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18 Cards in this Set

  • Front
  • Back
translating tendency or drift
tendency of single-rotor helicopter to move in the same direction as antitorque rotor thrust
the central body of an aircraft
centrifugal force
the apparent force that an object moving along a circular path exerts on the body constraining the object and that acts outwardly away from the center of rotation (e.g. blade pulling away from rotor disc)
blade coning
an upward sweep of rotor blades as a result of lift and centrifugal force
coriolis effect
the tendency of a rotor blade to increase or decrease its velocity in its plane of rotation when the center of mass moves closer or further from the axis of rotation
a rotor hub that rotates below the top of the mast, as on semirigid rotor systems
ground effect
a usually beneficial influence on rotorcraft performance that occurs while flying close to the ground. it results from a reduction in upwash, downwas, and bladetip vortices, which provide a corresponding decrease in induced drag.
gyroscopic precession
an inherent quality of rotating bodies, which causes an applied force to be manifested 90 degrees in the direction of rotation from the point where the force is applied.
translational lift
the additional lift obtained when entering forward flight, due to the increased efficiency of the rotor system.

-the rotor moves out of its vortices.
-the airflow is also more horizontal, which reduces induced flow and drag with a corresponding increase in angle of attack and lift.
rotational velocity
the component of relative wind produced by rotation of the rotor blades
induced flow
the component of air flowing vertically through the rotor system resulting from the production of lift
resultant relative wind
airflow from rotation that is modified by induced flow
transverse-flow effect
a condition of increased drag and drecreased lift in the aft portion of the rotor disc caused by the air having a greater induced velocity and angle in the aft portion of the disc
dissymmetry of lift
the unequal lift across the rotor disc resulting from the difference in the velocity of air over the advancing and retreating blades
velocity/never exceed

the speed beyond which an aircraft should never be operated. may change with altitude, density altitude, and weight.
the tendency of the rotor disc to tilt aft in forward flight as a result of flapping
centripetal force
the force that attracts a body toward its axis of rotation.

it is the opposite of centrifugal force.
the state where the rotor is being turned by aerodynamic forces and no power from the engine