multiple air dams??
 

has anyone ever installed an airdam in front,one in the center,and maybe one in the rear?

How the concept works eludes me, especially the one in the rear. :confused:

What are you thinking the centre and rear dams will do? More air deflection? Or do you mean side skirts and rear diffuser?

the concept, is for the second one to block some of the air that does not get blocked by the first airdam.the third might not even work.does this concept still elude you?

A belly pan will probably work better to smooth out the airlflow. More air dams seem superfluous.

Yes it does.

I can picture how they could be mounted and how they might look; that isn't the issue. The issue is, airdams (in the front anyway) work not because they are sleek, but because they direct air flow from draggy areas to less draggy areas. So for instance if I were to put one in front of the rear axle on my pickup, what exactly would it do? The "flow" under there is already a complete turbulent mess... it would shield that axle though... directing air up above, like to the floor of the box and all that nasty chassis stuff wouldn't help so a before axle dam would have to go up as far as it can? And/or be angled such that it tries to direct air down to the road? Or out to the sides?

And then there is the idea of one on the back. The very back? Where we are trying to make the wake zone smaller? I guess I can kind of imagine where trapping a rolling wave similar to why it is said that pickups are better with the gate up are better... but.... eh, I don't think the flow situation is the same down there next to the road.

The only thing I could see is two "mini dams" to direct air away from the rear tires.

Like Frank said, once the air is under there you will just be adding drag.
Now I have considered trying a sortof wedge shape cross between sideskirts and an air dam in front of my rear axle to force air out .

[QUOTE=Frank Lee;270789 So for instance if I were to put one in front of the rear axle on my pickup, what exactly would it do? The "flow" under there is already a complete turbulent mess...
[/QUOTE]I was thinking in front of the axle,before the floor curves.Ok, the rear one was a bad idea.

Just do Prius style air deflectors in front of the wheels and call it a day!

Yes, like the side skirts on a semi-truck which are inboard at the leading edge.

Not exactly a second air dam, but perhaps doing what the original poster of this thread had in mind. The way sc2dave describes it will not work, Frank Lee spells this out pretty well.

FAQs on Trucks
http://www.arb.ca.gov/msprog/truckst...tdynamics1.jpg

I've been having a hard time finding a photo on google, but Amigos (or something like them?) had an air dam behind the rear axle...

multiple
 

I've not seen nor heard of it being done.SAAB has has some interesting plastic bits under their cars,but I think it was more splash control than drag reduction.
RV motor homes and buses sometimes have a rubber or bristle splash control panel which spans the rear behind the rear wheels.

Some mid 80's Dodge Daytonas had side skirts from the factory, but not sure just how much they help?

If the bottom of your vehicle is flat bottomed, then yes, an aero feature in the middle of the underbody can be beneficial.

-It can deflect flow that has crept in behind the front tires, or around the front airdam back out from under the car before it hits the rear tires, axle, etc
-It can stop crossflow in yaw, ie air coming in from the left of the vehicle and impinging on the right rear tire

So, it can work in the right situation. However, it's probably simplest to add small, local tire spats in front of the rear tires, or skirts along the sides.

I have been thinking about this too. I plan to extend my belly pan all the way to the rear but what do I do with the rear axle? I was thinking about spats on either side of the drive-shaft in front of the axle.

I tried an air dam in front of the front tires on the front belly pan but it didn't do much and affected high speed stability.

The Inter-web is thick with big-rig aero ideas/aids.
Here is something that seems like it is what is being contemplated here:

http://www.blogcdn.com/green.autoblo...1297447593.png

Aerodynamic add-ons reduce fuel consumption of semi trucks by 7-12%

SmartTruck

If the bottom of the vehicle is flat, a spoiler/dam would just add drag. Why push air away from a smooth surface? Add wheel strakes instead and it'll be ideal.

See the post above for one example of what I meant. I didn't specifically mean an airdam.

What I meant was a device in the middle of a flat floor that manages the air that creeps back in under the car behind the front wheels or the air from the front of the car that flows between the front wheels. It can either be shielding the rear axles or directing the air back out around the rear tires.

Sorry for not being more clear.

However, I do agree that in most cases tire spats will give you asignificant bang for the buck/effort.

I have thought about a mid-car air dam. I would be concerned about adding turbulence under the car and creating a bad exit vortex. One idea I am toying with is an air dam that works with the wind instead of pushing against it. Sort of a resistive self-moving air dam. I am leaning towards exit air mods rather than a front dam.

Aero obviously changes the faster you go. I have heard that some new car is coming out with aero panels that only come out over a certain speed. Don't remember which car it was.