HELI
Introduction to Rotary Wing Aircraft, Vorlesung an der ZHAW SoE, Studiengang Aviatik
Introduction to Rotary Wing Aircraft, Vorlesung an der ZHAW SoE, Studiengang Aviatik
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Cartes-fiches
A. Because of the conservation of momentum
D. That a rotor with a smaller radius will generate a higher induced velocity – while generating the same thrust force
C. Smaller than descent velocity, without considering the final flare
B. Non-zero because the rotor does generate lift
D. A working state of a rotor characterized by unstable re-circulation through rotor disc
A. Windmilling is the working state of a rotor in which the flow gives energy to the rotor system – i.e it is the state in which wind turbines work when they generate power
C. Because the flow around the advancing blade is disturbed by compressibility effects and the retreating blade experiences inverse flow or very high angle of attack
A. While flying close to the ground a high-pressure cushion appears between rotor and ground
B. Power required decreases while generating the same lift
D. Compressibility effects on advancing blade and stall of retreating blade
A. Because the rotors are tilted forward at high-speed
C. Because at high speed the main rotor is partially unloaded since wing and propellers generate most of the necessary forces (forward thrust and lift)
B. Semi-rigid (also called “see-saw”), articulated, hingeless and bearingless
A. Rotor heads without mechanical hinges around flap and lead/lag axes
D. Rotor heads without mechanical hinges
A) Hingeless and bearingless, because these constructions (Bauweise) accommodate large hinge offset more conveniently.
(C) Yes, because aerodynamic forces generated by turbulence on the blades are transmitted to the fuselage through the rotor head.
(D) Because the hinge offset of semi-rigid rotors is zero.
(A) Carbon fibers and glass fibers composite.
(C) Provide control around the yaw axis.
(B) Low noise and safety on the ground.
(D) It is aerodynamically less efficient at high speed.
(A) No, never.
(A) Because the rotor of gyroplanes is not driven by the engine and operates permanently in windmilling state.
(B) The pitch angle is changed on all blades simultaneously
(C) The pitch angle is changed in function of blade azimuthal position.
(A) Collective pitch angle of tail rotor blades.
(D) A combination of differential collective and longitudinal cyclic
(B) Longitudinal cyclic on both rotors
(A) Approximately 90 degrees.
(C) Approximately 90 degrees.
(D) Approximately 180 degrees.
(A) Smaller drag force .
(A) Dampers on blades (affecting rotation around lead/lag axis) and landing gear.
(B) When starting or slowing down the main rotor with helicopter on ground.
(A) (1) Long time at high power setting, (2) no fixed airflow to rely on for cooling, (3) long time at high pitch and / or bank angles
(C) Category A are helicopters with “stay-up” capability in case of engine failure. Cat. B helicopter must perform an emergency landing if an engine failure occurs
(D) JAR-OPS 3 does not mention any Category C helicopter
(B) A flight in which an engine failure - occurring at any moment of the flight - would not force the pilot to perform an emergency landing.
(A) A flight in which an engine failure - except in the early take-off and late landing phases - would not force the pilot to perform an emergency landing.