SIFT Test – Aerodynamics Exam with
Complete Solutions
Thrust, Drag, Lift, Weight - ANS-What are the 4 forces acting on an aircraft
Thrust - ANS-The forward force produced by the propeller or rotor. It opposes or
overcomes the force of drag.
It generally acts parallel to the longitudinal axis.
Drag - ANS-Rearward, retarding force caused by disruption of airflow by the wing, rotor,
fuselage, and other protruding objects.
This opposes thrust and acts rearward parallel to the relative wind.
Weight - ANS-The combined load of the aircraft itself, crew, fuel, cargo, armaments, etc.
Pulls the aircraft downward because of gravity.
Opposes lift and acts vertically downward through the aircrafts center of gravity.
Lift - ANS-Opposes the downward force of weight, is produced by the dynamic effect of
the air acting on the airfoil, and acts perpendicular to the flightpath through the center of
_______.
Factors of Lift - ANS-Speed of the airflow
Density of the air
Total area of the segment or airfoil
Angle of Attack between air and airfoil
Generation of Lift - ANS-When the rotor and airflow move relative to each other and the
rotor turns the airflow in a direction perpendicular to that flow, the force required to do
this creates an equal and opposite force.
Angle of Attack - ANS-Angle between chord line and relative wind. Must have positive
_______ __ _______ to generate lift.
Total Weight - ANS-Helicopter must generate enough lift to overcome or offset the
______ _______ of the itself and its occupants.
G Load / Load Factor - ANS-When you bank a helicopter while maintaining a constant
altitude, the __ _______ increases.
Load Factor - ANS-Actual load on rotor blades divided by the normal or gross weight.
, Apparent Increase - ANS-30 degrees = 16% of the load
60 degrees = 2x the load
80 degrees.= 6x the load
Forward, Rearward, Sideward, Vertical - ANS-Types of Thrust
Resultant lift and thrust - ANS-Direction of movement of the helicopter is determined by
this
Antitorque pedal - ANS-Used to control the amount of thrust and a helicopter's pitch and
yaw.
Profile, Induced, and Parasite - ANS-Types of Drag
Profile Drag - ANS-Frictional resistance of the rotor blades passing through the air.
Increases moderately when airspeed increases.
Induced Drag - ANS-Generated by the airflow circulation around the rotor blades as it
creates lift.
High pressure beneath blade joins low pressure above blade to create vortex that trails
each blade as lift is produced.
Parasite Drag - ANS-Caused by components that don't produce lift (cabin, landing gear,
etc.)
Increases with airspeed
Any additional openings creates this as well.
Form Drag and Skin Friction. - ANS-Profile drag consists of this.
Total Drag - ANS-Sum of all three drag forces, as airspeed increases, parasite drag
increases, while induced drag decreases. Profile drag remains relatively constant with
some increase at higher airspeeds.
Results in ______ ______ curve
Low point on total drag curve - ANS-Point where lift to drag ratio is greatest and is
referred to as L/DMAX.
At this speed, total lift capacity of the helicopter when compared to the total drag of the
helicopter is most favorable.
Flight Controls - ANS-Collective Pitch Control
Throttle Control
Governor/Correlation
Cyclic Pitch Control
Anti-torque Pedals
Complete Solutions
Thrust, Drag, Lift, Weight - ANS-What are the 4 forces acting on an aircraft
Thrust - ANS-The forward force produced by the propeller or rotor. It opposes or
overcomes the force of drag.
It generally acts parallel to the longitudinal axis.
Drag - ANS-Rearward, retarding force caused by disruption of airflow by the wing, rotor,
fuselage, and other protruding objects.
This opposes thrust and acts rearward parallel to the relative wind.
Weight - ANS-The combined load of the aircraft itself, crew, fuel, cargo, armaments, etc.
Pulls the aircraft downward because of gravity.
Opposes lift and acts vertically downward through the aircrafts center of gravity.
Lift - ANS-Opposes the downward force of weight, is produced by the dynamic effect of
the air acting on the airfoil, and acts perpendicular to the flightpath through the center of
_______.
Factors of Lift - ANS-Speed of the airflow
Density of the air
Total area of the segment or airfoil
Angle of Attack between air and airfoil
Generation of Lift - ANS-When the rotor and airflow move relative to each other and the
rotor turns the airflow in a direction perpendicular to that flow, the force required to do
this creates an equal and opposite force.
Angle of Attack - ANS-Angle between chord line and relative wind. Must have positive
_______ __ _______ to generate lift.
Total Weight - ANS-Helicopter must generate enough lift to overcome or offset the
______ _______ of the itself and its occupants.
G Load / Load Factor - ANS-When you bank a helicopter while maintaining a constant
altitude, the __ _______ increases.
Load Factor - ANS-Actual load on rotor blades divided by the normal or gross weight.
, Apparent Increase - ANS-30 degrees = 16% of the load
60 degrees = 2x the load
80 degrees.= 6x the load
Forward, Rearward, Sideward, Vertical - ANS-Types of Thrust
Resultant lift and thrust - ANS-Direction of movement of the helicopter is determined by
this
Antitorque pedal - ANS-Used to control the amount of thrust and a helicopter's pitch and
yaw.
Profile, Induced, and Parasite - ANS-Types of Drag
Profile Drag - ANS-Frictional resistance of the rotor blades passing through the air.
Increases moderately when airspeed increases.
Induced Drag - ANS-Generated by the airflow circulation around the rotor blades as it
creates lift.
High pressure beneath blade joins low pressure above blade to create vortex that trails
each blade as lift is produced.
Parasite Drag - ANS-Caused by components that don't produce lift (cabin, landing gear,
etc.)
Increases with airspeed
Any additional openings creates this as well.
Form Drag and Skin Friction. - ANS-Profile drag consists of this.
Total Drag - ANS-Sum of all three drag forces, as airspeed increases, parasite drag
increases, while induced drag decreases. Profile drag remains relatively constant with
some increase at higher airspeeds.
Results in ______ ______ curve
Low point on total drag curve - ANS-Point where lift to drag ratio is greatest and is
referred to as L/DMAX.
At this speed, total lift capacity of the helicopter when compared to the total drag of the
helicopter is most favorable.
Flight Controls - ANS-Collective Pitch Control
Throttle Control
Governor/Correlation
Cyclic Pitch Control
Anti-torque Pedals
