by Ken Denmead
See the World from the Sky
In the last couple of years, there has been a spate of stories about enterprising students and other private citizens building and sending amazing balloons, with cameras and other instruments attached to them, miles into the sky. MIT student Oliver Yeh did it with $150 worth of materials (including a secondhand camera and a Styrofoam cooler) in September 2009. These packages then return with incredible pictures, providing yet more corroboration of the curvature and beauty of our planet. Such projects have to overcome some interesting technical challenges, such as GPS tracking and the necessity to keep equipment working in very cold, low-pressure conditions. Really, they are a kind of UAV (Unmanned Aerial Vehicle).
While launching a balloon several miles into the sky is a tremendously exciting project, it is not the kind of thing you can throw together with your kid over a weekend. This project, though, is designed to help you have the same kind of fun at lower altitudes and for significantly less expense (of both money and time).
A little research on the Internet tells us that, based on the lifting capacity of helium, a group of balloons with a volume equivalent to a 4-foot-diameter sphere (around 12.5 cubic feet) should be able to lift about one pound of payload. So, to pull this project off, we have to keep the mass of our entire build under that limit and/or fudge the number of balloons (and thus total helium volume) so we can get a little extra lift. If we can inflate the “normal” balloon that comes with the kind of party kit you can buy anywhere to about one inch in diameter, then we’ll need about 16 balloons to get the kind of lift we want (each one-foot balloon would hold about 0.75 cubic feet of helium).
The overall design concept is this: Build a “column” of helium-inflated balloons, not unlike what you see at fancy parties, hook a camera to it, and let ’em fly while keeping them tethered to the ground (you) with kite string. The camera itself needs to be set securely into some kind of padded open-face enclosure so that it won’t be jarred too severely upon a rough landing (though we’re hoping for a very controlled descent). And that enclosure has to be connected easily to the kite string so that the camera doesn’t go flying a lot farther than you want it to.
The balloon method I suggest using for this project is not the only way possible, of course. A kite could work, and could potentially be somewhat less expensive and require purchasing fewer materials. However, most inexpensive kites are not as inherently stable as balloons. Balloons want to go up and stay up, and it’s you keeping them from doing so, whereas a kite, unless it has caught the wind just right, wants to come down and crash into the ground. And because for a kite to work properly, it must be a windy day, it won’t keep an attached video camera as steady as will a placid bundle of balloons on a windless day (and please, let me stress that you want to do this project on as windless a day as possible).
It is at this point that the pro-kite community will argue that there are kites that can be very stable when aloft. This I do not contend. However, I’ll point out that such kites will cost at least as much as the helium we’re using, so we’ll say touché, and move on.
A Flip digital camera weighs just slightly more than five ounces, making it an excellent choice for the technical package. Plus, a lot of geeks already have one, so it may not be an extra expense for you for this project. If you have a different camcorder, check the weight. Anything much more sophisticated than the flash memory-based models available right now (Flip, Kodak, and similar) will likely weigh too much.
Of course, sending a valuable piece of technology up into the sky, tied to a bunch of balloons, may get you an odd look from your spouse, but we have no good suggestions here to help you with that, other than telling her or him it’s for science!
BUILDING THE CAMERA PACKAGE
STEP 1: Because you’ll want to get your video camera back, you’ll need to tether your craft, and even if the kite community is still smarting from the logical thrashing I just gave them, I do suggest using kite string since, really, it’s made for this sort of thing. One reference I found online cites a weight-to-length ratio for kite string as 1 pound for 8,700 feet of string. If we restrict ourselves to a commonly available 500-foot line, that adds only 0.9 ounce to the package when it reaches full height.
STEP 2: Next, we need a cockpit for your camera (no sniggering). My choice was a piece of Styrofoam I picked up at my local hobby shop. It was actually purposed for carving out mountains for model train landscapes, but the size and strength were right to work with, and the density was great for cutting with a chop saw. Foam packing material that comes in standard toy or equipment packaging may work as well, though it’s usually less dense and thus harder to cut cleanly. On the other hand, that means it’ll weigh less, so there is a fair trade-off.
STEP 3: We don’t need the piece of Styrofoam to be huge, so just cut it down with a chop saw or serrated knife to about double the size of the camera itself. Then trace the camera’s outline on one side (with a little fat), and use a mat knife to trim out a cavity into which the camera can be set.
STEP 4: To attach the anchor points to the camera, get your duct tape ready. Lay two zip ties (unzipped) laterally across the top of the foam block and then tack them down with a small square of tape. Do the same on the bottom. If you are an engineer like me, and want to feel you’re accounting for stress lines and such, have each zip tie in a pair oriented in opposite directions so that the points and heads are reversed. This is probably completely unnecessary, but don’t tell your kids that; rather, impress upon them the vital importance of this key design factor in ensuring stability and structural integrity. If they ask “Why?” just shake your head and tell them, “Someday, you’ll understand.”
STEP 5: With the zip ties tacked on at the top and bottom, take the duct tape and, starting from the back side of your package, make two complete passes down, under, up, and over, pressing the tape into the camera cavity each time you go around. Finish the tape on the back where you started. Now repeat this, going horizontally around the package, from back, around the front, to the back, and around again, pressing the tape into the cavity each time. Your finished product should look something like this:
With all this done, you’re about ready to fly. All you need is your anti-gravity technology!
BUILDING THE BALLOON COLUMN
To tie the balloons, you can use the classic thin iridescent ribbon that comes with many party tanks of helium and balloons. While it’s cheap stuff, it is very lightweight and has, as anyone who has tried to open a present by pulling the ribbon apart knows, tremendous tensile strength!
Building the balloon column is truly a partnering activity. One person should be inflating and initially tying each balloon while the other is assembling the column. The work flow should be as fo llows:1. Partner #1 (P1) inflates a balloon to about 90 percent of capacity and ties off the end with a single knot. Then hands it to P2.
2. P1 inflates a second balloon to 90 percent capacity, ties it off, and hands it to P2.
3. P2 takes the ends of each of the two balloons and ties them, using the ends of the balloons like string, double-knotting them together.
4. Repeat the first three steps.
5. P1 and P2 each take a tied pair of balloons. Hold them together with the tied centers crossing each other at a 90-degree angle. Twist the balloons around each other a couple times so that the tied centers become intertwined (rather like what you’ll see balloon-animal artists do to build their creations). Done properly, you should now have four balloons in a flowerlike shape.
6. Take one end of the ribbon and knot it around the intertwined middle so the balloon flower now has a string. Do not cut or trim the ribbon—leave it in its packaging so you can pull more from it while it’s connected to the balloons.
7. Repeat the first five steps to make another quad of intertwined balloons.
8. Take the ribbon that’s attached to the first quad of balloons, move down it about 6 inches, and loop the 6 inches of ribbon around the intertwined
middle of your next quad of balloons, going up, around, down, under, in, and out, almost as if you’re weaving the ribbon around each axis at the middle of the balloon. Finish up so that the ribbon can continue “down” to the next quad to be added.
9. Repeat the previous two steps until you have at least four quads of balloons tied together into the column.
How many balloons you’ll need will depend on the size of the balloons you get in your party kit. Usually they’ll inflate to a pear shape about 10 inches across, and 14 inches long. Once you have sixteen of these, in four quads, tied onto your ribbon, you can test the lifting capacity by running the ribbon through the wrist strap of your camera (which is the heaviest part of your build) and seeing if the camera lifts off. Keep in mind that you want it to lift pretty sharply—we don’t want neutral buoyancy here, we want to have a pretty strong lift. So if the balloons lift the camera, but weakly, add another quad of balloons to be sure.
When you have your balloons done, cut the ribbon about 18 inches below the bottom quad of balloons, and use all your Boy Scout or Wikipedia know-how to tie a knot in the end that creates a nonslipping loop. Pass the ends of the zip ties on the top of your camera cockpit through this loop, then zip them together so the balloons are securely attached to the package. Play with the zip ties so that, when the balloons pull upward, the package is oriented as straightly vertically as possible, for better filming.
Get your kite string and tie the same nonslip loop knot in the end of it. Do the same thing with the zip ties at the bottom of your package to secure the line.
Start the countdown! Now you can head out to a nearby field, park, or other open area where you can get some clearance around you, just in case. Take your camera (fresh batteries, cleared memory, please!) and the roll of duct tape with you.
When you’re ready, one person should hold the balloons while the other starts the camera recording, sets it into the cockpit (lens facing outward!), and tapes it with a pass or two of duct tape.
Launch your craft, and let the balloons take it away. On a windless day, you should be able to get the camera up to near the end of your kite string and get some really neat footage. Then, just like pulling in a kite, rewind your tether to bring the craft back to Earth. Go home, hook your camera up to your big-screen TV, and get a feel for what it’s like to be a bird (and find out which of your neighbors needs to clean their pool)!
An Even Geekier Idea!
For a bit more money, this project can turn into an even more amazing experience. You can purchase a wireless, battery-powered video camera (often sold as “surveillance” cameras) to put into the balloon package instead. Pick up a pair of video-projecting glasses, and watch the footage real-time!
Best Slip ’N Slide Ever
When I was a kid, I remember building a homemade Slip ʹN Slide with my friends to have some outdoor fun on a hot summer day. We’d usually cut up a number of black garbage bags and try to overlap them to create a good run. Then turn a sprinkler or two on them, and get busy.
These days, mass-produced Slip ’N Slide-type things are available at any big-box store for around $30. They’re big, bright, and even imaginative. Heck, you can drop a couple hundred bucks and get giant inflatable water slides that will fill up your whole yard.
What I’ve found over a few years with my kids and their friends is that the quality of construction usually makes these slides a one-or two-use product. And while I said they were imaginative, they’re usually not that big, since they’re designed for a mass market of people who won’t all have the yard space for a larger slide. So I started to wonder if there wasn’t something that could be done at home, in the DIY spirit of using garbage bags like I did as a kid, but a bit more durable and, you know, BIGGER. And what I came up with is easy to build, hugely fun to play with, durable, and simple to take apart and store for significant reuse.
This project may have the claim to fame of being the largest-scale but easiest-to-build in the book. We’re putting together the basic concept of the Slip ’N Slide (SNS) using durable over-the-counter materials. All you need is a $30 roll of heavy plastic, ten $2 pool noodles, a $10 sprinkler hose, and a couple rolls of peel-and-stick Velcro (about $7 a roll).
So what is an SNS at its core? It’s simply a long expanse of material that gets slippery when wet. It should have some kind of guides or berms on the sides to keep sliders from slipping off while traveling down its length. And it needs a water source.
1. To start, take your roll of heavy sheet plastic and lay it out on your yard or other assembly site. We tried some 6-milliliter plastic, 6 feet wide by 50 feet long for our sample slide, since it gave a nice width of sliding surface, and the length fit across our front yard. But, depending on your location, you may want a smaller or bigger (yeah!) slide. Figure out which side is the top (it’s a completely arbitrary decision since both sides are the same, but you have to pick one and stick with it), and place it facedown.
2. Lay the noodles around the perimeter of your plastic. You can leave a foot or so between each noodle. The standard length of a pool noodle is about 5 feet, so for our 50-foot long slide, we used eight noodles per side with about a foot of spacing, give or take, and then one noodle at either end.
3. Next, starting at one end, take a noodle and lay it on the plastic a few inches in from the outside edge. Pull the plastic over the noodle as if you’re going to wrap it up, and get enough overlap so about an inch of the plastic from the edge touches the plastic on the other side of the noodle toward the middle. This is where you’ll be sticking the Velcro.
4. Attach a 2-inch strip of the Velcro to the plastic at each end and in the middle of each noodle so that the plastic wraps over and under the noodle and is attached back to itself. Do this for all the noodles until you have a berm all the way around the perimeter of your slide.
5. Once you’re done, you have the underside of your slide. Flip it over, and you should have what looks a little like a very long, very narrow emergency slide from an airliner. Or a really cool waterslide.
6. Last thing we need is the water source. If you’re keeping it simple, just make sure you have a little slope and start running a hose at the top of the slide at the higher end (where you’ll start your slides from). Or if you have one or more lawn sprinklers, use those. For a little more money, pick up a 50-foot sprinkler hose and (if you also got the extra roll of Velcro) affix it to the side of the slide down one of the berms. Use your regular hose to feed water into it and you’ve got a perfect shower down your slide.
IMPORTANT TIP FOR A FLAT YARD: The best placement for an SNS is on a gentle downhill slope that peters out at the end to flat, but not all of us are lucky enough to have the perfect sliding real estate. If you’re building your SNS on a flat expanse of lawn, an added feature could be of use. Get a piece of rope about 6 or 8 feet long. Tie each end to a short piece of wooden dowel or a plastic handle like the ones that come with car window squeegees or toilet plungers. Make sure you have good knots, and perhaps wrap it all up in duct tape as well. You now have a towline. Position your child to sit at the starter end of the slide, either in a crisscross applesauce position or on his or her front or back, and have someone as big or bigger pull him while running down the slide. Once the initial friction is overcome, it’s not very hard to build up a bit of speed down the slide. Just make sure to have them let go before the end of the slide.
Now just wait for a warm day, collect the neighborhood kids, and become the best house on the block! Oh, and in case you hadn’t noticed, with all that Velcro, this thing is really easy to disassemble and fold away for another day.
Fireflies for Every Season
An enduring memory from the childhood of many people who grew up in rural or semirural areas is the sight of fireflies on a warm summer night. Watching the clouds of sparkling lights dancing around is a magical experience. But for people in urban areas, fireflies are harder to come by. Even if you do live in a firefly-friendly area, the summer lasts only so long.
With this project, you can enjoy the magic of fireflies anywhere, at any time of year!
We are busy parents, so sometimes even if we have the inspiration for a fun project to do with our kids, it takes some time to put our idea into action. I was inspired to make a cheap solar light based on an www.instructables.com post involving deconstructing solar garden lights and reinstalling them in Mason jars. My inspiration held out long enough for me to search fruitlessly for some cheap solar lights, but not long enough to make anything.
Fortunately for me, the Internet provided the answer rather quickly (via an especially good geeky project site called Evil Mad Scientist Laboratories—www.evilmadscientist.com). And I was finally able to make my dream happen!
For this project, purchase the following from your local electronics store (or order them online): 12 (or more) CR2032 3v batteries
A bag of 25 diffused 5mm yellow LEDs
A twenty-five-cent roll of electrical tape
Total cost was under $20. Each firefly costs about $1.50.
The build process is very, very easy:1. Unwrap the battery.
2. Slide one leg (lead) of the LED onto each side of the battery. It should light up. If it won’t light up, flip the LED around for a quick polarity lesson. The longer leg is the positive cathode.
3. A little tape around the battery covering keeps it lit.
At my house, proper presentation is the key to early adoption. You can’t be too excited about a new project or the kids will go back to the couch. But if you casually toss a lit firefly on the table and instruct them to stay out of the bag with the rest of the materials, they’ll have ten of them glowing before you come back from the restroom.