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POF > Primary Controls > Flashcards

Primary Controls Flashcards

1
Q

Elevator axis + movement

A

Lateral Axis
Pitch

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2
Q

Aileron axis and movement

A

Longitudinal axis
Roll movement

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3
Q

Rudder axis and movement

A

Yaw around normal axis

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4
Q

Essentials req for flight control systems

A

Forces need to be balanced
Feel system (airspeed increasing etc)
Response
Movement and harmony with other axis controls

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5
Q

Aerodynamic Balance - Inset Hinge

A

Reduce the distance of the moment arm

Only a small inset to around 25% otherwise behind CP can cause full selection with smaller inputs

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6
Q

Aerodynamic Balance - Horn Balance

A

Extends forward of the hinge and causes drag

Usually found on elevators and rudders

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7
Q

Aerodynamic Balance - Internal Balance

A

Flexible sealed diaphragm using static pressure to provide opposing hinge moment

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8
Q

Aerodynamic Balance - Balance Tab

A

Small control surface tab on TE that deflects in opposite direction to control surface

Reduces control effectiveness

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9
Q

Aerodynamic Balances - Anti Balance Tab

A

Tab deflects in same direction as control surface
Opposes the movement of control surface making the controls heavier.

Reduce possibility of over stressing aeroplane + light control feel at low speeds

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10
Q

Aerodynamic Balance - Servo Tab

A

Pilot moves the control tab which moves the control surface via force generation

Very ineffective at slow speed due to low forces over AC

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11
Q

Aerodynamic Balance - Spring Tab

A

Better version of servo tab
Prevent operation of servo tab at low speed and control directly.
High speeds spring compresses and pilot moves tab

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12
Q

Why do we need mass balancing

A

To prevent flutter

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13
Q

How do we avoid flutter

A

Adding mass ahead of hinge line to move CG forward of hinge line

Stay within flight envelope (reduce speed)

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14
Q

Power assisted controls

A

Provide additional force to operate control surfaces
Still feedback from controls

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15
Q

Full powered controls

A

Provide all power to remove control surfaces force
Via hydraulic forces
No direct connection between pilot and control surfaces
No aerodynamic feel don’t require aerodynamic balanced control surfaces

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16
Q

Artificial feel system is…

A

Controls provide no natural sense of forces acting on plane therefore Q feel system added (generates force in proportions to dynamic pressure)

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17
Q

Aileron controls - Up going wing

A

Deflected aileron downwards
AOA reduces on up going wing

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18
Q

Aileron - down going wing

A

Aileron is deflected upwards
AOA increases on down going wing

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19
Q

Ideal tailplane fin

A

Swept back and low aspect ratio
Larger stalling AOA

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20
Q

Elevator controls pitch down

A

Elevator deflected down
Tailplane will pitch upwards
Nose pitches down

“Pitch down the elevator must go down”

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21
Q

Elevator control pitch up

A

Elevator deflected upwards
Downwards reaction on tailplane
Nose pitches up

“Pitch up the elevator must go up”

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22
Q

Stabilator

A

All moving tailplane no elevator
Angle of attack changes of elevator

Pitch down the stabilator moves up to create total reaction upwards
To move nose down

Pitch up the stabilator moves down to create downward reaction
To move nose up

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23
Q

Comparison between elevator and stabilator

A

Elevator is a camber changing device where as stabilator is a AOA changing device

Better L/D ration on stabilator

24
Q

Trimmable horizontal stabiliser

A

Change angle of incidence via trim
Pitch control still controlled by elevators

25
Q

CG vs CP

A

CG is always in front of CP
Forward limit CG and aft limit CG

26
Q

Downwash on pitch control T-tail vs normal

A

T-tail planes more effective as clear of undisturbed airflow
Normal tails - change in relative airflow has to cope with turbulent air over TE

27
Q

Rudder Limiting Devices

A

Forces generated by tailplane could shear with high aerodynamic loads

28
Q

Main purpose of mass balancing

A

To stop control surface oscillating in front of the hinge line

29
Q

All Moving tailplane (stabilator) pitch up and down

A

Controls forward to pitch down the stabilator moves upwards

Controls rearward to pitch upwards the stabilator stabilator moves downwards

30
Q

Displacement controls

A

Rudder and elevator

31
Q

Rate controls are

A

Ailerons

32
Q

Adverse Aileron Yaw

A

Increased lift produced on upgoing wing increases induced drag
Reduce lift produced on downgoing wing reduces induced drag

Therefore:

Difference in drag between produces a moment that yaws the ac towards the upgoing wing

Use rudder

33
Q

Differential Aileron

A

Up going aileron is deflected more than the downgoing wing to induce higher form drag on the down going wing to counter higher induced drag on the up going wing

34
Q

Fries Ailerons

A

Increase drag on the up going aileron to induce form drag when deflected downwards remains inside the wing

35
Q

Large A/C controls in roll

A

Outboard ailerons only used in low speed flight - flaps extended for TO/LD

Lift spoilers used on upper surface with ailerons - up going aileron spoiler lifted to increase drag and reduce lift to create differential drag and yaw /roll

36
Q

Advantages/Disadvantages of spoilers

A
  • Reduce overall lift

+ Do not suffer from flutter
+ No twisting moment on the wing

37
Q

Flaperons

A

Combines flaps and aileron in single control surface

+ Improved lateral control
+ Reduced weight

38
Q

Coupling Unit

A

Unit that assists pilot with rudder inputs when roll is commanded

39
Q

Ground Spoilers

A

Dump lift once on ground

40
Q

Speed Brakes

A

Increase amount of drag
+ reduce airspeed rapidly
+ increase angle of descent
+ increase rate of descent
+ control airspeed in descent

41
Q

Speed Brakes on CL/CD

A

On polar curve moves down and right
Reduced L/D ratio
CLMAX reduced
Higher parasite drag

Fuselage mounted speed brakes should have no effect on CL

42
Q

Combined Controls

A

Flaperons - flaps + ailerons
Elevons - elevator + ailerons
Ruddervator - rudder + elevator

43
Q

Airbus side stick

A

No direct connection
Control inputs are request to computer
Executed/modified or ignored
No need for artificial feel system no trim

Risk of loss of situation awareness pilots cannot see each others inputs

44
Q

Equilibrium is

A

Forces/Moments equal and opposite (steady flight)

A/C can be in trim or out of trim in equilibrium

45
Q

Causes of out of trim forces

A

Change in thrust
Change in speed
Thrust asymmetry
Propeller slipstream effects

46
Q

Loss of control authority

A

Pilot runs out of elevator travel - CG is too far forward or aft when flaring on landing
Reduced control in one direction

47
Q

Countermeasures for a jammed THS

A

Reduce IAS if less control effectiveness needed
Increase IAS to improve effectiveness of a jammed primary control

48
Q

Essential requirement for flight controls are

A

Force
Feel
Response

49
Q

CG forward + Nose Up trim =

A

Rotation will be normal using normal rotation technique

Stabiliser is moved down to create downwards force on tailplane

50
Q

CG Aft + Nose Up Trim

A

Early nose wheel raising possible tail strikes

51
Q

CG Foward + Nose down trim

A

Rotation will require extra stick force

52
Q

CG Aft + Nose down trim

A

Rotation will be normal using normal rotation technique

53
Q

Aerodynamic balancing devices which improve control effectiveness

A

Horn balance
Anti balance tab

(Upforce together)

54
Q

Aerodynamic balancing devices which decrease control effectiveness

A

Balance tab
Servo tab
Spring tab

(Move in opposite direction to control surface)

55
Q

Aerodynamic balances devices which are neutral to control effectiveness

A

Inset hinge
Internal balance

56
Q

Factors that influence stabiliser position on take off

A

CG position
Take off mass
Flap setting

POF (25 decks)

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