Which type of drag decreases with an increase in speed?

Which type of drag decreases with an increase in speed?

• A. Parasite
• B. Induced
• C. Profile
• D. Skin Friction

Answer: (B)

The main idea is how different drag components change as speed changes. Induced drag comes from the wingtip vortices created by producing lift. As you fly faster, the wing can create the same weight lift with a smaller lift coefficient, which weakens the wingtip vortices. That means induced drag falls off with speed—roughly inversely with the square of speed in level flight. In other words, higher speed reduces the strength of the lift-induced vortices and the associated drag. Parasite drag, which includes profile drag and skin friction, behaves opposite. It grows with speed because it is tied to dynamic pressure and the flow conditions around the aircraft's surfaces. Profile drag is tied to the blade’s shape and how the flow presses and wraps around it, increasing with faster flow. Skin friction drag comes from viscous shear on surfaces and rises as Reynolds number increases with speed. So among these types, the one that decreases as speed increases is the induced drag, while parasite drag components increase with speed.

The main idea is how different drag components change as speed changes. Induced drag comes from the wingtip vortices created by producing lift. As you fly faster, the wing can create the same weight lift with a smaller lift coefficient, which weakens the wingtip vortices. That means induced drag falls off with speed—roughly inversely with the square of speed in level flight. In other words, higher speed reduces the strength of the lift-induced vortices and the associated drag.

Parasite drag, which includes profile drag and skin friction, behaves opposite. It grows with speed because it is tied to dynamic pressure and the flow conditions around the aircraft's surfaces. Profile drag is tied to the blade’s shape and how the flow presses and wraps around it, increasing with faster flow. Skin friction drag comes from viscous shear on surfaces and rises as Reynolds number increases with speed.

So among these types, the one that decreases as speed increases is the induced drag, while parasite drag components increase with speed.