Aerodynamics Flashcards

What is the primary force that opposes the weight of an unmanned aircraft in flight?

Answer: Lift

In flight, the primary force that directly opposes the weight of an unmanned aircraft is lift. Lift is an aerodynamic force generated by the movement of air over the aircraft's wings or rotors, creating a pressure differential that pushes the aircraft upwards. This upward force is essential for keeping the aircraft airborne against the pull of gravity.

How does increasing the angle of attack affect the lift generated by an unmanned aircraft's wing?

Answer: It increases lift up to a certain point

Increasing the angle of attack, which is the angle between the wing's chord line and the oncoming air, generally increases the amount of lift generated by an unmanned aircraft's wing. This is due to greater air deflection downwards, creating more upward force. However, this increase in lift is only effective up to a certain point, known as the critical angle of attack, beyond which a stall occurs.

What is the term for the point at which the airflow over an unmanned aircraft's wing becomes turbulent and separates from the surface, causing a sudden loss of lift?

Answer: Critical angle of attack

The critical angle of attack is the specific point at which the airflow over an unmanned aircraft's wing can no longer remain smooth and attached to the surface. Beyond this angle, the airflow separates and becomes turbulent, leading to a sudden and significant loss of lift, a condition known as a stall. Understanding this is crucial for preventing dangerous flight conditions.

In unmanned aircraft, what effect does an increase in airspeed have on the dynamic pressure exerted on the wings?

Answer: It increases dynamic pressure

In unmanned aircraft, an increase in airspeed directly leads to an increase in the dynamic pressure exerted on the wings. Dynamic pressure is a measure of the kinetic energy of the air flowing around the aircraft. Higher airspeed means faster airflow, which in turn generates greater dynamic pressure, a key factor in producing more lift.

What aerodynamic principle explains the lift generation due to the pressure difference above and below an unmanned aircraft's wing?

Answer: Bernoulli's principle

Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy. For an aircraft wing, the curved upper surface causes air to travel faster over it than the flatter lower surface, resulting in lower pressure above the wing and higher pressure below. This pressure difference generates the upward force known as lift.