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Flashcards in Wing and Control Theory Deck (88)
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Define sweepback

The angle at which wings are slanted from root to rip


Describe the pendulum effect

A rolling effect resulting from sideforce-generating surfaces being above or below the centre of mass in an aircraft


How does an aircraft move during a slip?

The aircraft is moving somewhat sideways as well as forward relative to the oncoming airflow


How can the four forces be manipulated to maximize performance?

Increase lift, increase thrust, reduce weight, reduce drag


Describe streamlining

Contouring an airfoil to reduce it's drag (increasing laminar flow and decreasing turbulent flow)


Describe what happens to the four forces when frost, snow, or ice is present on an aircraft. What is the related concept called?

Clean wing concept


Describe how drag affects performance


What is fairing?

A structure that produces a smooth outline along the surface of an aircraft to reduce drag


What are three ways of maximizing performance by reducing parasitic drag?

Streamlining, fairing, and the clean wing concept


When would you expect the most induced drag?

When lots of lift is being created at low speeds (heavy aircraft, high angle of attack, clean configuration)


Describe the ground effect

Reduction in induced drag occurs at the wing tips when an aircraft is in close promiximity to the ground. This increases lift


Describe the range and endurance curves


What increases every time you increase lift?

Induced drag


What is the relationship between the speed of the root and tip of a propeller?

The tip travels faster than the root


Why are propellers twisted?

The root has a greater angle of attack than the tip to balance the difference in speed, so propellers are twisted to maintain the same angle of attack at each radius location


Define pitch and describe the two different types

Pitch - angle of the propeller blade

Coarse pitch - high angle of attack, good for fast cruise yet sluggish in climb

Fine pitch - low angle of attack, great for climbing yet has slow cruising speed


Define fixed pitch

Angle of attack is set at installation and cannot be changed during aircraft operation


Define adjustable pitch

Pitch can be changed on the ground


Define variable pitch

Pitch can be changed from the cockpit in flight


Define constant speed pitch

Propeller rpm is selected and pitch is automatically adjusted by various mechanisms in order to maintain it


Compare what happens when oil pressure is lost in hydromatic and counterweighted constant speed propellers

Hydromatic: blades fail to the maximum rpm (fine) pitch position

Counterweighted: blades fail to the coarse pitch or feathered position


Define adverse yaw. What causes it?

The natural tendency for an aircraft to yaw in the opposite direction of a roll. It is caused by the difference in the lift and drag of each wing


Name the four causes of adverse yaw

Slipstream, asymmetric thrust, torque, gyroscopic effect


Name 3 design solutions to counter adverse yaw

Rudder offset, different washout, engine offset


When should you expect to use more right rudder?

At a high RPM and low speeds (accelerating or takeoff, in a climb, or in slow flight)


What wing properties do ailerons manipulate?

The effective camber, the effective chord, and the angle of attack


How do ailerons affect lift?

Raised aileron reduces lift, lowered aileron increases lift


What happens to the motion of an aircraft when the left aileron drops and the right aileron rises?

The left wing rises, the right wing lowers, and the aircraft rolls right


What happens when elevators produce lift on top?

The tail rises and the aircraft pitches nose down


What happens if the rudder produces lift the the right?

The tail is drawn to the right and the aircraft yaws left