Flight Theory & Principles Flashcards

If an airplane's airspeed is doubled while angle of attack remains constant, how does lift change?

Answer: Lift increases by a factor of four

Lift varies with the square of velocity, so doubling airspeed quadruples lift.

In straight-and-level flight, how does induced drag change as airspeed increases?

Answer: It decreases because a lower angle of attack is required

Induced drag varies inversely with the square of airspeed because less angle of attack is needed at higher speeds.

At the airspeed for maximum lift-to-drag ratio (L/Dmax), which condition exists?

Answer: Induced drag equals parasite drag

Total drag is lowest where the induced and parasite drag curves intersect, which is the L/Dmax point.

An airplane enters ground effect during landing. What is the primary aerodynamic result?

Answer: Induced drag decreases, causing a tendency to float

Ground effect restricts wingtip vortices and downwash within about one wingspan of the surface, reducing induced drag.

Wingtip vortices are strongest when the generating aircraft is:

Answer: Heavy, clean, and slow

Vortex strength is greatest at high angles of attack, which occur when an aircraft is heavy, clean, and slow.

Which statement about the critical angle of attack is correct?

Answer: It remains the same regardless of weight, airspeed, or attitude

A given wing always stalls at the same critical angle of attack; stall speed changes, but the stall angle does not.

What is the purpose of designing a wing with washout (twist that reduces tip incidence)?

Answer: To make the wing root stall before the tips, preserving aileron control

Washout lowers the tip's angle of attack so the root stalls first and the ailerons remain effective.