I am a part of the Time Attack Forums and I came across WCKDVPR's build of his Viper. So these are some more pics of what I am working on.

Here is the link to more pics hood louvers - Page 3 - Time Attack Forums

https://www.miataturbo.net/attachmen...ine=1370659022

https://www.miataturbo.net/attachmen...ine=1370659022

https://www.miataturbo.net/attachmen...ine=1370659022

https://www.miataturbo.net/attachmen...ine=1370659022

https://www.miataturbo.net/attachmen...ine=1370659022

That splitter looks a little high, but that is a sexy, down-to-business car.

Me like.

He says and I quote "I am up in the 220 range and it never got above 205 with the new ducting". A cool engine is a happy engine.

Makes sense, too much of air is getting parachuted into the void where the filters are.

I was looking around about radiator ducts and then what about a wing for the upper portion of the radiator duct.

He is some inspiration

https://www.miataturbo.net/attachmen...ine=1370924848

https://www.miataturbo.net/attachmen...ine=1370924848

I want more front end downforce. Here is one I drew up, but the air foil is to big, but you got the idea

https://www.miataturbo.net/attachmen...ine=1370924848

not sure how that would work, there would at least need to be a gap between the wing and the radiator.

Why?

"plucas" said to keep the radiator under 32mm thick.

There would be a swivel right above the radiator so the wing can be adjustable.

just an article that popped up on facebook

A BRILLIANT VIEW INTO AERODYNAMICS - Speedhunters

if the radiator is butted up against the bottom of the wing, then you're blocking the flow of air attached to the bottom. Remember, downforce is created by the pressure difference between the top and bottom surfaces of the wing.

Correct however its of the entire assembly not just 1 bit.

lol @ speedhunters
Article should be called "how to make your drift car look like a '80s rally car"

Also, how pretentious is that guy to call his own article "brilliant"?

Okay think about it this way. Flow closest to the wing flows faster than that farther away from the wing. This ensures that the static pressure reduction is greatest near the wing surface. This provides the turning effect to the flow farther away. Now, if you block the path of the flow closest to the wing, it will slow down the flow, and now you lose the turning effect on the flow farther away. Leave a gap, problem solved.

Just the opposite. Area closest to the wing is called a boundary layer. In this layer the air slows down due to friction. This layer is responsible for creating turbulence that you dont want.

U'd want to toss the radiator near the end of the wing where the boundary layer is the thickest and the air slows down and pressure increases.

Thats the likely spot.

But you'd need to do a lot of CFD on it to make any real downforce. Remember that radiator is going to kill the velocity of flow, its also going to have higher pressure in front of it than behind it. I'm in the camp of, the wing rad duct probably wont work (without a bunch of prototypes in the wind tunnel).

No. You are combining two features with competing interests.

For the wing to work, it needs low pressure below it.

For the radiator duct to work, it needs high pressure inside of it (which is below the wing)

You can't have high pressure and low pressure at the same time, so one of them wont work well.

Also, that second picture isn't a "wing", its just a gurney flap in front of the radiator duct exit. THAT is a great idea (I have one on my car too). It will create lower pressure at the radiator duct exit, reducing pressure behind the radiator.

Hmm let me guess, u dont know the pressure map of a wing?

I definitely do. Remember that the wing in this case is upside down.

Then u should know that at the end of the wing the pressure increases again where the air slows down.

Pic of course upside down.

https://www.miataturbo.net/attachmen...ine=1370955751

If your going to start going that far then why don't you just use a front wing like blackbird? A simple vented hood should reduce lift. Incorporating a wing above the radiator would be way too hard. If you design it wrong it might cause more drag, and more lift.

That's just how I see it.

I do, and if you stick a big flow restriction below it, it wont work. He is spot on, wings work by having low pressure high velocity air under them and higher pressure low velocity air above them. Radiators work by having higher pressure air in front of them and low pressure air behind them, and slow down the air passing through them. I know a cambered wing like that has a pool of stagnant air in the cambered pocket of varying size, and the back 1/3-1/4 of the bottom experiences flow separation. The boundary layer is going to be no more than 1/2" off the surface of the wing unless the surface finish is WAY too smooth.

If you stick the radiator at the back of that wing duct it will raise the pressure of ALL the air under the wing. If you put it at the front, the turbulence will completely fuck with how the air interacts with the wing, but at least there'll be low pressure under the wing. However there is going to be more surface area and higher speeds on the lower section of the rad duct so that would likely end up making more lift. Along that line of thinking, if you want to use a rad duct to make downforce, shape it like an inside out wing.

Well the debate is whether or not you should butt up the radiator across the wing or leave the half an inch or whatever room there is between the radiator and the wing. Obviously a different location for the radiator would be much better.

If you dont butt the rad up to the wing you'll certainly create some fast ass air against the wing for that 1-2 inches of width of the radiator. But you might end up with an ineffective radiator.

^ Like this.

I changed it up to a more realistic size

https://www.miataturbo.net/attachmen...ine=1370958749

And another idea that would be even more realistic

I am in a seminar so i will change to different designs through the day
I haven't got to show what the frontal view looks like yet

https://www.miataturbo.net/attachmen...ine=1370958749

Yep. If the wing is above the radiator, it might work but the radiator wont (no ducting). You'd be better off having the wing and the radiator ducting separate from each other (ala Blackbird)

You could also shake the front to be a bit sleeker to reduce drag

https://www.miataturbo.net/attachmen...ine=1370959279

A: Its WTAC which, in my books, is a respectable motorsport.

B: The last name of the guy he is interviewing is Brilliant.

Also, I checked out Andrew Brilliant's youtube cannel and he has a few videos of Matt Andrews in his time attack miata featured on there.

Is Matt Andrews his stage name?

Shit. Totally wrong use namer. Don't ask me how I got the two of them confused 'cus I don't know.

The radiator duct wing looks like it's way too complex to build for something that even in theory has shaky logic at best.
The second version with a wing placed above the cutoff line between the hood and the bumper has some problems with the theory too, but even if that was okay there's a significant practical issue - you can't see through the wing.
Remember that the air doesn't flow @ 0 up there, so even to set the wing to 0 AOA you'll be running it probably 20+ degrees AOA relative to the ground.

Moti

Here is the pic of the front https://www.miataturbo.net/attachmen...ine=1370977232

The width of the NA hood at the front is roughly 29" IIRC, put a 26-27" stick of 2x4 in your line of sight where you're thinking of putting the wing and see how you like it.
I suspect you're not going to like it at all even if it's flat, and it won't be.

If you were building it for track only with zero street usage, it might be okay, heck some of the cages that I'm building include a windshield diagonal and that's totally okay on track -
https://www.miataturbo.net/attachmen...ine=1370978327

For anything that has street use planned I'd avoid it.

Some cool CFD work on a Pikes Peak Subaru. Should be interesting to follow, but even the creation of a mesh for CFD is neat to see.

Subaru Impreza Pikes Peak

Might've gotten just a few of his ideas from the Peugot 208.. ;)

I believe that earlier in this thread we were discussing active rear wings for drag reduction..

This UK time attack Evo rocks just that. You can see the actuator on the rear of the upright:

https://www.miataturbo.net/attachmen...ine=1371109802

https://www.miataturbo.net/attachmen...ine=1371109802

Any idea how they control it? How does it know when to reduce/increase the AOA? I guess you could reduce AOA after cornering G's fall below a threshold value, and then increase it again as brakes are applied... but then what about corners you don't brake for? You wouldn't want to wait for cornering G's or steering input, because by then its too late. Maybe a button on the steering wheel?

Or you could map out the course and pre-program it using GPS.

Driver control?

I would think you would want a button/switch on it just like F1.

Ferrari has now moved their DRS to a switch next to the brake pedal. DRS is only activated when the driver's foot is on the switch.

Apparently they deactivate the DRS flap before getting on the brakes so the air has time to "reattach" to the wing.........I'm sure I did a poor job of explaining it.

Hm I was under the impression that the DRS stayed open until you hit the brakes and thats how it was regulated to be. Tap the button to open the flap, hit the brakes to close it.

Each team implements it slightly differently compared to the others.

http://www.auto123.com/en/racing-new...m?artid=155397

http://scarbsf1.com/blog1/2013/05/22...rs-activation/

I could imagine a number of ways to activate/deactivate it...depending on the use of the adjustable foil. If used for braking- could be button activated and deactivated by the brakes; could be speed dependent and read off of vehicle speed; could be a push-button on/off on the steering wheel. Given the picture has it activated and no brakes lights on might show it's driver operated or speed operated :dunno:

While not one of having aero/fluid education, I could imagine that using it for high-speed corners where brakes are not used could upset the balance of the car in an unpredictable way- sudden increase in drag/downforce on the rear reducing front grip when it is needed or even changing the pitch of the car/flow of air over the whole car when not under braking.

I find all of this stuff VERY interesting and do like to try to understand it as best as I can.

I'd imagine one of the best ways would be a direct ratio between Brake position and wing angle. The more you press the brake the higher the angle.

Having the aero balance change while you are in the braking phase doesn't sound like a good idea at all.

How come? Because i dont see any negatives to it.

I was thinking about this a few months ago, came to my own conclusion that the best application for someone without a wind tunnel or the desire to be the guinnea pig to test how much turning the wing into an air brake at 130 mph upsets the car, would be to simply have a button on the steering wheel that returns the wing to 0* aoa. Press it once you straighten out your corner exit onto a straight, gain a few mph, let go of the button a moment before you enter your braking zone and the wing returns to your pre-set aoa for however you have your aero balance set up.

In the second pic I posted, I am not so sure that the wing is being used as an air brake there - I think they were using the active wing similarly to how I suggested above, and given that they then could go for maximum downforce regardless of drag because it would zero out for the straights, they cranked the aoa on the wing up a lot. That pic looks like he's coming out of a turn and on the throttle, so there's no reason he'd have it running as an air brake at that point..

-Ryan

The need for breaking power is not directly correlated to the need for down force. Two examples come immediately to mind: 1. As mentioned earlier, maximum down force is desirable in flat-out cornering where the throttle is either pinned or just briefly let up. 2. In the middle and second half of a corner where, at most, brakes are lightly being used for trail braking, or not at all, such as when beginning to feed in throttle to exit.

There are two different kinds of active aero, and its important that we differentiate between them

1. Air brake. This is simple. When you are on the brakes, an aerodynamic element creates drag to assist braking. You can simply activate it with a brake switch.

2. Drag reduction. This is more complicated. In racing it is usually implemented by reducing the effectiveness of the wing and thereby also reducing its drag and down force. You have to have to either activate it manually, or have some sort of control scheme that knows when you don't need downforce.

A button on the dead pedal is fine for flapy paddle cars, but if you have to work a clutch your wing would be flapping up and down while you shifted gears :P

Thank you. I was just thinking in my head how I should write that out.

The way I see it, both can be useful, but the implementation of an air brake should be left up to the people with high powered CFD and wind tunnels as it has the potential to greatly upset the car. I think a DRS is more straight forward and is easier for the amateur to implement.

Well no, the angle is important, there is downforce and there is a point where it stalls and u lose all downforce and get a parachute. Of course theres also low downforce for high speeds.

Perhaps something along the lines of an integration between (numbers are just random numbers)

high speed + max throttle 10 degrees angle

any speed + 0-99% throttle 20 degrees

any speed + brakes % 20-70 degrees with the % of brakes varying the angle of the wing.

You could use a button on the steering wheel the same way Ferrari uses the foot switch. You probably have a bit more real estate to work with:

https://www.miataturbo.net/attachmen...ine=1371146094

I think that transitioning a wing from a high downforce AOA to a low downforce AOA (DRS) is more predictable and stable than transitioning from a high downforce AOA past the stall angle and into a weird, vortex generating state that the wing was never designed to operate in (Air Brake).

I've got a data acquisition system that can control it now based on G forces and other inputs.

Left G, right wing up
Right G, left wing up
Brakes, both wings up
acceleration, wing angle decreases as speed increases

You could also tune the angle for speed, and even tune it per track.

I would program it just like that except I would program the wings to keep making downforce until WOT. Like I said earlier, you want downforce in the last part of a corner when you are on the throttle, but not all the way.

On another note, I haven't actually gotten to mess around with aero much on track. I really enjoy the aero aspect of going faster and I want to play with just aero for a while. I was thinking of going back to completely stock (or maybe getting another, stock Miata) and using aero only to start dropping lap times. My question is, will stock tires and suspension components interfere with aero testing or make tweaks more apparent?

You'll probably get more benefit with more than stock power, since you'll need more power to get past the added drag from a wing, and the aero stuff make more of a difference the faster you're going.

IMO, the only way to properly do it is via a GPS signal unless you want to manually control it. If you wait until braking then you will be changing the balance in mid turn in a lot of cases. If you you base it off of G force then, again, you will be changing the balance of the car while turning. There are also plenty of turns that I go into WOT with aero that I couldn't without it, so having it work until WOT wouldn't really work either.

Having the active aero independent of strictly either G forces, throttle position, or brake actuation alone would allow you to properly set it up. Until then, I think you will be sacrificing speed one way or another.

You could probably set up something like what you guys are describing and be faster than without it. One possible way it to have it tied to the brake light, but on a 3-5 second timed relay. That way you lightly tap the brakes before a turn to activate it and go through the turn with it regardless of throttle position, brakes on, or g force. That is about the most efficient way I can think of to manually control it.

Rather than G control, its not very hard to add a steering position sensor.

I'd rather have my DRS on a button for the straight.