Stability Flashcards

1
Q

The distance between the CG and neutral point is called the ___ __ and is expressed as a percentage MAC

A

static margin

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2
Q

The forward limit of the static margin is usually determined by ___

A
  • A fast enough pitching rate

- A control force that is not too high

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3
Q

The aft limit of the static margin is usually determined by ___

A
  • Not exceeding a certain pitching rate

- A control force that is not too low

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4
Q

Lowering flaps will move the CP ___wards

A

rearwards

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5
Q

Extension of the landing gear will cause a nose ___ pitching moment, __creasing the tail down force

A

down, increasing

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6
Q

Damping __creases with altitude

A

decreases

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7
Q

Swept finds stall at a ___ angle of attack

A

higher

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8
Q

Explain the purpose of dorsal and ventral fins

A

They increase the direction stability during extreme sideslip conditions

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9
Q

The ventral fin has its greatest effect when flying at ___ pitch angles

A

high

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10
Q

The purpose of vortex strakes is to ___

A

Reduce yawing disturbance caused by the crossflow generated by aircraft with long noses at high AoA

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11
Q

The dihedral is the angle between ___

A

the 0.25 chord line of the wing and lateral axis

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12
Q

A ___ wingspan has a greater lateral stability

A

larger

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13
Q

Spiral instability occurs when __ stability is too great compared to ___ stability

A

directional, lateral

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14
Q

Dutch roll occurs when ___ stability is too great

A

lateral

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15
Q

Sweepback and dihedral increase the ___ stability only

A

lateral

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16
Q

With increasing altitude at constant IAS, the static lateral stability will ___ and the dynamic directional stability will ___

A

increase, decrease

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17
Q

With increasing altitude at constant Mach number, the static lateral stability will ___ and the aerodynamic damping is ___ meaning the dynamic directional-lateral stability will ___

A

not change, reduced, reduce

18
Q

Static stick force stability can be recognised by having to ___ the control column to maintain a speed above the trim

A

push

19
Q

The effect of wing downwash on static longitudinal sability is ___

A

negative

20
Q

A swept/straight wing and a high/low aspect ratio are the least affected by turbulence

A

swept, low

21
Q

Stick force stability means ___

A

with higher airspeed, you’re required to push further forward on the control column to keep the aircraft in straight and level flight.

22
Q

Negative stick force stability can be found during ___ flight as more ___ is required to keep the nose from dropping at high speeds

A

transonic, stick pulling, rather than pushing

23
Q

An inset hinge provides ___

A

aerodynamic balance

24
Q

A positive camber has ___ effect on longitudinal stability

A

no

25
Q

The pitching moment about the aerodynamic centre is always ___, regardless of angle of attack.

A

negative

26
Q

Phugoid damping is normally ___

A

weak

27
Q

Short period damping is normally ___

A

significant

28
Q

Speed and altitude vary ___ during the short period oscillation

A

slightly

29
Q

Speed and altitude vary ___ during the phugoid

A

significant

30
Q

Dorsal and ventral fins have a ___ effect on longitudinal stability, a ___ effect on lateral stability, and a ___ effect on directional stability

A

neutral, negative, positive

31
Q

The wing sweep angle is the angle between the ___ and the ___

A

quarter chord and the wing lateral axis

32
Q

Stick force stability depends on ___ stability

A

longitudinal

33
Q

Stick force stability is determined by the distance from ___ to the ___

A

neutral point CG

34
Q

A CG which is further forward means a ___ stick force stability

A

higher

35
Q

Manoeuvre stability will ___ with the static margin

A

increase

36
Q

The static margin is the distance from the ___ to the ___

A

manoeuvre point, CG

37
Q

Positive stick position stability means ___

A

that you pull back on the stick if the speed decreases, and push forward if it increases

38
Q

Fully hydraulic flight controls (don’t) require mass balancing

A

they do

39
Q

With increasing altitude and constant IAS, an aircraft with swept back wings will see ___ static lateral stability and ___ dynamic lateral-directional stability

A

increasing, decreasing

40
Q

With increasing altitude and constant Mach number, an aircraft with swept back wings will see ___ static lateral stability and ___ dynamic lateral-directional stability

A

no change in, decreasing