Aerodynamics--4 forces--Nakamura Lock, Phoenix, Balcony Bomber

What Is Aerodynamics?

Aerodynamics is the way objects move through air. The rules of aerodynamics explain how an airplane is able to fly. Anything that moves through air is affected by aerodynamics, from a rocket blasting off, to a kite flying. Since they are surrounded by air, even cars are affected by aerodynamics.

Dynamics of Flight  

What Are the Four Forces of Flight?

The four forces of flight are lift, weight, thrust and drag. These forces make an object move up and down, and faster or slower. The amount of each force compared to its opposing force determines how an object moves through the air.

What Is Weight?

Gravity is a force that pulls everything down to Earth. Weight is the amount of gravity multiplied by the mass of an object. Weight is also the downward force that an aircraft must overcome to fly. A kite has less mass and therefore less weight to overcome than a jumbo jet, but they both need the same thing in order to fly - lift.

What Is Lift?

Lift is the push that lets something move up. It is the force that is the opposite of weight. Everything that flies must have lift. For an aircraft to move upward, it must have more lift than weight. A hot air balloon has lift because the hot air inside is lighter than the air around it. Hot air rises and carries the balloon with it. A helicopter's lift comes from the rotor blades. Their motion through the air moves the helicopter upward. Lift for an airplane comes from its wings.

How Do an Airplane's Wings Provide Lift?

The shape of an airplane's wings is what makes it possible for the airplane to fly. Airplanes' wings are curved on top and flatter on the bottom. That shape makes air flow over the top faster than under the bottom. As a result, less air pressure is on top of the wing. This lower pressure makes the wing, and the airplane it's attached to, move up. Using curves to affect air pressure is a trick used on many aircraft. Helicopter rotor blades use this curved shape. Lift for kites also comes from a curved shape. Even sailboats use this curved shape. A boat's sail is like a wing. That's what makes the sailboat move.

What Is Drag?

Drag is a force that pulls back on something trying to move. Drag provides resistance, making it hard to move. For example, it is more difficult to walk or run through water than through air. Water causes more drag than air. The shape of an object also affects the amount of drag. Round surfaces usually have less drag than flat ones. Narrow surfaces usually have less drag than wide ones. The more air that hits a surface, the more the drag the air produces.

What Is Thrust?

Thrust is the force that is the opposite of drag. It is the push that moves something forward. For an aircraft to keep moving forward, it must have more thrust than drag. A small airplane might get its thrust from a propeller. A larger airplane might get its thrust from jet engines. A glider does not have thrust. It can only fly until the drag causes it to slow down and land.

Why Does NASA Study Aerodynamics?

Aerodynamics is an important part of NASA's work. The first A in NASA stands for aeronautics, which is the science of flight. NASA works to make airplanes and other aircraft better. Studying aerodynamics is an important part of that work. Aerodynamics is important to other NASA missions. When the space shuttle lands, it glides through the air. NASA had to use aerodynamics to figure out how to let the shuttle land safely. Even probes landing on Mars have to travel through the Red Planet's thin atmosphere. Having to travel through an atmosphere means aerodynamics is important on other planets too.

Aerodynamics

What makes a paper airplane fly? Air — the stuff that's all around you. Hold your hand in front of your body with your palm facing sideways so that your thumb is on top and your pinkie is facing the floor. Swing your hand back and forth. Do you feel the air? Now turn your palm so it is parallel to the ground and swing it back and forth again, like you're slicing it through the air. You can still feel the air, but your hand is able to move through it more smoothly than when your hand was turned up at a right angle. How easily an airplane moves through the air, or its aerodynamics, is the first consideration in making an airplane fly for a long distance.

Drag and Gravity

Planes that push a lot of air, like your hand did when it was facing the side, are said to have a lot of "drag," or resistance, to moving through the air. If you want your plane to fly as far as possible, you want a plane with as little drag as possible. A second force that planes need to overcome is "gravity." You need to keep your plane's weight to a minimum to help fight against gravity's pull to the ground.

Thrust and Lift

"Thrust" and "lift" are two other forces that help your plane make a long flight. Thrust is the forward movement of the plane. The initial thrust comes from the muscles of the "pilot" as the paper airplane is launched. After this, paper airplanes are really gliders, converting altitude to forward motion. Lift comes when the air below the airplane wing is pushing up harder than the air above it is pushing down. It is this difference in pressure that enables the plane to fly. Pressure can be reduced on a wing's surface by making the air move over it more quickly. The wings of a plane are curved so that the air moves more quickly over the top of the wing, resulting in an upward push, or lift, on the wing.

The Four Forces in Balance

A long flight occurs when these four forces — drag, gravity, thrust, and lift — are balanced. Some planes (like darts) are meant to be thrown with a lot of force. Because darts don't have a lot of drag and lift, they depend on extra thrust to overcome gravity. Long distance fliers are often built with this same design. Planes that are built to spend a long time in the air usually have a lot of lift but little thrust. These planes fly a slow and gentle flight.

YOUR JOB AS AN AERONAUTICAL ENGINEER (creation, design, and maintenance of travel machines, including airplanes, missiles, helicopters, satellites and spacecraft):

1. Understand the four forces of flight: lift, weight, thrust and drag.
2. Lift up must be greater than the weight due to gravity.
3. Thrust forward must be greater than the drag due to resistance.
4. Create many planes and test the balance of the forces of flight.
5. Make adjustments to optimize flight.

The directions to create the Nakamura Lock, Phoenix, and Balcony Bomber are in the attached pdf. In class, we focused on the Nakamura Lock since it has a world record 80.5 feet indoor flight, slightly longer than the other two planes. The NL is also easier to create and very reliable. When you throw your planes this week, think like an Aeronautical Engineer and balance the counter forces of weight and lift, and drag and thrust. For example, if you throw the NL too hard, an over abundance of thrust will actually create more drag, causing the plane to backstall. If you make the plane out of cardboard, the weight will likely be too much for the lift generated. Striking the perfect balance is a science that requires multiple trials.

I will attempt to create videos to create these planes and post on youtube.