Introduction to Flying Machines

Saturday May 16, 2020

You’re going to do several experiments that change air pressure and mystify your kids. The goal is to set them thinking about how and why things fly (you’ll do this by learning about air pressure and Bernoulli’s law).

 

While you are playing with the experiments in the video, see if you can notice these important ideas:

  1. Air pressure is all around us.
  2. Air pushes downward and creates pressure on all things.
  3. Air pressure changes all the time.
  4. Higher pressure always pushes.
  5. The faster air travels over a surface, the less time it has to push down on that surface and create pressure. Fast moving air creates low pressure regions.
  6. The four fundamental forces on an airplane are lift, weight, thrust, and drag.

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Introduction to Flying Machines

Sunday November 20, 2016

You’re going to do several experiments that change air pressure and mystify your kids. The goal is to set them thinking about how and why things fly (you’ll do this by learning about air pressure and Bernoulli’s law).


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While you are playing with the experiments in the video, see if you can notice these important ideas:


  1. Air pressure is all around us.
  2. Air pushes downward and creates pressure on all things.
  3. Air pressure changes all the time.
  4. Higher pressure always pushes.
  5. The faster air travels over a surface, the less time it has to push down on that surface and create pressure. Fast moving air creates low pressure regions.
  6. The four fundamental forces on an airplane are lift, weight, thrust, and drag.

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Spinning Ring

Tuesday May 31, 2016
Flying machines are just plain awesome, and ones that can fly without really looking like they should are even better! Throw this one like a football for longer flights!

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Airfoil

Tuesday May 31, 2016
The Ancient Chinese discovered that kites with curved surfaces flew better than kites with flat surfaces. A wing needs to have camber: the top needs to be slightly curved, like a bump, and the bottom is straight.

This is called an airfoil. Airfoils are designed to generate as much lift as possible with as little drag as possible. Here’s how you make an airfoil:

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Materials:

  • index card

  • tape

  • skewer or pencil




First, you set up how wide you want your wing to be. This is a chord line. One point on the chord line is the leading edge and one is the trailing edge.

Now add camber by pushing up the top surface until it curves. Now push that bump to the left so it’s more curved at the leading edge. How thick you make this will depend on how fast your wing is going to go and how much lift you need.

Now add the same thickness under the camber line to make the lower surface. Now you have an airfoil!

The airfoil uses Bernoulli’s principle. The top surface of the wing has more camber than the bottom surface, which means that air will flow faster over the top than it does underneath. This means that there’s less air pressure above the wing than under it, and this difference in air pressure makes lift.

How much lift? Well that depends on the airfoil shape, the size and shape of the wing, the angle it makes with the air, the density of the air, and how fast it’s going. Airplanes designed to fly slow have thicker airfoils than supersonic aircraft because the air flows slightly differently at fast versus slow speeds. Airplanes flying at high altitudes have less air molecules to generate lift in the same amount of air as lower flying planes.

If you’ve ever heard of “stalls”, it’s different when an airplane stalls than when a car stalls. What happens when a car stalls? The engine stops, right? If the engine stops in an airplane, it’s called an engine failure, not a stall. A stall is when the air stops flowing over the wing. The engine in an airplane can stop but air can still go over the wing, right? During an engine failure, a propeller airplane turns into a glider, which still can fly. So a stall happens when the wing tips up so high that air can’t flow over the top, so there’s no lower pressure and therefore no lift. If there’s no lift, the airplane turns basically into a rock and falls.

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Special Science Teleclass: Flying Machines

Sunday September 7, 2014

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!


Soar, zoom, fly, twirl, and gyrate with these amazing hands-on classes which investigate the world of flight. Students created flying contraptions from paper airplanes and hangliders to kites! Topics we will cover include: air pressure, flight dynamics, and Bernoulli’s principle.


Materials:


  • 5 sheets of 8.5×11” paper
  • 2 index cards
  • 2 straws
  • 2 small paper clips
  • Scissors, tape
  • Optional: ping pong ball and a small funnel

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Key Concepts

While the kids are playing with the experiments see if you can get them to notice these important ideas. When they can explain these concepts back to you (in their own words or with demonstrations), you’ll know that they’ve mastered the lesson.


  1. Air pressure is all around us. Air pushes downward and creates pressure on all things.
  2. Air pressure changes all the time.
  3. Higher pressure always pushes.
  4. The faster air travels over a surface, the less time it has to push down on that surface and create pressure. Fast moving air creates low pressure regions. (Bernoulli’s Law).
  5. The four fundamental forces on an airplane are lift, weight, thrust, and drag.

What’s Going On?

There’s air surrounding us everywhere, all at the same pressure of 14.7 pounds per square inch (psi). You feel the same force on your skin whether you’re on the ceiling or the floor, under the bed or in the shower.


An interesting thing happens when you change a pocket of air pressure – things start to move. This difference in pressure causes movement that creates winds, tornadoes, airplanes to fly, and some of the experiments we’re about to do together.


An important thing to remember is that higher pressure always pushes stuff around. While lower pressure does not “pull,” we think of higher pressure as a “push”. The higher pressure inside a balloon pushes outward and keeps the balloon in a round shape.


Weird stuff happens with fast-moving air particles. When air moves quickly, it doesn’t have time to push on a nearby surface, such as an airplane wing. The air just zooms by, barely having time to touch the surface, so not much air weight gets put on the surface. Less weight means less force on the area. You can think of “pressure” as force on a given area or surface. Therefore, a less or lower pressure region occurs wherever there is fast air movement.


There’s a reason airplane wings are rounded on top and flat on the bottom. The rounded top wing surface makes the air rush by faster than if it were flat. When you put your thumb over the end of a gardening hose, the water comes out faster when you decrease the size of the opening. The same thing happens to the air above the wing: the wind rushing by the wing has less space now that the wing is curved, so it zips over the wing faster, and creates a lower pressure area than the air at the bottom of the wing.


The Wright brothers figured how to keep an airplane stable in flight by trying out a new idea, watching it carefully, and changing only one thing at a time to improve it. One of their biggest problems was finding a method for generating enough speed to get off the ground. They also took an airfoil (a fancy word for “airplane wing”), turned it sideways, and rotated it around quickly to produce the first real propeller that could generate an efficient amount of thrust to fly an aircraft.  Before the Wright brothers perfected the airfoil, people had been using the same “screw” design created by Archimedes in 250 BC.  This twist in the propeller was such a superior design that modern propellers are only 5% more efficient than those created a hundred years ago by the two brilliant Wright brothers.


Questions to Ask

When you’ve worked through most of the experiments ask your kids these questions and see how they do:


  1. Higher pressure does which? (a) pushes (b) pulls (c) decreases temperature (d) meows (e) causes winds, storms, and airplanes to fly
  2. The tips on the edge of a paper airplane wing provide more lift by: (a) flapping a lot
    (b) destroying wingtip vortices that kill lift (c) getting stuck in a tree more easily (d) decreasing speed
  3. In the ping pong ball and funnel experiment, the ball stayed in the funnel was because:         (a) you couldn’t blow hard enough (b) you glued it into the funnel (c) the ball had a hole in it  (d) the fast blowing caused a low-pressure region around the ball, causing the surrounding atmospheric pressure to be a higher pressure, thus pushing the ball into the funnel
  4. If your plane takes a nose dive, you should try (a) changing the elevators by pinching the edges (b) change the dihedral angle (c) change how you throw it (d) all of the above
  5. What are the four forces that act on every airplane in flight?
  6. Draw a quick sketch of your plane viewed from the front with a positive dihedral.
  7. If you were designing your own “Flying Paper Machine Kit”, what would be inside the box?
  8. What’s the one thing you need to remember about higher pressure?
  9. What keep an airplane from falling?
  10. Where is the low pressure area on an airplane wing?

Answers:


1 (a, e) 2 (b) 3 (d) 4 (d) 5 (lift, weight, thrust, drag) 8 (higher pressure pushes) 9 (lift) 10 (top surface)


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Cartesian Diver

Sunday October 23, 2011

Rene Descartes (1596-1650) was a French scientist and mathematician who used this same experiment show people about buoyancy. By squeezing the bottle, the test tube (diver) sinks and when released, the test tube surfaces. You can add hooks, rocks, and more to your set up to make this into a buoyancy game!
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The test tube sinks because the when you squeeze the bottle, you increase the pressure of the water and this forces water up into the test tube, which then compresses the air inside the tube. When this happens, it adds enough mass to cause it to sink. Releasing the squeeze on the bottle means that you decrease the pressure and the water is forced back out of the tube.


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Streaming Water

Tuesday June 1, 2010

Fill the bathtub and climb in. Grab your water bottle and tack and poke several holes into the lower half the water bottle. Fill the bottle with water and cap it. Lift the bottle above the water level in the tub and untwist the cap. Water should come streaming out. Close the cap and the water streams should stop. Open the cap and when the water streams out again, can you “pinch” two streams together using your fingers?


Materials: A tack, and a plastic water bottle with cap, and bathtub


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What’s happening? First, you’re getting clean. Second, you’re playing with pressure again. Watch the water level when you uncap the bottle. As the water streams out, the water level in the bottle moves downward. Notice how the space for air increases in the top of the bottle as the water line moves down. (The air comes in through the mouth of the bottle.) When you cap on the bottle, there’s no place for air to enter the bottle. The water line wants to move down, but since there’s no incoming air to equalize the pressure, the flow of water through the holes stops. Technically speaking, there’s a small decrease in pressure in the air pocket in the top of the bottle and therefore the air outside the bottle has a higher pressure that keeps the water in the bottle. Higher pressure pushes!


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Sneaky Bottles

Tuesday June 1, 2010

This experiment illustrates that air really does take up space! You can’t inflate the balloon inside the bottle without the holes, because it’s already full of air. When you blow into the bottle with the holes, air is allowed to leak out making room for the balloon to inflate. With the intact bottle, you run into trouble because there’s nowhere for the air already inside the bottle to go when you attempt to inflate the balloon.


You’ll need to get two balloons, one tack, and two empty water bottles.


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Poke a balloon into a water bottle and stretch the balloon’s neck covering the mouth of the bottle from the inside. Repeat with the other bottle. Using the tack, poke several small holes in the bottom of one of the water bottles. Putting your mouth to the neck of each bottle, try to inflate the balloons.


A cool twist on this activity is to drill a larger hole in the bottle (say, large enough to be covered up by your thumb) and inflate the balloon inside the bottle with hole open, then plug up the hole with your thumb. The balloon will remain inflated even though its neck is not tied! Where is the higher pressure region now?


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Squished Balloon

Tuesday June 1, 2010

Fire eats air, or in more scientific terms, the air gets used up by the flame and lowers the air pressure inside the jar. The surrounding air outside the jar is now at a higher pressure than the air inside the jar and it pushes the balloon into the jar. Remember: Higher pressure pushes!


Materials: a balloon, one empty glass jar, scrap of paper towel , matches with an adult


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Blow up a balloon so that it is just a bit larger than the opening of the jar and can’t be easily shoved in. With an adult, light the small wad of paper towel on fire and drop it into the jar. Place the balloon on top. When the fire goes out, lift the balloon. The jar goes with it!


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Fountain Bottle

Tuesday June 1, 2010

As you blow air into the bottle, the air pressure increases inside the bottle. This higher pressure pushes on the water, which gets forced up and out the straw (and up your nose!).


Materials: small lump of clay, water, a straw, and one empty 2-liter soda bottle.


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Fill a 2-liter soda water bottle full of water and seal it with a lump of clay wrapped around a long straw so that the straw is secured to the mouth of the bottle. (The straw should be partly submerged in the water.) Blow hard into the straw. Splash!



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First Flying Lesson in an Airplane

Monday May 31, 2010

If your kids are hog-wild about flying and can't seem to get enough of paper airplanes, flying kites, and rockets, here's something you can do that will last their entire lifetime.

One of the best ways to introduce kids into the world of aeronautics and aviation is to get them inside a small airplane. By having the kids actually FLY, they get a chance to interact with a real pilot, see how the airplane responds to the controls, and get a taste for what their future can really be like if they keep up their studies in aerodynamics.

We're going to learn how to fly an airplane from a certified flight instructor.  He's going to walk you through every step, from pre-flight to take-off to landing.  You'll hear the radio transmissions from other aircraft flying in the area, how the control tower directs traffic, and more.  We've used a special microphone inside the cockpit to cut down on the engine noise (which actually was rigged up to only record when it heard voice sounds), so the sound might seem different than you expected.

Are you ready?

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Want to fly a REAL airplane? There are a few different ways you can do this:

  • Get a First Flight from the Young Eagles group in your area.
  • Rent this video from the library or video rental store: One-Six Right
  • Check out Flight Training to find local pilots and magazines you can really learn from.
  • Visit your local airport and ask for a list of CFIs (Certified Flight Instructors) who can provide you with your first flight.  It's usually much less expensive than you think!

When we teach our Summer Science Camps, one of the first things we do is give away a free airplane lesson.  We do this for a number of reasons, but first and foremost, to reinforce that when you teach science, you must do it by starting with the experiment first, then follow it up with the academic content. I know it sounds backwards from most approaches to teaching science, and it is!  BUT it's the best way that kids learn in the long-term.

With this method, you are able to introduce a topic that really gets kids excited because now they have a real-world, hands-on  application of it that really makes sense to them. When kids are excited about a subject, it's much easier for them to pick up the academics. Once they start asking you questions, they've signaled you that they are ready to learn more about it (like lift, drag, aerodynamics, wing design, etc.)

It's also such a wonderful thing to see the kids come up to us, years later, with their eyes still twinkling over the memory of their first flying lesson!

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How Airplanes Fly Through Clouds

Monday May 31, 2010
Ever wonder how airplanes fly through those fluffy white things in the sky? If they can't see where they are going, how do they get there?

You might be tempted to think: "GPS!" Ah, yes... but airplanes were flying through clouds long before GPS was ever invented. So how did they do it? That's what this video is all about.

Although most new planes are being outfitted with "glass cockpits", which is to say computer screens with GPS systems, there's really nothing like a plane with vacuum-tube instruments, crackling radios, transponders, VOS, and DMEs. We're going to show you how IFR pilots (those who are specially trained to fly only by instruments without peeking out the window) use their equipment to get the plane down to the ground.

Are you ready? Then strap on your seat belt and get ready to fly with a certified instrument flight instructor...

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Origami Airplane & Ninja Star

Monday May 31, 2010
This is a double-project, because each requires the scraps of the other. The origami airplane requires a square sheet of paper, and the ninja star needs the strip left over from turning a regular sheet of copy paper into a square sheet.

Both of these contraptions fly well if you take your time and make them carefully. Just watch yourself with the ninja star - it's not only fast and furious, the ends are sharp and guaranteed to turn heads... and necks.
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P.S. I learned how to make this ninja star back in 4th grade, where I was sworn to secrecy in the girl's bathroom with my best friend. Although I've made thousands of these, I've never showed anyone else! I've kept this secret for a long time, so I ask you now to keep these instructions a secret between us. Are you in?

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Magic Star

Monday May 31, 2010
My students love making this one, because it's not only a throwing star like the Ninja Star, but also opens up to be a frisbee! You'll need eight sheets of square paper, all the same size. They don't have to be large - I use two that are cut into quarters. Here's what you do:

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Materials:

  • eight sheets of square paper, any size (you'll see how to make this from only two sheets in the video)

  • ruler

  • straight edge or ruler

  • pencil

  • 15 minutes



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Why do airplanes need wings?

Monday May 31, 2010

 

Every flying thing, whether it's an airplane, spacecraft, soccer ball, or flying kid, experiences four aerodynamic forces: lift, weight, thrust, and drag. An airplane uses a propeller or jet engine to generate thrust. The wings create lift. The smooth, pencil-thin shape minimizes drag. And the molecules that make up the airplane attribute to the weight.

Think of a time when you were riding in a fast-moving car. Imagine rolling down the window and sticking out your hand, palm down. The wind slips over your hand. Suppose you turn your palm to face the horizon. In which position do you think you would feel more force against your hand?

When designing airplanes, engineers pay attention to details, such as the position of two important points: the center of gravity and the center of pressure (also called the center of lift). On an airplane, if the center of gravity and center of pressure points are reversed, the aircraft’s flight is unstable and it will somersault into chaos. The same is true for rockets and missiles!

How to Build an Airplane

Materials: balsa wood flyer

This video shows how to use a balsa airplane to show what all the parts (rudder, wings, elevator, fuselage) are for.  You can pick one up for a few dollars, usually at a toy store, or make your own (see second video below).

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Want to go for a REAL airplane flight?

You can learn how to fly an airplane from a real flight instructor without leaving your seat! Click here!

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Ping Pong Funnel

Monday May 31, 2010

As you blow into the funnel, the air under the ball moves faster than the other air surrounding the ball, which generates an area of lower air pressure. The pressure under the ball is therefore lower than the surrounding air which is, by comparison, at a higher pressure. This higher pressure pushes the ball back into the funnel, no matter how hard you blow or which way you hold the funnel. The harder you blow, the more stuck the ball becomes. Cool.


Materials: A funnel and a ping pong ball


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Insert a ping pong ball into a funnel. Place the stem of the funnel between your lips and tilt your head back so ball stays inside. Blow a strong, long stream of air into the funnel.


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Magic Water Glass Trick

Monday May 31, 2010

Where’s the pressure difference in this trick?


At the opening of the glass. The water inside the glass weighs a pound at best, and, depending on the size of the opening of the glass, the air pressure is exerting 15-30 pounds upward on the bottom of the card. Guess who wins? Tip, when you get good at this experiment, try doing it over a friend’s head!


Materials: a glass, and an index card large enough to completely cover the mouth of the glass.


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Fill a glass one-third with water. Cover the mouth with an index card and over a sink invert the glass while holding the card in place. Remove your hand from the card. Voila! Because atmospheric air pressure is pushing on all sides of both the glass and the card, the card defies gravity and “sticks” to the bottom of the glass. Recall that higher pressure pushes and when you have a difference in pressure, things move. This same pressure difference causes storms, winds, and the index card to stay in place.


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Hot Air Balloon

Monday May 31, 2010

About 400 years ago, Leonardo da Vinci wanted to fly… so he studied the only flying things around at that time: birds and insects. Then he did what any normal kid would do—he drew pictures of flying machines!


Centuries later, a toy company found his drawing for an ornithopter, a machine that flew by flapping its wings (unlike an airplane, which has non-moving wings). The problem (and secret to the toy’s popularity) was that with its wing-flapping design, the ornithopter could not be steered and was unpredictable: It zoomed, dipped, rolled, and looped through the sky. Sick bags, anyone?


Hot air balloons that took people into the air first lifted off the ground in the 1780s, shortly after Leonardo da Vinci’s plans for the ornithopter took flight. While limited seating and steering were still major problems to overcome, let’s get a feeling for what our scientific forefathers experienced as we make a balloon that can soar high into the morning sky.


Materials: A lightweight plastic garbage bag, duct or masking tape, a hand-held hair dryer. And a COLD morning.


Here’s what you do:


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Shake out a garbage bag to its maximum capacity. Using duct or masking tape, reduce the opening until it is almost-closed leaving only a small hole the size of the hair dryer nozzle. Use the hair dryer to inflate the bag, heating the air inside, but make sure you don’t melt the bag! When the air is at its warmest, release your hold on the bag while at the same time you switch off the hair dryer. The bag should float upwards and stay there for a while.


Troubleshooting: This experiment works best on cold, windless mornings. If it’s windy outside, try a cool room. The greater the temperature difference between the hot air inside the garbage bag versus the cold, still air, the faster the bag rises. The only other thing to watch for is that you’ve taped the mouth of the garbage bag securely so the hot air doesn’t seep out. Be sure the opening you leave is only the diameter of your hair dryer’s nozzle.


Want to go BIGGER? Then try the 60-foot solar tube!
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Diaper Wind Bag

Monday May 31, 2010

Lots of science toy companies will sell you this experiment, but why not make your own? You’ll need to find a loooooong bag, which is why we recommend a diaper genie. A diaper genie is a 25′ long plastic bag, only both ends are open so it’s more like a tube. You can get three 8-foot bags out of one pack.


Kids have a tendency to shove the bag right up to their face and blow, cutting off the air flow from the surrounding air into the bag. When they figure out this experiment and perform it correctly, this is one of those oooh-ahhh experiments that will leave your kids with eyes as big as dinner plates.


Here’s what you do:


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Cut an eight-foot section of the diaper genie bag and knot one of the ends. Hold the other end open, take a deep breath, and blow. How many breaths does it take for you to fill up the entire bag with air? Try this now…


After you know how many breaths it takes, do you think you can fill the bag with only ONE breath? The answer is YES! Hold the bag about eight inches from the face and blow long and steady into the bag. As soon as you run out of air, close the end of the bag and slide your hand along the length (toward the knotted end) until you have an inflated blimp.


Troubleshooting: If the bag tears open, use packing tape to mend it.


What’s going on? When you blow air past your lips, a pocket of lower air pressure forms in front of your face. The stronger you blow, the lower the air pressure pocket. The air surrounding this lower pressure region is now at a higher pressure than the surrounding air, which causes things to shift and move. When you blow into the bag (keeping the bag a few inches from your face), you build a lower pressure area at the mouth of the bag, and the surrounding air rushes forward and into the bag.


Substitution Tip: If you can’t locate a diaper genie, you can string together plastic sheets from garbage bags, using lightweight tape to secure the seams. You’ll need to make a 8-12” diameter by eight-foot long tube and close one end. When kids get their eight-foot bag inflated in just one breath, ask them: “Did you really have that much air in your lungs?”


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Gigantic Solar Balloon

Monday May 31, 2010

solar-balloonWe didn't include this particular experiment in our shopping list, as the tube's kind of expensive and can only be used for one particular experiment, BUT it's an incredible blast to do in the summer.

Here's the main idea - an incredibly loooooong and super-lightweight black plastic garbage bag is filled with air and allowed to heat itself in the sun. In a few short minutes, the entire 60-foot tube tube rises into the air. Before you try this experiment, try the Hot Air Balloon first!

Order the Solar Tube here.

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Your kids will actually get to see several science principles in action, including: hot air is less dense than cool air (when the balloon rises); black objects heat up faster (when the air heats up inside); gases expand when heated (you'll see the bag self-inflate as it heats up).

Here's what you do:

1. In the morning during summer, when there's no wind and it's still cool, stretch your tube out flat in the shade. If it's already hot, fill the tube indoors with a fan. It's the temperature difference that will make this bag rise. If the temperature of the air inside the tube is nearly the same as the outside air, then it will simply remain on the ground.

2. Open one end of the tube and (with a few friends to help you), walk (or run) to fill it full of air, and tie off the end when it's full. It may still be a bit baggy in some places - don't worry - it will fill itself out when it heats up.

3. Tie off a length of lightweight string (like kite string) to one end. This will make sure you can get your tube back!

4. Bring it into the sun and watch it slowly rise of the ground.

NOTE: Kids can get a bit overexcited when they do this experiment, so watch they don't puncture the bag. You can seal it back up with a thick strip of lightweight packing tape if needed.

DO NOT let the solar tube rise without the string. If it gets loose at higher altitudes, it's a serious threat to airplanes.

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Bomber Plane

Monday May 31, 2010

This is another favorite of mine - you can fold this one in under two minutes. Make sure you tweak your airplane to get it to fly just the way you want.



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Ring Thing

Monday May 31, 2010

Why can this thing fly? It doesn’t even LOOK like a plane! When I teach at the university, this is the plane that mathematically isn’t supposed to be able to fly! There are endless variations to this project—you can change the number of loops and the size of loops, you can tape two of these together, or you can make a whole pyramid of them. Just be sure to have fun!

Materials: Index card, straw, scissors, tape.

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Butterflying Cups

Monday May 31, 2010

This experiment is one of my favorites to use when teaching university-level fluid mechanics, because it is quite a complex task to demonstrate and analyze the aerodynamic lift. The easiest explanation is that lift is generated by the rotation of the cups. How and why the vortex generates lift is much more complex, but remember that as the air velocity increases, the pressure decreases. And remember... higher pressure regions always push.

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Materials: Two paper cups, 5 to 7 rubber bands, and tape.

Here's what you do:
1. Tape two paper cups together, bottom-to-bottom.
2. Chain together six rubber bands.
3. Loop one end of the rubber band chain over your thumb and hold your arm out horizontally straight, palm up. Drape the remainder of the chain along your arm.
4. Place the taped cups at the free end of the rubber band chain near your shoulder and slowly wind the rubber bands around the middle section of the cups. When you wind near the end, stop, stretch the chain back toward your elbow, make sure the rubber band comes from the underside of the cups.
5. Now release the cups. The cups should rotate quickly and take air, then gracefully descend down for a light landing.

You can try further experiments with your butterfly cups: Try reversing the rotation direction, spin the cups in a cloud of fog or smoke while your video-tape their flight, performing the same experiment underwater (add small particles to the water so you can see the lines of flow!), change the size of the cups, and change the number of cups.

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Hangliders

Monday May 31, 2010

Build your own paper version of a soaring, looping flying machine, much like the one DaVinci dreamed of. You can either hold this by the keep (the folded part on the bottom) and throw like a jet, or hold onto the very edge at the back and simply let go from a tall height. Either way, it'll still fly.

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Trouble flying? Click here to learn how to tweak your wings.

Want to know more about airplane design? Check out Why Airplanes Need Wings.
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Streak

Monday May 31, 2010

This is one of the fastest plane designs we've come across. Slick, swift, and strong, you'll need a hefty throw to break our record of 127 feet. If you do, let us know so we can celebrate with you!

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Trouble flying? Click here to learn how to tweak your wings.

Want to know more about airplane design? Check out Why Airplanes Need Wings.
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Dart Flyer

Monday May 31, 2010
This super-fast dart flyer requires only a sheet of paper and three patient minutes. Take the challenge and dig out a stopwatch and tape measure to record your best "time aloft" and "distance traveled". I usually write mine right onto the wing itself (on the underside).

In fact, each time it flies well, I'll take a measurement and so pretty soon my plane has a data table under the wing. This way, I know which plane to choose in a race!

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Nakamura Lock

Monday May 31, 2010

A classic that we just had to toss into the mix. The best thing about this plane it that it shows you how to fold an airplane without using tape. Notice how the wings of this airplane are different than the stunt plane designs - the swept back design mimics those used on fighter planes from the Air Force.

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Trouble flying? Click here to learn how to tweak your wings.

Want to know more about airplane design? Check out Why Airplanes Need Wings.
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Tweaking Your Airplanes

Monday May 31, 2010

iStock_000003125985XSmallWe’ve included several flying designs for you to test, including: stunt planes, fast jets, hang gliders, and a one that, mathematically-speaking, isn’t even supposed to fly.

The trick to any paper airplane, be it a dart, stunt, or glider, is in the tweaking. In order to turn a disappointing nose-diver into a stellar barrel-roller, you’ll need to pay close attention to your dihedral angle (angle the wings make with the horizon) and elevator angle (pinching up or down to the tail section).

Here’s how we do it:

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• Throw your airplane. Notice if you threw it hard, medium, or easy. Try modifying the throw to see which one works better for this particular airplane design. Stunt planes tend to work better with an easy throw and jets zoom with a fast throw.

• Now make the wing dihedral neutral (level with the horizon). Pinch up on the elevators a tiny bit and give it another like the throw that worked best last time.

• If the plane nose dives sharply, give it more of a pinch up on the elevators. If it nosed up first, then pitched down and crashed, you’ve got too much ‘up elevator’ in the back. What happens when you pinch one elevator up and one down?

• If the airplane still won’t fly correctly, then check your symmetry. Are your wings exactly the same size and shape? When you fold your airplane, do the wings sit right on top of each other? Most airplanes don’t like being asymmetrical, and it’ll show up when you try to fly.

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Roto-Helicopters

Monday May 31, 2010

Did you know that the Wright brothers figured out one of the biggest leaps in propeller technology?  Prop blades had basically stayed the same for about 2,500 years until they figured out to take an airplane wing, turn it sideways and rotate it to create thrust.  The main idea being a wing is that it needs to have a half-twist and the thickness needs to vary along its length (this is because you want to get the same amount of thrust at each point along its length, or one part of the propeller will generate more thrust and rip itself apart).

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This project is pretty bullet-proof—to fly the helicopters, all you need to do is drop them!

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Flying Fish

Monday May 31, 2010
We're going to make spinning, flying fish! All you need is a strip of paper and a pair of scissors to make these. If you 're like me, you'll make a whole grocery-bag full of a rainbow assortment and drop them from the upstairs railing - it's quite a show!

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Want more floating, flying, spinning contraptions? Click here for our roto-copters!
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Surfing Hangliders

Monday May 31, 2010

This is such a cool project that I had to include it in our Flying Machines archive. The science teacher who developed this project has a sincere love of gliders he calls "walk-along flyers". Note that the instructions for making this project are longer and more precise than usual, so take your time and go slow.

If your kids love airplanes, you'll be able to keep them busy for hours with this project! You will be flying a piece of paper, surfing it on a wave of air created with cardboard. Are you ready?  There are two different designs to choose from: the Tumblewing, which works by rotation, and the Hanglider.

Here's what you need:

  • piece of paper from a phone book
  • scrap of cardboard
  • scissors
  • help from a very patient adult
  • an afternoon (this project is super-sensitive and you need time and persistence to accomplish it!)

Tumblewing Design

You'll need to print out this Tumblewing template to get started.

Hanglider Design:

You'll need to print out this Hanglider template to get started.


A big THANKS goes out to projects developer and science teacher Slater Harrison for his ultra-cool flying inventions!


Stunt Flyer

Monday May 31, 2010

The best, all purpose, lazy afternoon loop-and-corkscrew stunt flying machine that we've found. This plane can easily go straight, or curve in a loop, or do a barrel roll, or boomerang back to you...and it can even do the bat maneuver (nose-up-nose-down-nose-up-nose-down-nose-up-nose-down...) with the right kind of tweaking. Spend extra time on those back elevators and you'll get a plane worthy of warm drafts.
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Trouble flying? Click here to learn how to tweak your wings.

Want to know more about airplane design? Check out Why Airplanes Need Wings.

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Genie in a Bottle

Monday May 31, 2010

While this isn’t actually an air-pressure experiment but more of an activity in density, really, it’s still a great visual demonstration of why Hot Air Balloons rise on cold mornings.


Imagine a glass of hot water and a glass of cold water sitting on a table, side by side. Now imagine you have a way to count the number of water molecules in each glass. Which glass has more water molecules?


The glass of cold water has way more molecules… but why? The cold water is more dense than the hot water. Warmer stuff tends to rise because it’s less dense than colder stuff and that’s why the hot air balloon in experiment 1.10 floated up to the sky.


Clouds form as warm air carrying moisture rises within cooler air. As the warm, wet air rises, it cools and begins to condense, releasing energy that keeps the air warmer than its surroundings. Therefore, it continues to rise. Sometimes, in places like Florida, this process continues long enough for thunderclouds to form. Let’s do an experiment to better visualize this idea.


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Materials: Two identical tall glasses, hot water, cold water, red and blue food dye, and an index card larger enough to cover the opening of the glasses



Fill two identical water glasses to the brim: one with hot water, the other with cold water. Put a few drops of blue dye in the cold water, a few drops of red dye in the hot water. Place the index card over the mouth of the cold water and invert the glass over the glass of hot water. Line up the openings of both glasses, and slowly remove the card.


Troubleshooting: Always invert the cold glass over the hot glass using an index card to hold the cold water in until you’ve aligned both glasses. You can also substitute soda bottles for water glasses and slide a washer between the two bottles to decrease the flow rate between the bottles so the effect lasts longer.


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Soda Can Trick

Monday May 31, 2010

When air moves, the air pressure decreases. This creates a lower air pressure pocket right between the cans relative to the surrounding air. Because higher pressure pushes, the cans clink together. Just remember – whenever there’s a difference in pressure, the higher pressure pushes.


You will need about 25 straws and two empty soda cans or other lightweight containers


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Lay a row of straws parallel to each other on a smooth tabletop. Place two empty soda cans on the straws about an inch apart. Lower your nose to the cans and blow hard through the space between the two cans.


Clink! They should roll toward each other and touch!


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Air Takes Space

Monday May 31, 2010

You’re about to play with one of the first methods of underwater breathing developed for scuba divers hundreds of years ago.! Back then, scientists would invert a very large clear, bell-shaped jar over a diver standing on a platform, then lower the whole thing into the water. Everyone thought this was a great idea, until the diver ran out of breathable air…


Materials: 12″ flexible tubing, two clear plastic cups, bathtub


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Part I: Fill the tub and climb in. Plunge one cup underwater so it fills completely with water. While the cup is underwater, point its mouth downward. Insert one end of the tubing into the cup and blow hard into the other end. The water is forced out of the cup!


Part II: While still in the tub, invert one cup (mouth downwards) and plunge it into the tub so that air gets trapped inside the cup. Place the second cup in the water so it fills with water. Invert the water-filled cup while underwater and position it above the first cup so when you tilt the first cup to release the air bubbles, they get trapped inside the second cup. Here you see that air takes space, because in both variations of this experiment the air forced the water out of the cups.


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Squished Soda Can

Sunday January 31, 2010

An average can of soda at room temperature measures 55 psi before you ever crack it open. (In comparison, most car tires run on 35 psi, so that gives you an idea how much pressure there is inside the can!)


If you heat a can of soda, you’ll run the pressure over 80 psi before the can ruptures, soaking the interior of your house with its sugary contents. Still, you will have learned something worthwhile: adding energy (heat) to a system (can of soda) causes a pressure increase. It also causes a volume increase (kaboom!).
How about trying a safer variation of this experiment using water, an open can, and implosion instead of explosion?


Materials – An empty soda can, water, a pan, a bowl, tongs, and a grown-up assistant.


NOTE: If you can get a hold of one, use a beer can – they tend to work better for this experiment. But you can also do this with a regular old soda can. And no, I am not suggesting that kids should be drinking alcohol! Go ask a parent to find you one – and check the recycling bin.


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Prepare an ice bath by putting about ½” of ice water in a shallow dish. With an adult, place a few tablespoons of water in an empty soda or beer can and place the can upright in a skillet on the stove. When the can emits a think trickle of steam, grab the can with tongs and quickly invert it into the ice dish. CRACK!


Troubleshooting: The trick to making this work is that the can needs to be full of hot steam, which is why you only want to use a tablespoon or two of water in the bottom of the can. It’s alright if a bit of water is still at the bottom of the can when you flip it into the ice bath. In fact, there should be some water remaining or you’ll superheat the steam and eventually melt the can. You want enough water in the ice bath to completely submerge the top of the can.


Always use tongs when handling the heated can and make sure you completely submerge the top of the can in the icy water. The water needs to seal the hole in the top of the can so the steam doesn’t escape. Be prepared for a good, loud CRACK! when you get it right.


Why does this work? By heating up the water in the can, you’re changing the state of water from a liquid to a has (called water vapor), which drives out the air, leaving the steam inside. When inverted and cooled, the steam condenses to a small volume of liquid water (much smaller than if it was just hot air). The molecules in water vapor are a lot further apart than when they are in a liquid state. Since the air inside the can has been replaced by the steam, when it cools quickly, it creates a lower air pressure region in the can, so the air pressure surrounding the outside of the can rapidly crushes the can.


If you look really carefully as it condenses, you’ll see cold water from the bowl zoom into the can, just like when you suck water through a straw. The vacuum created int he can by the condensing steam creates a lower pressure, which pushes water into the can itself. When you suck from a straw, you’re creating a lower air pressure region in your mouth so that the surrounding air pressure pushes liquid up the straw to equalize the pressure.


Remember, high pressure always pushes!


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Slingshot Rocket

Friday January 1, 2010

This project is simple, yet highly satisfying.  The current record distance traveled is 74 feet... can you beat that?  Make sure you launch these UP, not horizontally! You only need three items, all of which are in your house right now! First, you need a piece of...

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...paper, a skinny rubber band, and a pair of scissors.


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This project is simple, yet highly satisfying.  The current record distance traveled is 74 feet... can you beat that?  Make sure you launch these UP, not horizontally! You only need three items, all of which are in your house right now! First, you need a piece of...

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...paper, a skinny rubber band, and a pair of scissors.


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Bomber Plane & Wind Tunnel

Friday January 1, 2010
When designing airplanes, engineers pay attention to details, such as the position of two important points: the center of gravity and the center of pressure (also called the center of lift). On an airplane, if the center of gravity and center of pressure points are reversed, the aircraft’s flight is unstable and it will somersault into chaos. The same is true for rockets and missiles!

Let’s find the center of gravity on your airplane. Grab your flying machine and sharpened pencil. You can find the ‘center of gravity’ by balancing your airplane on the tip of a pencil. Label this point “CG” for Center of Gravity.

Materials:

  • sheet of paper

  • hair dryer

  • pencil with a sharp tip


We're going to make a paper airplane first, and then do a couple of wind tunnel tests on it.

For the project, all you need is a sheet of paper and five minutes... this is one my favorite fliers that we make with our students!


Find the Center of Pressure (CP) by doing the opposite: Using a blow-dryer set to low-heat so you don’t scorch your airplane, blast a jet of air up toward the ceiling. Put your airplane in the air jet and, using a pencil tip on the top side of your plane, find the point at which the airplane balances while in the airstream. Label this point “CP” for Center of Pressure. (Which one is closest to the nose?)


Besides paying attention to the CG and CP points, aeronautical engineers need to figure out the static and dynamic stability of an airplane, which is a complicated way of determining whether it will fly straight or oscillate out of control during flight. Think of a real airplane and pretend you’ve got one balanced on your finger. Where does it balance? Airplanes typically balance around the wings (the CG point). Ever wonder why the engines are at the front of small airplanes? The engine is the heaviest part of the plane, and engineers use this weight for balance, because the tail (elevator) is actually an upside-down wing that pushes the tail section down during flight.

Dart Flyer

Friday January 1, 2010
How does an airplane remain stable during flight? Positive stability means that the airplane is designed so that if the pilot jams on the controls during straight and level flight (in other words, pitch up hard), and then let go, the airplane will more or less return to straight and level flight.

Let's make another favorite flyer of mine...
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Here’s how stability works: When the airplane’s nose suddenly pitches up, the wind speed over the wings slows and decreases the lift on the plane. This causes the nose to tip downwards and the wind to rush over the wings again, creating more lift. This cycle eventually dampens out and soon the airplane is flying level again.

If, however, you have a negative stability (meaning that your CG is aft of or behind the CP), when the airplane suddenly pitches up, one of several things may happen, all of which require sick bags and a parachute. One of the worst cycles is this: When a tail-heavy plane noses down, the speed over the wings increases and provides more lift but only briefly, because a tail-heavy plane will keep its nose up until the wind speed slows so much that the winds stall. Lift is no longer generated by wind flowing over the wings, because there is no wind, and the airplane “falls” a distance until the air flows back over the wings. This generates a lot of lift very quickly until the tail section tilts the nose back up. The cycle continues to worsen each time with greater “fall” distances” that place huge structural forces on the fuselage or body of the plane until you jump ship.

Can you find both the center of pressure AND the center of gravity? Does it matter which one is closer to the nose for stable flight? (Hint... yes, it does!) Here are directions for how to make an easy wind tunnel to test your airplanes.

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Flying Contraptions

Friday January 1, 2010

Mathematically speaking, this particular flying object shouldn't be able to fly.  What do you think about that?

Why can this thing fly? It doesn’t even LOOK like a plane! When I teach at the university, this is the plane that mathematically isn’t supposed to be able to fly! There are endless variations to this project—you can change the number of loops and the size of loops, you can tape two of these together, or you can make a whole pyramid of them. Just be sure to have fun!

Find the Center of Pressure (CP) by doing the opposite: Using a blow-dryer set to low-heat so you don’t scorch your airplane, blast a jet of air up toward the ceiling. Put your airplane in the air jet and, using a pencil tip on the top side of your plane, find the point at which the airplane balances while in the airstream. Label this point “CP” for Center of Pressure. (Which one is closest to the nose?)

Besides paying attention to the CG and CP points, aeronautical engineers need to figure out the static and dynamic stability of an airplane, which is a complicated way of determining whether it will fly straight or oscillate out of control during flight. Think of a real airplane and pretend you’ve got one balanced on your finger. Where does it balance? Airplanes typically balance around the wings (the CG point). Ever wonder why the engines are at the front of small airplanes? The engine is the heaviest part of the plane, and engineers use this weight for balance, because the tail (elevator) is actually an upside-down wing that pushes the tail section down during flight.

When we use math to add up the forces (the pull of gravity would be the weight, for example), it works out that there isn’t enough lift generated by thrust to overcome the weight and drag. When I say, “mathematically speaking...” I mean that the numbers don’t work out quite right. When this happens in science for real scientists, it usually means that they don’t fully understand something yet. There are a number of ‘unsolved’ mysteries still in science.. maybe you’ll be able to help us figure them out?

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Pulse Jet Engine

Friday October 23, 2009

A rocket has a few parts different from an airplane. One of the main differences is the absence of wings. Rockets utilize fins, which help steer the rocket, while airplanes use wings to generate lift. Rocket fins are more like the rudder of an airplane than the wings. A fighter plane is like a cross between a rocket and an airplane, because of the high amount of thrust generated by the engines.

A pulse jet engine is something students make in college engineering courses under the direction of experienced professors. When I was a student, we made a small Pulse Jet Engine out of clear acrylic that burned bright and loud enough to wear eye and hearing protection.

These types of engines are very simple, as they have no moving parts. They've been used on scram jet engines and other types of supersonic craft.  A pulsejet engine works by alternately pushing out a hot breath of air rearward and then breathing in fresh air to replace it.  They can run on gasoline, diesel, or kerosene. 

The video below is for DEMONSTRATION PURPOSES ONLY. Please read text below the video.

Note: Please don't try to make one of these pulse jets! There are videos that will show you how, and not one of them I've found is safe to do without a supervising instructor... in fact, they are highly dangerous because of the types of containers and fuels people have chosen to try. The container must be able to withstand high thermal differentials and pressure changes, and the propellant chosen must not burn too hot or you'll explode the container.


Electric Spinning Flyer

Friday May 22, 2009
After you've made the paper flying machines, it's time to step it up and make an electric plane that really flies around in a circle. You can suspend this from a string tied to the ceiling or pop it into the eraser top on a wooden pencil. Either way, it's guaranteed to make you and your cat quite dizzy.

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Materials:

  • 1 wood pencil with eraser

  • AA battery pack

  • 3VDC motor

  • 5 popsicle sticks

  • 2 alligator clip leads

  • AA batteries for your battery case (Cheap dollar-store “heavy duty” type are perfect. Do NOT use alkaline batteries like Duracell or Energizer!)

  • 1 propeller (rip this off an old toy or hand-held fan or balsa wood airplane)

  • 1 tack


Here's what you do:


This is an excellent demonstration of Newton's Third Law: the propeller generates thrust in one direction, sending the airplane in the other. Since the airplane is attached to the long shaft, it's flight is restricted to a tight circle. It's important to be sure to balance the rod on your fingertip before attaching the tack, or it may not be able to correct this imbalance during flight. Give it a try!

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