This is the second installment of our lessons on flight. You can read about our first portion (which covers the four forces of flight and kites) in this post.
Hot Air Balloons, Airships, and Parachutes
Next in the human flight story is the hot air balloon. After reading Yasuda’s chapter on hot air balloons, airships, and parachutes, we tried creating our own hot air balloon. We failed, but it was fun and exciting enough to be worth your effort, even if it doesn’t work. Though Yasuda offered one option in her book, ‘Love objected to it because it relied on a hair dryer to work; he argued that it would confuse the matter by including blowing air in the process of causing the balloon to rise. While modern balloonists may use fans to help initially fill their balloons, the blowing air is not the mechanism that causes the balloon to rise.
After a quick internet search, I found several similar sets of instructions for a little hot air balloon using nubs of birthday candles; this one from Home Science Tools was fairly clear and concise. Since we didn’t have straws, we used bamboo skewers like another site suggested. Our first balloon went up in flames–very exciting–and our second inflated nicely but then the candles burned down to nothing, so it never lifted off. Despite our failure, it was a good chance to learn about the science and get a taste of the frustrations and failures scientists experienced (and still do!) during their explorations. After discussing the science behind what we were doing–and various reasons our balloons had not lifted off–we enjoyed a time-lapse of the Albuquerque Balloon Fiesta.
I desperately wanted to make a little helium-balloon blimp by attaching a basket with a rubber-band-powered propeller, but my desperate search for propellers at area stores turned up empty. We later stumbled across a hobby shop with propellers, but by then our unit was nearly done. If you ever try making a blimp, let me know! Instead, we had to settle for watching this video about the GoodYear Blimp (and blimps in general).
This chapter of Yasuda’s book included parachutes, as well–including instructions for making a small one. We actually skipped this project since we have experimented with parachutes multiple times in the past. Playing around with different types of parachutes actually makes for some interesting experiments and observations. For example, does Yasuda’s sample parachute (or one we made using a donut shape–with a tiny hole–cut from a plastic garbage bag) work better than a simple plastic bag tied to a Duplo guy? Do parachutes of plastic work differently than parachutes of fabric or tissue paper? Is there a best number of strings to attach a “person” to a parachute? Simply providing materials and asking questions can turn into a fun exploration, and it’s a great opportunity to bring in the scientific method.
Gliders and Airplanes
Ornithopters, of course, were a dead end, but that didn’t stop people from trying to create similar flying machines. And on their way to engine-powered success, early aviators did quite a lot with gliders. After reading about some famous early aviators in Yasuda’s chapter “People Can Fly!” we did some experimenting.
Yasuda suggests making gliders here, though her instructions are almost exactly the same as for her “ornithopter” activity earlier. If you had followed her instructions before, you’d be a bit disappointed here. THIS is really the time to do them. The kids had a great time with gliders and the scientific method. We started by looking at our little scientific method poster and moving step by step through the process. This led to a great discussion of control in experiments, as well as the realization that they had to test over and over again to see if the results were always the same–and sometimes revise their hypothesis or even adjust their whole experiment. If you want to formalize this process, One Happy Teacher has a scientific method record sheet you might find useful. Some of the questions the kids investigated were:
- What happens if I make my glider exactly the same except for the shape of the wing? (We tried triangle wings–which work pretty well–all the way to crazy-shaped wings–which lead to a crazy flight.)
- What happens if one wing is not the same size or shape as the other?
- What happens if I move the wings of my glider forward or back?
- Does changing the body material of your glider change how it flies? (We tested different straw diameters as well as bamboo skewers.)
Paper airplanes–despite their name–are also gliders. This website offers directions for a variety of different paper airplanes at different levels of difficulty. This is another great opportunity for experiments and comparisons and the scientific method. The kids were especially enchanted when Daddy showed them how making a small flap on the back of each wing–one bent up and one bent down–made their plane do barrel rolls.
Discussing gliders led to the revelation that people still use them, albeit mainly for entertainment. So of course we had to go browsing on YouTube for videos of hang gliders. Many of them disappointed the kids by having small motors attached in some way, but there was this video of someone hang-gliding down a ski run that they found pretty satisfying. (You can pre-watch to see if the background music is offensive. I neglected to note the lyrics, since we were so busy talking over it.)
Yasuda’s book offered a few more activities, but much of it had been covered by the NASA Forces of Flight materials (used in our intro to the study) and the airfoil experiment was a bust for us. But I’m getting ahead of myself…
Now, of course, we were getting to the technicalities of how wings work. Clearly, we needed to have a little chat about a fellow named Bernoulli. Thankfully, the Smithsonian’s How Things Fly site offers some fun demonstrations for this potentially-abstract concept. The kids had a grand time blowing pieces of paper and balloons and trying to understand Bernoulli’s principle. This short video entitled “How Do Airplanes Fly?” served to reinforce what we’d just seen and help apply it to airplane wings.
At this point we were going to try Yasuda’s airfoil activity. Thankfully I tested it out the night before–with zero success. So instead we made airfoil wings for our gliders and tested them out, and we were surprised and pleased at how well they did–as long as we managed to get a flat bottom and a gentle curve on the top.
To tie all these concepts together–the ideas of different wing shapes and Bernoulli and airfoils–we used a fun little simulation on the Smithsonian’s How Things Fly site. We’d already watched the intro to learn about the forces of flight, but now we could choose to try to design a plane that flies either higher or faster, testing out different wing shapes, angles, and materials to see the effect.
Since the Wright brothers are arguably the most famous early aviators, we read a relatively brief biography about them. (Most libraries will have a couple at different levels, so pick whatever one you think fits your family best.)
The chapter on “The Golden Age of Flight” gave some additional information on famous pilots and early milestones, while “Modern Aircraft” provided information about today’s airplanes (including call signs, which my kids thought were very exciting). To follow up on how modern planes are controlled, this short YouTube animation showed how the pilot’s controls are linked to the flaps/rudder/etc. in a small airplane, while this six-minute animation gives a more extensive look at how an airplane is controlled in the air. I’d love to have found someone who could let us get up close to an airplane, but we’re not that well-connected or wealthy.
This was a great time to review the four forces of flight, and we had a hilarious time with each of us pretending to be one of the forces acting on a milk-crate “airplane”. (I was lift and the little guy hung on the bottom of the crate acting as weight/gravity, while the other two held a tug-of-war as thrust and drag!) We acted out how each of our forces works as an airplane takes off, flies, and lands. I couldn’t take pictures, since I was too busy being lift.
Propellers and The End
Last but not least, I wanted to extend our understanding of airfoils to include propellers. NASA has an explanation of propellers on their “What is a helicopter?” education page (this one is for grades 5-8, but they have other versions). Sadly, the only helicopter activities I found were really whirly-birds and simply studied something that spins while falling, which I didn’t think was especially helpful in understanding how propellers generate lift. This was more of a read-and-discuss moment, though we do have one of those cheap hover-copters from the toy section, so we hauled it out to ponder the curvature of the blades and analyze how it flies.
(Yasuda’s book also includes a chapter on rockets, but since we studied those not long ago in conjunction with Pookie’s space obsession, I just left those alone on this round.)
At this point I was getting frustrated with the lack of hands-on opportunities and I couldn’t come up with any amazing tie-it-all-together activities to end our unit, so we just sorta petered out with another day of kite flying and lots of paper airplane testing. It was a little anticlimactic, but the kids didn’t seem to mind. Officially, our wrap-up was a big sheet of paper on which we brainstormed everything we had learned about flight. It was actually reassuring to see what sorts of things stuck in each child’s head.