Maximum gliding distance is achieved when which pair of drag components are equal?

Maximum gliding distance is achieved when which pair of drag components are equal?

• A. Lift equals weight
• B. Induced drag equals parasite drag
• C. Drag equals zero
• D. Speed equals stall speed

Answer: (B)

The best glide distance comes from balancing the two main drag components: induced drag and parasite drag. Induced drag is the drag produced by the lift the wing generates, and it decreases as you fly faster. Parasite drag comes from the aircraft’s shape, skin friction, and fittings, and it increases with speed. For a given amount of lift required to support the weight, total drag is Di + Dp. There is a particular speed at which these two drags are equal, and at that point the total drag is minimized for the required lift, giving the largest lift-to-drag ratio. That largest L/D means you travel farther horizontally for the same loss of altitude, i.e., maximum gliding distance. Other scenarios don’t optimize drag the same way—for example, simply having lift equal weight is a force balance, zero drag is impossible, and flying at stall speed raises induced drag dramatically, reducing glide distance.

The best glide distance comes from balancing the two main drag components: induced drag and parasite drag. Induced drag is the drag produced by the lift the wing generates, and it decreases as you fly faster. Parasite drag comes from the aircraft’s shape, skin friction, and fittings, and it increases with speed. For a given amount of lift required to support the weight, total drag is Di + Dp. There is a particular speed at which these two drags are equal, and at that point the total drag is minimized for the required lift, giving the largest lift-to-drag ratio. That largest L/D means you travel farther horizontally for the same loss of altitude, i.e., maximum gliding distance. Other scenarios don’t optimize drag the same way—for example, simply having lift equal weight is a force balance, zero drag is impossible, and flying at stall speed raises induced drag dramatically, reducing glide distance.