Wind tunnel math discussion

[eagle]

I saw that vid a long time ago , and to be honest its the reason I started reading and learning about aerodynamic changes and how I could mod my car

the reason is the same but in a smaller scale (dont have a ¼million supra)

but the wind tunnel employee at 2:16 - 2:50 says something a bit off I believe and I want to discuss

is that how aero works? I mean, I get what he is saying but...

https://youtu.be/bOmbXQbyvVM

I hope the thread is interesting to others as well

[JulianEdgar]

Originally Posted by eagle

I saw that vid a long time ago , and to be honest its the reason I started reading and learning about aerodynamic changes and how I could mod my car

the reason is the same but in a smaller scale (dont have a ¼million supra)

but the wind tunnel employee at 2:16 - 2:50 says something a bit off I believe and I want to discuss

is that how aero works? I mean, I get what he is saying but...

https://youtu.be/bOmbXQbyvVM

I hope the thread is interesting to others as well

The basic idea is correct - you can apply the V^2 rule to measured forces. eg 100kg lift at 100 km/h = 400kg at 200 km/h. (ie 200/100 = 2, 2^2 = 4. Therefore the forces go up by 4 times when you double speed.)

But.....

The chances of measuring anything accurately in such a tiny wind tunnel are basically zero. If you want to do some more reading as to why that is the case, look up terms like blockage factor, boundary conditions, wind tunnel testing with turning wheels, and so on.

Unless you can afford testing in a full-size wind tunnel, it's far better to measure aerodynamic factors in real world conditions. About the only thing you cannot measure on the road is drag coefficient as an absolute number.