Aerodynamic Forces - PPE
the load factor in a turn of 60 degrees is
2.00 Gs
In steady unaccelerated flight, lift equals ________.
Lift equals weight (because the sum of these opposing forces is always zero)
a standard-rate turn is defined as:
a turn rate of 3 degrees per second (the turn coordinator indicates only the rate and direction of turn; it doesn't display a specific angle of bank)
changes in the center of pressure of a wing affect the aircraft's
aerodynamic balance and controllability
which statement relates to Bernoulli's principle?
air traveling faster over the curved upper surfaced of an airfoil causes lower pressure on the top surface (so the pressure on top is lower than the pressure on bottom)
induced drag increases with:
an increase in the angle of attack (a higher AOA creates more lift and thus induced drag increases)
the load factor on any airplane during a constant altitude turn is determined by:
bank alone (at a constant altitude, during a coordinated turn in any aircraft, the load factor is the result of 2 forces: centrifugal force and weight caused by the degree of bank)
the therm "angle of attack" is defined as the angle between the:
chord line of the wing and the relative wind
induced drag increases when airspeed is:
decreased (the slower you're moving, the less lift you produce, thus lowering lift and lowering induced drag)
when are the four forces that act on an airplane in equilibrium?
during unaccelerated/steady flight
an aircraft leaving ground effect during takeoff will
experience an increase in induced drag and a decrease in performance if the thrust is unchanged
skin friction drag can be somewhat reduced by:
flush riveting, smooth paint, and waxing (removing any irregularities that may protrude above the wing surface)
which statement is most correct regarding form drag?
form drag increases as airspeed increases
parasite drag increases when airspeed is:
increased (the faster the airplane moves through the air, the greater the parasite drag)
the load factor on an airplane increases with
increases in weight, steep turns, and abrupt changes in airplane attidue
what is the relationship of lift, drag, thrust, and weight when the airplane is in straight-and-level flight?
lift = weight; thrust = drag
the four forces acting on an airplane in flight are
lift, weight, thrust, and drag (lift opposed weight, thrust opposes drag)
in what flight condition is torque effect the greatest in a single-engine airplane?
low airspeed, high power, high AOA
drag is produced by:
moving the airplane through the air (drag is the force that resists movement of an aircraft through the air)
the movement of the air effects the speed at which aircraft move
over the Earth's surface
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 (asymmetric propeller loading or P-factor occurs when the airplane is at a high angle of attack)
an airplane said to be inherently stable will
require less effort to control (it will tend to return to the original condition of flight if disturbed by a force such as turbulent air)
in straight-and-level flight, if thrust exceeds drag, then:
speed increases
the amount of excess load that can be imposed on the wing of an airplane depends upon the
speed of the airplane (at slow speeds, the maximum available lifting force of the wing is decreased - the wing will stall at lower excess loads and relieve the load)
what are the four flight fundamentals involved in maneuvering an aircraft?
straight-and-level flight, turns, climbs, and descents
angle of attack (AOA)
the acute angle between the wing chord line and the direction of the relative wind
when an aircraft is flying at a high AOA, the downward moving blade of the propeller has a higher resultant velocity, creating more lift than the upward moving blade causing:
the airplane's nose to pull (yaw) to the left
what causes an airplane (except a T-tail) to pitch nose down when power is reduced and controls aren't adjusted?
the down-wash on the elevators from the propeller slipstream is reduced and elevator effectiveness is reduced
what is parasite drag?
the drag caused by fuselage and other protrusions disrupting the flow of air (is comprised of all the forces that work to slow an aircraft's movement)
what force makes an airplane turn?
the horizontal component of lift (as an aircraft turns, lift becomes the result of two components: vertical lift which opposes gravity and horizontal lift which opposes inertia)
what is the critical AOA?
the point at which the wing will stall
what is form drag
the portion of parasite drag generated by the aircraft due to its shape and airflow around it, and increases with velocity
what is induced drag?
the rearward retarding force caused by the wings creating lift (it's inherent whenever an airfoil is producing lift and, is inseparable from the production of lift - aka it's always present if lift is produced)
which basic flight maneuver increases the load factor on an airplane as compared to straight-and-level flight?
turns (additional lift must be generated as the total lift becomes divided between horizontal and vertical components- the vertical must be equal to the weight of the aircraft to maintain level flight)
when does P-factor cause the airplane to yaw to the left?
when at high angles of attack (the aircraft's AOA results in the descending blade of the propeller having a higher AOA causing additional thrust on that side of the propeller)
