Basic Theory of Flight Flashcards
What are the factors affecting lift?
Velocity, surface area, shape of airfoil, and angle of attack
How does the angle of attack affect lift?
The greater the angle of attack, the more air displaced. With a greater angle of attack, the air has farther to go over the top of the airfoil. This increases the camber of the airfoil
How does the shape of airfoil affect lift?
The more camber an airfoil has, the faster the air moves over the top part and the less pressure the air has, so the greater the lift
What are the 4 airfoils on an aircraft?
Rudder, wings, elevators, propeller
What is a venturi?
A system for forcing the acceleration of air by constricting it in a cone shaped tube. In the constriction the velocity increases and the pressure decreases.
What is the term used to express the curve of the wing?
Camber
What is the angle of attack?
The acute angle between the chord line of the wing and relative wind. It affects the lift and drag of an aircraft.
How can pilots increase lift?
Fly faster, change the camber of the airfoil, change the surface area, change of angle of attack
How do ailerons work aerodynamically?
They change both the camber and angle of attack, which changes lift
In which direction does lift act?
Perpendicular to the relative flow and perpendicular to the span of the airfoil
In which direction does the elevator create lift?
On the underside
In which direction does the rudder produce lift when flying?
To the side
What are the four forces acting on an aircraft in flight?
Lift, weight, thrust, drag
In which direction does weight act?
Towards the centre of the earth
What is thrust?
Force that propels the aircraft
What are the sources of thrust?
Propellers, jet engines, turboprops
What is drag?
Resistance to forward motion
In which direction does drag act?
Parallel and opposite to the aircraft’s direction of travel
How does velocity affect parasitic drag and induced drag?
Parasitic drag increases with velocity, induced drag decreases with velocity
What is form drag?
A type of drag that is dependent on the shape of the aircraft
How does the shape of an aircraft affect form drag?
Bodies with a larger cross section will have higher form drag than bodies with a thinner cross section
What is skin friction drag?
A type of drag that arises from the friction of air against the surface of the aircraft
What is interference drag?
A type of drag generated by the mixing of airflow streamlines between different aircraft components (e.g the wing and the fuselage)
What is induced drag?
A type of drag that is the by product of lift. It is created by the interference between air on the top and bottom of an airfoil
What are wingtip vorticies?
Circular patterns of rotating air left behind a wing as it generates lift
What factors affect the intensity of wingtip vorticies?
Aircraft size, speed, and wing flap & landing gear configuration
Where is the best place to touch down when landing behind an aircraft which has just taken off?
Prior to the point where the large aircraft took off
Where is the best place to touch down when landing behind a large aircraft that just landed?
Beyond the point where the large aircraft touched down
What is minimum drag?
The point of intersection of induced drag and parasitic drag
Through which point can all the lift on an airfoil be said to be acting?
Centre of pressure
What are the various forms of parasitic drag?
Interference drag, skin friction drag, form drag
What is downwash?
When air is deflected downward by the underside of the wing
In which direction is wind deflected off the wing?
Downward
How does Newton’s Third Law affect flying?
When air is deflected downward by the underside of the wing, the wing is pushed up by a counter force (lift) equal to the force it took to deflect the air downward
Which parts of an aircraft can be used to change the camber of an airfoil?
Ailerons, flaps, elevator, rudder
Which part of an aircraft can be used to change the surface area?
Fowler flaps
Which parts of an aircraft can be used to change the angle of attack?
Elevator, flaps, rudder, ailerons
