General Knowledge

Question 1

chord

Answer 1

straight line of the width of the wing, from leading edge to trailing edge

Question 2

camber

Answer 2

a curved line of the width of the wing, running midway through the wing. this takes into account the curvature of the wing. will be longer than the chord.

Question 3

angle of attack

Answer 3

the angle between the chord and the relative air flow

Question 4

vertical axis

Answer 4

runs through the top and bottom of the airplane. yaw occurs through this axis. controlled by rudder.

Question 5

lateral axis

Answer 5

runs through the wingtips. accounts for pitch. controlled by elevators

Question 6

longitudinal axis

Answer 6

runs from nose to tail. accounts for roll. controlled by ailerons.

Question 7

four basic forces

Answer 7

lift: pacts perpendicular to the relative airflow
weight: acts toward the centre of earth
drag: acts parallel to the relative airflow
thrust: acts along the longitudinal axis in the direction of motion

Question 8

aspect ratio

Answer 8

the measue of the slenderness of a wing

ratio of the span to the chord

high aspect ratio most efficient

high aspect ratio is more slender

Question 9

laminar flow aerofoil

Answer 9

type of wing designed to produce less drag

desinged to move the airflow laminar much further back

maximum thickness of the wing is at 40-50% of chord (normal wing is at around 25%)

Question 10

angle of incidence

Answer 10

angle between the chord of the wing and the longitudinal axis of the aeroplane, fixed at the time of construction

Question 11

dihedral

Answer 11

angle which the wing makes with the horizontal , i.e. the angle which it points up

Question 12

lift equation

Answer 12

L = 1/2 x p x v² x S x Cl

or

lift = 1/2 x air density x true air speed squared x size of the wing in surface area x lift coefficient

Question 13

components of drag

Answer 13

major:
parasite drag, and induced drag

parasite drag is composed of:

skin friction-
friction caused by the surface of the aircraft. i.e. rivets

form drag-
caused by the shape of the object moving through the air, streamlined objects have lower form drag. fixed gear has higher form drag

interference drag-
caused when two objects are joined together. i.e. elevator meets tail. can be minimized by rounding corners in these points

profile drag is composed of form and skin drag

induced drag-
caused by lift. newton’s 3rd law, for every force there is an equal and opposite force. lift necessarily causes drag.

induced drag:

• haighest at low speed, lowest at high speed
• increases with increased weight
• increases with increased altitude
• increases with load factor (g’s)
• incrreases with angle of attack

parasite drag:

• composed of skin friction, form drag, and interference drag
• lowest a low speed, highest at high speed
• remains unchanged with aircraft weight
• reduced with increased altitude

best economy is at best lift to drag ration, i.e. best range

Question 14

ground effect

Answer 14

when flying at a height lower than one wing span, induced drag is significantly reduced. drag can be reduced up to 70%, lift increases 45%