Purpose
This lesson introduces the fundamentals of flight mechanics, covering the theory of flight and basic aerodynamic principles.
Objectives
By the end of this lesson, students should be able to:
- Identify the 4 external forces affecting flight.
- Explain the 3 Coordinate Frame Axes of flight and how flight surfaces maneuver each.
- Describe the elements of an airfoil.
- Understand stalls and their causes.
- Explain flight theories, laws, and principles related to fixed wing, rotary wing, and multi-rotor flight.
- Discuss weight and balance.
Aerodynamics
Aerodynamics studies how objects move through the air. It applies to everything from jet liners to sports balls.
Aeronautical Forces of Flight
Four key forces affect an air vehicle (AV): weight, lift, drag, and thrust.
- Weight: Acts downward toward Earth, dependent on mass and payload. To achieve flight, weight must be overcome by lift.
- Lift: Generated by air moving over the aircraft, perpendicular to the direction of flight, influenced by the AV's shape, size, velocity, and air density.
- Drag: Resistance opposing the AV's motion, dependent on shape and air qualities.
- Thrust: Produced by propulsion systems to counteract drag.
Airfoil
An airfoil is a wing or rotor blade cross-section designed to optimize lift-to-drag ratio.
- Leading Edge: Front part of the airfoil that meets the air first.
- Trailing Edge: Rear part where airflow rejoins, affecting turbulence.
- Chord: Imaginary line from leading to trailing edge, used to measure other elements.
- Camber: The curvature of the airfoil's surfaces affecting lift.
- Angle of Attack (AoA): Angle between the airflow and the chord, critical for lift and stall conditions.
Stall
A stall occurs when AoA exceeds the critical angle, causing a decrease in lift. It typically happens during takeoff (departure stall) or landing (approach stall). Recovery involves reducing AoA, maintaining wing level, and applying power to regain airspeed and lift.
Flight Control Axes
An AV rotates about three axes intersecting at the Center of Gravity (CG):
- Longitudinal Axis: Runs from nose to tail. Controlled by ailerons to roll or bank the AV.
- Lateral Axis: Runs from wingtip to wingtip. Controlled by elevators to pitch the AV up or down.
- Vertical Axis: Runs vertically through the CG. Controlled by rudders to yaw the AV left or right.
