How do aircraft fly?

Answer 1

There is two categories of aircrafts, the aerostats (lighter than air) and the aerodynes (heavier than air).

-Aerostat: the aerostat uses buoyance to float in the air in much the same way that ships float on the water.They are characterized by one or more large gasbags or canopies, filled with a relatively low density gas such as Helium, Hydrogen, or Hot air which is lighter than the surroundind air. When the weight of this is added to the weight of the aircraft structure, it added up to the same weight as the air that the craft displaces.

-Aerodyne: To fly it must move forwards through the air ,this movement of air over the aerofoil shape deflects air downward to create an equal opposite upward force, called lift, according to the Newton's third law of motion.

Aerodyne flight:

The best method to answer this question is thru the use of the lift formula:

L= (1/2p) (V2) (S) (CL)

1/2p (pronounced rho) is basically the density of the air. Cool dense air provides better pressure in creating lift.

V2 is the velocity of the airfoil flowing thru the air. Higher velocity creates more lift except when reaching velocities that exceed the sound barrier disrupting laminar flow over the airfoil.

S is the surface area of the airfoil. A larger surface area creates more lift. It may also create more weight which would increase the need for more lift.

CL is the coefficient of lift. Without getting to complicated, this is basically the efficiency of the airfoil design at an angle of attack. Angle of attack is essentially the angle between the chord line of the airfoil and air flow direction.

When air flows over the airfoil, the design of the foil seperates the airflow into an area of low pressure over the camber of the airfoil, and an area of high pressure below it. Obviously the difference between the two areas will cause the movement of the airfoil in the direction of low pressure thus creating lift.

Their are four forces at work in the creation of lift:

Lift - Explained above

Thrust - The force required to move the craft forward to create velocity of airflow.

Drag - The force created from the creation of lift and thrust. Parasitic, Induced, and Profile drag are the different types of drag working against lift.

Weight / Gravity - What must be overcome by lift.

Answer 2

aircraft is based on the third law of motion and thurst.