![Image](https://d2t1xqejof9utc.cloudfront.net/pictures/files/3683/large.PNG?1328856357)
on this screen you need to select external, then check the two check boxes at the top
you'll need to select gravity and it will give you a value something like -9.88...etc (this appears once you've selected it). Make sure you change this to the vertical axis. in this image its y. Make sure the other two axis are 0
![Image](https://d2t1xqejof9utc.cloudfront.net/pictures/files/3684/large.PNG?1328856358)
i know you can't see it, but at the top you need to select air
![Image](https://d2t1xqejof9utc.cloudfront.net/pictures/files/3686/large.PNG?1328856361)
here is where your problem is. In this picture lets use the z axis. because you want the air flowing in the direction of your model not in the direction of the z axis arrow (see bottom left) you'll need to put -75 in the velocity direction for axis x.
(or whatever m/s your running)
hope this makes sense? give me a shout once you've done it and i'll explain setting up goals to get your downforce and drag values
i don't claim to be a pro in solidworks, this is just what i've gained from youtube videos etc.
this is a good video, you can find part 2 easily. it gives you everything you need to know about running a test. it just misses out the gravity bit
http://youtu.be/ctBA_4rkhPo