Autocad advice!

[effer]

I would like to calculate the frontal surface of a Campagna T-Rex ( from a front picture ). Because I want to calculate its Cx ( 1/2 d S Cx v sq )

Knowing air density, frontal surface and Cx what would you suggest to me to calculate it experimentally? ( I have an idea but it is good to have different point of view... )

Is it possible with autocad?

Thanks!

 

[Aero]

What is Cx? Coefficient of something I assume. You also say you want to calculate Cx but list that as a known. Your equations look like the the eqns for coefficients of drag and lift...with some differences.

 

[Jin1976]

You mean Cd (Coefficient of Drag). I forgot the formula. :biggrin:

 

[Jimbo]

Effer,

You could use Autocad or you could do it in Photoshop if you wanted.

What you need to calculate is the frontal area. So, if you have a scale photo taken looking dead on the front of the object (car), all you need to do is find out the 2D area that is blocked out by the object from the front. Or more simply, the front silhouette of the vehicle. You could even get a good approximation with graph paper.

Of course, I don't know how accurate you need this to be.

-Jim

 

[caz-nsx]

College flashback :smile:

If you are trying to find the area of a 2D geometry you can use CAD tools, but then you have to draw it all out. If you can get access to a planimeter and a good picture you can acheive the same result much faster. Just scale your results.

http://whistleralley.com/planimeter/planimeter.htm

 

[Aero]

They're right about just scaling the frontal area. Using the 2D frontal area as any basis for calculating a drag coeff. (or whatever) is not going to be an accurate estimation anyway so why get the area exactly right if your other calculations are going to be a back of the envelope thing anyway. You're almost better just guessing.
You can probably do some google searching for drag coeff on motorcycles and maybe even find what you're looking for but I doubt it. I bet its probably around .5 or so.

 

[effer]

You mean Cd (Coefficient of Drag). I forgot the formula. :biggrin:

I think so...yes.

I am not familiar with Autocad nor Photoshop, is it easy to use?

Thanks all!