Rotorcraft Flying Handbook 1

Front 1

payload

Back 1

term for passengers, luggage, and cargo

Front 2

torque

Back 2

tendency of the helicopter to turn in the direction opposite the main rotor direction

Front 3

flap

Back 3

upward or downward movement of the helicopter blade

Front 4

feather

Back 4

rotation of the blade around the spanwise action (pitch change)

Front 5

lead or lag

Back 5

fore or aft movement of the blade

aka: hunting or dragging

Front 6

fenestron

Back 6

"fan-in-tail" antitorque system

Front 7

NOTAR

Back 7

air intake anti-torque system

Front 8

airfoil

Back 8

any surface which provides aerodynamic force when it interacts with a moving stream of air

Front 9

chord line

Back 9

imaginary straight line drawn from the leading edge to the trailing edge

Front 10

relative wind

Back 10

wind moving past the airfoil

direction always parallel, equal , and opposite to flight path of the airfoil

Front 11

angle of attack

Back 11

angle between blade chord line and direction of relative wind

Front 12

pitch angle

Back 12

angle between chord line and plane containing rotor hub

Front 13

axis-or-rotation

Back 13

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.

Front 14

tip-path-plane

Back 14

The imaginary circular plane outlined by the rotor blade tips as they make a cycle of rotation.

Front 15

aircraft pitch

Back 15

movement about helicopter's lateral (side-to-side axis), tipping helicopter forward or aft

Front 16

aircraft roll

Back 16

movement about helicopter's longitudinal axis (forward/aft axis), tipping helicopter to either side

Front 17

angle of attack

Back 17

angle between chord line and relative wind

Front 18

pitch angle

Back 18

angle between chord line and ref. plane containing rotor hub

Front 19

magnus effect

Back 19

pressure differential created by circulation around an object (e.g. a rotating cylinder)

Front 20

bernoulli's principle

Back 20

pressure differential on the air foil due to constriction of space (in a constricted tube)

Front 21

steady-state-flight

Back 21

when an aircraft is in straight-level, unaccelerated flight and all forces are in balance

Front 22

disc loading

Back 22

ratio of weight to the total main rotor disc area

Front 23

rotor disc area

Back 23

area swept by the blades of a rotor

Front 24

solidity ratio

Back 24

ratio of the total rotor blade area to the rotor disc area

Front 25

rotor blade area

Back 25

combined area of all the main rotor blades

Front 26

aircraft yaw

Back 26

movement of the helicopter about its vertical axis

Front 27

drag

Back 27

force that resists the movement of a helicopter through the air

Front 28

profile drag

Back 28

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

Front 29

induced drag

Back 29

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)

Front 30

parasite drag

Back 30

drag created by friction of nonlifting components of the aircraft

-major cause of drag at higher airspeeds
-varies with the square of the velocity

Front 31

total drag

Back 31

sum of profile, induced, and parasite drag

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