Make the Ben Bug and Tri Bug: Instructions and Video
Click here for the video that goes with the text.
If YouTube is blocked at your school, try this Schooltube link.
Back to Air Surf main page.
Back to sciencetoymaker main page.
|Ben Bug and Tri Bug (from scrap)||Baby Bug|
|The Baby Bug is a good beginning design and very efficient flying.|
Numbers in parentheses (1) correspond to the numbers in the corner of the accompanying video.
(1) This is Ben, one of my 6th grade students. His older brother made a Baby Bug and there was only scrap foam left over. So Ben invented a sleek-looking and good-flying glider from this scrap. Let's call it the Ben Bug. And from these two scraps you can make another glider called a Tri Bug. We'll start with the Tri Bug because it's a little easier to adjust.
(2) After you cut the front and back of the Baby Bug, put the two fatter triangles together like this. Use a little clear tape to hold the pieces together.
(3) Fold about 38 mm or 1 ½ inches from the ends. A ruler perpendicular to the back edge makes it easier. The back edges must line up evenly. Once you've established the fold, make the point stand straight up, perpendicular.
(4) This next step is hard to explain, but use your thumb and finger to sort of push, and almost pinch, the back edge. The goal is to bend just a tiny bit of the back edge UP. This flap isn’t quite 2 mm wide, and it bends up about 45 degrees.
(5) If you launch now the glider just flops around. It needs front weight.
Cut out the pattern for the Tri Bug front weight, or cut a scrap of printer paper about 4 mm wide by 90 mm long (which is about 5/32” by 3 ½”). Tape it onto the front with a little piece of tape.
(6) If you launch it now it might dive to the ground too fast. So curl the paper over the scissors.
Pinch from behind and launch, gently. If it pitches up and down in peaks and valleys, correct it by straightening the paper. This shifts the weight—or “center of gravity” forward. Straighten the front weight just until the Tri Bug glides smoothly, without much stalling.
(7) It shouldn’t turn much if the glider is symmetrical, but if it turns severely in one direction, try bending the back edge opposite the turn, up a little more. This seems to create some drag, which turns it the other way.
(8) Instructions for flying are at the end of the Baby Bug video, but try this. Deflect air upward with something flat like cardboard, a cereal box or a book. It has to be almost vertical, up and down, to deflect air up and over.
(9) When you fly, notice that when the glider is below the top of the board and ahead of the board, it goes down. Here I’m doing everything wrong. I launch low, let the glider get low on the board and the glider gets ahead of the board.
So try going so fast that you make the glider blow over the top of the board. Notice how the glider bumps up high just before going over. This is where you want to explore and experiment: where it starts to go up, but before it goes over.
Launch and fly high. Don't let it get ahead of you.
(10) Steer by pushing the glider in the direction you want it to turn. You can even experiment with hands only gliding. Hunt for the place where it bumps up.
(11) If you bend the front 5 mm of the leading edge to a gentle curve DOWN—especially in the middle--you can noticeably improve the Tri Bug’s flying efficiency. The curve is much more subtle than the back bend, and wider, and down.
With the front edge curved down, you have to readjust the front weight; shift it BACK a bit. You might be able to cut off some weight, further improving the efficiency. Experiment with the curve. See what works best.
(12) So, congratulations, you’ve gone from a couple of scraps to advanced aerodynamic investigation, all with your own hands.
The Ben bug is similar to build, but needs less weight in front. Even if you don’t get these scrap gliders flying right away, you’ve gained valuable practice for making and flying the other gliders. Happy flying!