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Aircraft System > Flight control lecture 1 > Flashcards

Flight control lecture 1 Flashcards

1
Q

Aircraft Flight Control Introduction

A

A pilot uses flight control systems to control the forces of flight and the
aircraft’s direction and attitude. It should be noted that flight control
systems and characteristics can vary greatly depending on the type of
aircraft flown. The most basic flight control system designs are mechanical
and date back to early aircraft. Flight control systems are subdivided into
what are referred to as primary and secondary flight controls.

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2
Q

For steady flight, the aircraft must be in a _________(zero moments around the
axes) and the controls enable this to be achieved for all possible configurations and
CG (Center of Gravity) positions.

A

a state of balance

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3
Q

The moment around an axis is produced by changing the aerodynamic force on the
appropriate aerofoil and this may be done by:

A
  • changing the camber of the airofoil
  • changing the angle of attack (incidence) of the aerofoil
  • decreasing the aerodynamics force by “spoiling” the airflow
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4
Q

the basic rotation controls around 3 axis:

A

longitudinal axis, lateral axis and vertical axis

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5
Q

rolling

A

longitudinal axis

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6
Q

is controlled by the ailerons, or for
some aircraft, spoilers, or by a
combination of the two.

A

longitudinal axis

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7
Q

turning the control wheel (____) left or right causes the aircraft to bank.

A

yoke, aileron

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8
Q

pitching

A

lateral axis

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9
Q

is controlled
by elevators or by a moving tail
plane.

A

lateral axis

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10
Q

pushing the control wheel forward or pulling it back causes the noise of the airplane to pitch down or up.

A

elevators

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11
Q

yawing

A

rudder

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12
Q

is controlled by the rudder

A

vertical axis

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13
Q

pressing on its pedal causes the noise of an airplane to move left or right.

A

rudder

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14
Q 
Helicopters utilize a \_\_\_\_ to
tilt the rotor in the desired
direction along with a
\_\_\_\_\_\_\_\_\_\_ to manipulate
rotor pitch and \_\_\_\_\_\_\_\_ to control yaw.
A

cyclic, collective lever, anti-torque pedals

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15
Q

AircraƏt Flight Control System Design

A

mechanically, hydraulically, electrically

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16
Q

The control surfaces are connected directly to the cockpit controls by
a system of cables, rods, levers, and chains.

A

mechanically

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17
Q

Movement of the cockpit control sends an electrical signal to the
control surface. The movement of the control may be achieved hydraulically.

A

electrically

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18
Q

The control surfaces are moved by hydraulic power. The control
valve may still be operated mechanically

A

hydraulically

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19
Q

The most basic flight control systems are ________ and, although they date back to the earliest aircraft types, they are in use in the majority of light, general aviation aircraft.

A

mechanical

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20
Q

In this design, a collection of mechanical
components such as ____, ___, ____, and _____ transmit the movement of the flight deck controls to the appropriate control surfaces

A

cables,pulley, rods and chains

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21
Q 
HYDRO-MECHANICAL
The complexity and weight of mechanical
flight control systems increase considerably
with the \_\_\_\_ and \_\_\_\_\_\_\_ of the
aircraft.
A

size, performance

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22
Q

The complexity and weight of mechanical
flight control systems increase considerably
with the size and performance of the
aircraft. _______ powered control
surfaces help to overcome these limitations.

A

Hydraulically

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23
Q

With ______ flight control systems, the
aircraft’s size and performance are limited
by economics rather than a pilot’s muscular
strength

A

hydraulic

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24
Q

A hydro-mechanical flight control system has two

parts:

A

mechanical circuit and hydraulic circuit

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25
Q

links the cockpit controls with the hydraulic circuits. Like the mechanical flight control system, it consists of rods, cables and pulleys.

A

The mechanical circuit

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26
Q

has hydraulic pumps, reservoirs, filters, pipes, valves and actuators. The
actuators are powered by the hydraulic pressure
generated by the pumps.

A

The hydraulic circuit,

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27
Q

The actuators convert hydraulic pressure into

control surface movements. The _______ servo valves control the movement of the actuators.

A

electro-hydraulic

28
Q

is the generally accepted term for those
flight control systems which use computers to process
the flight control inputs made by the pilot or autopilot,
and send corresponding electrical signals to the flight
control surface actuators.

A

fly-by-wire

29
Q

FBW

A

FLY-BY-WIRE

30
Q

This arrangement replaces
mechanical linkage and means that the pilot inputs do
not directly move the control surfaces. Instead, inputs
are read by a computer that in turn determines how to
move the control surfaces to best achieve what the
pilot wants.

A

FLY-BY-WIRE

31
Q

It is used to ensure that
the FBW aircraft stays within its certificated flight
envelope.

A

Feedback control of airspeed, Mach Number, attitude and angle of attack

32
Q

Two strategies are being used to achieve fly by wire

A

Airbus strategy, Boeing strategy

33
Q

the _______ of` ‘hard limits’ in which the
control laws have absolute authority control unless the
pilot selects Direct Law

A

Airbus strategy

34
Q

The ________ of ‘soft limits’ in which the pilot can
override Flight Envelope Protection and so retains
ultimate control over the operation of the aircraft.

A

Boeing strategy

35
Q

An aircraft must have sufficient ___ to maintain a uniform

flightpath and recover from the various upsetting forces.

A

stability

36
Q

is the characteristic of an aircraft that tends to cause

it to fly (hands off) in a straight-and-level flightpath.

A

stability

37
Q

is the ability of an aircraft to correct for conditions that act on
it, like turbulence or flight control inputs.

A

Stability

38
Q

two general types of stability

A

static and dynamic

39
Q

is the characteristic of an aircraft to be
directed along a desired flightpath and to withstand the
stresses imposed.

A

Maneuverability

40
Q

is the quality of the response of an aircraft to

the pilot’s commands while maneuvering the aircraft.

A

Controllability

41
Q

is the initial tendency of an aircraft to return to its original position when it’s disturbed.

A

Static stability

42
Q

here are three kinds of static stability:

A

positive, neutral, negative

43
Q

exists when the disturbed object tends to return to equilibrium

A

Positive static stability

44
Q

For example: The ball return to starting position when disturbed

A

positive static stability

45
Q

An aircraft that has ______ static stability tends to return to its original attitude when it’s disturbed. Let’s say you’re flying an aircraft, you hit some turbulence, and the nose pitches up. Immediately after that happens, the nose lowers and returns to its original attitude.It’s something you’d see flying an airplane like a Cessna 172.

A

positive

46
Q

exists when the disturbed object has neither tendency, but remains in equilibrium in the direction of disturbance.

A

Neutral static stability

47
Q

For Example: Ball remains in new position when disturbed

A

neutral static stability

48
Q

An aircraft that has _____ static stability tends to stay in its new attitude when it’s disturbed.

A

neutral

49
Q 
For example, if you hit turbulence
and your nose pitches up 5 degrees,
and then immediately after that it
stays at 5 degrees nose up, your
airplane has \_\_\_\_\_\_ static stability
A

neutral

50
Q

or static instability, exists when the disturbed object tends to continue in the direction of disturbance

A

Negative static stability

51
Q

For Example: Ball moves away from starting position when disturbed

A

negative static stability

52
Q

An aircraft that has _____ static
stability tends to continue moving away
from its original attitude when it’s
disturbed.

A

negative

53
Q 
For example, if you hit
turbulence and your nose pitches up, and
then immediately continues pitching up,
you're airplane has a \_\_\_\_\_\_\_ static
stability. For most aircraft, this is a very
undesirable thing
A

negative

54
Q

Stability which is how an airplane responds over time to a

disturbance.

A

dynamic

55
Q

There are three kinds of dynamic stability:

A

positive, neutral, negative

56
Q

Oscillations decrease in amplitude with time

A

Positive Dynamic Stability

57
Q

Aircraft with a ______ dynamic stability have

oscillations that dampen out over time

A

positive

58
Q

The Cessna 172 is a great example. If your 172 is trimmed for level flight, and you pull back on the yoke and then let go, the nose will immediately start pitching down. Depending on how much you pitched up initially, the nose will pitch down slightly nose
low, and then, over time, pitch nose up again, but less than your initial control input. Over
time, the pitching will stop, and your 172 will be back to its original attitude.

A

Positive Dynamic Stability

58
Q

The Cessna 172 is a great example. If your 172 is trimmed for level flight, and you pull back on the yoke and then let go, the nose will immediately start pitching down. Depending on how much you pitched up initially, the nose will pitch down slightly nose
low, and then, over time, pitch nose up again, but less than your initial control input. Over
time, the pitching will stop, and your 172 will be back to its original attitude.

A

Positive Dynamic Stability

59
Q

Oscillations are constant in amplitude with time

A

Neutral Dynamic Stability

60
Q

Aircraft with _______ dynamic
stability have oscillations that never
dampen out.

A

neutral

61
Q 
if you pitch up a
trimmed, neutrally dynamic stable
aircraft, it will pitch nose low, then
nose high again, and the oscillations
will continue, in theory, forever.
A

Neutral Dynamic Stability

62
Q

Oscillations increase in amplitude with time

A

Negative Dynamic Stability

63
Q

Over time, the pitch oscillations get more and

more amplified.

A

Negative Dynamic Stability

64
Q

Aircraft with ______ dynamic
stability have oscillations that get
worse over time.

A

negative

Aircraft System (11 decks)

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