Re: CAD programs

Robert Reynolds wrote:
> 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?

Look for "spline" or "Bezier" in the help screens.  That's the names for 
the technique of drawing complex curves, and every drafting package that 
I've played with has that feature, one way or another.

With the right package there should be some way enter the coordinates of 
your airfoil of choice, and have the drawing package complete the curve 
nicely.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html