Theory Of Flight Flashcards
Describe ‘Dynamic Pressure’
The active pressure felt by a stream of molecules hitting something
Define angle of incidence
The angle at which the wing is fixed to the air frame relative to the longitudinal axis
Define ‘Wing Chord’
A straight line joining the leading and trailing edges
Describe Aerofoil
A body when set at a suitable angle to a given airflow produces much more lift than drag
Describe kinetic and potential energy
Kinetic:
Energy produced by a body by virtue of motion.
Proportional to velocity
KE= 1/2mv*2
Potential:
Energy passed by an object by virtue of its position in a Force field
PE= Weight x Height
Boundary Layer
A very thing layer of air flowing over the surface of an aircraft wing. Molecules on the wing are motionless
Describe Pressure flow and how lift is produced
Pressure flow is a result of Bernoulli’s theorem. Total pressure in a flow must remain constant. Therefore when there are both high and low pressure in a given space, the higher pressure stream will move quickly to the low pressure stream in order to maintain a constant pressure.
Lift works by splitting the airflow across an aero foil into two streams, a low pressure flow caused by the airflow travelling further across the upper surface of the wing, and a higher pressure airflow travelling under the wing. This means the airflow travelling above the wing must increase its speed, and therefore its dynamic pressure to rejoin the airflow from the underside of the aero foil at the trailing edge of the aero foil. This creates a suction like phenomenon known as lift
Relative Airflow
Airflow relative to an aerofoil
Aerodynamic still
The point at which am aerofoil by increasing its AOA no longer produces lift
airspeed
- Speed of the aircraft relative to the air
- X number of particles move over the wing in a given time
- At twice the speed twice as many particles will move over the wing in the same time
Attitude
Is the pitch angle or the angle relative to the horizontal made by the wing
Stagnation point
The point at which the flow splits on the leading edge is the stagnation point
Define angle of attack
Angle between the cord and relative airflow
Describe ‘Static Pressure’
The unchanging pressure felt at any one time given a certain set of conditions
Define ‘mean wing camber’
A line halfway between the upper and lower surfaces
Will increase lift
