2005 RE Amemiya GT300 in air tunnel

 

that thing looks CRAZY

 

worlds most psychotic 7. That thing is amazing too bad its only a gt300 car. I could only imagine the power of a 4 rotar in gt500....Theyd probably get kicked out though after winning all the races hahaha. Question though, how big are those wheels?

 

friggin huge... j/k. dont kow

 

Man...I obviously don't know all the inner workings of a wind tunnel, but how can it be so expensive to make? It looks like just a big empty room, VERY high power fans in the front, one way exhaust from the rear, and a pole w/ smoke so you can see how the air travels. What am I missing? Cuz the basics look like something you could very well build, w/o the exponential costs I've heard of...

 

those wheels look like 19" or 20"
huge already and its not even on low profile tires

 

Ramy, I would imagine that part of the thing you're missing is that the room and everything in it (doors, viewing ports, etc), has to be built to withstand the pressure generated by the airflow. Such construction can be costly.

It is also more difficult to generate enough airflow to simulate high wind speeds than you might think. It takes large and specially designed fans to accomplish this.

Still, I don't see why it would be exhorbitantly expensive to build one, so I must be missing something too.

I wish there were more pictures of the RE-A car in the tunnel. It's pretty impressive how smooth the airflow is over the top of the car -- and notice how the air coming over the top is directed right onto the rear wing.

 

shouldnt the air be directed under the wing to create the down pressure against the car so it wont fly up? thats what ive always thought...

 

 

i mean i always thought the purpose of a wing was to direct the air so it would go under the wing so the down pressure can be pushed down on the back of the car, under the wing. im wrong arent i

 

Air pushes the wing down - The wing is attached to the rear of the car - Therefore, the air pushes the rear of the car down for traction

 

oh ahhaha thanks for the info ahahha

 

if the air went under the wing that would create lift. like the wing of a air plane

 

I'm no expert either, but if you look at the picture, once the air hits the wing it goes up. The air going up shows that the wing is reflecting the air and pushing the car downwards.

 

<====is the man...

 

actually, you are theoretically correct. an wing doesn't generate lift by air hitting the bottom if it, it generates lift by the air flowing more quickly over the curved top of it. faster moving air = lower pressure. a proper wing on a car works just like a wing on a plane, but upside-down for obvious reasons. so it needs air going under it to work efficiantly. that's why GT wings tend to be lifted up high.

if the air was only being deflected up by plainly hitting the top side of the "wing", it would be more like a spoiler and a lot less aerodynamic. the thing on this car looks like a combination of both approaches. but i honestly can't say why the pictures don't show air going under the wing, perhaps all that are comes around the cockpit.

maybe someone can explain it better.

 

I see some wires that are ran under the car in the first pic and then i dont see them in the rest. Does anybody know what those were for? Also does anybody know if there are sensors under the wheels to calculate the amount of downforce at the wheels during certain wind speeds??

Excellent Pics...That car is sweet

 

tunnel...i wouldnt think it would be cheap. obviously, it has to be big. chances are, its made for pressure. and im sure they dont just have a bunch of big lowes fans. surely they have some other source for air because since when does air come at your car spiraling? and for the open end exhaust.......dout it. its prob the same setup as the front pulling/pushing the air out so there isnt a drop in air speed/pressure.

 

i have a book that tells about the differnt types of windtunnels they use for that testing theirs a few differnt types i just need to get it back from a friend. i was at JGTC in december and out of all the cars the 7 was the loudest

 

I think limbar85 is on the right track. The main expense has to be the fan set up. It is hard to get air to flow straight and evenly throughout the tunnel. Also, I don't think that wind tunnels are pressurized.

I would imagine that scales under the tires could measure downforce. It looks like there are some in that tunnel.

 

the fans are way out in front. there is a grid like structure to straighten the airflow out so it is straight and not spiralled when it gets to the car. in theory, yes, it would be easy to build, but when you look at the pressure differentials being created on the walls, the structure has to be VERY solid. also, that's a cheap tunnel by today's standards... no moving floor. you can't get "realistic" results without a moving floor. those get EXPENSIVE. there are ways to simulate it, but you will never get accurate results without the wheels spinning to cause their effects on the undertray.

read "Driving Ambition," the story of the design and building of the McLaren F1 sometime. they have a decent little explanation in it of the wind tunnel testing they did.

 

Aaaaah......here we go.

The wing is designed the way that it is for 2 reasons, both of which have been touched on already. The outer parts of the wing (Away from the centerline of the car) have a fair amount of deflection to them. This is great for low speed to try and get the most from the wing, but it has a tremendous amount of drag. So then as you move towards the center of the wing, you'll see that it is almost parallel with the ground, except that the top is "flat" and the bottom is curved. This is basically an upside down airplane wing. This is great for high speed downforce, but does little at low speeds. So you can see that a careful balance is needed so that the outer parts are designed just right as not to create too much drag at higher speeds.

As far as the shape of the center section goes, I'll do my best to explain. If you look at the wing profile (Cross section) it looks like an upside down airplane wing, as particleeffect stated. so if the top of the wing is parallel with the ground, and the bottom is curved, you can see that the bottom curve is a "longer line" than the "straight top line" of the wing. When air goes over the wing it has to travel a certian amount of distance from the front of the wing to the back of the wing. if it has to go over the bottom of the wing, it has to go a longer distance from the front of the wing to the back of the wing. Here's the hard part to visualize:
1. 2 particles of air both start standing side by side at the fron of the wing.
2. 1 particle decides to go over the top, while the other goes over the bottom.
3. they both meet at the back of the wing at the exact same time.

So the particle on the bottom had to travel faster to meet the particle on the top at the same time at the back of the wing. Does this make sense? Because this particle traveled faster it created a higher pressure on the top of the wing, and a lower pressure on the bottom giving downforce, but only at high speed. It will give downforce at low speed, but it is so small, it doesn't really do much.

The wing is as high as it can be, so that it is in clean air. That way, it does not have to deal with any boundary conditions, shockwaves or vortices coming off of the body of the car. But the top plane of the wing cannot exceed the roofline, nor can it be any wider the the car itself.

What would be really cool, is if you could make flexible outer wings, while the center is rigid. That way at high speed, the low speed wings would bend out of the way to create less drag. This has already been addressed by the major sanctioning bodies, but I still think it would be cool.

 

The particle explanation is interesting, but a bit off. The air that travels over the curved surface of the wing (in this case, the bottom) is moving faster, and creating lower pressure. The air above the wing travels over a more turbulent route (it sort of rolls over the wing) and results in slower air flow that creates a high pressure area. High pressure flows to low pressure, and in the car of an automotive wing, creates downforce. The higher the angle of incidence of the wing, the more turbulence over the top, and the more downforce is applied. The variation on the incidence angles of the RE-A wing have more to do with the airflow to the wing, rather than creating downforce at different speeds.

Same principles apply to underbody diffusers. The venturi tunnels underneath the car expand from a small area to a large area, and the air under the car expands rapidly to fill the space. As the air accelerates to fill the tunnel, it creates a low pressure area, and the air above the car exerts downforce.

And wings create plenty of aerodynamic drag. Consider open wheel formula cars (IRL, CART, F1)) that have plenty of wing front and rear: F1 cars feature 900 hp, weigh 1200 lbs, and top speeds are only 215-220 mph....but do they ever corner with all that downforce. In fact, they generate enough downforce, that you could (theoretically) drive it upside down on the ceiling and it would stick!

Class over.

 

A proper wind tunnel is a hell of a lot more than just a "big empty room, VERY high power fans in the front, one way exhaust from the rear, and a pole w/ smoke so you can see how the air travels." Besides all the structural requirements to properly guide the massive airflow and withstand the major air pressures involved, you need the proper measurement devices (with attendant recording gear), up to and including various meters such as weight pads so that you can actually measure downforce.
Yep. Basically about the same size as an aircraft engine (some of them actually are aircraft engines). And the power requirements in order to run those fans border on building your own electrical substation to handle the massive current load. Not something "you could very well build, w/o the exponential costs..."

 

Alls I know is I want to stand where the car is and turn that sucker on high.

YEEEEEEEEEEEEEEEEEEEEEE HAWWWWWWWWWWWWW