Aircraft Performance & Limitations Flashcards
What causes a spin?
A spin is an aggravated stall that typically occurs from a full stall occurring with the airplane in a yawed state and results in the airplane following a downward corkscrew path.
As the airplane rotates around a vertical axis, the outboard wing is less stalled than the inboard wing, which creates a rolling, yawing, and pitching motion.
The rotation results from an unequal AOA on the airplane’s wings. The less-stalled rising wing has a decreasing AOA, where the relative lift increases and the drag decreases. Meanwhile, the descending wing has an increasing AOA, which results in decreasing relative lift and increasing drag.
What conditions are required for a spin to develop?
When the airplane’s wings exceed the critical AOA (stall) with a sideslip or yaw acting on the airplane, or beyond the stall.
Density altitude vs takeoffs and landings
Increased DA = greater takeoff speed, decreased thrust, and reduced net accelerating force resulting in a longer takeoff roll
Increased DA = increases the true airspeed of the airplane during final approach (while holding the same indicated airspeed) and increases the distance required to stop.
Explain ground effect.
When an aircraft in flight comes within several feet of the surface, ground or water, a change occurs in the flow pattern around the aircraft because the vertical component of the airflow around the wing is restricted by the surface.
This alters the wing’s upwash, downwash, and wingtip vortices. Ground effect, then, is due to the interference of the ground (or water) surface with the airflow patterns about the aircraft in flight.
The result is less drag and more lift.
What is meant by normal, utility, and aerobatic category?
The categories define the envelope an airplane is designed to operate in. Maximum safe load factors and permitted maneuvers change based upon which category your aircraft is operating in.
What 4 factors change air density?
Temperature, altitude, humidity, barometric pressure.
Define Va Maneuvering Speed
The maximum speed at which the structural design’s limit load can be imposed (either by gusts or full deflection of the control surfaces) without causing structural damage.
What is torque reacation?
Torque reaction involves Newton’s Third Law of Physics— for every action, there is an equal and opposite reaction.
this means that as the internal engine parts and propeller are revolving in one direction, an equal force is trying to rotate the aircraft in the opposite direction. (left turning tendency)
What is the definition of absolute ceiling, as it relates to aircraft performance?
At the absolute ceiling, there is no excess of power and the airplane can no longer climb.
What are the four phases of a spin and recovery?
Entry, incipient, developed, and recovery.
entry phase: the pilot intentionally or accidentally provides the necessary elements for the spin
incipient phase: transition from stall to full spin. Occurs from the time the airplane stalls and starts rotating until the spin has fully developed
Developed: you’re spinning now, please recover.
Recovery: PARE - power idle, ailerons neutral, full opposite rudder, elevator (nose) down, eventually transition to full power and a climb attitude
Explain adverse yaw
Adverse yaw is created when the ailerons are deflected and the airplane begins to bank. Since the downward DEFLECTED aileron produces more lift as evidenced by the wing RISING, it also produces more drag. This added drag causes the wing to slow down slightly. This results in the aircraft yawing toward the wing which had experienced an increase in lift (and drag). From the pilot’s perspective, the yaw is opposite the direction of the bank. The adverse yaw is a result of differential drag and the slight difference in the velocity of the left and right wings.
Why does humidity degrade performance?
Humidity will reduce performance because the presence of water content makes the air less dense.
What performance aspects does air density affect?
Air density has a direct effect on: lift produced by the wings, power output of the engine, propeller efficiency, and drag forces.
What are the effects of flying with a forward CG?
Higher stall speed, higher elevator control forces, slower cruise speed, more stable, nose heavy.
Define true airspeed
True airspeed is calibrated airspeed corrected for altitude and nonstandard temperature. Because air density decreases with an increase in altitude, an aircraft has to be flown faster at higher altitudes to cause the same pressure difference between pitot impact pressure and static pressure.
