8. Basic aerodynamics - Q&A

Under what conditions will an aircraft create best lift?

• Hot damp day at 1200 ft.
• Cold dry day at 200 ft.
• Cold wet day at 1200 ft.

The ISA

• assumes a sea level temperature of 25 degrees C.
• is referenced from the equator.
• is taken from 45 degrees latitude.

On an aircraft with an all-moving tailplane, pitch up is caused by

• decreasing tailplane incidence.
• forward movement of the control column.
• increasing tailplane incidence.

What effect does lowering flaps for takeoff have on aircraft speeds?

• Reduces takeoff speeds only.
• Reduces the landing speed only.
• Reduces both takeoff and landing speeds.

Stall commencing at the root is preferred because

• it provides the pilot with a warning of complete loss of lift.
• it provides a clear aerodynamic warning of the approaching loss of aileron effectiveness.
• it will cause the aircraft to pitch nose up before the outer wing sections lose their lift.

What produces the most lift at low speeds?

• High camber ratio.
• Low aspect ratio.
• High aspect ratio.

With the ailerons away from the neutral, induced drag is

• higher on the lower wing plus profile drag also increases.
• unchanged but the profile drag is somewhat higher.
• higher on the upper wing plus profile drag increases.

On a swept wing aircraft if both wing tip sections lose lift simultaneously the aircraft will

• yaw uncontrollably.
• pitch nose up.
• pitch nose down.

A flying control mass balance weight

• keeps the control surface C of G as close to the trailing edge as possible.
• tends to move the control surface C of G close to the hinge line.
• tends to move the control surface C of G aft of the hinge line.

The ISA

• assumes a sea level temperature of 25 degrees C.
• is referenced from the equator.
• is taken from 45 degrees latitude.

The power required at low altitude for a given IAS is

• unchanged with altitude.
• higher.
• lower.

Ignoring any small fin offset, the vertical fin of a single engined aircraft is

• parallel with both the longitudinal axis and vertical axis.
• parallel with the longitudinal axis but not the vertical axis.
• parallel with the vertical axis but not the longitudinal axis.

With an increase in the amount of flap deployment, the stalling angle of a wing

• remains the same.
• increases.
• decreases.

Power-off stall versus power-on stall:

• Power-on stalling speed is higher because the propeller slipstream increases the effective airspeed over the wing
• Power-on stalling speed is lower because the vertical component of thrust helps support the aircraft weight, reducing the lift requirement
• Power setting has no aerodynamic effect on the stalling speed regardless of engine type or thrust line orientation

Longitudinal dihedral (decalage) is:

• The angle of sweepback between the wing leading edge and a line perpendicular to the fuselage centreline
• The upward angle of the wings relative to the horizontal, which provides lateral roll stability in a sideslip
• The difference in angle of incidence between the wing and the tailplane - it contributes to longitudinal stability

An aircraft flying above the tropopause descends at a constant True Airspeed, its Mach No. will

• remain the same.
• decrease steadily.
• increase at a constant rate.

With an increase in the amount of flap deployment, the stalling angle of a wing

• remains the same.
• increases.
• decreases.

Stall commencing at the root is preferred because

• it provides the pilot with a warning of complete loss of lift.
• it provides a clear aerodynamic warning of the approaching loss of aileron effectiveness.
• it will cause the aircraft to pitch nose up before the outer wing sections lose their lift.

Induced Drag is

• never equal to profile drag.
• equal to profile drag at Vmd.
• equal to profile drag at stalling angle.

A centre of gravity position close to its aft limit will cause the aircraft to

• pitch nose down and increase its longitudinal stability.
• pitch nose up and decrease its longitudinal stability.
• pitch nose up and increase its longitudinal stability.

During flight, an aircraft is yawing to the right. The aircraft would have a tendency to fly

• right wing low.
• left wing low.
• nose up attitude.

In straight and level flight, the angle of attack of a swept wing is

• less than the aircraft angle to the horizontal.
• more than the aircraft angle to the horizontal.
• the same as the aircraft angle to the horizontal.

Extending a leading edge slat will have what effect on the effective angle of attack seen by the main wing at a given lift?

• Increase the angle of attack.
• Decrease the angle of attack.
• No effect on angle of attack.

What is the main purpose of a frise aileron?

• Increase drag on the up going aileron.
• Decrease drag on the up going wing surface.
• Help the pilot overcome aerodynamic hinge loads.

Mach trim operates

• in the longitudinal (pitch) sense.
• in the lateral (roll) sense.
• to reduce Dutch roll oscillations.