New Pricing: A2 Wind Tunnel

[A2WindTunnel]

The A2 Wind Tunnel will have new pricing in 2009.  We are offering teams a lower rate to help them get additional time in the tunnel for more valuable data information on their car(s).  Our regular hourly rate is now $390/hr.

Full Scale Racecar Wind Tunnel Pricing:  There are not many wind tunnels in North America that are capable of testing full scale race cars, but here is a list of the tunnels that are, along with pricing on 3 to illustrate how competitive A2’s pricing is for 2009.  This list covers A2 all the way to the most expensive and all others fall in-between on hourly rate.  Most of these tunnels don’t list pricing on their wiebsite (so I can't list what I know to be their $/hr without published info), and the list is as complete as I can find at this point.  If anyone has published pricing info on any of the tunnels listed I would gladly update the list.  (I can tell you that 90% of the tunnels listed are over $1000/hr) 

You can email dave@aerodynwindtunnel.com of call 704.799.1001 for more information.

www.A2WT.com

[1212FBGS]

What about the Swift tunnel? Texas?  didnt see them on the list.
kent

[A2WindTunnel]

Swift is a scale model tunnel.  Around 45% and this means you would have to build a scale replica of your car to test there. 

The list I put together is for Full Scale wind tunnels in North America that could roll a racecar right in.  Not all of the tunnels on the list are available to the general public.  From what I understand all of the manufactures (GM, Chrysler, and Ford) tunnels only test teams that get manufacture support and I don’t think just anyone can walk in off the street could test there.

[fredvance]

Doesnt Taxas A&M have a wind tunnel?

[A2WindTunnel]

1212FBGS;

Looks like you would be more interested in motorcycle testing from your page info.  I don't know if Swift tests Full Scale motorcycles (they have a picture on the site of a full scale motorcycle, but it does not appear to be connected to any fixtures or the balance, which leads me to ask, is it just a picture or are they really able to test them?)  If you have some info you would like to share I would gladly update the list to show them as a motorcycle tunnel.

Do you happen to know if they test motorcycles and what the hourly rate is for testing?  Also what range of motorcycles could test there?  I know it is not long enough for a streamliner like the BUB bike or similar.

[A2WindTunnel]

fredvance:

I am talking about FULL SCALE AUTOMOTIVE Wind Tunnels.  Texas A&M would be a scale tunnel for automotive testing.

If you have any info about Texas A&M for motorcycle testing I would gladly add that to the list as well if you get me some info on what they can test and how much$.  I know San Diego has a tunnel that test motorcycles as well, but I don't have any of that info either.

This was meant more for the automotive side of the forum, but if the motorcycle guys would be interested in tunnels that could test them I would be more then happy to update the list for that as well.  I don’t have any info on tunnels that are capable of testing full scale motorcycle, so any info would be appreciated.

[krusty]

Dave - Ha! I look at that list and see that A2, Ford, and Windshear are the only ones I haven't been to!    We used to do a lot of testing @ NRC in Canada and think they were about $1500 Cdn in the early part of this decade but the charges that were billed were converted to US$ as of that day's rate; they were great folks to work with, but a long trip and truckstop cold in the winter months. The quality of "entertainment" in Ottawa was a pleasant bonus, however.    Langley is interesting from an historical perspective ( 'flying' the plane in there!); I think it was around $12-1500 back then, too.   Wasn't really involved on the $ end so this may not be the most accurate recollection.  Will be in A2 in '09 so I can cross it off my list     vic

[fredvance]

I dont have any info it was just to see what A&M did?

[1212FBGS]

yes San Diego state has a tunnel but i dont think it is big enough to put a bike in... i'll call Dr Burns today and ask him.... we used the Tunnel at Southern Utah university (SUU) for our scaled liner...
kent

[Rex Schimmer]

A2 Dave,
I am presently working on the drawings and engineering for a small lakester, (streamlined body with exposed wheels) and obviously the rotation of the wheels will have a pretty large affect on the aero properties of the car. Does the A2 tunnel have some sort of method of spinning the wheels to simulate real life? Obviously with impending retirement and getting a couple of boys thru college, the lakester is several years off but I think some time in your tunnel would be money well spent.

Also can you do some "tuft" testing while in your tunnel? Lastly is the A2 tunnel more accurate if the car is smaller, less "blockage" I figure my total frontal area to be around 4 sq. ft, which is certainly smaller than a NASCAR car or a funny car.

Looking forward to any additional info that you present on your tunnel(s).

Rex

[A2WindTunnel]

Rex,

Wheel rotation has an affect on the vehicle and there are ways to simulate what the wheel is doing or where the air separating while rotating.  Think of them as 4 pneumatic pumps on your car pumping air out in a radial direction.  As you are up to speed the air is separating on the tire in a different location then non spinning.  Years back when Eaker was at the GM tunnel some of the indy car teams would test with a "trip strip" on about the 1 o'clock location of the wheel (looking from right side), but then found that even without the "trip strip" they saw the same trends.  In other words the incremental changes seemed to be the same and if they saw and improvement with a change on the car, it seemed to be the same whether the wheels were spinning or not.  The absolute numbers will change a little, but the more important thing in wind tunnel testing is that when you get the car in the wind tunnel you start with X (baseline).  Your goal then becomes how we are going to improve X to benefit the type of racing you do.  No two wind tunnels will yield the same absolute #'s but if they are designed properly the trends and increments will be about the same.  The reason these teams stopped using trip strips (I'm not speaking for all teams, just in this case) is because it is one more variable in the equation and if they don't get put on in exactly the right location and are not the exact size your numbers will be off from a previous test.  So, I would say that there are ways to recreate wheels spinning in a wind tunnel that does not spin wheels, and you can learn very valuable information whether you spin, use trip strips or don’t spin.   The more bells and whistles for your test (spinning wheels, rolling road, active boundary layer control, higher speeds, etc…) the more you will spend per hour.

The smaller frontal area would not make A2 any more precise.  There is an adjustable ceiling that we move for each type of car we test to accommodate blockage and the bounding streamlines to facilitate accuracy.  The precision in A2 is within 0.5% repeatability. 

If you would like to discuss further feel free to call me: 704.799.1001 or dave@aerodynwindtunnel.com

Dave

[Rex Schimmer]

Dave,
Thank you for your response! I can see what you are saying regarding the rotation or non rotating tires, it is not the exact numbers it is the trends. Make sense.

Thanks again!!

Rex

[Sumner]

Dave here is a question that I posted on one of your other threads, but wasn't sure if you saw it or not..................

Actually Seldom, I was just reinforcing Rex's inquiry on another thread concerning Lakesters (and Roadsters).  See what your biker mentality got you.

Yes I sure would like to know the typical Cd of an open wheel/tire like say a 26 inch good year.  I've heard all different figures and the one that sticks in my head, maybe not good, is about .40.

Thanks,

Sum

............. interested in a rough Cd figure for a 6 inch wide 26 inch diameter tire/wheel in open air (away from the body).

Thanks,

Sum

[Stainless1]

Sum, somewhere we got the info that open spinning wheels were a 1.16 to 1.21 depending on size.  Larger were the lower drag but still a little worse than a brick.  But I think A2 is on it with the baseline and then try to improve.  You are stuck with Open wheels in the lakester class so their drag doesn't really matter.  All you can do is try to get the best from the part you can change. 

[A2WindTunnel]

If you have open wheels then, yes, you are stuck with them unless you try various sizes (widths, heights) and different covers (flat vs. convex).  A wheel alone test will tell you about the wheel and which one is best, but what is that really telling you?  The car runs as a system and all the pieces/parts interact and talk with each other.  A solid axle will affect the wheels aero different then a control arm front suspension and any combo in between.  Also depending on how far away the wheel is to the body, the streamlines will not be parallel to the flow.  So testing the wheel alone is not the best representation of what is happening on your specific car.  And I would be careful with posting Cd # of a wheel.  You need to be really specific when you post 1.16 – 1.21 … Is that Cd or CdA?  What is the reference area if that is CdA (ft^2 or m^2)? Where did that # come from (a book, independent test)?  Aerodynamics is not as simple as if you have this Cd for one wheel you can just add 3 more to get the drag on the wheels for your car.  A parachute is something like Cd = 1.3 and a flat plate is close to Cd = 1.0 so those numbers you came up with seem really high for a Cd and that is why I am asking you to be more specific.

Here is a list of Cd for a few shapes.



This is the same on motorcycles.  Depending on the bike there different fenders might work better on some bikes but not others.

See two videos of open wheel car.  There is not smoke directly on the wheel, but you can see how the air off the front changes the flow at the back of the wheel and the flow is far from parallel to the wheel.
http://www.youtube.com/watch?v=1z9mTAW8Z0w
http://www.youtube.com/watch?v=mqi6wo8bVrs&feature=related