Theory of Flight

Aerodynamics and Theory of Flight Flight is made possible because of air; now you might be asking yourself what is air? Air much like water is a fluid It is a moving set of molecules Air also has the following: Mass Weight (the effect of gravity) Pressure (the force it exerts on an area) Density (how many molecules in a certain volume) Temperature (how fast the molecules move around) Newtons Law of Motion Since air has mass it behaves according to Newton's Laws of Motion which states that for every "action" there is an "equal" and "opposite reaction." It is the "action" of the aircraft on the air and the air's "reaction" that is the primary reason for flight. When Newton's Laws of Motion is used in flight it looks like this: A propeller pushes air backwards and the opposite reaction is that the plane is pushed forwards A rudder pushes air to one side, and the opposite reaction is that the tail is pushed to the other side (causing a turn) A wing forces air downwards and the opposite reaction is that the wing is pushed upwards (causing Lift) The Four Forces on an Aircraft Weight and Lift Weight - is the Force of Gravity on the aircraft Lift - is the force required by the aircraft to overcome its Weight and become airborne and contents Thrust and Drag Thrust - is the Force that pulls the aircraft through the air - usually this is generated by the propeller Drag - is the resistance of the air to the motion of the aircraft (and all its components) How is Lift Generated? There are 2 main sources of Lift for an Aircraft: Newton's 3rd Law: as the wing pushes air downwards, the air pushes the wing upwards Bernoulli's Theorem: as the velocity of air increases, its pressure decreases