Ground effect is more pronounced during takeoff or just prior to landing due to reduction of induced drag at altitudes less than the wingspan. Is this statement true or false?

Ground effect is more pronounced during takeoff or just prior to landing due to reduction of induced drag at altitudes less than the wingspan. Is this statement true or false?

• A. True
• B. False
• C. Only during cruise
• D. Only at high altitude

Answer: (A)

Ground effect is the reduction of induced drag and an increase in lift when the aircraft flies very close to the ground. When the airplane is within about one wingspan of the surface, the wingtip vortices are disrupted by the ground, which reduces the downwash behind the wing. With less downwash, the induced angle of attack is smaller for the same lift, so less energy is wasted in creating vortices and more is available for actual flight lift. This makes the aircraft more efficient near the ground, which is why takeoff and landing—phases spent close to the surface—show the effect most clearly. Far from the ground, ground effect fades and the usual induced-drag behavior returns, so the effect isn’t notable during cruise or at high altitude. So the statement is true.

Ground effect is the reduction of induced drag and an increase in lift when the aircraft flies very close to the ground. When the airplane is within about one wingspan of the surface, the wingtip vortices are disrupted by the ground, which reduces the downwash behind the wing. With less downwash, the induced angle of attack is smaller for the same lift, so less energy is wasted in creating vortices and more is available for actual flight lift. This makes the aircraft more efficient near the ground, which is why takeoff and landing—phases spent close to the surface—show the effect most clearly. Far from the ground, ground effect fades and the usual induced-drag behavior returns, so the effect isn’t notable during cruise or at high altitude. So the statement is true.