Fundamental of Flight, Stability, And Control

8/8/2019 Fundamental of Flight, Stability, And Control

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Fundamentals of Flight, Stability, and Control

Fundamentals of Flight,Stability, and Control


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The Four Forces of Flight

The four forces act on the airplane in flight

and also work against each other.


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The Force of Lift

How do we explain lift?

Newtons Laws of Motion and Bernoullis

Principal are used to explain lift.


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Newtons Second Law: force causes a change in

velocity which in turn generates another force.

Newtons Third Law: net flow of air is turned down

resulting in an equal and opposite upward force.

Newtons Laws


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Newtons Third Law states that for every actionthere is an equal and opposite reaction.

Newtons Third Law


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The Venturi Tube

Bernoullis first practical use of his theorem

Where are venturi tubes used today?

Air speeds up in the constricted spacebetween the car & truck creating a low-

pressure area. Higher pressure on the other

outside pushes them together.

A wing is really just half a

venturi tube!


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A fluid (and air acts like a fluid) speeds upas it moves through a constricted space

Bernoullis Principle states that, as air

speeds up, its pressure goes down.

Bernoullis Principle


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Slower moving air below the wing createsgreater pressure and pushes up.



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Air moving over the wing moves faster than the air below. Faster-moving air above exerts less pressure on the wing than the slower-

moving air below. The result is an upward pull on the wing from the

top, and a push from the bottom--lift!



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A wing creates lift due to a combination of

Bernoullis principal & Newtons third law

Creating Lift


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Lift vs Angle of Attack


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Pitch Around the Lateral Axis


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The elevator controls pitch. On

the horizontal tail surface, the

elevator tilts up or down,decreasing or increasing lift on

the tail. This tilts the nose of

the airplane up and down.

Elevator Controls Pitch


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Roll Around Longitudinal Axis


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The ailerons control roll. On

the outer rear edge of each

wing, the two ailerons move

in opposite directions, up and

down, decreasing lift on one

wing while increasing it on

the other. This causes the

airplane to roll to the left or

right.

Ailerons Controls Roll


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Yaw Around the vertical Axis


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The rudder controls yaw.

On the vertical tail fin, the

rudder swivels from side

to side, pushing the tail in

a left or right direction. Apilot usually uses the

rudder along with the

ailerons to turn the

airplane.

Rudder Controls Yaw


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The Force of Drag


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For an airplane to speed up while flying, thrust must be greater

than drag. Thrust can be generated by a propeller or jet turbine.

For an airplane to take off, lift mustbe greater than weight.

Lift and Thrust


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Fundamental of Flight, Stability, And Control