Two Soda Cans Explain Why Airplanes Fly

Lay a row of naked 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 and *clink* they should roll toward each other and touch!

Why does this happen? When air moves, the pressure decreases. This creates a lower (relative to the surrounding air) air pressure pocket right between the cans. Recall that higher pressure pushes, and thus the cans clink together. Just remember – whenever there’s a difference in pressure, the higher pressure pushes.

What kinds of questions can you ask about this project?  For example: What types of cans work and don’t work?  How much air pressure you you really need – would a hair dryer be a better choice?

Comments (1)

Measuring the Speed of Light

So this is a more advanced project… and one that takes patience.  There is an easy way and a hard way to do this project.  I particularly like the hard way better, because there’s more observational science involved and less mathematics.  But let’s start with the easy way first.

Easy Method for Measuring the Speed of Light In a transparent tupperware, make a batch of clear gelatin (like jell-o) and let it harden.  Skimp on the water so the mixture is very firm.  When ready, take it out of the fridge and shine a laser beam through the side of the tupperware… you’ll see the beam ‘bend’.  Carefully measure the angles of incidence and refraction and use Snell’s law to back-calculate the speed of light.

For reference, the index of refraction for ice is 1.31; for water at 20 deg. C is 1.33; for diamond it’s 2.42; for plexiglass it’s 1.51.  For your measurement to be completely accurate, you’ll need to remove the tupperware and measure it for the gelatin.

…to be continued…

Comments (1)

Solar Storms and Crazy Compasses

Once upon a time, people noticed some of the rocks on the planet stuck to other rocks… and soon after floated a shard of metal in water and noticed that it pointed the same direction no matter how you rotated the cup.  We know today about the earth having a magnetic field that keeps the needle pointing in the same direction… at least, until a thunderstorm bolts through the area.  When this happens, the needle spins around and doesn’t settle on any one particular area… a problem if you’re a sailor at sea.

Other things can cause small pockets of changing magnetic fields on the earth, such as solar storms.  The sun burps and spits out high energy photons and other particles all the time, some of which make it to earth, but most of which harmlessly pass by.  The ones we notice, however, happen when a magnetic loop on the sun snaps and breaks free, causing high energy particles to zoom toward earth.  When this happens, we get the ‘aurorae’ at the poles and pockets of fluctuating magnetic fields that are detectable with a small homemade device called a magnetometer.

You’ll need one clear, plastic bottle (soda or large water bottle with the label removed), thin cotton thread, a small magnet, an index card, a tiny mirror or thin piece of mylar, one naked straw, glue, tape, scissors, yardstick or measuring tape, and a laser.  The basic idea is this:  using an amplifier (light shot over a distance), you can detect very small changes in the magnetic field using a magnet on a low-friction spring (the thread).

Attach the bar magnet onto the index card and glue the small mirror to the magnet.  Suspend the card from the bottle cap with a length of thin string (you can test out fishing line, single fibers from nylon rope, sewing thread, etc.) and stick the whole thing inside a plastic bottle.  (You can cut off the bottom of the bottle to use as a bell-jar.)

After the card settles down, it’s time to play with the experiment.  Shine your laser on the mirror at a wide angle, and you should see a dot on the wall.  Tape a piece of paper to the wall and carefully mark the position.  Over the course of a few hours, you will notice the dot “move”.  Mark the new locations with the time and date.  Make sure you’ve got a wide angle – there should be at least 90 degreed between the incoming and outgoing laser beam.

What kind of questions can you think of to ask about this project?

Comments off

Science Project using Lasers

I get a lot of questions about how to turn  “cool”  projects into a true science fair project, and lasers are one of the activities people really want to know about. So here are the basics:

The word “LASER” stands for Light Amplification by Stimulated Emission of Radiation. A laser is an optical light source that emits a concentrated beam of photons. Lasers are usually monochromatic – the light that shoots out is usually one wavelength and color, and is in a narrow beam.  By contrast, light from a regular incandescent light bulb covers the entire spectrum as well as scatters all over the room. (Which is good, because could you light up a room with a narrow beam of light?)  A laser controls the way energized atoms release photons.

Quick note about lasers: cheap key chain lasers (like from “dollar” or “thrift” stores) work just fine with these projects. Do not use green lasers – they can cause permanent eye damage.

For starters, take your laser and zip around the house before bedtime finding cool things to shoot your laser at (or through).  Try clear bottles filled with different liquids (soap, milky water, vinegar, rubbing alcohol etc.).  Try lamps, (dark) clear light bulbs, windows, cut acrylic or crystal pieces, CDs, eyeglasses, saran wrap, colored cellophane, feathers, aluminum foil, and the mirrors in the bathroom  Once you find a cool effect, start your scientific investigation by honing in on a question you want answered – something that came up when you were playing with your laser.

One question that pops out naturally when we teach the Lasers class for kids is: “Does the beam pass through the window or reflect back?”  And when looking up the answer, we found that it did both (during our research step), which triggered another question about how lasers interacted with mirrors, from which we formulated the question and later our hypothesis…

Hopefully this gives you ideas and gets you started!

Comments off

Awesome Science Projects Now LIVE!

Okay – it’s here! You can now check out the latest awesome Science Fair Projects at this link:

Comments off

UFO Experiment

I know there are a LOT of science project ideas already out there, and our focus here at Supercharged Science has been to help you once you’ve already figured out your topic idea, but this is just one I wanted to share anyway… it’s one of my personal favorites, and not just because I wiped out the camera during the testing stage!

Click play to learn how to build your own butterflying cups – which mathematically speaking, are not supposed to be able to fly at all!

Comments (2)

Gearing up for Science Fair Season

We’re working hard to get out our latest Science Fair Project videos for the 2009 season – so you don’t have to work so hard at figuring out what and how to do it all! I’m in the lab right now and have only a quick break between video shooting, but I wanted to give you a heads up – we’ve finished recording the rocketry video yesterday and today we’re working on the solar power project. For some reason, these seem to be the top two out of all 200 projects we have that people really wanted to know about!

We’re going to have all the documentation, forms, project guide, step-by-step video, and more for every Science Fair Project link – which is different from the format we’ve had previously, which has been just how to do the experiment itself. But we realized that doing the experiment was only a small part of the whole Science Fair project experience!

So now we’ve made complete videos which detail each and every step, from researching topics to designing a quality question, to making a display board to giving a presentation… it’s all being included. We expect to have these available after the first of the year (January 1, 2009) so you have plenty of time to read over the project and do the activities yourself.

We’ll keep you posted as we go along – this is just a quick update as to what we’re up to! You can visit our website to see what we’re about at this link.

More soon,
The Supercharged Science Team

Comments off

The $1, One-Hour Science Fair Project

Since time is money, and you have neither if you’re kid on the night before your not-yet-started science fair project is due, we’ve got a secret recipe for success that could earn you the last-minute grade.

Topic: Aeronautics

Shopping List:

  • Copy paper, white and colored
  • Paperclips
  • Tape, scissors
  • Cardboard for your display (can be from an old box)
  • Digital camera (major plus if you have one)
  • Computer, printer, paper (and photo paper if you have it)
  • One hour

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

Think of a time when you were riding in a fast-moving car. Roll down the window and stick your hand out, palm down. Notice how easily the wind slips over your hand. Now turn your palm facing the horizon. Which way do you 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 somersaults into chaos. (The same is true for rockets and missiles!)

STEP #1 Getting Started Grab a sheet of paper and fold your best paper airplane design right now.  This article is a step-by-step process on taking you from idea to exhibit, so don’t just keep reading… grab the paper and fold!

Need help getting started?  Watch the video below to learn how to make stunt planes, jets, and hang gliders):

Now take your plane and balance it on your finger. Where does it balance?

Grab a hair dryer and using the cool setting (so you don’t scorch your plane), blast a jet of air up to the ceiling.  Put your airplane straight-and-level into the jet of air, and using a pencil tip on the top side of your plane, find the point at which the airplane perfectly balances while in the airstream.

Which one is closest to the nose?

Besides paying attention to the CG and CP points (and their relation to each other, as in ‘which one is closest to the nose?’), aeronautical engineers need to figure out the static and dynamic stability of the airplane… which is a complicated way of saying whether it will fly controllably or oscillate out of control during flight.

Airplanes usually balance (e.g. have their CG point) around the wings. 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 which pushes the tail section down during flight.

Positive stability means that the plane is designed so that if you jam on the controls during straight and level flight (e.g. pitch up hard), and then let go, the airplane will return to (more or less) straight and level flight. That process works like this: When an airplane in level flight suddenly pitches the nose up, the wind speed over the wings slows and decreases the lift from the plane, which causes the nose to tip downwards, which causes the wind to rush over the wings again, creating more lift. This cycle eventually dampens out and the airplane is flying level again.

If, however, you have a negative stability (meaning that your CG is aft of the CP), then when you pitch up suddenly, the aircraft may do one of several things… all of which require sick bags and a parachute. One of the worst cycles is this: When the tail-heavy plane pitches down, the speed over the wings increases and provides more lift but only briefly, because the tail-heavy plane pitches the nose up (automatically by design) and keeps the nose up until the wind speed slows down 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, generating a lot of lift very quickly until the tail section tilts the nose back up, and the cycle continues to worsen each time – greater “fall” distances” and huge structural forces on the fuselage (body) until you jump ship.

The great news is that many of these unsettling things have been figured out a long time ago by two amazing people: the Wright brothers. They are also the ones who took an airfoil (fancy word for “airplane wing”), turned it sideways and rotated it around quickly to produce the first real propeller that generated an efficient amount of thrust. (Before this time, people had been using the same ‘screw’ design created by Archimedes in 250 BC… over 2,000 years ago we’ve had about the same propeller design without much improvement made along the way…) The twist in the propeller design was also a unique invention from the Wright brothers, and modern propellers are only 5% more efficient than those created a hundred years ago by the two brilliant brothers.

STEP #2 The Question: Okay, so how can you turn these ideas into a science fair project?  Well, first you need to come up with a question, or a hypothesis.  Here are a few examples to get you started…  you can use one of these, or make up your own:

  • Does the CG need to be aft the CP for stable flight?
  • What dihedral angle (wing flex angle, more on that later) is best for long flights?
  • Does wing area affect time aloft?
  • How does elevator trim affect straight-and-level flight?

STEP #3 The Materials & Methods: Your project is deceptively simple… and very complex once you get into it (as you can see by the introduction section).  You’re now making flying paper machines (paper airplanes) through the eyes of an engineer.  So get a sheet of paper and make your best design right now and throw them around the room.  When you’re done, click here to watch a short video on how to make our favorite flying designs.  When you settle on a design you really like, you need to figure out what you are going to test (and change), and how you are going to measure it.

For example, if you want to measure the effect of moving a weight around on your airplane (you could simulate this by clipping a paper clip onto various parts of the airplane), the control would be no paperclip, and your vairable (the thing you’re testing) would be location of ONE paperclip. (If you start adding in more thn one paperclip, you’re now testing not only the location but the size of the weight, and this requires a whole separate testing procedure using the Scientific Method).

Another example: If you wanted to figure out how the dihedral angle affects your flight, your control is zero dihedral (wings are flat), and your variable would be to test different angles both flexed above and below the horizontal position, using a protractor to measure your angles.

If you wanted to test the position of the CP and the CG, you’ll need to find a way to move the CG of the plane without affecting other things, such as wing shape.  (Paperclips are good ways to shift the weight of a plane.)

Once you’ve settled on a variable (thing you are going to test) and a control (baseline), you can go to the next step.

STEP #4 Taking Data: Across the top of the page, write down the stuff that does NOT change during your experiment.  You need to record as much detail as possible, so if someone else wants to recreate your experiment, they have enough information to go on.  At the top of your page, include specifics, such as:

  • Your name (silly, yes.. and essential)
  • Date and time of day
  • Weather conditions (and wind speed, if you’re doing this outdoors – check the weather online for exact measurements if you don’t have a thermometer…
  • Airplane geometry that does not change throughout your entire experimentation process. This could be the wingspan (AKA chord length, which is the longest line you can draw across the wings from tip to tip), wing area (you can estimate this using math and geometry, or use a sheet of grid paper and count up the squares the area of the wing covers up), weight of paper (one sheet = 1 ounce, or 0.014 pounds), dihedral angle (use a protractor – this idea is covered in the video), wing flap (elevator or aileron) position (up, down, neutral), location of CG and CP points (see above details on how to do this).

Draw a line under all this information, and using a ruler, make yourself a table (grid) for taking your data underneath your information.  You’ll need columns for the things you are testing for, which could be:

  • Trial # (1, 2, 3 etc…)
  • What you changed (number of paperclips, position of paperclips)
  • Time aloft (seconds)
  • Distance traveled (feet)
  • Position of CG and/or CP
  • Performance (pitch up/down, yaw up/down (rotation about the vertical axis), roll up/down, and did it do so fast or slow?)
  • Dihedral angle (in degrees, positive or negative)

STEP #5 The Experiment: The fun part!  Start throwing your airplane around and jot down your results.  Although steps # 3 and #4 seem like a headache, they really set you up for successful tracking and data-taking for this part. Take LOTS of photos of your experiment, you, and anything else that will clearly demonstrate what you’re doing.

Think of it this way… you took care of all the detail work upstream, so when some part of your experiment actually works right, you can say, ‘Oh, that’s what I did!’  Speaking of which… if you’ve completed your table, it’s now time to jump to the next step.

STEP #6 The Results: Check over that table now… what do you find?  Where did your airplane perform the best?  Fly the highest? Zoom for the longest length of time?  It’s a lot easier to see when you write it down… but it’s even easier when you chart your data on a graph.  So go fire up your computer or grab another sheet of paper and mark out a grid.

You’ll want to choose a graph that shows whatever shows off your results the best.  You might have to play around with options here (which is why the computer is great here).  For more qualitative results, you can add in a “Performance Scale” and rate your plane’s performance from 0 to 10, and plot your dihedral angle on the horizontal scale and the performance rating on the vertical scale.  Don’t forget to add in units to your scales – if you’re plotting time aloft, make sure to add in the word ‘seconds’ somewhere, so people know what unit of measurement you’re referring to.  For example, if you’re charting “Distance Traveled” on one scale, is it meters or feet, or even miles you’re using to measure your plane’s performance?

And don’t worry if your numbers are not as you expected.  One of the biggest mistakes you can make is to fudge your data to match your hypothesis.  DON’T EVER do this!! You miss out on learning something new, and fudging is not doing real science.

STEP #7 The Conclusion: This is where you look at your results and answer your original question.  Personally, I like a concise, one-sentence conclusion that says it all.  After reading hundreds (if not thousands) of engineering reports, the accurately-stated one-liners are the winners.  If I want more detail, I’ll read the whole report.

STEP #8 Recommendations: This is a nice way to end the report.  Recommendations basically answer this one question:  “If you had more time, what would you test next?”  Maybe you’d test the number of paperclips, now that you know their ideal location.  Or maybe you’d play with the CP now that you know the best CG spot.  Whatever it is, jot it down on your paper.

STEP #9: Presenting Your Report/Building a Display Board: You’re now ready to build your display board, write your report, and learn how to present your findings. We’ve talk more about this in another article, as this one is getting rather long! See you soon!!

Comments (1)

Aurora on Film

Hey there! I know we don’t usually mention things we do outside of Science Fair project stuff, but this was way TOO COOL to pass up! We usually travel the country teaching live science workshops to kids – and have been doing that for the past decade or so – but this was our first time with a real live camera crew, stage, director, and everything!

Check out the photos the camera crew shot during our filming – Click this link and you’ll see we had such a blast…

Comments off

The 12-Hour Science Project

Okay, it’s the eve of your science fair project deadline, you haven’t even started your project, and you’re on the brink of calling Procrastinators Anonymous… but you’ve found your way here instead.  Here is our secret recipe for the world’s easiest science fair project that will take you less than 12 hours to complete, with one trip to the drug store. (To get the full-blown version (with 75-minute video) for under $10, click here.)

Shopping List:

  • Foam core display board
  • White copy paper
  • Colored (can be construction) paper
  • Fuji (white) film canisters (NOT Kodak)
  • Two packages (72 tablets total) of effervescent tablets
  • Measuring tape or ruler
  • Photo paper for your digital camera
  • Glue or double-sided sticky tape to nail down the photos and paper to the display board
  • Tablespoon measure (already in your kitchen?)
  • Thermometer (you probably already have this)
  • Stopwatch or clock (you’ll need to count in seconds)
  • Graph paper (you can make your own grid on a sheet of paper if you need to)

Your First Step: Play with the experiment first.

Place an effervescent tablet in a canister (you may need to break it into pieces) and fill part way with water. Working quickly, cap it and invert it on the sidewalk. Stand back… POP! You’ll find there’s an optimal water level for maximum height. If you work fast, you can get about four launches from one tablet. What happens if you try two tablets at once?

Here’s a short video so you can see what’s going on:

What’s going on? The tablets contain sodium bicarbonate (baking soda) and citric acid (a solid form of vinegar). What happens when you mix together vinegar and baking soda? It fizzes all over the place, doesn’t it? Note that this reaction takes place because the vinegar (acetic acid) is in a liquid state. Notice how the effervescent tablets contain both chemicals, but they don’t react until you get them wet.

The chemical reaction of sodium bicarbonate and citric acid generates gas carbon dioxide gas bubbles (the same molecule you burp after chugging an entire soda), and those bubbles foam up and out of the canister. When you cap it, there’s no room for the bubbles to go, and they build up pressure… and more pressure… and more pressure… until POP! There’s so much pressure that the canister just can’t hold it together anymore, and off flies the cap (or the canister, if you’re doing it upside-down).

Formulate your Question or Hypothesis: You’ll need to nail down ONE question or statement you want to test if it is true.  Be careful with this experiment – you can easily have several variables running around and messing up your data if you’re not mindful. Here are a few possible questions:

  • Do more tablets give  a higher flight?
  • Does more water give a higher flight?
  • Does less water give a higher flight?

Once you’ve got your question, you’ll need to identify the control and the variable. For the question: “Does more water give a higher flight?”, your control would be one tablet, and your variable is the amount of water.

Taking Data: Sticking with the Question “Does more water give a higher flight?”, here’s how to take data. Grab a sheet of paper, and across the top, write down your background information across the top of the paper, such as your name, date, time of day, weather (and wind conditions), size of tablet (in weight, or grams – check the box), water temperature (in degrees), and anything else you’d need to know if you wanted to repeat this experiment exactly the same way on a different day.

Then get your paper ready to take data… and write across your paper these column headers, including the things in ( ):

  • Trial #
  • Water (teaspoons)
  • Time to Launch (seconds) <– Note: This is the time it takes for the rocket to pop after you’ve capped it.
  • Maximum Altitude (feet)

Run your experiment starting with no water… while this seems pointless, you still need to test and see what happens.  Plus, this is an excellent time to pull out your camera and get a good photo of you doing your experiment (you’ll use this later on your display board). Run your experiment again and again, increasing the water amount by one teaspoon each time until you reach the volumetric limit of your film canister.  Be sure to use a fresh tablet EACH TIME, or you’ll also be varying the amount of fuel in this experiment also. Don’t forget to take photos as you go along – see if you can get a picture of the rocket actually blasting off the ground!

NOTE: Kodak (black) canisters will NOT work for this experiment!! Record your results.

Analyze your data. Time to take a hard look at your numbers!  Make yourself a grid (or use graph paper), and plot the Altitude Height (in feet) versus the Water Amount (in tsp). In this case, Water Amount goes on the horizontal axis, and Altitude does on the vertical axis).  You can make a second graph showing the Altitude (feet) and Time  to Launch (seconds).

For more advanced students, use your projectile motion equations from physics to check your measurements against your theoretical values.  Major bonus points!

Conclusion: So – what did you find out?  What water amount gives you the highest altitude?  Is it what you thought originally?  Science is one of the only fields where people actually throw a party when stuff works out differently than they expected!  That’s because scientists are really investigators, and they get really excited when they get to learn something new.

One of the biggest mistakes you can ever make is to fudge your data so it matches what you wanted to have happen.  Don’t ever be tempted to do this… science is based on observational fact.  Think of it this way: the laws of the universe are still working, and it’s your chance to learn something new!

Recommendations: Okay, so this is where you need to come up with a few ideas for further experimentation.  If someone else was to take your results and data, and wanted to do more with it, what would they do? Here are a few spins on the original experiment… your recommendations don’t need to be this crazy…

Add foam fins and a foam nose, hot glued into place (foam doesn’t mind getting wet, as paper does).Put the fins on at an angle and watch it spin as it flies upwards. You can also tip it sideways and add wheels for a rocket car. Stack them high for a multi-staging project, or strap three together with tape and launch them at the same time! You can also try different containers using corks instead of lids.

What other chemicals do you have which also produces a gas during the chemical reaction? Chalk and vinegar, baking soda, baking powder, hydrogen peroxide, isopropyl alcohol, lemon juice, orange juice…

Make the dislpay. Fire up the computer, stick paper in the printer, and print out the stuff you need for your science board.  Here are the highlights:

  • Catchy Title: This should encompass your basic question (or hypothesis).
  • Purpose and Introduction: Why study this topic?
  • Results and Analysis (You can use your actual data sheet if it’s neat enough, otherwise print one out.)
  • Methods & Materials: What did you use and how did you do it? (Print out photos of you and your experiment.)
  • Conclusion: One sentence tells all.  What did you find out?
  • Recommendations: For further study.
  • References: Who else has done work like this?  (Wernher von Braun, Robert Goddard, etc.)

For tips & tricks on making your exhibit board, click here.

Comments (1)