Theory Of Rotary Wing Flashcards
(77 cards)
Define settling with power?
A condition of powered flight in which the helicopter settles in its own downwash.
List the three simultaneous conditions required for settling with power.
a. Vertical or near vertical descent of at least 300 FPM
b. 20% to 100% engine power
c. Slow airspeed less than ETL
List the required recovery procedures for settling with power.
Increase airspeed with cyclic.
Reduce collective as altitude permits.
Adjust rotor RPM to normal operating range.
Define autorotation
The flight condition during which no engine power is supplied and the main rotor is driven only by the action of the relative wind.
Describe how a pilot prevents a rotor R.P.M. over speed during an autorotation with turn.
The pilot must prevent rotor RPM over speed with collective control.
List the three conditions required for dynamic rollover to occur.
a. Pivot point
b. Rolling motion
c. Exceed critical angle
Dynamic rollover occurs due to a combination of which two factors?
Physical and human
Which control input is required to recover from dynamic rollover on level ground?
Smooth, moderate collective reduction
Operating at what speed is most likely to produce retreating blade stall?
High forward speed
Describe the symptoms of retreating blade stall in a single rotor helicopter.
Abnormal vibration,
pitch-up of the nose,
and left roll.
Describe the recovery procedure from retreating blade stall.
Reduce collective pitch, regain control of the aircraft, reduce airspeed, increase rotor RPM to normal operation range, minimize maneuvering, and descend to a lower altitude.
Listed below examples of Newton’s Laws of Motion. To the right of each example, indicate which law is involved
A. Torque effect - Action / Reaction
B. More power is needed to obtain a desired RPM than is need to maintain the RPM - Inertia
C. Greater load, less acceleration
- Acceleration
If the airflow atop the airfoil increases, static pressure will
…decrease and dynamic pressure will increase
Define center of pressure
The point along the chord line of an airfoil through which all aerodynamic forces are considered
Define airfoil.
..any surface designed to produce lift when air is passed over it
List two basic types of airfoils.
A. Symmetrical
B. Non-symmetrical
Six descriptions of airfoil (blade) sections
Match the descriptions to the airfoil terms
Chord - Straight line from the leading edge to the trailing edge
Rounded edge - leading edge
Upper curvature - Upper camber
Lower shape - Lower camber
The length of the rotor blade from the point of rotation to the tip of the blade
- Span
Trailing edge - Tapered edge
Define rotational relative wind as applied to an airfoil.
The flow of air parallel and opposite to the flight path of an airfoil
Descriptions of airfoil movements. Match these movements to the rotational relative wind arrows.
Rotation only - look for a straight line Rotation and flapping up - look for and decline arrow Rotation and airspeed - look for a double headed arrow Rotation and flapping down - look for a ascending arrow
Define Induced flow.
…Downward flow of air through the rotor blades
Define resultant relative wind.
…Rotational relative wind modified by induced flow
How is the angle of incidence measured in a rotary-wing aircraft?
…The angle between the chord of an airfoil and the plane of rotation (tip path plane)
Define angle of attack?
…the angle between the chord of an airfoil and the resultant relative wind
Which flight control changes the angle of incidence differentially around the rotor system?
…the cyclic pitch control
