Aero II Flashcards
DEFINE boundary layer
layer of airflow over a surface that demonstrates local airflow retardation due to viscosity
DESCRIBE different boundary layer flows
laminar flow: air moves smoothly along in streamlines, little friction, easily separated
turbulent flow: streamlines break up and flow is disorganized and irregular, higher friction drag, adheres to surface better, delays BLS
DESCRIBE BL separation
when airflow separates from the surface due to lack of KE, and airflow beyond is a turbulent wake of low pressure (sucks wing back = form drag)
DEFINE CL MAX AOA
- stalling or critical angle of attack
- maximum CL achieved
- beyond this AOA, CL drops rapidly and plane stalls
DEFINE stall
condition of flight in which an increase in AOA decreases CL
EXPLAIN how stall occurs
airflow begins to separate from the sfc with the sep. point moving forward and thereore decreasing lift
IDENTIFY aerodynamic parameters causing a stall
- excessive AOA (above CL MAX AOA)
- BLS = less lift
- Low pressure wake = more drag
COMPARE power-on and power-off stalls
p-on stall speed wil be less since at high pitch, part of W is supported by T and propellor forces air over wings
DESCRIBE order of losing control effectiveness approaching stall in T-6B
A=>E=>R
ailerons to elevator to rudder
EXPLAIN diff. btwn true and indicated stall speed
- true AS is affected by altitude so true stall speed will increase
- indicated AS uses SL density so it will remain constant
EXPLAIN effects of gross weight, altitude, LF, and maneuvering on stall speed
- Weight decreases, stall speed decreases since L decreases
- altitude increases, stall speed stays same (sea level density used for indicated)
- LF icnreases, stall speed increases
- maneuvering increases stall speed
STATE purpose of using high lift devices
reduce T/O and landing speeds by reducing stall speed
DESCRIBE how different HL devices affect values of CL, CL MAX, and CL MAX AOA
CL for given AOA remains the same, CL Max, and CL MAX AOA increase
- Slots: HP air from below increases KE on top and delays separation
- either fixed or slats (automatic slots)
DESCRIBE devices used to control BLS
- Fixed slots are gaps at LE of wing that suck in HP air from bottom and push to top
- Slats are moveable LE sections used to form slots and are deployed aerodynamically, mechanically, hydraulically, or electrically
- Vortex generators: small vanes that disturb laminar airflow into turbulent
DESCRIBE devices used to change camber of an airfoil
Flaps
TE: plain (simple hinged portion), split (plate deflected from lower surface), slotted (moves away from wing to open a narrow slot btwn flap and wing for BLC), and fowler (moves down and aft for more camber and surface area plus slot for BLC)
LE: plain and slotted (same as TE versions)
DESCRIBE methods of stall warning used in T-6B
buffet, stick shaker, AOA display on PFD/HUD, AOA indexers (in each cockpit)
DESCRIBE stall tendencay of general types of wing planforms
Swept Wing: strong tip stall tend., easily stalled High Taper: strong tip stall tend. Rectanguler: strong root stall tend. Elliptical: even stall Moderate Taper (T-6B): even stall
DESCRIBE various methods of wing tailoring, including geom. twist, aero twist, stall strips, and stall fences
geom twist (T-6B): decrease in AOI from root to tip (root stalls first) aero twist (T-6B): gradual change in airfoil shape that increases CL MAX AOA at tip stall strips: sharply angled piece of metal on LE of root designed to induce stall on root first stall fences: redirect airflow along the chord and delay tip stall
DEFINE T/O and landing airspeed in terms of stall speed
- T/O: 20% above power off stall speed
- landing: 30% above
STATE various forces acting on a plane during T/O and landing transition
- T/O and landing: rolling friction (F_R), T (lots), W, L, and D
- net accelerating force: T-D-F_R
- net decelerating force: D+F_R-T
STATE the factors that determine the coefficient of rolling friction
rwy surface, rwy condition, tire type, and degree of brake application (little to none on T/O)
DESCRIBE the effects on takeoff and landing performance, given variations in weight, altitude, temperature, humidity, wind, and braking
Effect on T/O distance:
-^weight: direct squared relationship
-^altitude/temp/humidity: increase (T/O AS stays same)
-HW: decreases
-braking: increases (why the hell would you do this?)
Effect onlanding distance:
-^weight: direct squared relationship
-^altitude/temp/humidity: increase
-HW: decreases
-braking: decreases (why the hell would you not do this?)
DESCRIBE the effects of outside air temperature (OAT) on airplane performance
4H Club: High, Hot, Heavy, Humid
When 3 or more present, expect degraded perf.
DEFINE maximum angle of climb and maximum rate of climb profiles
max angle: occurs at velocity and AOA of T_E max (@ L/D max for TJ and up/left for TP)
max rate: occurs at veloicty and AOA of P_E max (up and right for TJ and @ for TP)
EXPLAIN the performance characteristics profiles that yield maximum angle of climb and
maximum rate of climb for turboprops
max angle: at V less than L/D MAX AS and AOA greater than L/D MAX AOA
max rate: at L/D MAX AS and L/D MAX AOA
DESCRIBE the effect of changes in weight, altitude, configuration, and wind on
maximum angle of climb and maximum rate of climb profiles
^weight/alt and lowered LG/flaps: decrease MROC and MAOC performance
HW: increases MAOC, no change to MROC
DESCRIBE the performance characteristics and purpose of the best climb profile for the
T-6B
- MAOC too close to stall speed so recommended is 140 KIAS
- this will clear obstacles with better margin above stall speed
DEFINE absolute ceiling, service ceiling, cruise ceiling, combat ceiling, and maximum
operating ceiling
absolute: max ROC = zero
service: altitude at which an AP can maintain a max ROC of only 100 fpm
cruise: altitude at which an AP can maintain a max ROC of only 300 fpm
combat: altitude where max P_E allows only 500 fpm climb
max operating: ???
STATE the maximum operating ceiling of the T-6B
31,000 ft
STATE the relationship between fuel flow, power available, power required, and velocity
for a turboprop airplane in straight and level flight
- fuel flow varies directly with P_A
- minimum fuel flow for eq. flight will be found on the P_R curve
- V determined by looking on P_R curve
DEFINE maximum range and maximum endurance profiles
max range: maximum distance traveled over the ground for given amt of fuel
max endurance: max amount of time an AP can remain airborne for given amt of fuel
EXPLAIN the performance characteristics profiles that yield maximum endurance and
maximum range for turboprops
max range: at L/D MAX AS AND AOA
max endurance: at V less than L/D MAX AS and AOA greater than L/D MAX AOA
DESCRIBE the effect of changes in weight, altitude, configuration, and wind on
maximum endurance and maximum range performance and airspeed
^weight: worse ME/MR and increased ME/MR AS
^alt: ME/MR increase
deploy LG/flaps:ME/MR decrease
HW: decrease MR, no effect on ME
DEFINE Mach number
- ratio of TAS to LSOS
- M=V/a=TAS/sqrt(gammaRT)
DEFINE critical Mach
free airstream M# that produces first evidence of local sonic flow
STATE the effects of altitude on Mach number and critical Mach number
Mach increases and the TAS that Mcrit is achieved is lower since LSOS is lower b/c T is lower
DEFINE maximum glide range and maximum glide endurance profiles
MGR: when engine fails, need to glide as far as possible
MGE: minimum rate of descent
EXPLAIN the performance characteristics profiles that yield maximum glide range and
maximum glide endurance
MGR: @ L/D max
MGE: V less than L/D MAX AS, AOA greater than L/D MAX AOA
DESCRIBE the effect of changes in weight, altitude, configuration, wind, and propeller
feathering on maximum glide range and maximum glide endurance performance and airspeed
^weight: no effect on MGR
^alt: increase MGR and MGE
^wind: decreases MGR, no effect on MGE
deploy LG/flaps: reduces MGR and MGE
DESCRIBE the locations of the regions of normal and reverse command on the turboprop
power curve
Reverse: Left of point down and left of L/D MAX (left of max endurance)
EXPLAIN the relationship between power required and airspeed in the regions of normal
and reverse command
Velcoities below max endurance lead to T/P deficit that will eventually slow the plane to a stall
DEFINE nosewheel liftoff/touchdown speed
NWLO/TD speed: min safe AS that the NW may leave the runway during T/O, or the
min AS at which the nosewheel must return to the rwy following a landing
STATE the pilot speed and attitude inputs necessary to control the airplane during a
crosswind landing
ailerons into wind, fly slightly faster
STATE the crosswind limits for the T-6B, in a classroom
25 kts
DEFINE hydroplaning
causes AP’s tires to skim atop a thin layer of water on a rwy
STATE the factors that affect the speed at which an airplane will hydroplane
tire pressire
DESCRIBE the effects of propeller slipstream swirl, P-factor, torque, and gyroscopic
precession as they apply to the T-6B
Prop. slipstream swirl: prop imparts corkscrew of air on plane that hits vert. stab and yaws plane left
P-factor: yawing to left because of increased descending bite of prop
Torque: engine spins CW, N3L says plane wants to rotate CCW
Gyro. Precession: descending causes left yaw
DESCRIBE what the pilot must do to compensate for propeller slipstream swirl, P-factor,
torque, and gyroscopic precession as they apply to the T-6B
Prop. slipstream swirl: R rudder
P-factor: when adding power, add left rudder
Torque: rudder and automatic TAD
Gyro Precession: R rudder when pitching down
DESCRIBE the effect of lift on turn performance
Must increase lift to maintain altitude
DESCRIBE the effect of weight on turn performance
turn rate and radius independent of weight
DESCRIBE the effect of thrust on turn performance
max thrust can only overcome so much induced drag
DESCRIBE the effect of drag on turn performance
max thrust can only overcome so much induced drag
DEFINE turn radius and turn rate
turn radius: measure of radius of circle the flight path scribes
turn rate: rate of heading change in dgs/sec
DESCRIBE the effects of changes in bank angle on turn performance
^theta: turn rate increases, turn radius decreases
DESCRIBE the effects of changes in airspeed on turn performance
^V: turn rate decreases, turn radius increases
DESCRIBE the effects of aileron and rudder forces during turns
aileron: ???
rudder: keeps turn coordinated, overcome adverse yaw
step on the ball
skid (too much)
slip (too little)
EXPLAIN the aerodynamic principle that requires two G’s of backstick pressure to
maintain level, constant airspeed flight at 60 dg bank
- weight hasn’t changed, only being supported by vertical component of lift
- back stick pressure necessary to increase AOA, thereby increasing lift
DESCRIBE the relationship between load factor and angle of bank for level, constantairspeed-fligh
- exponentially direct relationship
- low at low theta
- 2 at 60
- 6 at 80
DEFINE load, load factor, limit load factor, and ultimate load factor
load: stress-producing force, equal to W in SLUF load factor (n): ratio of total lift to airplane's weight, limit n: greatest n an airplane can sustain without any risk of perm. deformation ult. n: maximum n that airplane can withstand without structural failure (about 7g for T-6B)
DEFINE static strength, static failure, fatigue strength, fatigue failure, service life, creep,
and overstress/over-G
static strength: measure of a material’s resistance to a single application of a steadily increasing load/force
static failure: breaking or serious permanent deformation of a material due to a single application of a steadily increasing load/force
fatigue strength: measure of a material’s ability to withstand a cyclic application of load/force over long period of time
fatigue failure: breaking (or ser. perm. deform.) of a material due to cyclic application of a load/force
service life: number of applications of load/force that a component can withstand before it has probability of failing
creep: metal subjected to high stress and temp. tends to stretch/elongate
overstress/over-G: condition of possible perm. deform. or damage that results from exceeding the limit n
DEFINE maneuvering speed, cornering velocity, redline airspeed, accelerated stall lines,
and the safe flight envelope
man. speed/cornering velocity (V_a): IAS at maneuver point where accel. stall line and limit n line intersect
redline AS (V_NE): highest AS AP is allowed to fly
accel. stall lines: lines of max lift, represent max n AP can produce based on AS, determined by CL MAX AOA
safe flight env: portion of V-n diagram bounded by ASL, limit n lines, and V_NE
DESCRIBE the boundaries of the safe flight envelope, including accelerated stall lines,
limit load factor, ultimate load factor, maneuver point, and redline airspeed
redline: limit because of Mcrit, a/c temp, STRUCTURAL failure, or controllability
limit n: limit bc of overstress
accel. stall lines: stall
man. point: transition from stall to overstress
DEFINE asymmetric loading and state the associated limitations for the T-6B
- uneven production of lift on wings
- caused by rolling pullot, trapped fuel, or hung ordnance
- +4.7/-1 g
DEFINE static stability and dynamic stability
static: initial tend. of an object to move twd/away from original eq. position
dynamic: position wrt time, or motion of an object after a disturbance
DESCRIBE the characteristics exhibited by aircraft with positive, neutral, and negative
static stabilities, when disturbed from equilibrium
positive: initial tend. toward original eq. position
negative: intiial tend. to continue moving away from eq. following disturbance
neutral: initial tend. to accept displacement position as new eq.
DESCRIBE the characteristics exhibited by aircraft with positive, neutral, and negative
dynamic stabilities, when disturbed from equilibrium
positive: reduced oscialltions over time
negative: increasing osciallations over time
neutral: oscillations maintain amplitude
DESCRIBE the characteristics of damped, undamped, and divergent oscillations, and the
combination of static and dynamic stabilities that result in each
damped: positive static, positive dynamic
undamped: positive static, neutral dynamic
divergent: positive static, negative dynamic
EXPLAIN the relationship between stability and maneuverability
maneuverability and stability are opposites
STATE the methods for increasing an airplane’s maneuverability
1) give AP weak stability
2) larger control surfaces
STATE the effects of airplane components on an airplane’s longitudinal static stability
- If component’s AC is fwd of plane’s AG, it is destabilizing
- straight and fwd swept wings destab.
- fuselage destab.
- horz. stab. is best pos. contributor to long. stab
- A/C is long. stable if disturbance causes pitch and A/C rights itself
EXPLAIN the criticality of weight and balance
- if CG shifts too much, aero. balancing can be thrown off
- if past neutral pt., unstable
STATE the effects of airplane components on an airplane’s directional static stability
- straight wings, small pos. effect
- swept, small pos. effect
- fuselage neg. effect
- vert. stab largest pos. effect
- directionally stable if distrubed L or R around vertical but rights itself
STATE the effects of airplane components on an airplane’s lateral static stability
- dihedral most pos. effect
- high wings = pos.
- low wings = neg.
- swept = pos
- vert. stab = large pos.
- laterally stable if disturbance rolls A/C L or R but rights itself
STATE the static stability requirements for, and the effects of, directional divergence
- negative directional static stability caused by damaged vert. stab
- causes out of control flight, yaw broadside to wind
STATE the static stability requirements for, and the effects of, spiral divergence
- strong directional stability but weak lateral stability
- disturbance causes wing dip, yaw into wing, positive feedback into tight downward spiral
STATE the static stability requirements for, and the effects of, dutch roll
- strong lat. stab but weak dir. stab
- dist. causes roll left, lat stab increases left wing lift but nose yaws left into RW, pattern repeats in S turns
- tail wagging
DEFINE proverse roll
the tendency of an airplane to roll in the same direction as it is yawing
DEFINE adverse yaw
the tendency of an AP to yaw away from the direction of aileron roll input
EXPLAIN how an airplane develops phugoid oscillations
- upward gust causes alt. increase and AS decrease
- plane noses over slightly and increase AS and decrease alt.
- repeat
EXPLAIN how an airplane develops pilot induced oscillations
PIO are caused when a pilot makes a correction at the same time the AP is correcting itself
DEFINE asymmetric thrust
directional control problems if one engine fails (on multi-engine craft)
DEFINE a spin
aggrevated stall that results in autorotation
- A/C must be stalled
- yaw must be present
DEFINE autorotation
combination of roll and yaw that propogates itself due to asymmetrically stalled wings
DESCRIBE the aerodynamic forces affecting a spin
- A/C must be stalled
- yaw must be present
- both wings stalled, but asymmetrically
- conservation of angular momentum dictates spins
STATE the characteristics of erect, inverted, and flat spins
erect: result of +G entry
inverted: result of -G entry
flat: characterized by flat attitude and transverse or eyeball out Gs
DESCRIBE the factors contributing to aircraft spin
- higher the AS at entry, worse the poststall gyration severity will be
- during a stall, L and R wings balanced until yaw introduced
DISCUSS the effects of weight, pitch attitude, and gyroscopic effects on spin
characteristics
- ^weight: slower spin entry and smaller oscillations
- pitch down: increases rotation rate, stall speed varies inversely with pitch attitude
- GP: right spin, nose pitches down by
STATE how empennage design features change spin characteristics
- horz. stab surface placement can block rudder if placed to far fwd.
- dorsal fin: increases vert. stabilizer and decreases spin rate and aids in stopping autorotation
- ventral fin: decrease spin rate and aid in maintaining nose down attitude
- strakes: increase horz. stabilizer area to keep nose pitched down to prevent flat spin and create anti-rotational force
STATE the cockpit indications of an erect and inverted spin
erect: -altimeter: rapid decrease -AOA: pegged @ 18+ units -AS: 120-135 KIAS -turn needle: pegged in direction of spin -VSI: 6000 fpm -att. gyro: maybe tumbling inverted: -altimeter: rapid decrease -AOA: pegged @ 0 units -AS: 40 KIAS -turn needle: pegged in direction of spin -VSI: 6000 fpm -att. gyro: maybe tumbling
DESCRIBE the pilot actions necessary to recover from a spin
1) retract: gears, flaps, and speedbrake
2) PCL: idle
3) rudder: full opposite to turn needle deflection
4) control stick: fwd of neutral with ailerons neutral
5) smoothly recover to level flight after spin rotation stops
DESCRIBE a progressive spin
- results if during recovery, pilot puts in full opposite rudder but keeps full aft stick
- after 1-2 rotations, reverses spin direction
- violent and disorienting
DESCRIBE an aggravated spin
- caused by maintaining pro-spin rudder while moving control stick fwd of neutral
- steep nose down pitch and increased spin rate
- severe disorientation
DESCRIBE wake turbulence
spiraling masses of air that are formed at the wingtip when an airplane produces lift
-jet wash/wingtip vortices
DESCRIBE the effects of changes in weight, configuration, and airspeed on wake
turbulence intensity
heavy, slow, and clean is worst
- heavy: plane is developing more lift
- slow: induced drag dominant here
- no LG or flaps to prevent it
DESCRIBE the effects of wake turbulence on aircraft performance
- induced roll (loss of control)
- induced flow field (pushes A/C down)
STATE the takeoff and landing interval requirements for the T-6B
- min. T/O spacing is 2 mins
- min landing spacing is 3 minutes
DESCRIBE procedure for wake turbulence avoidance during takeoff
- rotate before hvy A/C rotation by 300 ft and stay above FP
- rotate fwd of hvy A/C NW tdown point
DESCRIBE procedure for wake turbulence avoidance during landing
- stay above hvy A/C’s approach
- tdown before hvy’s rotation
DEFINE wind shear
sudden change in wind direction and/or speed over a short distance in the atmos.
STATE the conditions that will lead to an increasing performance wind shear
- T/O: light HW changes to strong HW through climb out
- Landing: strong TW changes to light TW on final
STATE the conditions that will lead to a decreasing performance wind shear
- T/O: strong HW changes to light HW through climb out
- Landing: light TW changes to strong TW on final
DESCRIBE the effects of wind shear on aircraft performance
can help or hurt
- IPWS on T/O: steeper climb
- IPWS on landing: fast, long unless power removed, then fall short
- DPWS on T/O: drop in AS, near stall
- DPWS on landing: lift lost, nose down, below GS, so pilot adds power and lands fast and long unless doesn’t and falls short
DESCRIBE procedures for flying in and around wind shear
- T/O: longest rwy, takeoff flaps, delay rotation by WS, rotate to normal attitude, abort if WS near Vrot
- landing: flaps to TO and increase approach speed by WS, establish proper pitch, trim, and power, don’t make large power reductions
DESCRIBE wind shear avoidance techniques
- delay T/O or landing until WS gone
- consider going around
- consider diverting
