Posted on

EPP Foam Citabria Prototype

The Citabria Prototype is now completely cut out with the CNC.  I have a few minor adjustments to do before I cut out the next few planes.  I will be giving some to friends for beta testing.  I am also documenting the process with both video and pictures.  This picture are all the foam parts ready to be assembled.  The total weight of the foam is 10.3 ounces.  The wingspan is over 52″.   I can’t wait to fly this later this week!!!

I’m still planning to use a 480 plus electric motor on a 3s-2200mah battery.

Posted on

Citabria Wing Design Finalized

Citabria Wing Set

I finally finished the design on the Citabria wing.

Wing is hotwire cut on my CNC from #1.3 White EPP Foam.

This was challenging due to the wing tips having a compound taper.  My CNC was at it’s limitations for the majority of the hotwire cut.  It took a lot of CAD work and tinkering to finally get the wing tip to fit in the machine and properly cut out.  I think I cut over 10 different wing tips before I finally got it.  I also had other challenges like buggy software, loss of files on my computer, and in general several (I’ll spare you the long story!) unexpected external events that pulled me away from the project.

I’m really excited about the Citabria.  It is finally coming together and I can’t wait to fly it.  I’m still shooting for a target of about a 480 size motor, 3s-2200mah battery, and the wing span will be 54″ with a removable wing.  If you want a clipped wing version, then don’t add the wing tips to have a 48″ wingspan.  Or just cut off the ends of the main wing to make it shorter.  I think this will have some silly STOL capabilities with a 54″ wingspan and flaps.  I can’t wait to play with it.

I am now getting over a cold, so the fuselage may take a few extra days to complete.  I’m trying to decide exactly how I will make it.  One thought is to do a clam shell style design with a left and right shell that is hollowed out with my mill.  The downside of this is that the entire fuselage will need to be cut out with the mill which means rougher cuts and longer CNC time.  The other option, which I might actually go for, will be to have the fuselage made in three different sections.  We’ll have the main center section sandwiched between a thinner left and right sheet.  This will allow me to use the mill to hollow out the center section, but the outside pieces from the sheet will leave the outside of the fuselage smoother.  Do you have another idea?  Let me know.