand storm I was in last weekend. It might do more than the original blade spoiler, but it's really just decoration.

This is more along the lines of where my head is going. https://www.circletracksupply.com/cts-.060-breakaway-8.00-spoiler-kits.html?cat=301 In CAM, you can't run the end-plates, but you could on a track day. It doesn't look nearly as pretty other wings/spoilers, but I bet it's effective.

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