1. Physics of Flight

2. Four Forces
There are four forces that act on the plane while in flight
Lift
Gravity
Thrust
Drag

3. Lift Lift lifts or pushes the plane upwards
Lift is generated by uneven flow of air over the wings
Air must move faster over the top of the wings to generate lift.
Curved wings can cause the unevenness
Angle of attack can cause the unevenness

4. Creating lift
Lift is created by moving air, specifically air moving faster over the top of the wing than over the bottom
An airplane must gain enough speed traveling down the runway before it can take off
This is generating enough difference in air speed to create the lift needed to fly

5. Center of Lift
If the wing were a square, the balancing point of the lift would be in the center of the square
Since wings are not square, the center of the lift is not in the middle
The center of lift is where lift in the front and back of the plane is balanced.

6. Gravity
Gravity is the force pulling everything towards the center of the earth
To stay in flight, a plane must have the same or more lift than pull of gravity

7. Center of Gravity Gravity is a force that pulls down on a plane.
Some planes have more mass at one end than the other, so there is more pull at this end of the plane
Center of gravity is where the pull of gravity is balanced equally.

8. Finding the Center of Gravity
Hanging the plane from a string will help you find the center of gravity
The center of gravity is not found yet, because the plane is not balanced

9. Finding the Center of Gravity
When the string is attached to the center of gravity, the plane will be balanced
Balancing Act

10. Balancing Act
A plane will fly best when the center of gravity and the center of lift are in the same location
If the center of lift is further aft (back) the nose will go down
If the center of lift is further fore (forward) the nose will go up

11. Helping the Balance
Adding a turn up or down to the trailing edge will tilt the plane up or down (same direction as the bend)

12. Thrust Thrust is the force that pushes forward on a plane.
A real plane generates continuous thrust from its engines
The paper airplane gets its thrust from the throw in flight or the launcher

13. Drag Drag is the force the pushes backwards on a plane
Drag is caused by wind resistance and “pushes” the airplane backwards. It increases/decreases with an increase in speed.
The faster something moves, the more drag is generated

14. Four Forces
There are four forces that act on the plane while in flight
Lift
Thrust
Drag
Gravity