AE103
Card Set Information
Author:
strent61
ID:
247936
Filename:
AE103
Updated:
2013-11-21 23:28:16
Tags:
Aerodynamics
Folders:
Description:
15-02
Show Answers:
Define Vector
Quantity of magnitude and direction
Define Force
Push or pull exerted on a body
Define Mass
Quantity of molecular material
Define Volume
Amount of space occupied
Define Density
Mass/Volume (Mass per unit volume)
Define Weight
Force toward the Earth on mass (gravity)
Define Moment
Force applied a distance from a fulcrum
Define Work
Done when a force moves a body
Force x distance
Define Power
Work per unit time - Work/Time
Define Energy
Capacity to do work
Define Potential Energy
Energy of position or state
Define Kinetic Energy
Energy of motion
What happens to air density and temperature as altitude increases?
Both decrease
What atmospheric properties affect pressure?
Density -
_{p }
Temperature - T
P =
_{p}
RT (R= gas constant)
What is static pressure?
Force that molecules of air exert on each other by their
random
movement
What is dynamic pressure?
Measurement of impact pressure of a large group of air molecules
moving
together
What is total pressure?
Dynamic + static
Define True altitude
Actual height above MSL
Define Pressure altitude
Height above standard datum plane (29.92)
Define Density altitude
Pressure altitude corrected for temperature
Define Indicated airspeed
Airspeed from ASI
Define Calibrated airspeed
IAS corrected for instrument error
Define Equivalent airspeed
CAS corrected for compressibility
significant approached speed of sound
Define True airspeed
Speed through an air mass
What is groundspeed?
TAS corrected for winds
What happens to TAS in a constant IAS climb?
Increases
Define Wingspan
Length, wingtip to wingtip
Define Chordline
Infinitely long line through leading & trailing edge of airfoil
Define Chord
Width of wing
Measure of the wing along the chordline, from leading edge to trailing edge
Define Tip chord
Width of wing at tip
Define Root chord
Width of wing at root
Define Average chord
Average of all chords
Define Wing area
Wingspan times average chord
Define Taper
Reduction in chord from root to tip
Define Sweep angle
Angle between 1/4 chord line and line parallel to the lateral axis
Define Aspect ratio
Wingspan/average chord
Define Wing loading
Weight/wing area
Define Angle of incidence
Angle between chordline and longitudinal axis
Define Dihedral angle
Upwards slope of wing viewed from head-on
Define Pitch attitude
Angle between longitudinal axis and horizon
Define Flight path
Aircraft path through air
Define Relative wind
Airflow experienced by aircraft/airflow
Define Angle of attack
Angle between relative wind and chordline
Define Mean camber line
Line halfway between upper and lower surface of airfoil
Define Symmetric airfoil
Mean camber and chordline are equal
Define Aerodynamic center
Point on chordline where changes in aerodynamic forces take place
Define Spanwise/chordwise flow
Spanwise- parallel to leading edge
Chordwise- perpendicular to leading edge (produces lift)
What is the relationship of thrust and drag, lift and weight, in level, unaccelerated flight?
Thrust = drag; Lift = weight
What is the relationship between lift and weight, thrust and drag, during takeoff ground roll?
Weight > lift; Thrust > drag
What is equal, but opposite relative wind?
Flight path
What are the three airplane axis?
Longitudinal, vertical, lateral
What are the motions about the axis?
Roll - Longitudinal
Yaw - Vertical
Pitch - Lateral
Aileron axis?
Roll
Elevator axis?
Pitch
Rudder axis?
Yaw
What is the center of gravity?
Point where weight is concentrated
What is the normal relationship between the aerodynamic center and the center of gravity?
CG is forward of aerodynamic center
What are the results of the CG being too far aft or too far forward?
Too far aft - tail heavy
Too far forward - nose heavy
What are the components of aerodynamic force?
Lift and drag
What is the relationship of lift and drag to the relative wind?
Drag is parallel
Lift is perpendicular
Changing which factor in the lift equation will affect lift the most?
V (velocity)
L = 1/2
_{p}
V
^{2}
C
_{L}
S
How can the pilot change lift?
Primarily with AOA and velocity
Also by changing camber with flaps
What is the relationship between velocity and angle of attack in level flight?
Inverse relationship; AOA increases as velocity decreases
What factor changes in maintaining level flight at 1000 ft versus 18000 ft?
TAS increases (decreased density requires increased velocity)
What is total drag?
Parasite + induced
What are the 3 types of parasite drag?
Form, Friction, Interference
Define Form drag
The difference between static pressure of the leading and trailing edges
Define Friction drag
Turbulent airflow in the boundary layer
Define Interference drag
Mixing airflows between aircraft components
What effect does lowering the gear have on drag?
Parasite drag increases
What happens to pitch as the gear is lowered?
Nose pitches down
Describe the effects on lift and drag causes by raising or lowering flaps
Lowering T/O flaps - more lift/little more drag
Lowering flaps from T/O to LDG - little more lift/ lot more drag
Raising from LDG to T/O - Lot less lift/ little less drag
What is induced drag?
Drag from lift
How does increased weight change induced drag?
Increases induced drag (airspeed constant)
At what velocities is induced drag greatest?
Greatest - slower
Least - faster
In level unaccelerated flight, what is the relationship between total drag and total thrust?
Equal
What is the relationship between total drag and velocity?
Drag decreases to a point, then increases
What is L/D
_{MAX}
Lowest point on the total drag curve
the ratio of lift to drag is greatest
Contrast thrust and shaft horsepower
Shaft - engine output
Thrust - propeller output
What is propeller efficiency?
Ability to convert shaft HP to thrust HP
Is 100% propeller efficiency possible?
No, gearbox friction and propeller drag
What determines power available?
Power produced at a given PCL setting, velocity and density
Define Thrust required
Thrust needed to overcome drag (T
_{R}
= D
_{T}
)
Thrust required = Total drag
Define Power required
Power needed to produce T
_{R}
(thrust required)
Define Excess thrust
T
_{A}
> T
_{R}
; climb or accelerate
Thrust available > Thrust required
Define Excess power
P
_{A}
> P
_{R}
; climb or accelerate
Power available > Power required
What is the relationship between velocity and, T
_{R}
and P
_{R}
?
T
_{R}
decreases to L/D
_{MAX}
_{then increases}
_{}
P
_{R}
decreases to airspeed below L/D
_{MAX}
then increases
What is the result of P
_{A}
being greater than P
_{R}
?
Acceleration or climb
What happens to power required as altitude increases?
Increases
What effect does a change in configuration have on T
_{A}
and T
_{R}
?
No effect on T
_{A}
_{}
Gear and/or flaps down requires increased T
_{R}
What effect does a change in configuration have on P
_{A}
and P
_{R}
?
No effect change on P
_{A}
Gear and/or flaps down requires increased P
_{R}
What factors increase takeoff or landing roll?
More weight; Higher alt; Warm temp; Higher humidity; Less headwind; More tailwind
Changing which factor has the greatest effect on performance?
Weight
Define Max rate of climb
Most alt in least time
Define Max angle of climb
Most alt in least distance
Define Best glide speed
Airspeed that gives max power-off range
Define Max range
Max distance for set amount of fuel
Define Max endurance
Max time airborne for set amount of fuel
What factors decrease glide range?
Dirty configuration; Unfeathered prop; Lower alt; More headwind; Less tailwind
What factor changes groundspeed, but has no effect on TAS?
Headwind or Tailwind
Where does max range for a propeller aircraft occur?
L/D
_{MAX}
Where does max endurance occur?
Some airspeed less than L/D
_{MAX}
What factors increase both max range and max endurance?
Less weight; Clean config; Higher alt; Colder temp
Where is the region of reverse command?
Left of max endurance on P
_{R}
chart
What is the region of reverse command?
The part of the P
_{R}
curve where a decrease in airspeed requires an increase in power
What is critical Mach?
Airspeed where first evidence of local supersonic flow occurs
Yaw resulting from propeller airflow past rudder
Slipstream swirl
Roll opposite propeller rotation
Propeller torque
Yaw resulting from asymmetric propeller thrust
P-factor
Action to correct slipstream swirl
Right rudder
Correction for P-factor
Opposite rudder
Action to correct for propeller torque
Opposite aileron
How many G's are required for a level 60 degree bank turn in a T-6 (or any aircraft)?
+2.0G
What control inputs are necessary for a coordinated level turn?
Stick/Rudder in direction of turn, then neutral; Stick back; PCL forward
Define Slip
Insufficient rudder in direction of turn; Needle & ball on same side
Define Skid
Too much rudder in direction of turn; Needle & ball opposite sides
Why must back pressure be added in a turn?
To increase total lift
Why must power be increased during a turn?
Increased AOA, therefore increased induced drag, therefore increased power
What factors limit the max bank angle and min turning velocity?
Weight, Altitude, Load factor, Stall AOA, Engine performance, Wing loading
What two things determine turn rate and radius?
Velocity & angle of bank
Define Turn radius
Radius length of turn
Define Turn rate
Rate of heading change
Define Load factor
Load/weight
Define Limit load factor
Max load without damage
Define Ultimate load factor
Max load without failure (150
^{o}
)
Define Maneuvering speed
Cornering velocity - max speed where abrupt inputs will not cause damage
Define Asymmetric G's
Aileron or rudder deflected while pulling G's
What are the T-6 asymmetric load limits?
-1.0 to 4.7
What happens to load factor as bank increases?
Increases
Define Static stability (positive & negative)
Initial tendency to move forward or away from original state
Positive- towards
Negative- away
Define Dynamic stability
Measurement of displacement over time after disturbance
Define Sideslip angle
Angle between longitudinal axis and flight path
Define PIO (Pilot Induced Oscillations)
Pilot and longitudinal stability correcting for oscillations simultaneously
Describe directional static stability
Stability of longitudinal axis around vertical axis
Contrast stability and maneuverability
More stable, less maneuverable
Less stable, more maneuverable
Inverse
Describe boundary layer separation
Point where airflow no longer adheres to wing
Why does boundary layer separation occur?
Decreasing kinetic energy; increasing adverse pressure gradient
What is a stall?
An increase in AOA results in a decrease in C
_{L}
(coef of lift)
Contrast airspeed and roll tendency between a power-on stall and a power-off stall
Power on
: Lower speed, rolls left
Power off
: High speed, rolls right
What factors change stall airspeed?
Weight, altitude, load factor
How will the stall AOA change with an increase in weight?
Doesn't (AOA never changes) - Stall speed increase
How is the stall speed changed by a steeper bank angle?
Increases
What happens to stall speed when G's are increased?
Increases
In what order are the flight controls lost in a stall?
Aileron
Elevator
Rudder
What is the function of leading edge slats?
Suppress boundary layer separation
Where does boundary layer separation move forward on the C
_{L}
curve?
Bend point before C
_{L}
MAX
Where does the stall occur on the C
_{L }
curve?
C
_{L}
MAX (stall region to right)
What is the T-6 stall AOA?
18 units
What provides stall warning in the T-6?
Stick shaker, AOA gauge
When is the stick shaker activated?
5-10 knots above stall speed
What two factors are necessary for a spin?
Stall and yaw
Contrast lift and drag between a stalled aircraft and a spinning aircraft
Stalled
: Equal lift & drag
Spin
: Asymmetric lift & drag
What is the cause of asymmetry?
Yaw
Describe an erect accelerated spin
Stick other than full aft
Why is a left spin different from a right spin?
Gyroscopic effect of prop
What is poststall gyration?
Aerodynamic forces resulting in movement about the 3 axis
What is the primary factor affecting poststall gyration intensity?
Airspeed
Describe asymmetric wing stall
Uneven lift & drag (yaw) on opposite wings causes auto-rotation
When the stick is full aft, what happens to the pitch of a spinning T-6? What happens to the rotation rate?
Pitch flattens
Rotation rate slows
What is the primary difference between an inverted vs erect spin?
Inverted
: Negative G's
Erect
: Positive G's
What are the characteristics of a right spin?
Lower pitch (steeper), more oscillations, longer to stabilize, rotation rate increases
Which flight control provides the greatest anti-slip force?
Opposite rudder
What factors affect wingtip vortex strength?
Weight, speed, configuration
What generates wake turbulence?
Production of lift
Which direction do wingtip vortices rotate?
Left
: Clockwise
Right
: Counter-Clockwise
Describe the descent characteristics of wingtip vortices
Sink 400-500ft/min
Max sink 800-900ft/min
Last ~2min
Which aircraft produce the strongest vortices?
Heavy, clean, slow
What are the hazards of wake turbulence?
Induced roll, induced flow field (downward)
Worst case
: Loss of control
When do wingtip vortices begin?
At rotation
When do wingtip vortices stop?
Nosewheel down
What is the minimum spacing when
taking off
behind a large or heavy aircraft?
2 minutes
When should you lift off/land behind a heavy aircraft?
T/O
: Before rotation
LDG
: Beyond nosewheel down
Is wake turbulence from aircraft operation on other runways a hazard?
Yes
What effect would a 5 knot crosswind have on vortices?
Can hold vortices on runway or blow to parallel runway (~5kt speed)
What is minimum spacing when landing behind a large/heavy aircraft?
Large - 2min
Heavy - 3min
What is minimum spacing around a hovering helicopter?
3 rotor diameters
What is your flight path and touchdown behind a landing heavy aircraft?
Flight path
: Above
Touchdown
: Beyond nosewheel touchdown
What is wind shear?
Sudden change in wind direction or speed
Describe a
decreasing
performance wind shear
Lesser to greater tailwind OR
Greater to lesser headwind
= Airspeed, pitch & VSI decrease
Describe an
increasing
performance wind shear
Greater to lesser tailwind OR
Lesser to greater headwind
= Airspeed, pitch & VSI increase
What are the cockpit indications of flying through a microburst?
Increasing performance windshear, downwash (VSI), decreasing performance windshear
With a reported 5 knot loss, what adjustments should you make?
T/O flaps, 5 knots add
What is the maximum airspeed adjustment?
10 knots
A body at rest tends to remain at rest...
Law of Equilibrium
The measurement of the average kinetic energy of air particles is called
Temperature
What is the benefit of a tapered wing?
Structural stiffness
Law of interaction?
For every action there is an equal and opposite reaction
Which airfoil produces no lift at zero degrees angle of attack?
Symmetric airfoil
What is the benefit of geometric and aerodynamic twist on a wing?
The wing root stalls before the wing tip
Parasite drag is define as drag
caused by anything other than the creation of lift
In level flight an increase in velocity will
decrease induced drag
Ground effect is the phenomenon that reduces ___ due to a decrease in ___
induced drag; downwash
Thrust available ___ as a velocity increases for a prop driven aircraft
Decreases
As velocity increases, a propeller's P
_{A}
will initially increase then
Decrease
To roll the airplane to the right
Right aileron rises decreasing lift, left aileron lowers increasing lift
For the nose of the airplane to pitch up, the
trailing edge of the elevator must move up in relation to the horizontal stabilizer
Increasing the camber of the wing
increases lift
The T-6A has which kind of trailing edge flags?
Split flaps
Aerodynamic force is the
result of pressure and friction distribution over an airfoil
A ___ airfoil produces lift at zero degrees AOA
positively cambered
Maximum excess power for a prop-driven aircraft occurs ____ L/D
_{MAX}
at
As altitude increases, power available _____
decreases
Takeoff distance can be reduced by
increasing wing camber
P-factor is caused by
one prop blade creating more thrust than its opposing blade
Asymmetric G limits are lower than symmetric because
the lift on the up-going wing is experiencing more G than what is read on the accelerometer
Neutral dynamic stability is
oscillations never dampen but remain at a constant amplitude
What is lateral stability?
Generates forces that reduce the bank angle and returns to wings-level
Cross-coupling causes
spiral and directional divergence
Max glide range is obtained by
flying at L/D
_{MAX}
Slipstream swirl is most noticeable
at high power settings and low airspeed