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31 Cards in this Set

  • Front
  • Back
term for passengers, luggage, and cargo
tendency of the helicopter to turn in the direction opposite the main rotor direction
upward or downward movement of the helicopter blade
rotation of the blade around the spanwise action (pitch change)
lead or lag
fore or aft movement of the blade

aka: hunting or dragging
"fan-in-tail" antitorque system
air intake anti-torque system
any surface which provides aerodynamic force when it interacts with a moving stream of air
chord line
imaginary straight line drawn from the leading edge to the trailing edge
relative wind
wind moving past the airfoil

direction always parallel, equal , and opposite to flight path of the airfoil
angle of attack
angle between blade chord line and direction of relative wind
pitch angle
angle between chord line and plane containing rotor hub
the imaginary line about which the rotor rotates. It is represented by a line drawn through the center of, and perpendicular to, the tip-path plane.
The imaginary circular plane outlined by the rotor blade tips as they make a cycle of rotation.
aircraft pitch
movement about helicopter's lateral (side-to-side axis), tipping helicopter forward or aft
aircraft roll
movement about helicopter's longitudinal axis (forward/aft axis), tipping helicopter to either side
angle of attack
angle between chord line and relative wind
pitch angle
angle between chord line and ref. plane containing rotor hub
magnus effect
pressure differential created by circulation around an object (e.g. a rotating cylinder)
bernoulli's principle
pressure differential on the air foil due to constriction of space (in a constricted tube)
when an aircraft is in straight-level, unaccelerated flight and all forces are in balance
disc loading
ratio of weight to the total main rotor disc area
rotor disc area
area swept by the blades of a rotor
solidity ratio
ratio of the total rotor blade area to the rotor disc area
rotor blade area
combined area of all the main rotor blades
aircraft yaw
movement of the helicopter about its vertical axis
force that resists the movement of a helicopter through the air
profile drag
drag from the frictional resistance of the blades passing through the air

-does not change much w/ change of angle of attack
-increases moderately with airspeed
induced drag
drag from the airflow circulation around the rotor blade as it creates lift

-high pressure air and low pressure air meet, creating vortices at the blade tips, creating a downwash. This inclines total lift aft.
-high with high angle of attack (thus, high at low airspeeds)
parasite drag
drag created by friction of nonlifting components of the aircraft

-major cause of drag at higher airspeeds
-varies with the square of the velocity
total drag
sum of profile, induced, and parasite drag

-L/Dmax refers to the point where the lift-to-drag ratio is greatest