Lernkartei AV (Seite 1 von 2)

Karten	59
Sprache	English
Kategorie	Technik
Stufe	Universität
Erstellt / Aktualisiert	22.06.2016 / 22.06.2016
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When air passes through an oblique shock wave,

total pressure and Mach number both decrease

total pressure and Mach number both increase

total pressure decreases while Mach number increases

total pressure increases while Mach number decreases

Flow separation on an airfoil is caused by

turbulence in the boundary layer

surface roughness

adverse pressure gradients

boundary layer transition

none

The critical Mach number for a wing increases when

its thickness increases

its sweep angle increases

its lift coecient increases

its lift coecient decreases

In straight and level flight, if the airspeed is doubled the induced drag

doubles

halves

becomes four times higher

becomes four times smaller

In general, when the wing trailing edge flaps are deflected

the stall angle of attack may decrease but the maximum lift coefficiet increases

the stall angle of attack and the maximum lift coefficient both increase

the lift coefficient increases at all angles of attack up to the stall

The airspeed for minimum power required

corresponds to the maximum L/D ratio

is higher than the airspeed for maximum L/D ratio

is lower than the airspeed for maximum L/D ratio

is the slowest speed at which the airplane can fly

The static margin is defined as the distance between

the tail aerodynamic center and the airplane center of gravity

the wing-body aerodynamic and the airplane center of gravity

the wing-body aerodynamic center and the neutral point

the neutral point and the airplane center of gravity

In a coordinated turn with 60 bank, the stalling speed is approximately

the same as in level flight

40% higher than in level flight

60% higher than in level flight

twice as high as in level flight

An airplane with a large wing dihedral and a small vertical tail will probably have

well damped dutch roll characteristics and a divergent spiral mode

poorly damped dutch roll and a divergent spiral mode

good lateral stability and a stable spiral mode

poor lateral and directional stability

When air passes through an oblique shock wave,

static pressure and Mach number both decrease

static pressure and Mach number both increase

static pressure decreases while Mach number increases

static pressure increases while Mach number decreases

In straight and level flight, if the airspeed is doubled the zero-lift drag

doubles

halves

becomes four times higher

becomes four times smaller

In general, when the wing slats are deflected

the stall angle of attack decreases but the maximum lift coecient increases

the stall angle of attack and the maximum lift coecient both increase

the lift coecient increases at all angles of attack up to the stall

The airspeed for minimum thrust required

corresponds to the maximum L/D ratio

is higher than the airspeed for maximum L/D ratio

is lower than the airspeed for maximum L/D ratio

is the slowest speed at which the airplane can fly

The effective dihedral of an airplane is reduced by

a positive wing sweep angle

a high wing position

deflecting the flaps

the vertical tail

An airplane with no wing dihedral and a large vertical tail will probably have

well damped dutch roll characteristics and a divergent spiral mode

poor lateral stability and a stable spiral mode

poorly damped dutch roll and a divergent spiral mode

good lateral and directional stability

The shear stress on a flat plate is

directly proportional to viscosity

inversely proportional to the velocity gradient at the wall

directly proportional to the Reynolds number

highest near the leading edge of the plate

In our course we asume that the flow through a sound wave is ....

isentropic

not affected by the sound wave

adiabatic

reversible

Normal shockwave:

What changes across the shockwave

Flow direction

Mach number

static pressure and density

total pressure

Normal shockwave:

Across the shock wave the Mach number ....

decrease to subsonic

increases

Normal showck wave:

Across the shock wave the static pressure ...

increase alot

decreases alot

is constant

Normal shockwave:

Across the shock wave the total pressure ...

decreases alot

increases alot

is constant

The total energy of a air molecule across a shockwave, considering insentropic flow, does ....

increases

does not change(v decreas but rho riese)

decreases

Fly analogy

The fly hits your skin in the car, this resembles ....

static pressure

total pressure

Fly analogy

Your standing outside the fly flies out of the window of a bypassing car and hits your skin, this resembles ....

total pressure

static pressure

A pitot-static probe for itself measures... and ....

static pressure

total pressure

dynamic presure

Normal shockwave:

Across the shockwave the static temperature..

decreases

increases

Normal shockwave:

Across the shockwave the total temperature...

increases

stays the same (for a perfet gasI

decreases

The pressure through the boundary layer in a direction perpendicular to the surface is...

increasing towards the outer edge of the boundary layer

constant

decreasing towards the outer edge of the boundary layer

The boandary layer thickness ... as the flow moves over a body

grows

shrinks

The shear stress of a laminar boundary layer is ... than that of a turbulent one.

less

more

Under the same flow conditions a turbulent boundary layer will be ... than a laminar boundary layer

thiker

thinner

The moment about the aerodynamic center of an airfoil is ...

is equal to zero

is usually positive

is constant with respect to the angle of attack

is usually negative

angle of attack is the angel between the relative wind and ...

chord line

chor

Mean camber line

camber

The Reynolds number has a big influence when the airfoil is in ...

the stalling region

the normal angle of attack region

all ranges of the angle of attack

Profiles with positive camber have a ... cm,c/4

negative

neutral

positive

changing

The center of pressure is the point where ...

lift is zero

drag is zero

the lift and drag act on the airfoil

thicker airfoils have a ... Mcrit than thin ones

lower

higher

cp can by definition not be ....

>1

<1

>0

=0

<0

As the aspect ratio is increased

induce drag is decreased

induce drag is increased

induced drag is constant

induce drag is... for an elliptical wings

maximum

minimum

AV

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