Principles of Flight and Aerodynamics Flashcards
7 cards from real ATPL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Principles of Flight and Aerodynamics flashcards as text
The critical Mach number is defined as the free-stream Mach number at which:
Answer: Sonic airflow first appears somewhere on the aircraft
The critical Mach number is the free-stream speed at which local airflow first reaches Mach 1.0 on the aircraft — typically over the upper wing surface at its thickest point.
Mach tuck (tuck-under) experienced in transonic flight is primarily caused by:
Answer: Rearward shift of the center of pressure due to shock wave formation
As Mach number increases into the transonic range, shock wave formation causes a rearward migration of the center of pressure, generating a strong nose-down pitching moment.
Vortex generators are small devices attached to wing surfaces primarily to:
Answer: Re-energize the boundary layer to delay flow separation
Vortex generators mix high-energy free-stream air with the slower boundary layer, increasing its momentum and delaying separation to higher angles of attack.
When operating in ground effect, an aircraft experiences:
Answer: Decreased induced drag and increased effective lift for the same AOA
Ground effect suppresses wingtip vortex formation, reducing induced drag and the downwash angle, which effectively increases the lift curve slope and produces more lift for the same AOA.
The load factor (n) is defined as the ratio of:
Answer: Total aerodynamic lift to aircraft weight
Load factor n = Lift / Weight and represents the number of 'g's the structure experiences; in straight-and-level unaccelerated flight n = 1.0.
The design maneuvering speed (Va) is defined as:
Answer: Maximum speed at which full deflection of a single primary control will not overstress the airframe
At Va, the aircraft will reach the limit load factor via a stall before structural limits are exceeded with full single control deflection — above Va, full inputs can cause structural failure.
Wing sweep on jet transport aircraft primarily benefits cruise performance because it:
Answer: Raises the critical Mach number by reducing the velocity component perpendicular to the leading edge
Swept wings effectively increase the critical Mach number because only the velocity component normal to the leading edge governs compressibility effects, allowing higher cruise Mach numbers.