Principles of Flight Flashcards
What is the name for the initial tendency of an aircraft to develop forces that further remove the aircraft from its original position when disturbed from a condition of steady flight?
Negative static stability
During the entry to a right turn, the nose of the aircraft swings to the left before it follows into the right turn. What kind of turn entry is this and how is it corrected?
This is a slipping turn, which is corrected by more right rudder pressure as the turn is initiated.
What is the name for the initial tendency of an aircraft to develop forces that return the aircraft from its original position when disturbed from a condition of steady flight?
Positive static stability
What kind of oscillations are the result of negative dynamic stability and positive static stability in an aircraft?
divergent oscillations
What kind of oscillations are the result of positive dynamic stability and positive static stability in an aircraft?
convergent oscillations
What is it called when the aircraft experiences airspeed increases and decreases as it works to maintain a constant angle of attack for a given trim?
Phugoid Oscillations
What happens to the vertical component of lift and the sink rate as the angle of bank is increased?
The vertical component of lift decreases and sink rate increases.
What is the purpose of wing dihedral angle?
To increase lateral stability.
During flight with zero angle of attack what can be said about the pressure along the upper surface of the wing?
It is less than atmospheric pressure.
Which is the critical engine on most light multi engine planes with clockwise rotating propellers?
The left engine, because the resultant thrust (due to p-factor) of the running right engine acts with a much greater arm and creates stronger yaw to the left.
If the center of gravity of an aircraft is moved from the aft limit to beyond the forward limit, how will it affect the cruising and stalling speed? Why?
The cruising speed will decrease in the stalling speed will increase. The tail has to generate more downward force to balance the heavier nose and the wings must fly at a higher angle of attack to produce more lift to counteract that force.
Why do you roll level before recovering from a nose low unusual attitude?
To minimize the increased load factor to just what is needed to raise the nose. Also, to avoid tightening a spiral dive.
Why don’t you roll level before recovering from a nose high unusual attitude?
The additional horizontal component of lift helps reduce negative forces on the airframe in the pushover.
How is stall speed related to load factor?
Stall speed increases in proportion to the load factor.
What kind of oscillations are the result of neutral dynamic stability and positive static stability in an aircraft?
continuous oscillations
What kind of a turn produces more centrifugal force than banking force?
A skidding turn.
Which wing drops when a cross controlled stall or skidding turn becomes a spin? Why?
The inside wing drops because it is more stalled due to being at a higher angle of attack, blanketed by the fuselage and subject to spanwise flow that further reduces lift.
Which wing drops when a slipping turn progresses to a stall? Why?
In a slipping turn, the outside wing is at a higher angle of attack somewhat blanketed by the fuselage, so it stalls first.
Explain a slipping turn.
In a slipping turn, not enough rudder is used to counter the adverse yaw created by the lowered elevator and as a result the rate of turn is less than required for the angle of bank. The ball is on the inside of the turn because the centriputal force is greater than the centrifugal force.
What is a coordinated turn?
A coordinated turn is one in which the rate of turn is matched to the bank angle, which causes the nose of the aircraft to be directly into the relative wind throughout the turn.
How does the inclinometer in a turn coordinator work?
In a coordinated turn, the centripital force (horizontal component of lift) and the centrifugal force are equal which holds the ball balanced in the middle opposite the lift vector. In a slipping turn, the centripital force is greater than the centrifugal force, which pulls the ball to the inside of the turn. In a skidding turn, the centrifugal force is greater than the centripital force, which pulls the ball to the outside of the turn.
What are the forces of flight?
Lift, weight, thrust and drag.
What is lift?
Lift is the force that acts upward, perpendicular to the relative wind as a result of airflow passing over the wing.
What is drag?
Drag is the force that opposes thust. It is generated by the resistance of the aircraft and its parts moving through the air.
What is unaccelerated flight?
When lift equals weight and thrust equals drag, the aircraft is in steady flight.
What are factors that increase the stall speed?
Increased load factor
Banking
Increased weight
Forward CG loading
Icing
What are factors that decrease stall speed?
Flaps
Aft CG
Decreasing the weight does what to the stalling speed?
The 1G stalling speed is decreased.
Where is the center of lift located?
On training aircraft, aft of the center of gravity, at the theoretical point where all the lifting force is assumed to be concentrated.
Angle of Attack is the angle between the wing’s ___________ and the __________.
Chord Line, Relative Wind
In straight-and-level, unaccelerated flight, the sum of opposing forces acting on the aircraft is always ___.
Zero
If you load an aircraft tail-heavy, the center of gravity (CG) will be aft and the nose will more easily pitch ___ than if it were in a forward loading configuration.
Upward
What is ground effect and how does it affect the aircraft?
Ground effect is the range from the ground to 1/2 wingspan height in which induced drag is greatly reduced. It occurs because the wingtip vortices and downwash have something to push directly against.
What happens to induced drag and parasite drag as your true airspeed increases?
As you accelerate and your true airspeed increases, the amount of parasite drag will rise exponentially due to increased aircraft interference with the air. However, induced drag decreases because you need a lower angle-of-attack in order to maintain a desired altitude at a higher true airspeed.
What are the components of parasite drag?
Skin Friction Drag - caused by everything that is not perfectly smooth about the airplane’s surface
Form Drag - caused by the vertical cross section of the airpane
Interference Drag - caused by mixing airflows at right angles
What are the components of total drag?
Parasite drag - increases as the square of the true airspeed
Induced drag - increases with angle of attack and therefore decreases as true airspeed increases
As an aircraft’s weight increases, its maneuvering speed (Va) ______.
Increases.
Because a heavy aircraft flies at a higher angle of attack, it will reach the critical angle of attack sooner when a full control input is placed on the aircraft. Because of that, Va increases as the aircraft’s weight increases.
As CG moves further aft, what happens to stability?
Less stable
What is the load factor of an aircraft in a constant altitude, 60 degree bank turn?
2.0 G
