Equilibrium in flight is achieved when?

Equilibrium in flight is achieved when?

• A. The thrust exceeds drag
• B. The forces of flight are equal and opposite
• C. Lift equals weight
• D. Drag equals weight

Answer: (B)

Equilibrium in flight means the net force on the aircraft is zero. When forces balance and act in opposite directions, there is no acceleration, so the airplane maintains its current speed and flight path. In level, steady flight this shows up as lift balancing weight to hold altitude and thrust balancing drag to maintain speed. Because the forces are equal and opposite, their vectors sum to zero, keeping the aircraft in a steady state. If one pair weren’t balanced, the aircraft would accelerate in that direction (up or down, faster or slower, or start to turn), changing its flight condition.

Equilibrium in flight means the net force on the aircraft is zero. When forces balance and act in opposite directions, there is no acceleration, so the airplane maintains its current speed and flight path. In level, steady flight this shows up as lift balancing weight to hold altitude and thrust balancing drag to maintain speed. Because the forces are equal and opposite, their vectors sum to zero, keeping the aircraft in a steady state. If one pair weren’t balanced, the aircraft would accelerate in that direction (up or down, faster or slower, or start to turn), changing its flight condition.