The Flying Machine Book
Build and Launch 35 Rockets, Gliders, Helicopters, Boomerangs, and More
By Bobby Mercer
Chicago Review Press Incorporated Copyright © 2012 Bobby Mercer
All rights reserved.
The ability to fly has amazed people since time began. The earliest humans watched birds soaring in the sky and dreamed of joining them. Kites were probably humankind's first attempt to reach the skies. The Chinese first started flying kites around 400 BO, for ceremonies and just for fun.
Leonardo da Vinci was the first person known to seriously study flight. His drawings described his theories on bird flight. Da Vinci even drew pictures of imaginary flyers that would allow a person to fly under his or her own power. Although none were built for over 400 years, his designs inspired the invention of the helicopter.
In the late 1700s, hot air gave human-powered flight a lift. People discovered that hot air rises, so a bag filled with hot air will float. This led to the invention of the hot air balloon. Hot air balloons soared over Europe in the 1780s, giving people the opportunity to realize their dreams of flying through the air.
Around 1800, Englishman George Cayley took flying in a new direction when he discovered the modern airfoil. Cayley, often called the Father of Aviation because of his studies, is acknowledged as the first person to realize that the battling forces governing flight were lift, thrust, drag, and weight. He also built the first glider capable of holding a person, and that first flyer was a 10-year-old boy. Cayley also experimented with rudders and flaps, just like you will on the flyers in this book.
Of course, the Wright brothers pioneered powered flight, but Cayley's work is more closely related to the flying machines you will be building.
Each chapter in this book focuses on one type of flyer: helicopters, rockets, boomerangs, and different types of gliders. Not all the flyers are easy to make, and many take practice to perfect. But with a little patience, your flyer can reach the sky.
The Bernoulli Principle
Daniel Bernoulli's dad, a brilliant mathematician, never wanted his son to study math. Instead, he wanted Daniel to study medicine because it paid better. Daniel did go into medicine but never forgot his love of math. As a math professor in his 20s, he discovered a principle that combined his interests in math, science, and medicine, and it made him both famous and rich.
At the time of his discovery, Bernoulli was working with blood. He wanted to know about the relationship between blood pressure inside an artery and the speed of the blood through the artery. He soon realized that if he punctured a tube carrying a fluid with a thin pipe, the fluid would go up the pipe. And more interestingly, how far it rose (due to pressure) was related to the speed of the fluid past the end of the pipe. For the next 150 years in Europe, physicians would measure blood pressure by piercing a patient's artery with a thin glass tube. Luckily for you and me, we have a safer way to measure blood pressure today.
Even though Bernoulli was working with a liquid, the same principle works for gases such as air. Scientists classify both liquids and gases as fluids, since they flow.
You can see Bernoulli's principle at work by doing this simple experiment. Hold a long strip of paper (a dollar bill works well) tucked tightly just under your bottom lip. Blow hard, directly outward, and the strip will rise. Fast-moving air creates a low pressure above the paper, and the strip lifts.
Now, let's put Bernoulli's principle to work and learn more about the science of flight.
Flight is governed by four forces: lift, thrust, drag, and weight.
Thanks to Mr. Bernoulli, we now know that as air moves over an airfoil (airplane wing, helicopter rotor blade, etc.), the air over the top has to travel a greater distance. Because it travels a greater distance in the same amount of time, it moves faster than the air moving under the wing. Faster air has lower pressure than slower air. High pressure under the wing will lift the wing up toward the area of lower pressure.
Thrust comes from the engine on most traditional airplanes, or from the rocket engine on a rocket. Thrust causes the plane to fly forward. However, since you won't be using engines in this book, your flying machines' thrust will come from other sources. You will use muscle power and stretched rubber bands for most of your flyers. After you launch a flyer, only inertia keeps the flyer moving forward.
Moving things want to stay moving. Inertia is the resistance to change in motion. One example of inertia is when your body goes forward on a bus as the bus slows to a stop. Inertia will keep your flyer going until air friction (drag) causes it to slow. Since inertia depends upon the mass of an object, you will often add small weights, such as pennies and paper clips, to help keep your flyers going.
Thrust and drag wage a constant battle as flyers soar. Drag is friction from the air. As a flyer moves through the air, it pushes air molecules out of the way. The more air molecules it hits, the more drag it feels. For that reason, drag depends on speed. Also, the larger the frontal area pointing into the flowing air, the greater the drag force. For example, a jet is more streamlined and aerodynamic than a small prop-driven plane because its nose is tapered. To minimize drag for your flyers, you will make them aerodynamic by giving them small pointed fronts to help them slice through the air.
Weight pulls us down — all of us. Weight is the archenemy of lift for a flying machine. Lift attempts to keep something up and weight pulls it down. Although airplanes (and flyers) must be made of strong materials, those materials must be of the lightest weight possible. The heavier the material, the more lift that's needed to overcome it.
While building and launching flyers, you have to keep safety in mind. Here are a few rules to make your flying time safe and enjoyable.
1. Always ask for adult permission to build any of the flyers in this book.
2. Never aim a flyer at people, pets, or breakable stuff. Outside is a great place to launch most of these flying machines. You'll have longer flights and less chance of breaking Mom's glassware. (Most flyers, however, can be flown indoors. Just be cautious when doing so.)
3. Be very careful with scissors. Many of the flying machine materials can be cut with safety scissors, but sometimes sharper points are needed. Have an adult or older sibling help you when you use pointed scissors or a knife.
4. When using a stapler, keep both hands well away from the stapler jaws.
Paper folding is the key to many good flyers. The best way to fold paper is with your thumb or index finger. Using your thumbnail to completely smooth out creases is also a valuable skill.
In this book, a "hot dog" fold is made lengthwise down the paper. This leaves you with a long, skinny, folded piece of paper just like a hot dog bun. A "hamburger" fold is made across the piece of paper and leaves you with a short, wide, folded piece like a hamburger bun.
You will use a variety of paper tosses to get various flyers up, up, and away.
1. Wrist flick: This is the most basic flyer toss. Grab the flyer between your thumb and index finger, then flick your wrist forward away from your body.
2. Frisbee toss: Just like tossing a Frisbee, this method is designed to get the flyer spinning. Place your thumb on top and curl your fingers beneath the flyer. Put your palm toward your belly button. Quickly extend your wrist, and away your flyer will spin.
3. Boomerang toss: Boomerangs are actually thrown overhead. Grab the bottom of the boomerang, then hold it over your throwing shoulder almost perfectly upright. Extend your elbow and let it fly forward. The boomerang toss takes practice to perfect. The Aussie is the perfect flyer to practice with. Boomerang pros have to practice for a long time to master the curved flyer, so be patient.
4. Finger flick: The finger flick is a valuable technique for the Basic Fingerrang and all of its cousins. The flick is done by curling your finger to below the knuckle of your thumb. The more you curl it, the more energy you store in your finger. Using muscles to straighten your finger will cause the Fingerrang to flick forward. Some people use their index finger, while others find more success with their middle finger. Try both to see what works best for you.
You call use common materials to make fun flying rockets. The rockets in this chapter will start with simple designs and progress toward the more challenging.
Rockets fight a constant battle of thrust, weight, lift, and drag. Thrust comes from the rocket engine and pushes the rocket up. At the same time, weight pulls down on the rocket, and drag also acts against the upward motion. Think of it as a giant game of tug-of-war. For a rocket to lift off, thrust has to win the battle with weight and drag. Lift is just a tiny part the process and only happens when the rocket is no longer going straight up.
Rocket thrust comes from the rocket's engine. Usually this power comes from burning rocket fuel, but in the flyers you'll build it will come from rubber bands and air pressure. Your family probably wouldn't approve of you burning rocket fuel in the house anyway. But you may want to try building model rockets someday — they do burn rocket fuel.
Rockets are stabilized and steered by the fins on the side and by redirecting the engine nozzles. The fins redirect air just like flaps on a plane. The engine nozzles can be redirected by the use of gimbals, which allow the nozzle to swing in different directions. The gimbals redirect thrust and allow the rocket to launch at the correct angle.
When the rocket gets to space, tiny retroactive rocket engines steer the craft. Retro rockets only blow in one direction, but each faces a different direction. When fired in the right combination using Isaac Newton's Third Law of Motion (for every action, there is an equal and opposite reaction), the rocket will turn. Similar retro rockets allow the rocket to speed up or slow down as needed. There is no drag in space because there is no atmosphere, so the rocket just keeps zipping along at a constant speed until the retro rockets fire. Over 99 percent of the rocket fuel is used up during launch to overcome weight and drag to propel the rocket into space.
Let's stay on Earth and build our own rockets.
Basic Straw Rocket
A simple rubber band will launch this Basic Straw Rocket high above the treetops.
Index card (or scrap cardstock)
Step 1: Using your thumb and index finger, flatten one end of a drinking straw.
Step 2: Using scissors, cut the flat end of the straw about 1 inch from the tip.
Step 3: Cut two strips, each 1 inch by 3 inches, from an index card to create the rocket's fins. (Note: You can also use magazine insert cards or any scrap cardstock.)
Step 4: Insert the two strips into the slit that you cut in the end of the straw. Staple them securely. These will be the rocket fins. Don't fold them out yet.
Step 5: Insert a rubber band about 1 inch into the other end of the straw.
Step 6: Staple across the rubber band end of the straw. Take care to "capture" the rubber band through the two prongs of the staple. Stapling through the rubber band itself weakens the rubber band and leads to shorter flights (and broken rubber bands). If the rubber band breaks, just staple in another one.
Step 7: Fold out the fins to create an X.
Step 8: Hook the rubber band on the end of the ruler. Hold the fins and pull back. Let go of the fins and watch the rocket blast off. Instead of the ruler, you can also use the Straight-as-an Arrow Launcher (page 164).
Advanced Flight Topics
While flying your Basic Straw Rocket, here are a few experiments you can do: Pull back the rubber band to different lengths and see how that changes the flight path. Try bending the fins to get the rocket to spin as it flies. Launch your rocket at different angles. Which angle gives you the greatest distance? Which angle gives you the greatest time in the air? Challenge a friend to build his or her own rocket and then have a rocket race.
Build this super sleek high-flying cruise missile that can fly over your house.
Three drinking straws
Step 1: Use the scissors to cut three straws so they are each about 4 inches long. Then cut one of the straws to be ¼ inch shorter.
Step 2: Stack the straws in a triangle and even up one end. Wrap a piece of tape around that end. This will be the rear end of the Cruise Missile.
Step 3: Cut a ½-inch-wide strip of scrap cardstock — magazine covers, index cards, file folders, or old greeting cards will all work. Fold the strip exactly in half and press down the crease with your thumbnail. Then, from the fold, measure 1 inch and bend both wings out. The double fold will be the tail and the single thicknesses will be the wings. The wing/tail assembly should look like a Y, as shown. Don't worry yet about the wings' length; you will trim them later.
Step 4: Slide the tail (double fold) between the two long straws. The wings should come out between the long and short straws on either side. Slide all the way until you reach the tape strip at the rear.
Step 5: Wrap a piece of tape around the straws just in front of the wing/tail assembly to hold it in place. Trim the wings to the desired length. (You might try 1 inch for your first Cruise Missile.) You can make them all the same length, but you don't have to.
Step 6: Take a piece of tape and hold the sticky side up. Lay a rubber band across the tape so that it sticks. Make sure the rubber band is flat on the tape.
Step 7: Place the rubber band beneath the bottom (short) straw and press up. Wrap the tape ends around the nose of the Cruise Missile.
Step 8: Now you are ready to launch your Cruise Missile. Hook the rubber band on the ruler (or the Straight-as-an-Arrow Launcher from page 164). Pull back the rubber band and let the Missile fly. Remember: Don't aim at friends, pets, or Mom's breakable stuff.
Advanced Flight Topics
Thrust is key for rockets, so pull harder on the rubber band to make the Missile go farther. You can easily cut and replace the front tape to experiment with different size rubber bands. You can also try full-size straws to see how the flight path changes or build the Cruise Missile with bigger (or smaller) wings and see what happens.
An empty water bottle and a big foot will help this rocket soar 20 to 30 feet.
Sheet of paper
Flexible drinking straw
Empty plastic water bottle
Optional: small weights, such as pebbles or marbles
Step 1: Use the scissors to cut a sheet of paper into fourths. Roll one ¼ sheet around the straw but make sure it is not too tight since the straw will be the launch pad. Wrap a small piece of clear tape around both ends and the middle of your rocket to form a tube.
Step 2: Fold one end of the rocket body tube over and secure it with clear tape. This will be the nose of the rocket.
Step 3: Now it's time to make the tail fin. Lay a 3-inch piece of masking tape on the table, sticky side up. Then place the tail of the rocket in the center of the sticky side.
Step 4: Place another 3-inch piece of masking tape over the top of the other one, but put this piece sticky side down. Don't worry if the pieces aren't exactly the same size. You'll trim the fins in the next step. (Continues...)
Excerpted from The Flying Machine Book by Bobby Mercer. Copyright © 2012 Bobby Mercer. Excerpted by permission of Chicago Review Press Incorporated.
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