CAD programs

I've been looking for a CAD program for creating model plans.  I 
downloaded a few free ones to see which features I like and which ones I 
don't like.  I've noticed that circle, arc and ellipse are very common 
features, but I haven't seen a program yet that will do the complex 
curves required for drawing airfoils.

I downloaded the free version of RC CAD, but it looks more like a toy 
than a drafting program.  The help file says I can select different 
airfoils with the full ($49.95) version, but you still can't make real 
plans with it.

The reason I'm looking is so I can draw plans for some of my designs and 
offer them to the public on my website.  I want to make the drawings 
detailed enough for a relative beginner to be able to build a decent 
airplane from them.  The first plane I'm trying to do is a 6 foot 
wingspan bomber that is capable of carrying 7 aluminum cans or a couple 
of rolls of toilet paper.  So far I've drawn most of the structure in 
the fuselage, but I just don't know how to draw the airfoil.  Any 
suggestions?