The Four Forces in Flight

Four forces act on an aircraft: lift (up), weight (down), thrust (forward) and drag (back). In steady level flight they balance in pairs — lift equals weight, thrust equals drag. If thrust exceeds drag the aircraft accelerates; if lift exceeds weight it climbs. The vectors here scale with your inputs so you can see the balance tip.

• Try this: Trim for level flight: adjust until lift = weight and thrust = drag. What state shows?
• Try this: Add thrust beyond drag. Does the aircraft climb, or accelerate? Which pair is unbalanced?
• Try this: Raise the angle of attack. Lift rises — but watch drag climb too. Why?