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Old 06-05-2006 | 04:17 PM
  #10  
J_Whitney
 
Joined: Jun 2006
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From: Castro Valley, CA
Default RE: Let's Loft!

ORIGINAL: Chad Veich

Geardaddy, Compufoil will indeed reduce this whole process down to a few minutes and is well worth the money. I have it and have used it but have not gotten really comfortable with it yet. One thing, not every airfoil that one may need for a scale airplane is available in Compufoil and I have not reached the point where I can edit the existing airfoils to get where I want to go. Guess I need to learn a bit more about interpreting airfoil coordinates! Still, lofting the old fashioned way is a good skill to know and have in your "tool box" even if you are using some form of lofting software most of the time. I'd be very interested in somebody doing a tutorial on how to really use Compufoil effectively.

Mike, if you have any sort of drafting skills at all then you are ahead of the game when it comes to learning CAD. The majority of the basics necessary to draw up plans can be learned quickly. However, learning to really use CAD to its' full potential may take years! I'm at the point where I can find ways of doing most of what I want to do but my gut tells me there are more efficient methods that I have not learned yet. I really am considering taking some night courses in ACAD just to learn some of the finer points. I use ACAD every day at work, and have for the last 6 years or so. However, I use it in a pretty limited capacity for my job. I've learned far more drawing airplanes than I have learned at work!

Kelsey B, thanks for the kind words. Generating the airfoils can be easy or quite difficult depending on what tools you have available and what airfoils you need. For those designing scale models I highly recommend you bookmark "The Incomplete Guide to Airfoil Usage" found here: http://www.ae.uiuc.edu/m-selig/ads/aircraft.html
This site lists the root and tip airfoils for a huge number of aircraft. Some airfoils are quite easy to find references on while others can be impossible. Of course, if you're not going to use the scale airfoil then the whole process may be much simpler.
Chad, check out the autocad commands MEASURE and DIVIDE, and the related commands PDMODE and PDSIZE. Divide will divide a line (circle or arc) into any number of user specified segments, placing a point (PDMODE and PDSIZE) at each segment. MEASURE will place a point at whatever distance along a line (circle or arc) the user specifes, with no regard for "leftovers". i.e. - you tell it to measure along a line that is 10.5" by a distance of 1" - there will be a 0.5" piece "left over". Both commands are really handy if you want to put an object on another object a repetitive numver of times.

BTW - the input ordinates for Compufoil start at the leading edge, go back along the top and continue forward along the bottom. Once you figure that out, it should be easy to input your own ordinates.

HTH,
Jeff