Degraded / Jammed Elevator

A degraded or jammed elevator will result in less effective elevator maneuverability in pitch control. Center of gravity position with a jammed/degraded elevator The best position for the center of gravity with a degraded/jammed elevator…

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yaw damper

Yaw and Roll Dampers

The purpose of a yaw damper is to (1) prevent Dutch roll and (2) coordinate turns. The purpose of a roll dampers is to (1) damp/remove Dutch roll, (2) provide roll damping in turbulence, and…



Leading-edge slats Leading-edge slats increase the wing’s chamber area and mean aerodynamic chord (MAC), thereby increasing its coefficient of lift (CL) maximum, which reduces the aircraft’s stall speed. Krueger flaps Krueger flaps are leading-edge wing…



What are spoilers, and how do they work? Spoilers consist of opening panels that extend from the upper surface of the wing and have the effect of spoiling/disturbing the airflow over the wing (drag), thereby…

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Control Surfaces

Primary/main flight controls Elevator: Controls the motion around the lateral axis, known as pitch/pitching. Ailerons: Control the motion around the longitudinal axis, known as roll/rolling. Rudder: Controls the motion about the normal/vertical axis, known as yaw/yawing….

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What is directional stability? Directional stability is the tendency for an aircraft to regain its direction (heading) after the aircraft has been directionally disturbed (e.g., an induced yaw) from its straight path. This is achieved…

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Dutch Roll

What is Dutch roll? Dutch roll is an oscillatory instability associated with swept-wing jet aircraft. It is the combination of yawing and rolling motions. When the aircraft yaws, it will develop into a roll. The…

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Why an aircraft stalls? An aircraft stalls when the streamlined/laminar airflow (or boundary layer) over the wing’s upper surface, which produces lift, breaks away from the surface when the critical angle of attack is exceeded,…

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Coffin Corner

What is coffin corner? Coffin corner occurs at an aircraft’s absolute ceiling, where the speeds at which Mach number buffet and prestall buffet occur are coincident, and although trained for, in practice, they are difficult…

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Mach Tuck

What is Mach tuck? Mach tuck is the nose-down pitching moment an aircraft experiences as it passes its critical Mach number (Mcrit). Mach tuck is a form of longitudinal instability that occurs because of the…