i think the A2 guy is right and wrong... right fron the standpoint that you can refine the body without the wheels spinning but wrong in implying you can get results without the sum of the whole package... you can get you lakester as dialed in as possable but as soon as you spin those tires all your hard work may just go out the window... especially if the wheels are close to the body for the wash to screw up your nice new bodywork... if at all possably test as you will be running... it may be more money getting into a tunnel that has a rolling road like swift but it wont be waisted money like if you test without....kinda like peeing in the wind ....
kent
Like I said, there are ways to simulate the turbulence of the wheels spinning in a non-spinning application. Is it perfect? No, it's a simulation, and for indy car teams to have done this for many years I can't imagine all those engineers would consider it "peeing in the wind". I'm pretty sure they found some value in testing this way or why waste the $$ and time? Is any wind tunnel perfect? No. A wind tunnel is a testing laboratory with a
Controlled environment to keep variables to a minimum and able to give precise, accurate, repeatable data. Even rolling road wind tunnels have limitations and compromises. I am on here to help you guys learn about wind tunnel testing and the importance of aero. I think 1212FBGS is missing my point. The point is you are not looking for absolute values no matter which wind tunnel you test at, and a "simulation" of the wheels spinning is not the best, but you will still see what changes help and hurt the car. You also need ask your self this. If a rolling road wind tunnel is the only way to test, then why would non-rolling road wind tunnels exist? Because you can still learn useful information without the wheels spinning and race teams have done this since the 70's before they had rolling road wind tunnels.
I am not on here by any means to say that A2 is the only wind tunnel, and everyone should test here . However, A2 is a great wind tunnel for $390/hr when compared to other options. I did put the list off all my competitors (Full Scale Car) on this thread for all of you to see what options are out there and the costs associated to see if they might better benefit your racing program. I did say peviously that I do not have info on which tunnels test motorcycles or costs, but welcome any info that someone is willing to share. There is one FULL SCALE rolling road wind tunnel in North America (wind shear) at $4500/hr (Swift is not a FULL SCALE wind tunnel for cars). Another one is AeroDYN, which has an active boundary layer control system (simulated moving ground plane) with spinning wheels, automated ride heights, and is where nearly 100% NASCAR teams test at $1600/hr. If you think the add $$ is worth the wheels spinning for your car, and the only way you can get useful data, then I welcome you to book some time at either of them. We have NASCAR Cup, Nation Wide, and Truck teams in A2 testing without wheels spinning and the teams seem to find the information learn very valuable and useful (these teams have been to AeroDYN, full scale and scale rolling road tunnels). I have also had several open wheel car teams in that found the information valuable, and the LS open wheel cars and motorcycles that have tested did go faster after the information learned in A2 (for whatever that is worth).
Track testing is another option and can be done, but you have many variables to keep track of, and one variable you cannot control on the track is the natural conditions. If you make one pass early then make one late, what are the changing conditions between the two? : head wind, cross wind, temp, salt conditions, engine, tires, etc... There are engineers at all the auto manufactures that have made careers out of track testing and even they will tell you it is not a simple thing to do. You do need to validate what you learn in a wind tunnel with track testing, but just putting something on at the track and looking at your speed is not the whole picture. Just a 5mph head wind can affect your drag at top speed. So does that mean that the piece you put on didn't work? Did it add downforce and added traction made the change in speed or was it drag related? These are just a few questions that you need to ask yourself when track testing. Plus the time/$$ it takes to track test. Say it takes you 4 hours to make two passes where the conditions changed and you are not sure how to interpolate the data. In a wind tunnel you could make 25 runs and test 25 different things and know exactly how much of an affect it had on drag, downforce front/rear, side force front/rear. How many trips/$$ to the salt would it take to test 25 things in “ideal” conditions to find the best configuration for your car/motorcycle?
Here is a video of A2 conduction a bicycle track test at Lowe’s Motor Speedway. They did not talk about all the variables that we monitored because they didn't have time and it would probably make the video really boring to those non-nerds. But it did show that it can be done and it correlates with what we learned in the tunnel.
http://www.testrider.com/fly.aspx?layout=player&video=1 I think this might need to be split to 2 treads: cars and motorcycles. What do you guys think? We have been talking about open wheel LS cars and then a motorcycle question gets thrown in which is two different set of answers when it comes to rolling road tunnels that can test a car or a motorcycle. I don't want the car guys to think they can test in a scale tunnel, and at the same time I don't want motorcycle guys to think that there is only one rolling road wind tunnel in North America they can test.