Principles of Flight - AC

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This flashcard set delves into the principles of flight, covering topics like drag, lift, and stability, with a focus on aircraft control surfaces such as ailerons, flaps, and the elevator. It explores how factors like angle of attack, speed, and wing position influence flight dynamics, including turns and stalls. The set is tailored for university-level students studying aerodynamics, providing insights into the forces and mechanics that govern flight, making it invaluable for those aiming to understand or operate aircraft effectively.

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149

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Sprache

Englisch

Kategorie

Technik

Stufe

Universität

Erstellt / Aktualisiert

25.12.2024 / 20.01.2025

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With regard to the forces acting, how can stationary gliding be described?

The sum of air forces acts along the direction of air flow

The sum of air forces acts along with the lift force

The lift force compensates the drag force

The sum of air forces compensates the gravity force

What is the result of extending flaps with increasing aerofoil camber?

Maximum permissible speed increases

Minimum speed increases

Minimum speed decreases

C.G. position moves forward

Following a single-wing stall and pitch-down moment, how can a spin be prevented?

Deflect all rudders opposite to lower wing

Rudder opposite lower wing, releasing elevator to build up speed

Pushing the elevator to build up speed to re-attach airflow on wings

Pulling the elevator to bring the plane back to normal attitude

Considering longitudinal stability, which C.G. position is most dangerous with a normal gliding plane?

Position beyond the rear C.G. limit

Position beyond the front C.G. limit

Position far back within permissible C.G. limits

Position too far aside permissible C.G. limits

The static pressure of gases works...

in all directions

only in flow direction

only in the direction of the total pressure

only vertical to the flow direction

Which are the correct parameters of the International Standard Atmosphere (ISA)?

1013.25 hPa at MSL, +15° C at MSL, environmental lapse rate 2°/1000 ft

1000 hPa at MSL, +15° C at MSL, environmental lapse rate 2°/100 m

1013.25 hPa at 36000 ft, -56.5° C at the tropopause, environmental lapse rate 2°/1000 ft

1013.25 hPa at MSL, 0° C at MSL, environmental lapse rate 2°/1000 ft

Bernoulli's equation for frictionless, incompressible gases states that...

total pressure = dynamic pressure - static pressure

total pressure = dynamic pressure + static pressure

static pressure = total pressure + dynamic pressure

dynamic pressure = total pressure + static pressure

If surrounded by airflow (v>0), any arbitrarily shaped body produces...

drag

constant drag at any speed

drag and lift

lift without drag

All aerodynamic forces can be considered to act on a single point. This point is called...

center of gravity

lift point

transition point

center of pressure

The center of pressure is the theoretical point of origin of...

all aerodynamic forces of the profile.

gravity forces of the profile.

all forces of the profile.

only the resulting total drag.

Number 1 in the drawing corresponds to the... See figure (PFA-010)

chord.

chord line.

trailing edge.

camber line.

Number 2 in the drawing corresponds to the... See figure (PFA-010)

angle of attack.

chord line.

chord.

profile thickness.

Number 3 in the drawing corresponds to the... See figure (PFA-010)

camber line.

chord line.

chord.

thickness.

Number 4 in the drawing corresponds to the... See figure (PFA-010)

camber.

thickness.

chord line.

trailing edge.

The angle between the chord line and the direction of the oncoming airflow is called...

angle of stream.

angle of incidence.

angle of attack.

angle of lift.

Which type of boundary layer does the figure show? See figure (PFA-001) BL: Boundary layer SF: Surface

Laminar boundary layer

Turbulent boundary layer

Separated boundary layer

Interference layer

The angle of attack is the angle between...

the chord line and the oncoming airflow.

the chord line and the longitudinal axis of an aeroplane.

the undisturbed airflow and the longitudinal axis of an aeroplane.

the wing and the fuselage of an aeroplane.

Which type of boundary layer does the figure show? See figure (PFA-002) BL: Boundary layer SF: Surface

Laminar boundary layer

Turbulent boundary layer

Separated boundary layer

Interference layer

The ratio of span and mean chord length is referred to as...

wing sweep.

trapezium shape.

tapering.

aspect ratio.

Which point on the aerofoil is represented by number 2? See figure (PFA-009)

Transition point

Separation point

Stagnation point

Center of pressure

Which point on the aerofoil is represented by number 3? See figure (PFA-009)

Transition point

Separation point

Stagnation point

Center of pressure

Which point on the aerofoil is represented by number 4? See figure (PFA-009)

Transition point

Separation point

Stagnation point

Center of pressure

The start of vortex development is created during which phase of flight?

While setting take-off power during take-off run

While setting flaps to lower position

As soon as the aircraft starts moving

When lift is being generated during rotation

Which property is specific for a streamlined shape as compared to other shapes?

With other parameters remaining constant, it shows the lowest drag

Besides drag it always produces lift

With other parameters remaining constant, it shows the highest drag

Its drag is independent of the airflow speed

Which point on the aerofoil is represented by number 1? See figure (PFA-009)

Transition point

Separation point

Stagnation point

Center of pressure

What pattern can be found at the stagnation point?

The laminar boundary layer changes into a turbulent boundary layer

Streamlines are divided into airflow above and below the profile

The boundary layer starts separating on the upper surface of the profile

All aerodynamic forces can be considered as attacking at this single point

Which of the following options describes the pressure pattern at a lift-generating wing profile passed by airflow?

Pressure below remains unchanged, lower pressure is created above the profile

High pressure is created above, lower pressure below the profile

Low pressure is created above, higher pressure below the profile

Pressure above remains unchanged, higher pressure is created below the profile

The position of the center of pressure at a positively shaped profile...

moves to the trailing edge while the angle of attack becomes smaller.

does not move since it is independent of the angle of attack.

moves to the leading edge while the angle of attack becomes smaller.

is located at approximately 25% of the chord, measured from the leading edge.

The position of the center of pressure at a positively shaped profile...

moves to the leading edge while the angle of attack becomes greater.

Does not move and it is independent of the angle of attack.

moves to the leading edge while the angle of attack becomes smaller.

is located at approximately 25% of the chord, measured from the leading edge.

In which way does the position of the center of pressure move at a positively shaped profile with increasing angle of attack?

It moves forward first, then backward

It moves backward until reaching the critical angle of attack

It moves forward until reaching the critical angle of attack

It moves to the wing tips

During a regular flight, shortly before stalling the aircraft, what is approximately directly proportional to the lift of the wing?

Angle of attack

Angle of incidence

Aileron deflection

Elevator deflection

Which statement about lift and angle of attack is correct?

Increasing the angle of attack too far may result in a loss of lift and an airflow separation

Increasing the angle of attack results in less lift being generated by the aerofoil

Decreasing the angle of attack results in more lift being generated by the aerofoil

Too large angles of attack can lead to an exponential increase in lift

Which statement about the airflow around an aerofoil is correct if the angle of attack increases?

The stagnation point moves up

The stagnation point moves down

The center of pressure moves down

The center of pressure moves up

Which statement about the airflow around an aerofoil is correct if the angle of attack decreases?

The center of pressure moves forward

The stagnation point moves down

The stagnation point remains constant

The center of pressure moves aft

The angle (alpha) shown in the figure is referred to as... See figure (PFA-003) DoF: direction of airflow

angle of incidence.

lift angle.

angle of inclination.

angle of attack.

With a constant angle of incidence, how is the change of the profile shape called?

Aspect ratio

Geometric washout

Wing span

Aerodynamic washout

In order to improve the stall characteristics of an aircraft, the wing is twisted outwards (the angle of incidence varies spanwise). This is known as...

geometric washout.

arrow shape.

aerodynamic washout.

V-form.

Which option states a benefit of aerodynamic washout?

At high angles of attack the effectiveness of the aileron is retained as long as possible

Structurally the wing is made more rigid against rotation

Greater hardness because the wing can withstand more torsion forces

With the washout the form drag reduces at high speeds

Which statement concerning the angle of attack is correct?

Increasing the angle of attack results in decreasing lift

The angle of attack cannot be negative

The angle of attack is constant throughout the flight

A too large angle of attack may result in a loss of lift

If you double the airflow speed, how does the parasite drag coefficient change?

It is quadrupled

It is doubled

It does not change

It is octuplicated

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