# Flight Test

lunifer's version from 2016-06-18 16:10

## Forces

What is a force?A push or pull in any direction.
What is the gravity/weight force?Gravity is an invisible force. It is a pull that goes downwards, and works against things trying to fly.
What is the drag force?Drag is a force that slows a moving object down. For example, when a race car releases a parachute, that parachute created a drag force to slow the car down. It works against things trying to fly.
What is the lift force?Lift is a force that goes upward.
What is the thrust force?Thrust is a force that goes forward. On an airplane, this is usually produced by the engines.

## Gas and Air

What happens when gas is heated?The particles of the gas will move faster and become further apart, basically expanding.
Why does hot air rise?When gases are heated, the particles become further apart, which means that the gas will become lighter, making it rise.

## Hot Air Balloons

Who invented the Hot Air Balloon?2 brothers named Joseph and Etienne Montgolfier.
How does a hot air balloon float?Heated air is put in the balloon part. The heated air will rise, bringing the hot air balloon with it.
What is the main problem about a hot air balloon?They are impossible to control.
How is a hot air balloon let down?A flap can be pulled to let hot air out of the balloon, eventually landing the hot air balloon.

## Laws of Flight

Bernoulli's Law of PressureThe faster air flows, the less pressure it has.
Law of FlightObjects always go from high pressure to low pressure.
Newton's Third LawIf there is a force in one direction, there is an equal force in the opposite direction.

## Airships

Explain what helps an airship fly.If you fill a balloon wit a gas that was lighter than the air around it, the balloon would be able to rise.
What was the name of the airship that burned up?the Hindenburg
What is a gas commonly used today in airships?helium
Why is hydrogen a shitty choice for an airship?Hydrogen explodes when it comes in contact with a spark/flame.
What is the main purpose of an airship?Advertising

## Kites

Where and when were the first kites built?China, 400 BCE
What keeps a kite in the air?Kites rely on the wind to keep them in the air.
How does wind help a kite stay in the air?The wind hits the kite at an angle making an area of high pressure on the front side of the kite, where the air is "squeezed together", and a low pressure area on the back side of the kite. Since objects try to go in the direction of the lowest pressure, lift is created, keeping the kite in the air.

## Gliders

What makes a glider different from an airplane?Gliders do not have any engine or source of power.
How does a glider fly?Gliders fly using the currents of the wind, and the special shape of their wings.
List 2 ways a glider can be launched.1) A giant elastic band shoots the glider into the air like a sling shot. 2) They are towed in the sky behind an airplane, and at a certain point, and unhooked from the plane so that it can glide.
Describe how a glider's wings work.When the leading edge of the wing goes through the air, the air is split by the wing. The air moving over longer, curved top of the wing travels faster than the air under the bottom of the wing. Objects try to go in the direction of low pressure air, which provides lift for the glider.
What controls the direction of the glider, and where is it located?Direction is controlled by the rudder, which is located at the back of the glider.
What controls the up and down movement of the glider, and where is it located?Up and down movement is controlled by moving the elevators, which are located at the back of the glider.
What are thermals, and how are they used to keep gliders in the air?Thermals are rising air currents. They are caused by areas that heat up quickly in the sun, like a dark field. Because hot air rises, it will help the glider stay in the air.
How do mountains/hills help a glider fly?If wind were to hit a mountain/hill, the wind would be deflected upwards, causing air currents to go up and lift a glider very high.

## Airplanes

Who invented the first airplane?Orville and Wilbur Wright
What makes the glider and airplane alike?They both use the special shape of their wings to fly.
What is a Propeller-Driven Airplane?They are airplanes that use a propeller to move the plane through the air.
How do blades on an airplane help with flying?When the blades spin, they "bite" into the air in the front of the plane and push it towards the back of the plane. This makes the plane move forward, moving air over the wings and creating lift.
When were jet engines developed, and where?During World War II, in Germany.
How does a jet-driven airplane work?First, a turbine in the front of the engine spins and "draws" cold outside air into the engine. Next, the air is mixed with jet fuel. A spark lights the jet fuel, and the air is heated and expands. Then, the spinning turbine at the front stops the heated air from escaping from the front, so the air would instead escape at the rear engine. The escaping gases go backwards, sending the plane forwards. (Newton''s Third Law)
What are 2 advantages that a propeller-driven plane have over a jet plane?They are cheap to build, and are reliable.