MAKE A MOSQUITO WALKALONG/AIR-SURF GLIDER (text only)
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Below are text details for the video about making a Mosquito walkalong/ air-surf glider. 1.) Translate to any language. There are also print-friendly, illustrated instructions here.
The pattern for the Mosquito Glider is here http://www.sciencetoymaker.org/airsurf/images/GLIDERS/MosquitoPattern.pdf
First, a word about the music. Starting in the 1970s Alan Stivell revived world interest in the Celtic harp. His website is here http://www.alan-stivell.com and you can see the original early concert here http://www.youtube.com/watch?v=x_4-dx03sso
Mosquito Gliders are made from extremely low density foam that I call Time Warp, sliced to a thickness of .5mm. It is not unusual to accidentally rip the first piece. Handle it very gently. You can buy the foam from sciencetoymaker.org inexpensively and the sheets come with a glider that is already made, ready to fly. Examining and flying the ready-to-fly glider will make it much easier to make your first glider. You won’t just be blindly following directions. Walkalong gliders are great to experiment with, but follow the directions exactly for the first one—then innovate. You can get foam sheets and ready-to-fly gliders here.
Although you will be able to construct gliders in a few minutes once you are familiar, the first glider you make will seem to take forever. If making a walkalong glider that you can surf on an invisible wave of air is important enough, you’ll find the time and attention to invest in the first one.
3.) Print Pattern
It is possible for the size of the patterns to become distorted—usually smaller. In the print dialogue box of Acrobat PDF Reader and Safari, do not allow “fit to page”. Set it to “100%” or “no scaling”. For Explorer and Mozilla go to File, Page Setup, and uncheck the “shrink to fit” or similar option. After you print out, there is a 2 inch and/or 5 centimeter scale check to make sure it’s correct.
4.) Rough Cut Pattern
There are some black dots on the pattern in three places: the front point and the two back corners. Cut on these dotted lines so that the pattern will fit ok on the foam.
5.) Tape the Pattern to the Foam
Get the pattern centered on the foam as shown, so the pattern is completely on the foam, not sticking over the edge. Equal amounts of foam stick out each side, so you can tape the pattern to the foam on the ends. I am using red tape only so it shows up on camera. Do not fold the tape over to the other side.
6.) Fine Cut (but not taped ends yet!)
Cut on the outside solid line BUT DO NOT CUT OFF THE ENDS WITH THE TAPE YET. You need to make 5 folds before separating the foam from the pattern. When cutting, I cut exactly on the outside edge of lines.
7.) Fold on the Dashed Lines (starting with front camber)
You are just establishing the folds in this step. Later you will set the exact angles. Use a paperback book that is at least 6mm thick to make folds.
Start with the 2 front “camber” folds. Tuck the glider under just
the cover of the book so that one of the dashed “camber” lines
just peeks out. The camber folds create an airfoil shape that makes for a more
efficient, easier to control glider than one with a flat wing.
Fold down using your finger to push firmly against the edge of the book. With your other hand, hold the book cover down, close to the fold. The paper pattern protects the foam as you fold. When you take it out and flip it over, you should see a clear, straight fold line. Put it in again and fold the other dashed front camber line.
8.) Fold Dihedral
Put the foam/pattern in again so the dashed center line peaks out from the cover, but this time fold UP. It’s a good idea to use a ruler or something flat so as to apply the pressure evenly. Fold just enough to create a permanent bend; you only need a little bit of bend. Be careful not to rip the foam, because here you are pushing against the foam directly, without the protection of the paper. This fold creates the “dihedral” in the wing: a slight upsweep of the wings that increases flight stability. You do not have to fold all the way over. Just enough of a bend to make a permanent fold is enough.
9.) Fold Back Elevons
Finally, put the foam/paper in under the cover again with the back flaps (elevons) and their dashed lines peaking out. Again, fold UP: and again it’s a good idea to use something flat to avoid tearing (small tears will not hurt anything). Unlike the other folds, the elevon folds are creased more. Fold them all the way over and push down on the ruler. These folded-up elevon flaps stabilize flight by preventing diving.
Make sure you’ve made the folds correctly before proceeding. With the paper pattern on top, the front cambers fold down; the dihedral sweeps up; the back elevons bend up.
10.) Separate from Pattern, Add Front Weight
Cut off the taped ends on the solid line. You should now be able to separate the foam from the pattern. Pull apart carefully so as not to rip the foam.
11.) Tape on Front Weight (various options: paper, copper, etc.)
The front weight keeps the glider going forward. Without it, the glider flounders. The best front weight will be long and flexible so you can adjust it easily by bending forward or backward.
You can use lots of things for front weight. If you are using the ultra-low density foam from sciencetoymaker, then the following suggestions for paper and copper wire will get you close to the right amount of weight. You will still have to fine-tune it, below.
On the pattern page there is a pattern for a weight of paper, and paper works well. For front weight that’s a little stronger—good for taking off right from the board--the sciencetoymaker ready-to-fly gliders use the very thin copper wires that are found in any wire that plugs into the wall. If you are throwing away something electrical anyhow, you can strip the insulation off and salvage the copper. I suggest about 3” or about 76 mm. to start with. You might have to add or snip off a little weight.
You could also make a very thin wire out of aluminum foil.
Whatever you use for front weight, use a very small piece of tape to hold it on. I use thin, clear tape (I used red tape here just so it would show up on camera). The tape should not be bigger than a ½ inch by ½ inch square (12 or 13mm square). I know that it seems unimaginable that a piece of tape a little bigger than that would weigh too much, but it’s so!
Put the diamond-shaped tape at the end of the weight (this is tricky with wire because it wants to stick to your fingers more than the wire). Tape in on so the corner of the tape is at the front, leading edge tip of the glider, on top. Bend the glider down 90 degrees as a starting position, and adjust from there.
12.) Check Angles: Front Camber
I know that the first time building a glider seems to take forever and you are itching to fly. But this first time you have to learn to adjust the glider.
Cut out the front angle gauge. You can check the angle from the top or from the bottom. Carefully bend the foam make it conform to the angle of the front gauge. If you find that the foam springs back too much rather than taking the correct angle, I find that it helps to pinch the folds too much. Then I bend them back to the position and they seem to stay in position better.
13.) Cut out the back angle gauge and use it to make sure both the back angles are bent up that much, to 45 degrees. Later, you might have to bend one or the other more, to correct for turning, but start out with a 45 degree bend.
14.) Check the center, dihedral angle. The wings should slant up just a little bit. Too much dihedral will give you poor flying results, though.
15.) Test Glide
You will need very calm air to fly in. Outdoor air is almost never calm enough to fly. Even inside, air conditioning is aggressive in some indoor spaces. You don’t need a big room, but you need very still air.
Make sure that you are holding it right-side up with the back flaps bent up; the front wire is bent down. Hold the glider—gently--from the back. Hold it in such a way that you do not lose your dihedral.
Hold the glider high, slant it slightly downward, give it a slow, gentle push only to flight speed and let go. Try to figure out which of these is happening: a very slow, steady glide; diving (too steep and too fast) and stalling (bobbing up and down in peaks and valleys). A little bit of stalling is actually good to learn with. Stalling and diving are opposites.
16.) Severe Stalling
A little bit of bobbing is ok, but if the glider stalls severely, first check that the back (elevon) flaps are not bent more than 45 degrees up. If they are ok, then you need more front weight. You can add tape, hot glue, whatever. Alternately, for small adjustments you can you can bend the front weight FORWARD. That shifts the “center of gravity” (balance point of the glider) forward.
17.) Opposite that, if the glider dives (or seems to fly too fast) then you can cut off front weight or bend the front weight backward, to shift the center of gravity toward the back.
Keep these 4 rules in mind as you adjust.
a. Adding more front weight (tape, glue, wire) reduces stall, but can make diving worse.
b. Opposite a, cutting off weight reduces diving, but can make stalling worse.
c. For fine-tuning, you might not have to actually cut or snip weight. Bending the front weight forward is the same as adding weight (reduces stalling).
d. Bending the front weight toward the back of the glider is the same as cutting off weight.
I think it is best to adjust until the glider just bobs a little—not full stalling—then either fly it that way or adjust only to the point where the bobbing disappears. I think it is better to have a little bobbing than it is to have a little diving.
18.) Severe Turning
First, make sure that the glider is actually turning even after launch. I’ve seen a lot of people—including myself—unconsciously launch a bit left or right; and then it flies straight. Or wind causes a turn one time and people assume that it is turning by itself. So we have to look at whether it keeps turning and turning, or did it just start out that way?
If the glider always turns and keeps turning throughout the glide, you can correct it by bending the back flap, the one which is on the opposite side of the way it is turning. Bend the flap up a little. It will provide a little more drag and pivot the glider toward straight flight. However, there is a limit to how far the flaps should be bent up. At some point there will be too much drag and the back flaps will just act like brakes, so you could bend the other side down instead. 90 degrees up is too much.
19.) Once you can make a glider and fly it, experiment. At first, just change one variable at a time. So, what happens if you un-bend the elevons? How much can you flatten them before something happens? What happens if you fold in more front wing camber, or less? When you have played around with what happens when you change those variables, then you gain an intuitive understanding of flight stability. You’ll be able to build and adjust gliders easily, without thinking.
But we cannot have you not using your brain, so the next step is to start building your own designs. I am working on a new video about some of the basic dynamics that go into creating a design: weight, CG, airfoil, reflex, aspect ration, etc. Creating your own glider designs is quite maddening…and so rewarding! I’d like to hear about your frustrations and triumphs. You can contact me (Slater Harrison, aka sciencetoymaker) at http://www.sciencetoymaker.org/CONTACT.html
I will be starting a design page on the sciencetoymaker.org website to show
the world the many directions that walkalong gliding/air-surfing is going.