Total drag and polar drag Flashcards
What is Vmd
Speed to fly with minimum drag..
Parasite drag and induced drag equal.
What is speed stability
The tendency of an aircraft to return to its original speed after a brief disturbance without the pilot needing to adjust thrust.
Only occurs when aircraft is flying at speeds greater than Vmd
What is speed unstable
A natural tendency to diverge from its original speed following a brief disturbance.
What is speed neutral
Speeds either side of Vmd plane. Aircraft exhibits neither a tendency to return to is original speed or diverge further from speed.
What is the effect of Vmd by altitude
Vmd will get faster (move right on drag curve). Greater amount of unstable speeds.
How does weight affect Vmd
Weight will increase Vmd as more lift required and that causes more induced drag.
How does configuration affect Vmd
Parasite drag will increase. Vmd is reduced. Stable speeds range increases.
What does the drag polar do
Measure of efficiency of the wing at different coefficients of lift.
What Alpha is the most efficient for L/D ratio
4% best L/D ratio. Ratio becomes worse as AOA increases or decreases.
Stalling angle 16% L/D ratio falls rapidly.
