Aircraft Components and Controls Flashcards
7 cards from real SIFT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Aircraft Components and Controls flashcards as text
What is the primary purpose of an aircraft's vertical stabilizer?
Answer: Provide directional (yaw) stability about the vertical axis
The vertical stabilizer provides weathervane-like yaw stability, keeping the aircraft aligned with the relative wind and resisting unwanted yaw movements.
During autorotation in a helicopter, which component supplies energy to keep the rotor turning?
Answer: The stored inertia of the rotor and upward airflow through the rotor disk
In autorotation, rising air through the rotor disk (and initially rotor inertia) drives the rotor blades, providing lift for a controlled descent without engine power.
What is the function of the 'feathering hinge' (or pitch change bearing) in a helicopter rotor blade?
Answer: Allows the blade to rotate about its spanwise axis to change pitch angle
The feathering hinge (pitch change bearing) allows each rotor blade to rotate about its spanwise axis, changing its angle of attack in response to cyclic and collective inputs.
On a fixed-wing aircraft, what is the function of the 'elevator'?
Answer: Controls pitch by deflecting the horizontal tail surface
The elevator is the movable portion of the horizontal stabilizer that deflects up or down to pitch the nose of the aircraft up or down.
What is 'translational lift' in helicopter flight?
Answer: The increased efficiency and lift gained as the helicopter transitions from hover to forward flight
Translational lift occurs as the helicopter moves forward and the rotor exits its own downwash, gaining more efficient airflow through the disk and a noticeable increase in lift.
In a fully articulated rotor system, the 'lead-lag hinge' is designed to:
Answer: Allow blades to move fore and aft in the plane of rotation to absorb Coriolis forces
The lead-lag (drag) hinge allows rotor blades to move slightly fore and aft in their plane of rotation, absorbing the Coriolis effect that occurs as blades flap.
What is the purpose of 'winglets' on a fixed-wing aircraft?
Answer: Reduce induced drag by limiting wingtip vortices
Winglets are vertical extensions at the wingtip that reduce the strength of wingtip vortices, decreasing induced drag and improving fuel efficiency.