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Old Sep 14, 2011, 06:25 PM
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Cool
Walkalong gliders

Has anyone seen or tried these before? I stumbled across them the other day and thought it was pretty cool. To learn about them go to sciencetoymaker.org
Let me know what you think. And sorry if i didnt post this in the correct place. Have fun all!
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Old Sep 15, 2011, 09:21 AM
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Upvector's Avatar
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Paul McCready invention...???

Quote:
Originally Posted by zoomer088 View Post
Has anyone seen or tried these before? I stumbled across them the other day and thought it was pretty cool. To learn about them go to sciencetoymaker.org
Let me know what you think. And sorry if i didnt post this in the correct place. Have fun all!
...seen this....???

Walkalong Glider with Tyler MacCready (3 min 37 sec)
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Old Sep 15, 2011, 09:45 AM
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I first became aweare of th type when I met Pete Plumb, back in th elate 80's when we shared a booth and travel arrangements from California's Central Valley to IMS Pasadena.

Pete took one of my "legal sized" product flyers and folded it into a paper airplane, of the flying wing type. He then proceeded to fly it around the table using my table top foam board sign.

Not to take anythig away from the young (then) MacCready boys, bu t Pete who worked on the original Condor, said the atmoshere among the crew at Shafter Field was conducive to aerial exprimentation of all kinds, and was one of many things they did in the "off times" for laughs. Pete operates his Cerified Aircraft Repair Station, about 200 300 yds from the Kremer monument, comemorating where the first sustained human powered flight took place.
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Old Sep 15, 2011, 03:45 PM
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That was really cool. I would love to build a foam glider like that. I've been working on making a foam cutting hot wire but the lionel train transformer i've been using makes the wire too hot... :/ Just melts the foam into a black goo.... lol I've got a few paper gliders, but they fly too fast for small indoor rooms.
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Old Sep 24, 2011, 01:06 PM
SlingWinger
San Bernardino, California, United States
Joined Oct 2004
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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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Old Sep 24, 2011, 01:32 PM
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I've got a foam one like in the video. They came in a two or three pack and I got them at a toy store of some sort. Prior to that I had seen them demonstrated on TV. The person was making them out of telephone book paper as it was very light.

Jim
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Old Sep 24, 2011, 01:43 PM
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i use the squishiest lightest eps foam i can find and cut it to about 1mm thick, that stuff is so light it only takes a tiny piece of tin foil or brass shim to make just about any shape glide. i even did some asymmetrical gliders with it, they all fly slower than a normal walking speed
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Old Sep 24, 2011, 04:07 PM
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so i made just the model you were describing, a 13 inch span hang glider plan-form and it works real nice

its cut from 2mm depron sheet, total weight before cutting the skeleton is 1.9 grams, after it was 0.3 so that removed 1.6 grams of weight keeping just enough foam to hold its shape. i rounded all the inside corners to help prevent the foam from tearing (just as the skeleton planes do for indoor rc models)
the covering is a very very thin plastic bag which with the spray adhesive added 0.1 grams so its AUW is 0.4 grams.

after fiddling with the outer ribs to get the washout right, it floats across the room nicely, now i need to build a pilots frame and a pilot
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Old Sep 25, 2011, 02:11 AM
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I really like the looks of that plastic covered glider you made. Would you be able to make the same thing from a foam take out container? Or something of that sort. I have no idea where I can get depron where I live.
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Old Sep 25, 2011, 03:11 AM
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a foam container or even foam plates may work, only difference would be that you would make the wings in 2 pieces instead of one, and maybe a bit smaller than i did.

i added a control frame and a pilot to it also. it took the weight up to 0.6 grams, but it still flies really slow and stable. its interesting that it never needed any ballast weight to fly, just trimming.
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Old Sep 25, 2011, 02:19 PM
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Whats the wingspan on your glider? Can you fly it with just your hands?
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Old Sep 25, 2011, 02:42 PM
SlingWinger
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Great job Derk!
While your glider looks slightly different than the ones I make, I'd say you hit the nail on the head!

Zoomer 088,
Any source of lightweight sheet foam will work, but if you're going to use the "beaded" injection molded kind you'll want to make a hot wire so you can make thin sheets from it. Don't be intimidated by this, A short hot wire about a foot long, using a piece of "E string" guitar wire or it's equivalent will do fine using a cheap transformer, or the motor output from an RC ESC, using your Tx as a controller. Only need maybe an amp or three.
At these very low speeds and sizes, the Reynolds number is extremely low, which means with airflow more viscous than it is inertial. That's the way it was explained to me anyhow, but what it boils down to is that your wing can't be too thin, and it's easy to bend in too much camber, although of course you do need some of it. For this type of model flying lightness is God.

The foam picnic plates are made from "extruded" foam and aren't beaded like the injection molded stuff. This foam has a smooth "skin" side and a more grainy or foamy looking side, while Depron doesn't have this. Depron is less dense and softer. The picnic plates are cheap and thin enough, but you can run meat trays thru the hot wire slicer and get any thickness you want, you can even make sheets that are tapered in cross-section, even "airfoil" shapes which allow for thicker leading edges than trailing edges, giving better ding resistance. Don't be afraid of making the hot wire slicer, after some practice you'll be a proud pro, and it will really open up your horizons.
I've seen them powered with a few D sized batteries even. Just run the wire across a piece of flat board, scrap particle board is fine. Use some sort of spring or weights to take up the slack as the wire will expand it's length as it heats. Place shims under the wire to give the thickness you want, and slide the foam over the wire with a a book or something on top to hold it flat. You can just tilt the board and let gravity slide it.

Derk has intermediate ribs on his glider, which add a little weight but probably give a bit more control over the gliders' shape. I only use the center and tip ribs, and because it's sheet foam instead of balsa sticks, I like to make rounded wingtips, and use a bit of taper and higher aspect ratios, not for any aerodynamic reasons but for aesthetics. I fly hang gliders and I like the way the modern gliders look, especially my Seedwings Sensor 610.

Keep up the Good Work guys!

Steve
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Old Sep 25, 2011, 03:24 PM
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Cool! Thanks for all the help guys!! I don't plan on giving up on the hot wire. So as soon as i can get something going ill post some pics.
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Old Sep 25, 2011, 04:07 PM
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Is there any way you could post a vid of it flying?
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Old Sep 25, 2011, 06:52 PM
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well, i could have yesterday as the weather was really calm, but today its trying to rain and very windy

but i will try to get one somehow.
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