Aircraft Theory of Flight A1 Jeopardy

Theory of Flight

• Lift is generated due to the pressure difference between the upper and lower surfaces of an aircraft wing.
• The four main forces acting on an aircraft in flight are lift, weight, thrust, and drag.
• The angle between the wing chord line and the relative wind is called the angle of attack.
• Increasing the angle of attack increases both lift and drag.
• Induced drag can be minimized by increasing the aircraft's speed or increasing the wingspan.

Flight Control Surfaces

• The primary flight control surfaces are ailerons (roll, longitudinal axis), elevators (pitch, lateral axis), and rudder (yaw, vertical axis).
• Flaps increase lift and allow for lower stall speeds.
• Trim tabs are used to relieve control pressure by aerodynamically offsetting control surface forces.
• Spoilers disrupt airflow, reducing lift and increasing drag, which aids in roll control and braking on landing.
• Fly-by-wire systems enhance safety and performance by using electronic interfaces to control aircraft surfaces, allowing for computer-mediated stability and control augmentation but introducing concerns about system redundancy and potential software malfunctions.

Aerodynamic Principles

• Bernoulli's principle states that as the speed of a fluid increases, the pressure decreases, which is fundamental to understanding how airfoils generate lift.
• Viscosity is a fluid's resistance to flow, affecting the airflow around an airfoil by creating a boundary layer.
• The boundary layer is a thin layer of air near the surface of the airfoil that increases skin friction drag.
• Laminar flow is smooth, layered airflow, while turbulent flow is chaotic and irregular; turbulent flow increases drag more significantly than laminar flow.
• The Kutta-Joukowski theorem relates lift generated by an airfoil to the speed of the airfoil, the density of the air, and the circulation around the airfoil, providing a crucial method for calculating lift.

Aircraft Stability

• Static stability refers to an aircraft's initial tendency to return to equilibrium, while dynamic stability describes how the aircraft returns to and maintains equilibrium over time.
• Longitudinal stability concerns the aircraft's tendency to maintain its pitch attitude, with the horizontal stabilizer playing a key role.
• Dihedral, the upward angle of the wings, enhances lateral stability by increasing lift on the lower wing in a slip or roll.
• Dutch roll is a coupled lateral-directional oscillation that can be prevented or dampened through yaw dampers and proper aerodynamic design.
• Aeroelasticity can cause flutter and other stability issues due to the interaction between aerodynamic forces and the aircraft's structural flexibility.

Stall Characteristics

• Aerodynamic stall occurs when the angle of attack is too high, causing airflow separation and a loss of lift.
• The critical angle of attack is the angle beyond which a stall occurs, and it is crucial because exceeding it results in a significant reduction in lift.
• Stall characteristics vary with wing design; rectangular wings tend to stall at the root first, elliptical wings stall evenly, and swept wings stall at the tip first.
• Stall strips and leading-edge slats are used to control airflow and improve stall characteristics by delaying or preventing airflow separation.
• Stall recovery involves reducing the angle of attack, applying appropriate control inputs, and increasing airspeed to regain lift.