Principles of Flight Flashcards
Static Pressure?
Can be thought as the pressure exerted by the air of atmosphere itself - it is the same in all directions and surrounds a stationary object just as it surrounds a moving object.
Dynamic Pressure?
is a pressure caused by the movement of an object through the air or the flow or air past an object.
How does a pressure constant work
Static Pressure + Dynamic Pressure is a constant, in other words if dynamic pressure increases, static pressure decreases. This happens for example at the narrowest part of a venture as air moves through
Aerofoil?
Cross sectional area of a wing
The Chord line?
Straight line through the edge to the trailing edge.
The camber of an aerofoil?
Curvature.
Angle at which lift acts relative to airflow?
90 degrees.
Angle of attack?
The angle between the chord line of the aerofoil and the relative airflow.
Centre of pressure?
The point at which the force of lift appears to act. The distribution of lift changes with the angle of attack.
As the angle of attack increases?
The centre of pressure moves forward.
What is the coefficient of lift?
Measure of the lift generation properties of an aerofoil. As angle of attack increases, the coefficient of lift increases until a certain point (critical staling angle) beyond which the coefficient of lift reduces rapidly.
Coefficients of drag?
A measure of the drag generation properties of an object such as an aerofoil. (or aircraft)
Wake Turbulence?
Generated by a wing moving through the air, in particular at the wingtips where the airflow from under and over the wing surfaces meet and form a vortex.
Which type of aircraft create the most wake turbulence?
The larger, heavier and slow flying aircraft create the most wake turbulence.
Parasite drag?
Term used for drag caused by moving an object through the air
The ground effect?
This occurs when the aircraft wing is close to the surface (within a height equivalent of one wing span) ground effect modifies the airflow around the wing so that induced drag is reduced and as a result both lift and airspeed will increase, up to a certain point.
The Stall?
Occurs when smooth airflow over the wing breaks down and the airflow separates from the wing - this leads to a marked loss of lift and a significant increase in drag.
When does the stall occur?
When the wing reaches the critical angle of attack once the angle is reached the wing will stall regardless of airspeed.
Lift Augmentation: trailing edge flap?
reduces stall speed and increases both lift and drag. A wing stalls at a shallower stalling angle of attack when flaps are extended.
Lift Augmentation: Leading edge slots or slats?
re-energise airflow over the wing, and the wing stalls at steeper greater angle of attack if the wing has slots or slats.
the Boundary layer?
Layer of air closest to the surface of a moving object is the boundary layer.
where does thin Laminar boundary occurred?
leading edge of the wing where the fluid first meets the object.
Where does turbulent boundary occur?
further along the wing as the surface boundary thickens. Creates more drag, however it is less prone to separating from the surface.
Static stability?
a measure of how readily an aircraft returns towards its original attitude, following a disturbance
dynamic stability?
Measure of how easily the restoring motion caused by static stability is damped out so that the aircraft settles back at its original attitude.
positive stability?
returns aircraft to original position.
neutral stability?
disturbance gets no worse
negative stability?
disturbance increases.
differential ailerons?
going up aileron moves through a greater angle than the down-going aileron.
where are the limiting load factors?
Aircraft’s flight manual / pilots operating handbook
Flight load limits: Normal?
3.8
Flight load limits: Utility?
4.4
Flight load limits: Aerobatic?
+6
V-n envelope manoeuvring envelope?
used to set up the limiting factors and airspeeds of the aircraft.
V-a airspeed (design manoeuvring speed)
Max speed at which a full and abrupt movement of a flying control can be made without causing structural damage.
Slipstream effect?
the spiral corkscrew motion of the propeller slip stream (propwash) creates a force in the vertical tail in particular which yaws the aircraft to the left if the propeller is rotating clockwise.