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Question: The angle of attack of an aerofoil section is defined as the angle between the:
undisturbed airflow and the chord line
undisturbed airflow and the mean camber line.
. local airflow and the mean camber line.
local airflow and the chord line
2
In a stationary subsonic streamline flow pattern, if the streamlines converge, in this part of the pattern, the static pressure (I) will ...and the velocity (II) will
(I) decrease, (II) increase.
(I) increase, (II) increase.
(I) decrease, (II) decrease.
(I) increase, (II) decrease.
3
The SI units of air density (I) and force (II) are:
(I) kg / m³, (II) N.
(I) kg / m², (II) kg.
(I) N / kg, (II) kg.
(I) N / m³, (II) N.
4
The units of wing loading (I) W / S and (II) dynamic pressure q are:
(I) N / m, (II) kg.
(I) N / m², (II) N / m².
(I) N / m³, (II) kg / m².
(I) kg / m, (II) N / m².
5
The aeroplane drag in straight and level flight is lowest when the:
induced drag is lowest.
parasite drag equals twice the induced drag
induced drag is equal to zero
parasite drag is equal to the induced drag.
6
Considering a positive cambered aerofoil, the pitch moment when Cl=0 is:
infinite
equal to zero.
negative (pitch-down).
positive (pitch-up).
7
On a un-swept wing, when the aerofoil is accelerated from subsonic to supersonic speeds, the aerodynamic centre :
remains unchanged.
shifts aft by about 10%.
slightly shifts forward.
shifts from 25% to about 50% of the aerofoil chord.
8
The lift coefficient of a symmetrical aerofoil section at zero angle of attack is:
zero
positive, if the centre of pressure coincides with the centre of gravity.
negative.
positive
9
An aeroplane maintains straight and level flight while the IAS is doubled. The change in lift coefficient will be:
x 0.5
x 0.25
x 4.0
x 2.0
10
Which formula or equation describes the relationship between force (F), acceleration (a) and mass (m)?
F=m. a
m=F.a
a=F. m
F=m / a
11
The static pressure is acting:
only in the direction of the total pressure.
only perpendicular to the direction of the flow.
in all directions.
only in direction of the flow.
12
Lift is generated when:
a certain mass of air is accelerated in its flow direction.
a symmetrical aerofoil is placed in a high velocity air stream at zero angle of attack.
the flow direction of a certain mass of air is changed.
a certain mass of air is retarded.
13
Which one of the following statements about Bernoulli's theorem is correct?
The total pressure is zero when the velocity of the stream is zero
The dynamic pressure decreases as static pressure decreases
The dynamic pressure is maximum in the stagnation point
The dynamic pressure increases as static pressure decreases
14
If in a two-dimensional incompressible and subsonic flow, the streamlines converge the static pressure in the flow will:
decrease
increase initially, then decrease
not change
increase
15
Bernoulli's equation can be written as: (pt= total pressure, ps = static pressure and q=dynamic pressure)
pt = ps / q
pt = ps - q
pt = q - ps
pt = ps + q
16
Which of the following statements about boundary layers is correct?
The turbulent boundary layer gives a lower skin friction than the laminar boundary layer
The turbulent boundary layer is thinner than the laminar boundary layer.
The turbulent boundary layer has more kinetic energy than the laminar boundary layer.
The turbulent boundary layer will separate more easily than the laminar boundary layer
17
The Cl - alpha curve of a positive cambered aerofoil intersects with the vertical axis of the Cl - alpha graph:
nowhere
in the origin
above the origin
below the origin.
18
The angle of attack of a two dimensional wing section is the angle between:
angle of attack.
climb path angle.
glide path angle.
angle of incidence.
19
On a swept wing aeroplane at low airspeed, the "pitch up" phenomenon:
is caused by wingtip stall.
is caused by extension of trailing edge lift augmentation devices
is caused by boundary layer fences mounted on the wings.
never occurs, since a swept wing is a "remedy" to pitch up.
20
The lift formula is: (rho = density)
L = CL ½rho V² S
L = n W
L = W
L = CL 2rho V² S
21
An aeroplane is in a level turn, at a constant TAS of 300 kt, and a bank angle of 45°. Its turning radius is: (given: g= 10 m/s²)
2381 metres.
9000 metres.
3354 metres.
4743 metres.
22
Which one of the following statements about the lift-to-drag ratio in straight and level flight is correct?
At the highest value of the lift/drag ratio the total drag is lowest.
The highest value of the lift/drag ratio is reached when the lift is zero.
The highest value of the lift/drag ratio is reached when the lift is equal to the aircraft weight.
The lift/drag ratio always increases as the lift decreases
23
Drag is in the direction of - and lift is perpendicular to the:
relative wind/airflow.
longitudinal axis.
chord line.
horizon.
24
If the nose of an aeroplane yaws left, this causes:
a roll to the left
a roll to the right
a decrease in relative airspeed on the right wing
an increase in lift on the left wing
25
At a load factor of 1 and the aeroplane's minimum drag speed, what is the ratio between induced drag Di and parasite drag Dp?
It varies between aeroplane types.
Di/Dp = 1/2.
Di/Dp = 2.
Di/Dp = 1.
26
The correct drag formula is:
D= CD ½ 1/rho V² S
D= CD ½ rho V S
D= CD ½ rho V² S
D= CD 2 rho V² S
27
Question: The value of the parasite drag in straight and level flight at constant weight varies linearly with the:
square of the speed.
speed.
square of the angle of attack
angle of attack.
28
An aeroplane accelerates from 80 kt to 160 kt at a load factor equal to 1. The induced drag coefficient (i) and the induced drag (ii) alter with the following factors:
(i) 4 (ii) 1/2
(i) 1/16 (ii) 1/4
(i) 1/4 (ii) 2
(i) 1/2 (ii) 1/16
29
What is the effect of high aspect ratio of an aeroplane's wing on induced drag?
It is reduced because the effect of wing-tip vortices is reduced
It is increased because high aspect ratio has greater frontal area
It is unaffected because there is no relation between aspect ratio and induced drag
It is increased because high aspect ratio produces greater downwash
30
The additional increase in drag at Mach numbers above the critical Mach number is due to:
increased skin friction.
increased interference drag.
increased angle of attack
wave drag.
31
Air passes a normal shock wave. Which of the following statements is correct?
The velocity increases.
The static temperature decreases
The static pressure decreases
The static temperature increases
32
The bow wave will first appear at:
a Mach number just below M = 1
a Mach number just above M = 1.
Mach 1.
the critical Mach number
33
Two methods to increase the critical Mach number are:
thin aerofoils and sweepback of the wing
thin aerofoils and dihedral of the wing.
thick aerofoils and dihedral of the wing
positive cambering of the aerofoil and sweepback of the wing.
34
A commercial jet aeroplane is performing a straight descent at a constant Mach number with constant mass. The operational speed limit that may be exceeded is:
VMO
VNE
VD
MMO
35
The relationship between the stall speed VS and VA (EAS) for a large transport aeroplane can be expressed in the following formula: (SQRT= square root)
VS= VA SQRT(3.75)
VS= VA SQRT(2.5)
VA= VS SQRT(2.5)
Va= VA SQRT(3.75)
