Make the Easy Dragonfly Helicopter
Wherein young Heroes become empowered by making and flying helicopters (whilst learning a thing or two about patience when winding them up).
Here is the embedded instructional video on YouTube. If YouTube is blocked at your school, click to stream on this highly compressed video file (16MB MPEG).
Below are instructions for the easier version of Dragonfly Helicopter with an already-made injection-molded propeller. The numbers correspond to the steps, also numbered on the video.
1.) What if you just don’t have the time to make a Dragonfly Helicopter completely from scratch; and/or you’re working with young kids? The EZ Dragonfly does not fly as high as the scratch-built kind but it’s easier even for young kids to participate in building and it making it goes fast enough that it works for a crowded event. It will still go as high as a gym ceiling. [You have to wind it up a lot though—a good way to learn patience. ]
2.) Put a propeller on a balsa stick. Hold it close or else this might happen. [there are a few extra sticks if that happens]
You might notice that the propeller is not quite perpendicular. It’s OK, it’s supposed to be like that. [The reason is that the propeller is made for model airplanes, which tend to ascend at too steep and angle, then stall. But if the propeller is pointed slightly down, there is less stalling, better flight for model airplanes. And it does not hurt the flight of helicopters at all] The propeller is so efficient that it will act like a windmill when air hits it. But don’t clock somebody.
3.) This is the mother of all rubber bands. From one end, cut a piece 28 cm or 11”—which happens to be the length of North American printer paper. [A piece of 8 ½ by 11 printer paper—the long way—is a fast way to measure it. But A4 is longer. Use sharp scissors to cut. Nonstick scissors (Teflon coated) work especially well]
Tying is easy, but confusing at first. The overhand is the simplest knot there is—just make a loop and put the end through. But we put the two ends together and treat them like one strand. [By the way, mountain climbers know this as the European Death Knot!] But we need to move the knot to the end. Pull tight gently tight. Hold inside the loop, right next to the knot, and pull. Amazingly, the knot moves toward the end. This does not work with regular rubber bands, but this special stuff for model airplanes is amazing.
4.) The rubber band hooks onto the propeller in front, and it needs another hook in back. Try to make the back hook on the same side as the front hook. Cut or pull the cotton off a swab stick. Cut some tape and stick it in the corner at an angle like this. Wrap the tape around. Cut off the extra. The knot always goes in the back. [because it tends to get caught on the fuselage] We don’t want the rubber band to cross like this because of friction; but if it does, just flip the propeller the other way.
5.) Cut the wing from the flat part of a recycled foam plate or takeout container. Print out a pattern page and cut out a double pattern. Tape it on the ends. Rough-cut off those pesky edges. The thin foam cuts easily with scissors once you’re past that. Once you have a set, you have easy tracing patterns.
Tape the ends of the rectangles together. Get the rubber band out of the way and put the wing on so it’s about 25mm from the propeller. Attach it with a couple of pieces of tape. Rub the tape so it really stays on.
It’s optional to curve the wings up—which is called dihedral. It makes the flying more stable. Splitting the wings to look more like dragonflies does not affect the flight.
When you put the rubber band back on, make sure it does not catch on the wing like this—too much friction. Decorate if you want to
6.) Your helicopter will go higher if you dab some soapsuds, liquid soap or shampoo right here to reduce friction.
As the propeller is facing you, wind the propeller clockwise. Most people do not wind enough at first. The first 50 or so turns don’t do much. Then, as the propeller pushes back more, each turn means higher flight.
If this project works well for you, please help spread the word about a good hand-on science project. If it is not working well for you, communicate with me—Slater—about what’s happening so we can solve the problem.
7.) [Paper is heavier than foam and not as rigid, so it is not rigid enough to stick out far away from the fuselage. But these paper wings with lots of surface area compensate. Note that paper becomes very limp and weak in humid weather. It might stop working once it absorbs moisture from the air.]
If you don’t have thin foam, you can make the wings out of paper. Although paper is heavier and doesn’t look like a dragonfly, it’s easy and flies almost as well. Just cut a piece of printer paper into quarters. It’s best to orient the long side perpendicular to the fuselage. Whatever side the back hook is on, put the paper on the OPPOSITE side. A couple pieces of tape hold it on. I like to clip the top corners. [the top corners of paper are weak, so they can flutter around and cause problems.
You can fly the helicopters just like this. An advanced aerodynamic trick is bending flaps in the bottom corners like this. It resists spinning even more.
As the wind from the propeller is diverted one way by the flaps, the reactive force on the wing the opposite way. If you make the flap the correct way, it makes the wing more effective for keeping the fuselage from spinning too much.
Pattern for Easy Dragonfly Wings
Back to the Dragonfly Helicopter Introduction Page
Make an Eco-Empirical Dragonfly Helicopter
Make an Easy Dragonfly Helicopter
Make Dihedral Magnus Effect Gliders to Launch Up
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