SIFT (Army Aviation)/74 Exam Questions
with Accurate Answers
Profile drag - -Caused by the blades frictional resistance
-Induced drag - -Downwash
-Parasite drag - -Components attached to a helicopter that dont contribute
to lift
-Total drag - -Sum of profile, induced, and parasite drag.
-Bernoullis principle - -As flow increases, pressure decreases
-Phases of flight - -Takeoff, climb, cruise, descent, landing.
-Flat and curved side pressure - -Flat side is high pressure, curved side is
low pressure
-Angle of attack - -Angle between the chord line and the relative wind ( it's
an aerodynamic angle)
-angle of incidence - -Angle between chord line and the rotor systems place
of rotation ( mechanical angle)
-Stall region - -The inner one quarter of the blade.
-Driving region - -In between the stall and driven region.
-Driven region - -The outer 30% of a blade.
-Blade twist - -Greater pitch angles near the root and shallower near the
blade tip
-Effective translational lift - -Experienced between 16 to 24 knots
-In ground effect - -Additional lift is provided from the ground when the
altitude is one length or less then the main rotor diameter.
-Rotational relative wind - -Tip path plane, wind velocity is greatest at the
tip of each blade
-Rotor system parts (4) - -Hub, tip, root,twist
, -Total aerodynamic force - -Two components comprise this lift and drag
-Translating tendency ( drift ) - -A helicopter with one main rotor tends to
drift in the direction of the tail rotor thrust
-First law of motion - -Until acted on by an external force, an objects
velocity will remain constant ( an object at rest will remain at rest and in
object in motion will remain in motion until a force is applied)
-Second law of motion - -Algebraically is F=m*a ( how the velocity of an
object changes when it is subject to another force)
-Third law of motion - -for every action there is an equal and opposite
reaction
-Acceleration of gravity - -Is 9.81 m/s squared
-Torque equation - -T= F*r
-Gravitation potential energy - -PE= m*g*h (m is mass, g is 9.81, and h is
height)
-Work equation - -W=F*d
-Stiction friction - -Force necessary to start sliding an object
-Simple machines - -Devices that change the direction or magnitude of
force
-mechanical advantage - -Defined as the output force dived by the force
applied
-Class 1 lever - -Mechanical advantage is the same on each side
-class 2 lever - -Mechanical advantage greater than one ( out put closer to
fulcrum)
-Class 3 lever - -Mechanical advantage less than 1 (output further from
fulcrum)
-Pascals law - -Transmission of pressure
-High reconnaissance - -This is used to direction and speed of wind, a
touchdown point, suitability of landing area, approach and departure, and
obstacles for both ( good at 300 to 500 feet)
with Accurate Answers
Profile drag - -Caused by the blades frictional resistance
-Induced drag - -Downwash
-Parasite drag - -Components attached to a helicopter that dont contribute
to lift
-Total drag - -Sum of profile, induced, and parasite drag.
-Bernoullis principle - -As flow increases, pressure decreases
-Phases of flight - -Takeoff, climb, cruise, descent, landing.
-Flat and curved side pressure - -Flat side is high pressure, curved side is
low pressure
-Angle of attack - -Angle between the chord line and the relative wind ( it's
an aerodynamic angle)
-angle of incidence - -Angle between chord line and the rotor systems place
of rotation ( mechanical angle)
-Stall region - -The inner one quarter of the blade.
-Driving region - -In between the stall and driven region.
-Driven region - -The outer 30% of a blade.
-Blade twist - -Greater pitch angles near the root and shallower near the
blade tip
-Effective translational lift - -Experienced between 16 to 24 knots
-In ground effect - -Additional lift is provided from the ground when the
altitude is one length or less then the main rotor diameter.
-Rotational relative wind - -Tip path plane, wind velocity is greatest at the
tip of each blade
-Rotor system parts (4) - -Hub, tip, root,twist
, -Total aerodynamic force - -Two components comprise this lift and drag
-Translating tendency ( drift ) - -A helicopter with one main rotor tends to
drift in the direction of the tail rotor thrust
-First law of motion - -Until acted on by an external force, an objects
velocity will remain constant ( an object at rest will remain at rest and in
object in motion will remain in motion until a force is applied)
-Second law of motion - -Algebraically is F=m*a ( how the velocity of an
object changes when it is subject to another force)
-Third law of motion - -for every action there is an equal and opposite
reaction
-Acceleration of gravity - -Is 9.81 m/s squared
-Torque equation - -T= F*r
-Gravitation potential energy - -PE= m*g*h (m is mass, g is 9.81, and h is
height)
-Work equation - -W=F*d
-Stiction friction - -Force necessary to start sliding an object
-Simple machines - -Devices that change the direction or magnitude of
force
-mechanical advantage - -Defined as the output force dived by the force
applied
-Class 1 lever - -Mechanical advantage is the same on each side
-class 2 lever - -Mechanical advantage greater than one ( out put closer to
fulcrum)
-Class 3 lever - -Mechanical advantage less than 1 (output further from
fulcrum)
-Pascals law - -Transmission of pressure
-High reconnaissance - -This is used to direction and speed of wind, a
touchdown point, suitability of landing area, approach and departure, and
obstacles for both ( good at 300 to 500 feet)
