ATPL Principles of Flight and Aerodynamics 3

Question 1

The critical Mach number is defined as the free-stream Mach number at which:

Accepted Answer

Sonic airflow first appears somewhere on the aircraft

Answer

The aircraft achieves fully supersonic flight

Answer

Wave drag begins to decrease after its transonic peak

Answer

Mach tuck becomes uncontrollable

Question 2

Mach tuck (tuck-under) experienced in transonic flight is primarily caused by:

Accepted Answer

Rearward shift of the center of pressure due to shock wave formation

Answer

Loss of elevator control effectiveness at high speed

Answer

Increased induced drag from shock-induced separated flow

Answer

Compressor surge in the jet engine intake

Question 3

Vortex generators are small devices attached to wing surfaces primarily to:

Accepted Answer

Re-energize the boundary layer to delay flow separation

Answer

Reduce parasite drag at cruise speeds

Answer

Generate additional lift by creating vortex lift

Answer

Reduce wingtip vortex-induced drag

Question 4

When operating in ground effect, an aircraft experiences:

Accepted Answer

Decreased induced drag and increased effective lift for the same AOA

Answer

Increased induced drag and decreased lift

Answer

Increased parasite drag and a higher stall speed

Answer

No aerodynamic change until within one wingspan of the surface

Question 5

The load factor (n) is defined as the ratio of:

Accepted Answer

Total aerodynamic lift to aircraft weight

Answer

Aircraft weight to total aerodynamic lift

Answer

Engine thrust to total aircraft drag

Answer

Wing lift area to total gross weight

Question 6

The design maneuvering speed (Va) is defined as:

Accepted Answer

Maximum speed at which full deflection of a single primary control will not overstress the airframe

Answer

Maximum speed for flight in severe turbulence

Answer

Best glide speed in no-wind conditions

Answer

Maximum structural cruising speed (Vno)

Question 7

Wing sweep on jet transport aircraft primarily benefits cruise performance because it:

Accepted Answer

Raises the critical Mach number by reducing the velocity component perpendicular to the leading edge

Answer

Increases maximum lift coefficient at low speeds

Answer

Reduces span loading and therefore induced drag at cruise

Answer

Improves lateral stability and low-speed handling