Unit 2 Unmanned Aircraft Module 1 The UAS Component 1.2 – Airframe and Wing Design

Airframe and Wing Design Forces of Flight Lift Weight Thrust Drag 107.3 Definitions The following definitions apply to this part. If there is a conflict between the definitions specified in §1.1 of the chapter, the definitions in this part control for purposes of this part: Control station means an interface used by the remote pilot to control the flight path of the small unmanned aircraft. Corrective lenses means spectacles or contact lenses.

Airframe and Wing Design Lift Opposes the downward force of weight Produced by the dynamic effect of air acting on the airfoil Acts perpendicular to the flight path through the center of lift Weight The combined load of the aircraft, crew, fuel, and cargo Pulls downward due to gravity Opposes lift acting vertically downward through the center of gravity (CG)

Airframe and Wing Design Thrust The forward force produced by the power plant/propeller or rotor Opposes the force of drag Generally acts parallel to the longitudinal axis Drag The rearward force caused by the disruption of airflow by the wing, rotor, fuselage, or other protruding object Opposes thrust acts rearward parallel to relative wind

Airframe and Wing Design Bernoulli's Principle Describes basic principle of pressure differential As the velocity of air increases the pressure of the air decreases

Airframe and Wing Design Airfoils Any surface that provides an aerodynamic force when interacted by a stream of air Typical airfoils air moves over the top and accelerates creating lower pressure Air moving below slows down creating higher pressure and lift Upwash is the deflection of oncoming air as it moves up and over the wing’s leading edge Downwash is the deflection of the air down past the trailing edge of the wing

Airframe and Wing Design Chord line is a line that connects the leading and trailing edges of a wing cross-section Camber is the curvature of the surface of the upper and lower halves of the wing Angle of attack is the angle between the cord line and the relative wind Relative wind is wind parallel and opposite to the flight path

Airframe and Wing Design 107.3 Definitions The following definitions apply to this part. If there is a conflict between the definitions specified in §1.1 of the chapter, the definitions in this part control for purposes of this part: Small Unmanned Aircraft means an unmanned aircraft weighing less than 55 pounds on takeoff, including everything that is on board or otherwise attached to the aircraft. Small unmanned aircraft system (small UAS) means a small unmanned aircraft and its associated elements (including communication links and components that control the small unmanned aircraft) that are required for the safe and efficient operation of the small unmanned aircraft in the national airspace system.

Airframe and Wing Design Stall Dangerous condition that results from the separation of air from the upper surface of an airfoil resulting in loss of lift Velocity of air over the airfoil does not effect stall by is affected by angle of attack The angle at which separation occurs is called the critical angle of attack Separation starts at the trailing edge and works forward as the angle of attack increases

Airframe and Wing Design Wing design factors Wing design will affect the performance of the wing Major wing characteristics include Camber Wing Planform Aspect ratio Total wing area

Airframe and Wing Design Aspect Ratio The ratio between length and width of the wing Higher aspect ratios give less drag for the same amount of lift

Airframe and Wing Design Planform The overall shape of the wing when seen from above or below Elliptical Have minimum drag but has a much more significant stall characteristic Rectangular Less efficient then elliptical Stalls start at the wing root and work outwards, allowing ailerons to still be effective in a stall

Airframe and Wing Design Tapering Less drag then rectangular and more effective at higher speeds Stalls start slightly inboard of the wing tips Allows for higher aspect ratio and reduction of weight Sweptback Found in commercial airline jets Provides better efficiency at higher speeds and decreases drag

Airframe and Wing Design Wing types Affect stability of the aircraft Dihedral will produces a smaller movement Anhedral reduces stability of the craft