Thread: Cool Walkalong gliders
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Old Sep 24, 2011, 12:06 PM
dayhead is offline
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San Bernardino, California, United States
Joined Oct 2004
1,962 Posts
Building and flying extremely lightweight gliders is easy and fun. Try my method:

Cut out a simple swept back flying wing shape from thin sheet foam. The picnic plates from the grocery store work well. Then cut away most of the foam, so that you have about a 1/4 to 3/8" wide center keel, or rib, and leading edges and a tip rib about the same width.

Pre-shrink some tissue or better yet find the thinnest and lightest plastic bag material. The stuff from the dry cleaners is pretty good but you may find some lighter stuff, especially from indoor free-flight resource companies. You need very little strength and the lighter the better.

Smooth out the plastic or tissue and tape it down on a board. There is evidence than a "crinkly" surface will fly better than a smooth one, but I just do it any old way, they fly fine.

Take some glue and using a finger smear it on the foam frame, try for a consistent but minimal thin coat. Lay it on the covering and gently rub it down. Use a very thin and very sharp blade to cut off the extra covering.
My gliders don't have a rigid trailing edge, they are like two sailboat sails joined together, or a hang glider if you will. A rigid trailing edge will just require more ballast on the nose.

Notice that as you bend in a bit of camber there at the leading edge and center keel junction the tip ribs will rise at the trailing edge, giving a bit of washout. This, combined with the sweep back angle of 13 to 20 degrees, will provide some "planform reflex" that will provide a slight nose-up pitching moment. The sweep back in the planform will provide an adequate amount of directional stability, you shouldn't need any fins. If you add dihedral, be careful, a little goes a long way and too much will require the addition of more directional stability in the form of fins, which only add dead weight and drag.

Find some paper stickers and cut them into little squares and other shapes. When a frame gets bent and creased, just straighten it out and use the stiff paper tape to reinforce it.

If you start out with extra wide leading edges, enough to make the glider nose heavy, you can trim the CG by simply cutting down the width of the leading edges, thereby avoiding adding dead weight in the form of ballast.
However, it's fun to experiment with using pendulum stability for flying wings. Use a piece of paper clip wire or the wire from one of those twist ties.

Coil up a small length of the wire at one end, then bend an L shape into the other end and bend the leg of the L into another L. Tape this onto the bottom of the center keel at about mid chord, and simply bend the wire as necessary to adjust the CG. Keep in mind that you can bend it side to side as well as fore 'N' aft. Also experiment with the length of your pendulum, which by the way can serve as a handle for launching.

A little extra flavor can be added by using the wire to make a triangle shaped "control bar". This, combined with a foam or paper "pilot", will make a fun hang glider looking plane. There are many hang gliding websites to find pictures and illustrations, manufacturer sites will have sample planforms you can print out and use, along with side views of the pilot in flight. Try Wills Wing.

You can make a bunch of these all at once after a bit of practice. Winter is just around the corner, take all the kids to a gym for the next birthday party, I guarantee you'll be a hero as far as the kids and their mom's are concerned.

I would post pictures, but every time I try to do anything with my computer other than writing I get screwed up.
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