Aerodynamics Flashcards

Which factor primarily determines the critical angle of attack for a given airfoil?

Answer: Airfoil shape and camber

Critical angle of attack is a fixed aerodynamic property of the airfoil's shape and camber, not affected by speed or weight.

What happens to induced drag when an aircraft's airspeed is doubled at the same altitude and weight?

Answer: It is reduced to one-quarter

Induced drag varies inversely with the square of airspeed, so doubling speed reduces induced drag to one-quarter of its original value.

Ground effect reduces induced drag primarily because it:

Answer: Restricts the formation of wingtip vortices

Ground effect limits downwash and vortex formation near the ground, reducing induced drag significantly during takeoff and landing.

An aircraft experiencing 'Dutch roll' is showing instability about which axes?

Answer: Lateral and vertical simultaneously

Dutch roll is an oscillatory coupling of roll and yaw (lateral and vertical axes) common in swept-wing aircraft with high dihedral.

What is the effect of increasing aspect ratio on an aircraft's aerodynamic efficiency?

Answer: Reduces induced drag

A higher aspect ratio reduces wingtip vortex strength per unit span, decreasing induced drag and improving the lift-to-drag ratio.

Which condition most accurately describes 'coffin corner' in high-altitude flight?

Answer: The margin between Mmo and Vs narrows until they converge

At coffin corner, the indicated stall speed and the maximum operating Mach speed converge, leaving almost no usable speed range.

Dihedral in a wing design primarily provides stability about which axis?

Answer: Longitudinal (roll)

Dihedral creates a self-correcting rolling moment when one wing drops, providing positive lateral (roll) stability.