The Flight Unit
Claire, Bridget, Vivian & Teri
Claire:
Lift: Lift is the force that helps to keep the airplane aloft. Lift also helps by equaling out gravity
or weight. The Flaps, the Wing, and the Slats of the airplane help to create lift. The Spoiler
changes the lift.
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Lift Equation: L = Cl * ρ * V2 / 2 * A L: Lift, CI: Coefficient, ρ: Density, V2 : Velocity2,
A:Wing Area
A coefficient is a number in front of a variable.
Weight: The airplane is pulled down because of weight or gravity. Weight acts against the lift.
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The weight equation: We = m*ge W: Weight, M:Mass, G:Gravitational Acceleration
Thrust: Thrust helps to push the airplane forward. Thrust is created by the propellers of the plane.
Thrust overcomes drag. The Turbine engine helps create and generate thrust.
Drag: Is the friction that slows down an airplane. It pulls against the plane acting against the
thrust. The winglet of the airplane helps decrease the drag of the airplane.
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The drag equation: D = Cd * ρ * V2 / 2 * A; D: Drag, Cd: Coefficient, ρ: Density, V2 :
Velocity2, A: Reference Area.
Vivian:
Overall Airfoil Shape:
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Each airplane has a different airfoil shape.
Sometimes airfoils are created with certain leading and trailing edges to create different
amounts of lift.
An airfoil usually has a longer distance on top of it to create higher velocity (speed) and
lower pressure.
The bottom of the wing is usually flat and has a shorter distance than the top causing
higher pressure.
Airfoils are more likely to be curved than flat because when they were tested with a flat
surface, it caused lift, but more drag. The curved airfoil helps generate lift but less drag.
When airplanes are at higher altitudes and at fast speed, the airfoil tends to be a bit
thinner than another plane that goes to lower altitudes. This allows air to flow faster on
top of the airfoil.
Both of these parts of the airfoil help create lift.
Lift is in the wings of an airplane.
The process of lift needs to have the airplane interact with a liquid or gas.
Lift acts against a force called weight.
Lift and airfoil designs also can be used on cars. When cars are being driven, air flows up
and over the car and underneath the car too. The top of the car is usually curved while the
bottom is flat, so the car also can use an airfoil design.
Bridget:
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Bernoulli’s Principle states that when the speed of a moving fluid, liquid, or gas
increases, the pressure of the fluid, liquid, or gas decreases.
So, when the pressure of the fluid (liquid or gas) decreases, it allows airplanes to fly. This
principle applies to airplanes because of the airfoil on a plane.
As the air connects with the airfoil it separates splitting, going on to the top and bottom of
the airfoil.
As the air travels above the airfoil, the pressure decreases because; the air above has a
greater velocity than the air below the airfoil. Because the air below the airfoil has a
lower velocity than the air above the airfoil, the pressure below the airfoil is greater than
above the airfoil, allowing the plane to fly.
Parts of the Airfoil:
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Mean Camber: The curved line seperating the lower and higher surfaces of an airfoil.
Upper Camber: The upper part of an airfoil that is curved.
Lower Camber: The lower part of an airfoil that is curved.
Teri:
Why are the different surfaces of the airfoil are shaped the way they are?
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The top of the airfoil is more rounded so it creates low pressure when the air goes over it.
The bottom of the air foil is less rounded than the top but still rounded because it needs to
have high pressure when the air goes past it.
A round leading edge and a sharp, flat trailing edge add to a wing's ability to generate
more lift and less drag.
The length of the airfoil section is determined by placing the leading and trailing edges
their desired distance apart. This length is called the chord line.
Then you would add the camber line above the chord line with a slight curve. This helps
generate lift.
Then add a curved line above the camber line. The amount of thickness that is added will
depend on the amount of strength needed in the wing and the speed the airplane will
usually fly.
Add the same amount of thickness below the camber line.
Size and Shape of an airfoil
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The airfoil shape provides a lifting force when air flows around it.
An airfoil has a thick, rounded front and a thin sharp back end.
Since the top of the wing has more camber than the bottom, the air flows faster over the
top of the wing than it does under the bottom.
There is less air pressure above the wing than beneath the wing.
How do the different surface shapes affect lift and drag?
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The lift on an airfoil is the result of its angle of attack and the shape.
The difference in air pressure above and below the wing causes lift.
The amount of lift depends on the wing's airfoil shape, the size the angle of attack, the
density of the air and the speed of flight.
An airfoil shape is used to give the greatest lift possible to an airplane.
Air flowing over the top of a wing also tends to flow inward toward the fuselage.
How does size affect lift and drag?
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For example, if you had a paper plate at the right angle of attack it may create lift but it
also creates a lot of drag because of its size and that it does not create low pressure on the
top and high pressure on the bottom.
If the size is too big it will create drag and slow the plane down.