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M11 > M11.1 > Flashcards

M11.1 Flashcards

1
Q

What is it dangerous to operate on the horizontal stabiliser to compensate for the tuck under effect?

A

The elevators

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2
Q

What are the two main types of waves formed in supersonic flow?

A

Shockwaves and expansion waves

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3
Q

When is an oblique shockwave formed?

A

When the supersonic air stream moves in a new flow direction

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4
Q

What happens with the deflection of the elevator in subsonic flight?

A

The deflection of the elevator in subsonic flight increases the downward forces because of the higher acceleration of the airstream on the lower side of the horizontal stabiliser

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5
Q

What Mach number would a normal shockwave take place?

A

1.2

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6
Q

What are two ways of reducing wave drag?

A

Using vortex generators and applying the area rule

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7
Q

What does a shockwave do to useful energy?

A

Converts it to heat energy

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8
Q

What forms on the leading edge when speed exceeds the speed of sound?

A

A bow wave

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9
Q

The rudder is used for ….. control, which is controlling the aircraft around the …. axis

A

Yaw, vertical

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10
Q

For a ruddervator (V tail), if both move up/down then it has a … function. If one moves up and the other moves down it has a … function.

A

Elevator, rudder

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11
Q

For an elevon, when both surfaces are moved up/down they provide … function. When one moves up and the other moves down it provides a … function.

A

Elevator, aileron

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12
Q

What are the secondary flight controls?

A

Slats, flaps, flight spoilers, and trim systems

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13
Q

How do balance and anti-balance tabs change the force required to move the control surfaces?

A

A balance tab assists the movement of the control surface but decreases the efficiency of it and the anti-balance tab increases the efficiency but more effort is needed to deflect the control surface

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14
Q

What is the rod called that connects both anti balance and balance tabs to the wing?

A

Tab rod

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15
Q

What are anti balance and balance tabs?

A

They are extensions to the control surface on the wing

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16
Q

What is the advantage of using an anti-balance tab?

A

They increase the effectiveness of the control surfaces

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17
Q

In what region is there a large increase in wave drag?

A

The transonic region

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18
Q

With regards to the swept wing affect, at Mach 0.8, do you get a shock wave on a thinner profiled wing?

A

No, however on a thick profile a shockwave is formed

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19
Q

What is the most common sweep angle on a modern jet aircraft?

A

30°

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20
Q

Aircraft that fly in the transonic and supersonic region, do they have thin or thick wing profiles?

A

Thin profiles

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21
Q

What kind of aircraft would you find a side stick on?

A

Fly by wire aircraft

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22
Q

Where are the control inputs for the secondary flight controls located?

A

On the pedestal in the cockpit

23
Q

What is the main use of flight control?

A

To change the forces acting on the aircraft around the three main aircraft axis

24
Q

On large aircraft what is used to help with moving controls?

A

Aerodynamic balance

25
Q

When does an expansion wave occur?

A

It occurs when the supersonic airflow turns away from the normal flow direction

26
Q

What are the two typical super sonic profiles?

A

Double wedge profile and circular arc profile

27
Q

When a normal shockwave occurs what is the effect on the total pressure?

A

It is very strong and therefore causes a great reduction in total pressure

28
Q

When does airflow over the surface of a flat plate profile passed through an expansion wave?

A

The airflow on the upper surface passes through an expansion wave at the leading edge and then an oblique shockwave at the trailing edge. The airflow on the bottom of the plate does the opposite, the airflow passes through and a bleak shockwave first and then the expansion wave.

29
Q

With reference to a transonic profile, what does the use of the entire outer skin as the torque box, allow?

A

Because the skin is used as the torque box it means that a thinner, lighter material can be used

30
Q

What does greater wing chord thickness allow?

A

Greater fuel capacity

31
Q

What is the disadvantage of a transonic profile?

A

At certain aircraft speeds the drag produced by the transonic profile is higher than that for the conventional profile

32
Q

Flow separation is also known as?

A

Shock stall or high speed stall

33
Q

What is a vortex generator used to improve?

A

Boundary layer control

34
Q

What are trim systems used for?

A

To compensate for aircraft imbalance

35
Q

What do the three mechanical cockpit controls operate?

A

Elevators, ailerons, roll spoilers, and the rudder

36
Q

What control surface requires a mixer unit?

A

Ruddervators

37
Q

What are the three main axes and motions of an aircraft?

A

Lateral (y)/Pitch, longitudinal (x)/Roll and vertical (z)/Yaw

38
Q

What is the difference in definition between primary and secondary flight controls?

A

Primary controls are needed in order to safely control an aircraft but secondary only improve the aircraft performance

39
Q

What is the intended design function of a stabilator?

A

Fully movable to enhance manoeuverability and eliminate Mach tuck

40
Q

With a fowler flap what is the percentage of lift increased by?

A

95%

41
Q

What are the main drag devices?

A

Speed breaks (Airbrakes) And spoilers

42
Q

Where are airbrakes located on aircraft?

A

Anywhere where the structure can deal with big air loads

43
Q

Why are flaps used for landing and also take off?

A

Reduce speed for landing and increase lift for takeoff

44
Q

What is the purpose of a variable swept wing?

A

To improve the performance of the aircraft at low and high speeds

45
Q

Describe a transonic wing profile?

A

The transonic profile has a flatter upper surface, more curved leading edge and a thinner trailing edge than a conventional wing shape

46
Q

What happens to shockwaves on a transonic wing profile?

A

Because the upper surface of the wing is flatter the airflow doesn’t move so fast and this produces a smaller shockwave

47
Q

What increases with a transonic wing profile?

A

The critical Mach number

48
Q

What is the speed of sound in metres per second in dry air at 20°C?

A

323.2 m/s

49
Q

What are the three different speed regions?

A

Subsonic, transonic and supersonic

50
Q

What is the function of a trim tab?

A

To compensate for aircraft imbalance

51
Q

How do you calculate Mach number?

A

Aircraft speed/speed of sound

52
Q

What are the two types of aerodynamic balance?

A

Horn balance and insert hinge

53
Q

What are the three methods of transmission to a control surface?

A

Mechanical, Hydraulically, electrically

M11 (7 decks)

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