For a given IAS an increase in altitude will result in
- an increase in induced drag.
- no change in the induced drag.
- an increase in profile drag.
Explanation from PART66Online
Indicated airspeed is a direct measure of dynamic pressure, so holding IAS constant holds the dynamic pressure constant at every altitude. In level flight the wing must still support the same weight, so the lift coefficient and the angle of attack are unchanged, and the induced drag coefficient and the induced drag are unchanged with them. What rises with altitude at a given IAS is the true airspeed, and therefore the power required, not the drag force. Profile drag is likewise tied to dynamic pressure and does not rise either.
Kugen asked · 1 Oct 2012
i thought induced drag is inversely proportional to altitude?
Community Comments (2)
With a decrease in density the aircraft must fly with a greater angle of attack (CL) to compensate for the loss of lift. Induced drag is dependant upon AOA, therefore induced drag increases with altitude.
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