Ref Chapter 5 Ans: Lift, Drag, Thrust, Weight   Thrust— forward force produced by the powerplant/propeller or rotor opposes force of drag. act parallel to longitudinal axis (in general but not must)   Drag— rearward, retarding force caused by disruption of airflow by the wing, rotor, fuselage, and other protruding objects drag opposes thrust (in … Continue reading What’s 4 forces?