SIFT (Army Aviation Information) Practice Test| QUESTIONS AND ANSWERS

SIFT (Army Aviation Information) Practice Test| QUESTIONS AND ANSWERS The typical structure of a helicopter is a ______ (fill in the blank) with a ____ (fill in the blank) protruding upward out of it. - Fuselage (the body of the craft), Mast. The engine of the craft drives power upward through the ____ (fill in the blank) to the rotor blades, which are controlled by the pilot. - Mast This main rotor is used to generate ____ (fill in the blank). - Thrust. ____ (fill in the blank) is balanced by a second rotor, usually a tail rotor, which is intended to account for the effects of ____ (fill in the blank). - Thrust, Torque. What are the two main types of aircraft? - Rotorcraft and Fixed Wing. The main advantage of a helicopter over an airplane is its ability to takeoff ____ (fill in the blank). It can also ____ (fill in the blank). This means helicopters can be used to takeoff from and land in places that would be impossible for planes. They can also perform tasks such as dropping cargo or troops into challenging positions. - Vertically, Hover. What are the different Helicopter types? - Single Main Rotor, Tandem Rotor, and Coaxial Rotor. This is the most common design for a helicopter- a ____ (fill in the blank) 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 ____ (fill in the blank), rather than being used solely for lift. - A Single Main Rotor, Torque. 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 to lift. Consequently, ____ (fill in the blank) helicopters are some of the fastest and most powerful in existence. - Tandem 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 ____ (fill in the blank) and allowing for greater cargo and passenger capacity as a result. - Coaxial Rotor Helicopter, Payload. ____ (fill in the blank) is created by the engine, or engines, of the helicopter. It is transferred into motion via the ____ (fill in the blank) and ____ (fill in the blank). Sufficient ____ (fill in the blank) is needed to overcome the drag and the weight of the helicopter and keep moving it forward. - Thrust, Mast and Rotors, Thrust. ____ (fill in the blank) 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 ____ (fill in the blank) which impact helicopters. - Drag What are the 4 different types of Drag? - Profile Drag, Induced Drag, Parasite Drag, Total Drag. ____ (fill in the blank) is caused by the frictional resistance of helicopter blades passing through the air. - Profile Drag. What are the two subcomponents of Profile Drag? - Form Drag and Skin Friction. ____ (fill in the blank) increases as the speed of the helicopter increases. - Form Drag. ____ (fill in the blank) is caused by microscopic roughness of the helicopter blades. Any roughness on the surface causes air to become trapped and drag to increase. - Skin Friction. ____ (fill in the blank) is caused by airflow circulation around the blades creating vortices. This type of drag incr