Army Flight Warrant Officer SIFT
Test Questions and Answers 100% Pass
Helicopter Structure - ✔✔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 - ✔✔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 - ✔✔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 - ✔✔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
© EMILY CHARLENE YEAR 2025-2026, ALL RIGHTS RESERVED 1
, 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 - ✔✔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 - ✔✔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 - ✔✔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 - ✔✔Form drag increases as the speed of the helicopter increases.
Skin Friction - ✔✔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 - ✔✔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 - ✔✔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.
© EMILY CHARLENE YEAR 2025-2026, ALL RIGHTS RESERVED 2
Test Questions and Answers 100% Pass
Helicopter Structure - ✔✔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 - ✔✔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 - ✔✔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 - ✔✔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
© EMILY CHARLENE YEAR 2025-2026, ALL RIGHTS RESERVED 1
, 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 - ✔✔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 - ✔✔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 - ✔✔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 - ✔✔Form drag increases as the speed of the helicopter increases.
Skin Friction - ✔✔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 - ✔✔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 - ✔✔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.
© EMILY CHARLENE YEAR 2025-2026, ALL RIGHTS RESERVED 2
