Aircraft Systems and Aerodynamics Flashcards

In an aircraft's electrical system, what is the purpose of a bus bar?

Answer: To act as a common distribution point connecting power sources to multiple electrical circuits

A bus bar is a conductor that serves as a central distribution point, connecting one or more power sources to multiple electrical loads throughout the aircraft.

What causes 'compressor stall' in a turbine engine?

Answer: Disruption of smooth airflow through the compressor stages, causing one or more stages to stall aerodynamically

Compressor stall occurs when compressor blade angle of attack exceeds the critical angle, disrupting airflow through the compressor and causing a sudden loss of compression with possible bangs and thrust loss.

What does the term 'sweepback' on a wing design primarily provide?

Answer: Delayed onset of compressibility effects by reducing the component of airflow perpendicular to the leading edge

Wing sweepback effectively reduces the Mach number component perpendicular to the leading edge, delaying the onset of wave drag and allowing higher cruise speeds before critical Mach is reached.

What is the purpose of a 'squat switch' (weight-on-wheels switch) in aircraft systems?

Answer: To sense whether the aircraft is on the ground and enable or inhibit certain systems accordingly

Squat switches sense ground contact through compression of the landing gear oleo struts, enabling ground-only systems and inhibiting air-only systems to prevent inadvertent operation.

What is 'dihedral effect' in aircraft lateral stability?

Answer: A restoring roll moment that returns the aircraft toward wings-level when it slips sideways

Dihedral effect produces a restoring roll moment when the aircraft sideslips; the lower wing presents a higher angle of attack to the relative wind, generating more lift and rolling the aircraft back level.

In the context of piston engines, what is 'detonation'?

Answer: Uncontrolled, explosive combustion of the fuel-air mixture in the cylinder ahead of the flame front

Detonation is spontaneous, uncontrolled ignition of the end-gas in the cylinder ahead of the advancing flame front, creating pressure spikes that can damage pistons, rings, and cylinder heads.

What is the primary advantage of a constant-speed propeller over a fixed-pitch propeller?

Answer: It maintains an optimal blade pitch angle to match engine RPM to changing flight conditions, maximizing efficiency

A constant-speed propeller uses a governor to automatically vary blade pitch, keeping engine RPM constant and allowing the propeller to operate at its most efficient angle throughout the flight envelope.