Wind Tunnel Smoke Testing

[A2WindTunnel]

I know lots of you have interest in wind tunnel testing and aerodynamics, but wind tunnel data/info is not easily accessible.  Here is a video of some smoke testing in AeroDyn and A2 that you guys might find interesting.  In the video are some smoke tests preformed in both tunnels and I even included a few motorcycle videos since I know there are lots of motorcycle guys on here.

http://www.youtube.com/watch?v=LOH570HyAVw

Dave

[lvsalt]

Very Nice

[RidgeRunner]

      Learned a lot with just one quick viewing, as usual answers bring with them more questions.  Lot more to think about and study these winter nights, keeps the brain working.

     Thanks for posting.

                               Ed

[stratman59]

Thanks for sharing very interesting!

Robbie

[wobblywalrus]

Dave, that was interesting.  Thanks for showing it.  Are there sensors on the pad to measure the force it takes to hold the vehicle in place, so the drag coefficient can be calculated? 

[A2WindTunnel]

At both wind tunnels there is a 6-component balance instrumented with load cells under the floor in the basement that will measure

-Drag
-Lift Front (negative lift is down force)
-Lift Rear
-Side force front
-Side force rear
-Pitching moment
-Rolling moment
-Yawing moment

AeroDyn will capture the cars at the frame rails (in all 4 corners) with ride height actuators and the wheels set on rollers that connect to the balance as well.  We take out the shocks and springs so the car is free to move vertically to any attitude the team wants to test.

A2 is more of a general propose wind tunnel and we have pads that connect to the balance in a wide variety of configurations with a wheelbase range of 40-240 inches, track range of 40-76 inches.  Motorcycle wheelbase range: 40-80 inches.  If we were to remove the flooring the car would be free standing on the balance and this is how we take measurements in the wind tunnel.

Attached is a picture of the floor and pad arrangement in the A2 tunnel.

[SPARKY]

is it practical to test partial vechs like noses, tops, bottoms?

[JackB750]

Hey, I know that orange bike!

Seriously, all of what Dave is saying here is true. A few hours in the A2 tunnel can unlock substantial improvements in any LSR program. I know it did for us!

If anyone is interested in learning more about their test process from one who has been there, feel free to contact me by PM here or email at jhbfly@yahoo.com.

Jack Broomall

[A2WindTunnel]

Insert Quote
is it practical to test partial vechs like noses, tops, bottoms?

There are so many interactions that happen with a vehicle that I’m not sure you could decipher the data into something that would translate to the finished vehicle.  An example is just sealing up a radiator opening would have any effect on drag, front lift, & rear lift all together, so what you do up front can translate all the way to the rear and its not as simple as just adding up components to get a result because the air has to pass over all the components together as one system, and they all “talk” to each other aerodynamically.

Another example is a rear wing on a car.  You could test the wing alone and get data on it, but now you put it in close proximity to a deck lid, and you have change the suction side distribution of the wing (lower side) and the streamline of the air are now changed since it is now traveling at and downward angel from the roof down the rear glass as where in free stream it is horizontal to the floor.  Any separation off the A-B-C pillars or rear glass will affect the air flow over the wing and something like a scoop could be turbulent enough to affect the center section of the wings performance and will not let it work as well as the outer section of the wing in cleaner air.

I’m not sure if that helps answer your question any better?  If not, can you give me an example of what types of components you would be talking about?

[A2WindTunnel]

Hey, I know that orange bike!

Seriously, all of what Dave is saying here is true. A few hours in the A2 tunnel can unlock substantial improvements in any LSR program. I know it did for us!

If anyone is interested in learning more about their test process from one who has been there, feel free to contact me by PM here or email at jhbfly@yahoo.com.

Jack Broomall

Jack,

It was great to have you in the tunnel and glad you had a productive day of testing.  Thanks for the use of the pictures and footage for the video.  It was a big hit at the PRI show in Orlando and you got some comments on your bike.

Dave

[joea]

Jack how many mph gain can you attribute to the aero
changes you made from the windtunnel info...?....

[joea]

bump...

[PorkPie]

A windtunnel is good to prove the concept.......... 

But the right way is - at first you check the base and investigate where improvements are necessary....and therefore you need not a windtunnel.......you need experience in seeing the airflow  .

Sometimes there are very small things......and a small modification of them bring you a big step forward.

See Stainless bike.....the changes he done was so small......but the effect was......a speed increase from 200 mph to 210 mph.....and the Junior in the 2 Club.....

For someone from the outside....who has nothing to do with aerodynamic....had said.....what this need to be changed...
why....what kind of improvement will bring this change.......but airflow is a very strange character...... 

[k.h.]

Hey, Mr. Amo--  I sent a link to Rocky's article on your bike to an engineer who ran at Bonneville some decades ago.  Here is his response:  "Finally took the time to open the web page you provided; nice bodywork from an aero point of view - real nice.  I wanted to do somewhat the same, but had an agreement with "Company X" (k.h. edit) to have the bike as close to production as possible." 

Bikes have a lot of eddy and drag creating areas to deal with, what with the front aero broken by gaps to fenders, cut outs for rider, etc.  Doing smoke can help with identifying places of turbulence, but the round front/pointy back streamlining get about as good as possible and stay within the rules.  There is one more significant factor on the fastest sit-on bike that (it appears to me) makes it different, but I won't mention it here.  From the safety and comfort of my armchair, there is one thing I would change.  I won't mention that here either.  As for the wind tunnel, I'm waiting on full scale parts for an aero project unrelated to LSR, then have to use a tunnel to test them.  These folks in N.C. aren't that far away . . . hmmm.

[JackB750]

We spent just over a half day in the tunnel with two bikes. First we ran my 750P-P Suzuki GSXR 750 just as it had been run at Speedweek about 8 weeks earlier. As you know there is a pretty limited menu of things that can be tweaked on a P-P bike. We did however find about 8 aero HP mostly by fidding with tuck position as well as suit, helmet, and boot details. We also learned that some things that are accepted as "conventional wisdom" aren't necessarily true. This bike had run 172.242 on a 172.029 record (couldn't quite manage that backup run!). At those speeds 8 aero HP would translate to 2-3 mph - a very worthwhile improvement on a production class bike. We'll find out more next August-stay tuned! We also ran baseline tests on the orange GSXR 1000 that you may have seen in the A2 youtube video (also Dave Salazars avatar!). Aside from learning that the 1000 is overall lower drag than the production 750 (bike is an ex-KWS motorsports AMA Road Race bike with race bodywork) we confirmed some of the tuck things we learned on the 750. From the smoke studies we gained considerable insight regarding some ideas to clean up flow in sensitive areas such as between front fairing "beak" and the front fender interface, behind the rider's butt, and around riders feet/boots. From the time we rolled the first bike into the building till we drove out was less than 6 hours. The whole experience was very efficient. We received a  good complete data summary as well as video and photo results. This is a cost effective way to learn how to go faster.
Jack