Army Flight Warrant Officer SIFT
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Helicopter Structure - CORRECT ANSWER - The typical structure of a helicopter is a
fuselage (the body of the craft) with a mast protruding upward out of it. The engine of the craft
drives power upward through the mast to the rotor blades, which are controlled by the pilot. This
main rotor is used to generate thrust. This thrust is balanced by a second rotor, usually a tail
rotor, which is intended to account for the effects of torque. In the USA, UK and Germany, it is
conventional for the main rotor to rotate counterclockwise. The opposite is true in other
countries. Throughout this book, reference will be made only to counterclockwise main rotors.
Single Main Rotor Helicopter - CORRECT ANSWER - This is the most common design
for a helicopter -a single main rotor generating power, with a secondary rotor, such as a tail rotor,
used to offset the effects of torque. One disadvantage of this design is that some power is used
for countering torque, rather than being used solely for lift.
Co-axial Rotor Helicopter - CORRECT ANSWER - This type of helicopter features two
sets of blades rotating above and beneath each other. The two sets of blades are mounted to the
same mast, but rotate in opposite directions to each other. This has the advantage of reducing
payload and allowing for greater cargo and passenger capacity as a result.
Tandem Rotor Helicopter - CORRECT ANSWER - This helicopter design features two
main rotating blade sections: front and rear. Each set of blades rotates counter to the other,
meaning that torque is automatically offset. There is no need for additional measures, such as a
tail rotor, to deal with torque. Because of this, all of the power from the engine can be used for
lift. Consequently, tandem rotor helicopters are some of the fastest and most powerful in
existence.
Thrust - CORRECT ANSWER - Thrust is created by the engine, or engines, of the
helicopter. It is transferred into motion via the mast and rotors. Sufficient thrust is needed to
overcome the drag and the weight of the helicopter and keep it moving forward.
, Drag - CORRECT ANSWER - Drag is a force which acts against thrust. In the case of
helicopters, drag is caused by the shape and size of the aircraft disrupting the flow of air as it
travels. There are several types of drag which impact helicopters.
Profile Drag - CORRECT ANSWER - Profile drag is caused by the frictional resistance of
helicopter blades passing through the air. It has two components: form drag and skin friction.
Form Drag - CORRECT ANSWER - Form drag increases as the speed of the helicopter
increases.
Skin Friction - CORRECT ANSWER - Skin friction is caused by microscopic roughness
of the helicopter blades. Any roughness on the surface causes air to become trapped and drag to
increase.
Induced Drag - CORRECT ANSWER - Induced drag is caused by airflow circulation
around the blades creating vortices. This type of drag increases when the helicopter is flying at
lower speeds, and decreases when it is flying at higher speeds. During low speed flight, induced
drag is the main cause of drag for helicopters.
Parasite Drag - CORRECT ANSWER - Parasite drag is the drag created by the helicopter
components that are external to the fuselage. For example, the landing gear, cowlings and doors
can all create parasite drag. Parasite drag slows down the speed of a helicopter by opposing
thrust.
Total Drag - CORRECT ANSWER - Total drag is the sum total of the profile, induced and
parasite drag acting upon the helicopter at any given time. The point at which the total drag is
lowest is the preferable point for maximum endurance, best rate of climb, and minimum rate of
descent in autorotation.
Weight - CORRECT ANSWER - Weight is a force which results from the combined mass
of the helicopter being acted upon by gravity. It is a downward force which acts through the
center of gravity of the helicopter. Weight is reliant upon more than just the mass of the
helicopter itself. When a helicopter is flying a curved flight path, the angle at which the
helicopter banks has an impact upon the total weight.
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Helicopter Structure - CORRECT ANSWER - The typical structure of a helicopter is a
fuselage (the body of the craft) with a mast protruding upward out of it. The engine of the craft
drives power upward through the mast to the rotor blades, which are controlled by the pilot. This
main rotor is used to generate thrust. This thrust is balanced by a second rotor, usually a tail
rotor, which is intended to account for the effects of torque. In the USA, UK and Germany, it is
conventional for the main rotor to rotate counterclockwise. The opposite is true in other
countries. Throughout this book, reference will be made only to counterclockwise main rotors.
Single Main Rotor Helicopter - CORRECT ANSWER - This is the most common design
for a helicopter -a single main rotor generating power, with a secondary rotor, such as a tail rotor,
used to offset the effects of torque. One disadvantage of this design is that some power is used
for countering torque, rather than being used solely for lift.
Co-axial Rotor Helicopter - CORRECT ANSWER - This type of helicopter features two
sets of blades rotating above and beneath each other. The two sets of blades are mounted to the
same mast, but rotate in opposite directions to each other. This has the advantage of reducing
payload and allowing for greater cargo and passenger capacity as a result.
Tandem Rotor Helicopter - CORRECT ANSWER - This helicopter design features two
main rotating blade sections: front and rear. Each set of blades rotates counter to the other,
meaning that torque is automatically offset. There is no need for additional measures, such as a
tail rotor, to deal with torque. Because of this, all of the power from the engine can be used for
lift. Consequently, tandem rotor helicopters are some of the fastest and most powerful in
existence.
Thrust - CORRECT ANSWER - Thrust is created by the engine, or engines, of the
helicopter. It is transferred into motion via the mast and rotors. Sufficient thrust is needed to
overcome the drag and the weight of the helicopter and keep it moving forward.
, Drag - CORRECT ANSWER - Drag is a force which acts against thrust. In the case of
helicopters, drag is caused by the shape and size of the aircraft disrupting the flow of air as it
travels. There are several types of drag which impact helicopters.
Profile Drag - CORRECT ANSWER - Profile drag is caused by the frictional resistance of
helicopter blades passing through the air. It has two components: form drag and skin friction.
Form Drag - CORRECT ANSWER - Form drag increases as the speed of the helicopter
increases.
Skin Friction - CORRECT ANSWER - Skin friction is caused by microscopic roughness
of the helicopter blades. Any roughness on the surface causes air to become trapped and drag to
increase.
Induced Drag - CORRECT ANSWER - Induced drag is caused by airflow circulation
around the blades creating vortices. This type of drag increases when the helicopter is flying at
lower speeds, and decreases when it is flying at higher speeds. During low speed flight, induced
drag is the main cause of drag for helicopters.
Parasite Drag - CORRECT ANSWER - Parasite drag is the drag created by the helicopter
components that are external to the fuselage. For example, the landing gear, cowlings and doors
can all create parasite drag. Parasite drag slows down the speed of a helicopter by opposing
thrust.
Total Drag - CORRECT ANSWER - Total drag is the sum total of the profile, induced and
parasite drag acting upon the helicopter at any given time. The point at which the total drag is
lowest is the preferable point for maximum endurance, best rate of climb, and minimum rate of
descent in autorotation.
Weight - CORRECT ANSWER - Weight is a force which results from the combined mass
of the helicopter being acted upon by gravity. It is a downward force which acts through the
center of gravity of the helicopter. Weight is reliant upon more than just the mass of the
helicopter itself. When a helicopter is flying a curved flight path, the angle at which the
helicopter banks has an impact upon the total weight.
