Aircraft Motion
Physics of Aircraft
Weight and Thrust
Secondary Controls
Straight and Level
Aircraft Design Features
The Stall
Practice Exam

Total Drag

Total Drag

In flight, the aircraft is experiencing both parasite and induced drag. Their combined effect is known as total drag.

At low speeds, total drag is high because the induced drag is high. At high speeds, total drag is high because parasite drag is high.

Minimum Drag Speed

The total drag is at its lowest value in the middle of the speed range where the values of both parasite and induced drag are relatively low. This point is known as the minimum drag speed (VMD).

In straight and level flight, lift is equal to weight. If you fly straight and level at the minimum drag speed (VMD) the aircraft will be producing the necessary lift to maintain level flight while generating minimum drag. So you will be flying at the best lift/drag ratio. The next lesson looks at the L/D Ratio in more detail.