Straight + level Flashcards
An aircraft of a certain weight is flown at 150 kt IAS at 1000 ft. If the same aircraft was flown at 150 kt IAS at
20000 ft, the angle of attack required to maintain level flight would be
[a] greater because of the reduced density at 20000 ft
[b] less because of the reduced drag in the thinner air
[c] greater because the TAS would have to be higher
[d] the same
D
In level flight lift must equal weight. If weight is unchanged, lift will be unchanged. Since lift is the result of IAS and angle of attack, if IAS is the same, angle of attack must also be the same.
Devices such as slats, slotted flaps and vortex generators act to modify the behaviour of the
[a] tip vortices
[b] boundary layer
[c] free air stream
[d] total drag
B
These devices are sometimes referred to as boundary layer control devices [BLC].
Compared with nil wind conditions, a headwind component during cruise will result in
[a] a reduction in maximum range and a reduction in maximum endurance
[b] a reduction in maximum range but no change in maximum endurance
[c] no change in either maximum range or maximum endurance
[d] no change in maximum range but a reduction in maximum endurance
B
Wind has no effect on endurance.
To achieve maximum range when a head or tail wind exists, the correct speed to use is
[a] the best lift/drag ratio speed in all conditions
[b] higher than best lift/drag ratio speed in a tailwind, and lower in a headwind
[c] higher than best lift/drag ratio speed in a headwind, and lower in a tailwind
[d] lower than the best lift/drag ratio speed in both a headwind and a tailwind
C
For two aircraft, identical in every respect except for gross weight, to achieve maximum range in nil wind
conditions
[a] both should fly at the same speed
[b] the heavy aircraft should fly faster than the light one
[c] the heavy aircraft should fly slower than the light one
[d] the heavy aircraft should fly faster than the speed which produces its best lift/drag ratio
B
Both aircraft should fly at the same angle of attack. Since the heavy one needs more lift, it must fly at a higher IAS.
Ignoring all other considerations the theoretical height to fly at in a piston engined aeroplane to achieve maximum
range is-
[a] as low as possible
[b] as high as possible
[c] at full-throttle height
[d] the height at which the indicated airspeed is highest
C
The airframe is at its most efficient at any height as long as the IAS is equal to the best lift/drag ratio speed. However the engine will not be at its most efficient unless the throttle is wide open - a wide open throttle means there is least resistance to the air flowing into the cylinders. Theoretically the aircraft should be flown at a height at which full throttle
produces the best lift/drag ration IAS. Then both the engine and the airframe will be happy.
For an aircraft at a particular gross weight to maintain level flight at a particular height and IAS, a particular
power setting is required. If the gross weight is increased
[a] a larger angle of attack and more power would be required
[b] a larger angle of attack would be required but no change in power
[c] the same angle of attack could be used along with increased power
[d] a smaller angle of attack and more power is required
A
The question specifies a particular IAS. If weight is increased, a larger angle of attack will be required. This will cause an increase in drag also. Power would have to be increased to maintain IAS.
When flap is lowered on an aircraft in flight
[a] lift and drag both increase
[b] lift decreases and drag decreases
[c] lift decreases and drag increases
[d] lift increases and drag decreases
A
It is really the total reaction which increases. That causes an increase in both lift and drag.
Drag will increase by a bigger proportion than lift, reducing the lift/drag ratio.
An aircraft is in straight and level flight at constant power. As weight reduces with fuel burn-off, level flight
may be maintained by
[a] increasing indicated air speed and raising the nose
[b] increasing indicated air speed and lowering the nose
[c] decreasing indicated air speed and raising the nose
[d] decreasing indicated air speed and lowering the nose
B
If power remains constant, the nose must be lowered to allow lift to remain equal to the reducing weight. This means a reduction in drag, therefore more speed for the same power.
Consider an aircraft maintaining straight and level flight at the speed which produces maximum endurance. If
level flight is to be maintained,
[a] more power will be required if speed is reduced
[b] less power will be required if speed is reduced
[c] less power will be required if speed is increased
[d] less power will be required if speed is changed to the speed of minimum drag
A
Since maximum endurance occurs at the speed which requires minimum power, any other speed, higher or lower, will require more power.
The term ‘S’ in the lift formula [CL1/2P V^2S ], represents-
[a] the total surface area of the top and bottom wing surfaces
[b] the maximum plan area of the wing
[c] the surface area of the wing and tailplane
[d] the surface area of the curved upper surface of the wing.
B
The term ‘S’ always represents the plan area of the wing. That is the area enclosed by the wing if it was drawn in plan view onto a flat surface. The curved upper surface of the wing would have a slightly greater area than the plan view.
The term P in the lift formula [CL1/2P V^2S ], represents-
[a] the temperature of the air
[b] the density height of the ambient air
[c] the ambient atmospheric pressure
[d] the mass of a unit volume of air.
D
Rho stands for density. Density is the mass per unit volume.
The term1/2p V^2 in the formula in [CL1/2P V^2S] is most closely associated with-
[a] true airspeed
[b] surface area of the wing
[c] wind speed
[d] indicated airspeed
D
Indicated Air Speed is a function of both the density of the air and the true airspeed.
The term ‘one half rho times the velocity squared’ is actually a measure of the kinetic
energy of a unit volume of air. This value is most accurately represented in the cockpit
by the airspeed indicator.
You are required to hold over an aerodrome to wait for fog to clear. To ensure the maximum possible holding time
available you should fly-
[a] as high as possible at minimum drag.
[b] as low as possible at minimum power.
[c] at any height as long as you use minimum power.
[d] at any height as long as you fly at minimum drag
