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        Discussion Scratch building foam trainer, need ideas

#1 kc8qvo Apr 30, 2006 05:47 PM

Scratch building foam trainer, need ideas
Hello, I am scratch building a styrofoam trainer. I had some electronics just lyin around so I thought I would make something of all of it. Anyway, I need some ideas on constructing the wing. I have 1/4" foam sheet (the blue stuff from lowes) and a 1" thick sheet, but I dont think I need to use any of that. I was going to cut ribs out of the 1/4" stuff and wrap it with the same 1/4" foam. My big question is what should I use as a spar(s)? Also, do I need a leading edge or will the foam wrapped around the ribs be enough?

The wingspan is 48 inches, chord is 8 1/2 inches, and power is a regular speed 400 and gearbox.


#2 stafphoto Apr 30, 2006 06:16 PM

For wing spars you can use either carbon fiber or small wood dowl rods.

#3 arx_n_sparx Apr 30, 2006 07:02 PM

Steve: I'd use the 1/4" foam for the spar - set CF rods into the top and bottom to really stiffen things up. FG rods can be used too - they're almost as strong and much cheaper - try Balsa Products for those. Or you can use a yardstick like I said back on RCCanada ;)

The foam will wrap around very nicely without having to resort to using a joint at the LE. Make sure you tape the snot out of the outside of the wing skin (run the tape perpendicular to the spar) using clear packing tape before you do the wrap. After the glue sets up the tape can be removed.


#4 cyclops2 Apr 30, 2006 07:26 PM

I always put in a 75% deep, full length main spar, of 3/32" ply or use a thin piece of knot free wood, if you have a table saw in the neighborhood.

Do the same on some horizontal stabilizers that show guy wires installed.

Did both on 3 Piper trainers.

Good for panic, 5G pullouts!

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