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Ft. Rucker theory of flight > Theory of flight > Flashcards

Theory of flight Flashcards

1
Q

List the two components of total aerodynamic force

A

Lift and drag

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2
Q

Describe the relationship of lift to resultant relative wind

A

Perpendicular

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3
Q

Describe the relationsship between drag and resultant wind

A

Drag is parallel to and in the same direction of the resultant wind

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4
Q

Which type of drag decreases with an increase in airspeed?

A

Induced

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5
Q

Which type of drag increases with an increase in airspeed

A

Parasite

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6
Q

Define dissymmetry of lift

A

Differential (unequal) lift between advancing and retreating halves of the rotor disk

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7
Q

Relative wind velocity on the advancing blade equals blade speed _________ airspeed

A

plus

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8
Q

Relative wind velocity on the retreating blade equals blade speed ___________ airspeed

A

minus

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9
Q

What causes the advancing blade to flap uo?

A

An increase in lift

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10
Q

What causes the retreating blade to flap down?

A

A decrease in lift

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11
Q

How does the helicopter compensate for dissymmetry of lift?

A

Flapping

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12
Q

How does the pilot control dissymmetry of lift?

A

Cyclic feathering

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13
Q

Define blowback

A

Change in the attitude of the rotor system

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14
Q

How does the pilot correct for blowback?

A

Cyclic feathering

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15
Q

Which forces in the lift equation can the pilot control?

A

Coefficient of lift and airspeed

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16
Q

What are the three factors in air density (1/2 rho) tha will affect lift?

A

Pressure, temperature and humidity

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17
Q

A semi-rigid disk tilts relative to the_____

A

Mast

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18
Q

An articulated disk tilts relative to the _______

A

Hub

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19
Q

Define centrifugal force

A

Outward force produced whenever a body moves in a curved path

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20
Q

Define rotor blade coning

A

Upward flexing of the rotor blades

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21
Q

Rotor blade coning is a compromise between which two forces?

A

Lift and centrifugal force

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22
Q

Define gyroscopic precession

A

When a force is applied to a rotating body, it will manifest 90 degrees after application in the direction of rotation

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23
Q

Why is blade twisting necessary?

A

To distribute the lifting force more evenly along the blade

24
Q

A pedal turn to the right requires __________ (more/less) power than a pedal turn to the left.

25
Define translating tendency
Tendency of a single rotor helicopter to drift right while hovering
26
List four methods used to overcome translating tendency in single rotor helicopters
Rigging the cyclic Tilting the mast Left cyclic Automated flight-control/stabilization augmentation system
27
List the four rotor blade actions
Rotation Flapping Feathering Hunting
28
Describe the relationship of total force to the tip path plane?
Perpendicular
29
When the rotor disk is tilted, what are the two components of total force?
Lift and thrust
30
What are the two flight conditions
Balanced and unbalanced
31
At what altitude would the aircraft be in ground effect?
Less than one rotor diameter
32
Loss or apparent loss, of ground effect is caused by? a\_\_\_\_\_\_\_\_\_\_\_\_ b\_\_\_\_\_\_\_\_\_\_\_\_ c\_\_\_\_\_\_\_\_\_\_\_\_ d\_\_\_\_\_\_\_\_\_\_\_\_ e\_\_\_\_\_\_\_\_\_\_\_\_ f\_\_\_\_\_\_\_\_\_\_\_\_
a. An altitude greater than one rotor diameter b. Trees and bushes c. Tail grass and uneven terrain d. Hovering over water e. Beginning of translational movement f. Hovering into the wind
33
Define effective translational lift (ETL)
When the rotor completely outruns the recirculation of old vortices and begins to work in relatively undisturbed air
34
Effective translational lift occurs at an airspeed of?
16-24KTS
35
Transvers flow effect is noticeable at an airspeed of
10-20KTS
36
Label the components
1. Tip path plane / plane of rotation 2. Chord line 3. Axis of rotation 4. Rotational relative wind 5. Induced flow 6. AOA 7. Resultant relative wind 8. Angle of incidence 9. Lift 10. Drag 11. TAF (resultant force)
37
List the three simultaneous conditions required for settling with power
Vertical or near vertical descent of at least 300 fpm / 20-100% engine power / slow airspeed less than ETL
38
Required recovery procedure for setlling with power
Increase airpseed with power / Reduce collective as altitude permits / Adjust rotor RPM to normal operating range
39
Define autorotation
The flight condition which no engine power is supplied and the main rotor is driven only by the action of the relative wind
40
Dynamic rollover occurs due to a combination of which two factors
Human and physical
41
Operating at what speed is most likely to produce retreating blade stall
High forward speed
42
Symptoms of retreating blade stall
Abnormal vibration, pitch-up and left roll
43
Describe the recovery procedure from retreating blade stall
Reduce collective pitch / regain control of the aircraft
44
Define true airspeed
CAS corrected for density error
45
Define rotational relative wind
The flow of air parallel and opposite the direction of the flight path
46
Define resultant relative wind
Rotational relative wind modified by induced flow
47
Define induced flow
Downward flow of air through the rotor blades
48
How is the angle of incidence measured
Between the chord of an airfoil and the plane of rotation
49
Define angle of attack
The angle between the chord of an airfoil and the resultant relative wind
50
Takeoff to a hover is an example of which of Newtons three laws?
Action/reaction
51
What is total force a component of?
Lift and thrust
52
How do you obtain ETL?
Horizontal flight or hovering in a headwind
53
What happens at max flap up at 3 o'clock in relation to induced flow and AOA?
Induced flow increases and AOA decreases
54
List the four causes for excessive coning
Low RPM's / High gross weight / high G maneauvers / turbulent air
55
Three adverse effects to excessive coning
Loss of disk area / loss of total lift / stress on the blades
56
What happens to the fwd half of the disk at the transverse flow effect?
Induced flwo decreases, AOA increases

Ft. Rucker theory of flight (1 decks)

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