Chapter 2 Aerodynamics Flashcards
The four forces acting on an airplane are
Lift, weight, thrust, drag
When are the four forces that act on an airplane in equilibrium?
During unaccelerated flight
Airplanes climb because of
Excess thrust
Lift acts at a ___ degree angle to the relative wind
90
The minimum forward speed of the airplane is called the ____ speed
Stall
You can determine the proper climb attitude for your airplane by referring to the
Airspeed indicator
The chord line is an imaginary line connecting the
Leading edge of the wing with the trailing edge
The chord line is used to represent
The general shape of the wing
The definition of chord enables us to understand
The angle the wind meets a wing that may vary in size and shape
Relative wind results from the motion of the
Airplane through the air
Relative wind is ___ and ___ to the airplanes motion.
Opposite to, equal
Relative wind is ___ which way the airplane’s nose is pointed.
Independent of
The term “angle of attack” is defined as the angle
Between the wing chord line and the relative wind
An important principle to understand when dealing with angle of attack is that the nose (therefore the wing) can be pointed on an incline that’s ___ the actual climb path.
Different from
Wings are expressly built to plow through air molecules separating them either above or below while offering little resistance in the ___ direction
Horizontal
Wind deflected downward by the airfoil creates a/an ___ movement of the wing.
Upward
Bernoulli figured out that the faster the air flows over a surface, the ___ pressure it exerts on that surface
Less
Air flowing faster over a curved surface causes a slight ___ in pressure on that surface
Decrease
High velocity airflow over the wing causes a slight decrease in pressure on the wing’s upper surface. In other words, the pressure on ___ the wing is now ___ than the pressure on bottom of the wing.
Top, less
Since high pressure always moves toward low pressure, the wing ( which just happens to be in the way) is pushed ___ in the process.
Upward
Because of the wing’s shape, even at a very small angle of attack, a cambered wing will adds a slight curve and ___ to the wind.
Acceleration
At a relatively slow speed ( such as during takeoff), the wing’s engineered curve isn’t capable of curving or deflecting enough air ___ the produce the necessary lift for flight.
Downward
Raising the nose slightly increases the angle of attack which forces the air to undergo an additional ___ greater than that which the ___ of the airfoil can produce.
Curve, engineered shape
An increased angle of attack permits the airplane to produce the necessary lift for flight at a ___ airspeed.
Slower
As the angle of attack increases, an airplane can fly at a ___ speed and still develop the necessary lift for flight.
Slower
As the angle of attack exceeds approximately 18 degrees the air molecules flowing over the wing don’t negotiate the turn very well. When this happens, they spin off or burble into the free air, no longer providing a uniform, high-velocity, laminar airflow over the wing. The wing ___
Stalls
When the critical angle of attack is exceeded, the airplane will
Stall
All wings have what?
a critical angle of attack
If the wing stalls, you need to do one very important thing:
Reduce the angle of attack to less than its critical value
You can unstall a wing by ___ the angle of attack
Reducing
You should realize that an airplane can be ___ at any attitude or any airspeed
Stalled
Whether an airplane exceeds its critical angle of attack is independent of…
attitude or airspeed
If an airplane stalls, the first step in recovering is to decrease the angle of attack by moving the elevator control ___ or releasing ___ on the elevator control
forward, back pressure
Once the airplane is no longer stalled it should be put back in the desired attitude while making sure you don’t ___ again
Stall
Which of the following may indicate the onset of a stall?
Stall horn sounding, diminished control response, noticeable buffet
When the weight of an airplane is increased, the airplane stalls at ___ indicated speed.
a higher
An increase in weight (apparent or real) means the wings must develop more ___ to remain airborne
lift
The critical angle of attack at which the wing stalls ___
Never changes, regardless of airplane weight
The angle of attack at which an airplane wing stalls will ___
remain the same regardless of gross weight
Increasing the airplane’s weight will not affect the ___ of attack at which the airplane stalls
Angle
Which basic flight maneuver increases the load factor on an airplane as compared to straight-and-level flight?
A turn
If the airplane “feels” twice as heavy as it actually is, then the lift must ___ if the airplane is to maintain altitude.
double
An increased load factor will cause the airplane to
Stall at a higher airspeed
When the bank increases, the nose wants to ___
Pitch down, which results in the pilot pulling on the elevator to maintain altitude, causing an increased angle of attack
Why is it important for a pilot to be especially sensitive to the amount of G-force he or she is experiencing while maneuvering the airplane?
Increasing G-force always means an increase in stall speed
What are the most important parts of your anatomy for avoiding stalls?
Your brain, for planning to avoid steep turns near the ground and your butt for sensing G-force which helps alert you to an increase in stall speed
Drag is the airplane’s natural response to an object’s movement through the ___
Air
Wings are designed to deflect air ___ while offering very little ___ resistance
Vertically, Horizontal
The two basic forms of drag are:
Parasite and induced drag
Parasite drag is the result of
Friction
As airspeed doubles, parasite drag ___
Quadruples
Induced drag is resistance to motion induced by the wing turning some of its ___ into ___
Lift, Drag
As the airplane speeds up, induced drag ___ while parasite drag
Decreases, Increases
When induced and parasite drag curves are added together, they produce the ___ curve
Total Drag
The lowest spot in the total drag curve is your magic number, a specific airspeed known as the
Best L/D speed
The sum of the parasite and induced drag curves reveals a point on the total drag curve where drag is at a minimum. the speed associated with this point is
The airplane’s maximum power-off glide range
The most important rule to remember int he event of a power failure after becoming airborne is to
Immediately establish the proper gliding attitude and airspeed
In a power-off glide, the best L/D speed allows the airplane to glide a ___ forward distance with a ___ amount of altitude loss
Maximum, minimum
Gound effect allows an airplane flying close to the runway to become or remain airborne at a slightly ___ speed
Lower-than-normal
High pressure on the botoom of the wing causes air molecules to move sideways (toward the wingtip) in the direction of ___ pressure on top of the wing. This action is responsible for the creation of ___
Lower, wingtip vortices
Wing tip vortices rotate which way about the wingtip?
Outward, upward and inward
Wingtip vortex action increases with an increase in
Angle of attack
The wingtip vortex not only spirals around the wingtip, it also adds a/an ___ to the air behind and along the wing’s span
Downward flow
AT higher angles of attack the downward bending of the relative wind in the vicinity of the wing changes the direct of the ___ wind. This newly bent relative wind is often called the ___ relative wind.
Relative, Local
Recalling that effective lift always acts ___ to the relative wind, when the angle of attack increases, the total lift force tilts ___ slightly.
Perpendicular, rearward
Floating caused by the phenomenon of ground effect will be most realized during an approach to land when at
less than the length of the wingspan above the surface
Ground effect results from a/an ___ in induced drag
Decrease
Ground effect is most likely to result in which situation?
Becoming airborne before reaching recommended takeoff speed
When operating in ground effect what happens to induced drag?
Induced drag decreases; therefore, any excess speed at the point of flare may cause considerable floating
If you’re approaching at a speed above the normal approach speed, make it a point to ___ before entering ground effect to prevent an excessive landing roll.
Slow down
What causes an airplane (except a T-tail) to pitch nose down when power is reduced and controls are not adjusted?
The downwash on the elevators from the propeller slipstream is reduced and elevator effectiveness is reduced.
As the airplane become airborne and flies out of ground effect, the wing’s downwash…
Increases
It’s possible, when attempting to climb out of ground effect, to become airborne without sufficient climb speed, then attempt to climb and have the nose ___ slightly
pitch up
During landing, as the airplane enters ground effect and the downwash diminishes, the nose tends to pitch…
Downward
Low wing airplanes experience ___ ground effect than their high wing cousins
More
Extending or retracting flaps changes the wing’s ___ and ___ characteristics.
Lift, drag
Lowering flaps lowers the trailing edge of the wing, ___ the angle the chord line makes with the relative wind. This increases the wing’s lift.
Increasing
When the flaps are lowered, the lowered trailing edge ___ the curvature on part of the wing, resulting in increased air velocity over the wing’s upper surface.
Increases
Because of the larger angle of attack and greater curvature, flaps provide you with ___ lift for a given airspeed
More
What’s the reason for putting flaps on airplanes
To create the lift necessary to maintain flight at slower airspeeds
If the wind is gusty, you might use ___ flap extension than in non-gusty conditions.
Less
The beginning of the white arc is known as the…
Power-off, full-flap stalling speed
What is one purpose of wing flaps?
To enable the pilot to make steeper approaches to a landing without increasing the airspeed
One of the main functions of flaps during approach and landing is to…
Increase the angle of descent without increasing the airspeed
What force makes and airplane turn?
The horizontal component of lift
Tilting the total lift force while in a turn means ___ lift is available to act vertically against the airplane’s weight.
Less
Which axis runs through the center line of the airplane form nose to tail?
Longitudinal
Airplanes roll about what axis?
The Longitudinal axis
Which axis runs from wing tip to wing tip, sideways
lateral axis
Airplanes ___ about their lateral axix
Pitch
The purpose of ailerons is to ___ the airplane in the direction you desire to turn
Bank
Ailerons function to allow the right and left wings to develop ___ lift
different amounts of
When the control wheel (or stick) is turned to the right or left, the ailerons simultaneously move in ___.
different directions
Adverse yaw is
an undesirable byproduct of turning.
What is the purpose of the rudder on an airplane?
To control Yaw
Not using the rudder during a turn will result in ___ turn
An uncoordinated
As the airplane slows down and enters a stall, which of the following three control surfaces is the last to lose control authority?
Rudder
Applying forward pressure on the control wheel (or stick) deflects the elevator ___ causing the tail to ___.
Downward, rise
The purpose of the trim tab is to ___ control pressure required of the pilot
eliminate
Which direction does the trim tab move relative to the primary control surface it affects?
Opposite
In what flight condition is torque effect the greatest in a single-engine airplane?
Low airspeed, high power
The left turning tendency of an airplane caused by P-factor is the result of the …
Propeller blade descending on the right producing more thrust than the ascending blade on the left
P-factor is more likely to cause the airplane to yaw to the left…
at high angles of attack
In what flight condition must an aircraft be placed in order to spin?
Stalled
During a spin to the left, which wing(s) is/are stalled?
Both wings are stalled
A typical situation that often results in a spin occurs when …
A pilot overshoots the turn to the final approach and applies rudder to align the nose with the runway while holding the bank angle constant with aileron.
Parasite drag is caused by …
friction of protruding airplane parts with the air
Generally speaking, parasite drag
is a result of the design of an airplane and there is little the pilot can do to reduce it
As an airplane’s airspeed doubles, parasite drag…
Quadruples
Induced drag is
the rearward pull of the total lifting force.
At small angles of attack induced drag is at its highest or lowest point?
lowest
If you are trying to reach a destination on limited fuel…
Fly at the airplane’s maximum range speed
A good reason to use maximum endurance speed is..
to minimize fuel consumption, e.g., while waiting for the weather to clear
The maximum endurance speed is always ___ the maximum range speed
less than
in the “region of reversed command,” slower level flight requires…
more power
To maintain an airplane’s best L/D (lift over drag ratio), a decrease in weight requires
A decrease in airspeed
You can determine an airplane’s best glide speed
by referring to the POH or the owner’s manual.
To prevent structural damage to the airplane during turbulence,
Maintain flight at or below the airplane’s design maneuvering speed.
Which V-speed represents maneuvering speed?
Va
With respect to the certification of aircraft, which are categories of aircraft?
Normal, Utility, Acrobatic
The amount of excess load that can be imposed on the wing of an airplane depends upon the…
Speed of the airplane
When the airplane’s weight decreases, the maneuvering speed…
decreases
What is an important airspeed limitation that is not color coded on airspeed indicators?
Maneuvering speed
Upon encountering severe turbulence, which flight condition should the pilot attempt to maintain?
Level flight attitude
How will frost on the wings of an airplane affect takeoff performance?
Frost will disrupt the smooth flow of air over the wing adversely affecting its lifting capability.
Why is frost considered hazardous to flight?
Frost spoils the smooth flow of air over the wings, thereby decreasing lifting capability.
How does frost affect the lifting surfaces of an airplane on takeoff?
Frost may prevent the airplane from becoming airborne at normal takeoff speed.
Frost on the airfoil ___ the airplane’s stalling speed
Increases
