Drag High Angle of Attack– Low Speed Low Angle of Attack– High Speed Total Drag Stall Induced Drag Parasite Drag L D- MAX CG 5 1 Glideslope Root Wing Chord $^{Relativ}$e  $_{Wind}$ Flightpath Lift Drag W$_{L}$ W$_{D}$ Weight Resultant force  of lift and drag  components  that support the  weight during  flight Component  of weight  that  opposes  lift (W$_{L}$) Component of weight acting along flight path. (some call this thrust component during gliding flight)(W$_{D}$) Resultant force Angle of Attack Figure 2-18.  Airspeed versus drag. Figure 2-19.  Typical forces in gliding flight with no engine thrust. Weight is a measure of the force of gravity acting upon the  mass of the WSC aircraft. Weight consists of everything  directly associated with the WSC aircraft in flight: the  combined load of the total WSC aircraft (wing, wires, engine,  carriage, fuel, oil, people, clothing, helmets, baggage, charts,  books, checklists, pencils, handheld global positioning  system (GPS), spare clothes, suitcase, etc.).  During gliding flight, weight is broken down into two  components. The component that opposes the lift, acting  perpendicular to flight/glide path, and the component that  opposes the drag and acts in the direction of the fl ight/glide  path. During gliding flight, this component of weight is the  weight component providing the forward force which some  call thrust for gliding fl ight. During gliding, straight, and descending in unaccelerated  fl ight: to produce level flight, the relative wind stream becomes  horizontal with the Earth and the AOA remains about the  same. As described for the airplane in the Pilot’s Handbook  of Aeronautical Knowledge, thrust equals total drag for level  fl ight.  [Figure 2-20] When in straight and level, unaccelerated fl ight: Lift (L) = Weight (W) Thrust = Total Drag (D$_{T}$) Lift (L) and Drag (D) components = Resultant force (RF)  = Weight (W) Total Drag (D$_{T}$) = Weight component (W$_{D}$) in the direction  of fl ight Lift (L) = Weight component (W$_{L}$) that opposes lift Similar to airplanes, gliders, and PPC during gliding fl ight,  less lift is required because the resultant force composed of  lift and drag provides the force to lift the weight. In other  words, in gliding flight, drag helps support the weight.  [Figure 2-19] At a constant air speed, the amount of thrust determines  whether an aircraft climbs, flies level, or descends. With the  engine idle or shut off, a pilot is descending or gliding down.  Maintaining a constant airspeed, when enough thrust is added  At a constant airspeed, when excess thrust is added to produce  climbing flight, the relative air stream becomes an inclined  plane leading upward while AOA remains about the same.  The excess thrust determines the climb rate and climb angle  of the fl ightpath.  [Figure 2-21] When in straight and climbing, unaccelerated fl ight: Lift (L) = Component of weight that opposes lift Weight (W) = Resultant force (F$_{R}$) of lift (L) and excess  thrust to climb (T$_{E}$) Thrust = Total drag (D$_{T}$) plus rearward component of  weight 2-10  Thrust  Weight