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STATE the various forces acting on an airplane during the takeoff and landing transition
- Takeoff Forces
- Rolling Friction: accounts for the effect of friction between the landing gear and the runway.FR=u(W-L)
- Weight on Wheels reduces as a plane generates lift, causing rolling friction to decrease.
- Net Accelerating Force: Takeoff performance is dependent upon acceleration. An airplane must overcome rolling friction and drag.
- T-D-FR=Net Accelerating Force
- Lift and drag are functions of airspeed, so they are zero at first but increase as the plane accelerates.
- Landing ForcesThe same forces that are present during takeoff are present during landing.
- During landing roll, thrust and weight still remain nearly constant.
- Lift and drag are greatest immediately upon touchdown and decrease over the remaining landing roll.
- As lift decreases, weight on wheels increases causing rolling friction to increase.
- Drag and rolling friction will decelerate the plane.
- D+FR-T=Net Decelerating Force
STATE the factors that determine the coefficient of rolling friction
The coefficient of lift is dependent upon runway surface, runway condition, tire type, and degree of brake application.
- FR=Rolling Friction
- u=coefficient of friction
W-L=Weight on Wheels
DESCRIBE the effects on takeoff and landing performance, given variations in weight, altitude, temperature, humidity, wind, and braking
- Weight: the greatest factor in determining takeoff distance. Increase weight increases takeoff distance. Doubling the weight will increase the takeoff distance by a factor of four.
- Altitude: higher altitude (meaning lower air density) requires a higher takeoff velocity and decreases the amount of thrust our engine can provide. Takeoff roll acceleration decreases and minimum takeoff distance increases.
- Temperature: Higher temperature decreases air density. Takeoff roll acceleration decreases and minimum takeoff distance increases.
- Humidity: Higher humidity decreases air density. Take off roll acceleration decreases and minimum take off distance increases.
- Wind: A headwind will decrease takeoff distance by reducing the ground speed associated with the takeoff velocity. A Tail wind will increase takeoff distance.
- Braking: will increase takeoff distance.
- Increase in weight will increase landing distance since greater airspeed is required to support the airplane.
- Altitude: an increase in altitude will increase landing since the reduced density results in a higher landing velocity.
- Temperature: an increase in temperature will increase landing since the reduced density results in a higher landing velocity.
- Humidity: an increase in Humidity will increase landing since the reduced density results in a higher landing velocity.
- Wind: A headwind reduces landing distance because it reduces ground speed. A tailwind increases landing distance.
- Aerodynamic braking - increasing parasite drag on the airplane by holding a constant pitch attitude after touchdown and exposing more of the airplane's surface to the relative wind.
- Mechanical braking - effective only after enough weight is transferred to the wheels and the airplane has slowed sufficiently.
- Reverse thrust or beta
DESCRIBE the effects of outside air temperature (OAT) on airplane performance characteristics
Higher temperature causes density to decrease, resulting in decrease performance.
EXPLAIN the performance characteristics profiles that yield maximum angle of climb and maximum rate of climb for turboprops
- Max AOC occurs at the velocity and angle of attack that produce the maximum thrust excess.
- For turboprops, this is achieved at a velocity less than L/DMAX
- Max ROC occurs at the velocity and angle of attack that produce the maximum power excess.
- For Turboprops, this is achieved at L/DMAX
DESCRIBE the effect of changes in weight, altitude, configuration, and wind on maximum angle of climb and maximum rate of climb profiles
- ↑ Weight = ↓ Max TE, PE = ↓ MAX AOC, ROC
- ↑ Altitude = ↓ Max TE, PE = ↓ MAX AOC, ROC
- Gear, Flaps=↓Max TE, PE = ↓ MAX AOC, ROC
- Tailwind = ↓ Max TE, PE = ↓ MAX AOC, ROC
- Headwind= ↑ Max TE, PE = ↑ MAX AOC, ROC
DESCRIBE the performance characteristics and purpose of the best climb profile for the T-6B
- Max AOC could cause operation close to stall speed, so best climb speed is used.
- This speed will meet or exceed any obstacle clearance requirements while providing a greater safety margin.
DEFINE absolute ceiling, service ceiling, cruise ceiling, combat ceiling, and maximum operating ceiling
- Absolute Ceiling
- The altitude where an airplane can no longer perform steady climb, max rate of climb is 0
- Service Ceiling
- The altitude where an airplane can maintain a max rate of climb of only 100 ft/min
- Cruise Ceiling
- The altitude at which an airplane can maintain a maximum climb rate of only 300 ft per minute
- Combat Ceiling
- The altitude where maximum power excess allows only 500 feet per minute rate of climb
- Max Operating Ceiling
- The maximum Altitude an airplane can go
STATE the maximum operating ceiling of the T-6B
STATE the relationship between fuel flow, power available, power required, and velocity for a turboprop airplane in straight and level flight
- Thrust is not provided directly by the engine, so there is no direct relationship between thrust and fuel flow.
- Fuel flow varies directly with the power output (PA).
- Minimum Fuel Flow for equilibrium flight will be found on the power required curve at Minimum PR.
- Once the velocity is determined for straight and level flight, the pilot must adjust the throttle to eliminate any thrust or power excess.
DEFINE maximum range and maximum endurance profiles
- Maximum Range
- the maximum distance traveled over the ground for a given amount of fuel.
- Maximum Endurance
- the maximum amount of time that an airplane can remain airborne on a given about of fuel.
EXPLAIN the performance characteristics profiles that yield maximum endurance and maximum range for turboprops
- Max Endurance
- Minimum fuel flow occurs at minimum PR for turboprop.
- Maximum endurance is found at a velocity less than L/DMAX and an AOA greater than L/DMAX AOA
- Max Range
- To find max range we must minimize fuel flow per unit of velocity.
- Any straight line from the origin represents a constant ratio of fuel flow to velocity.
- The minimum ratio that allows the airplane to remain airborne occurs where the line from the origin is tangent to the PR curve for turboprops.
- Max range for turboprop is found at L/DMAX AOA and velocity.
DESCRIBE the effect of changes in weight, altitude, configuration, and wind on maximum endurance and maximum range performance and airspeed
- Increase weight
- -TR and PR increase, requiring fuel flow to increase.
- -Max Endurance will decrease
- -Max Endurance Airspeed will increase
- -Max Range will decrease
- -Max Range airspeed will increase
- Increase Altitude
- -Move TR to the right, and PR up and right.
- -Temperature decreases, making turbine engines more efficient, requiring less fuel.
- -Throttle setting increases but fuel flow decreases.
- -Max Endurance increases
- -Higher altitude allows the plane to fly at a great TAS while burning less fuel.
- -Max Range increases.
- -*Turbojet will notice greater gain because of the turboprop's loss of propeller efficiency with altitude.
- -Lowering the landing gear or flaps causes the thrust required and power required curves to shift up.
- -Max Endurance decreases
- -Max Range decreases
- -Since range is distance over ground, ground speed must be considered
- -Headwind: ground speed is less than true airspeed, decreasing max range.
- -Tailwind: ground speed is greater than true airspeed, increasing max range.
- -Wind has no effect on max endurance.
DEFINE Mach number
The ratio of the true airspeed of an object moving through the air to the local speed of sound in the air.
DEFINE critical Mach
the free airstream Mach number that produces the first evidence of local sonic flow.
STATE the effects of altitude on Mach number and critical Mach number
- An increase in altitude will decrease the speed of sound, and TAS will increase for a given IAS.
- With an increase in airspeed, the indicated redline airspeed must decrease in order to keep a subsonic plane below MCRIT
EXPLAIN the performance characteristics profiles that yield maximum glide range and maximum glide endurance
- Max Glide Range
- The angle of descent is directly related to the thrust deficit.
- To achieve minimum angle of descent (Max glide range), we must minimize thrust deficit.
- Max Glide range occurs at L/DMAX
- Any change of AOA away from L/DMAX would decrease glide range
- Max glide range velocity is L/DMAX regardless of engine type
- Max Glide Endurance
- To minimize the rate of descent, the pilot must fly at the velocity where the minimum power deficit occurs.
- This occurs at the bottom of the PR curve
- Max glide endurance velocity is less than L/DMAX, and the angle of attack is greater than L/DMAX 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
- Increase Weight
- -TR and PR curves shift up and right, increasing the velocity.
- -Max glide range is not affected as long as L/DMAX AOA is maintained
- -Max glide endurance will decrease due to increase in velocity
- Increase Altitude
- -Max glide range will increase
- -Max glide endurance will increase
- Lower gear/Flaps
- -Drag increases
- -Max glide range will decrease
- -Max glide endurance will decrease
- -Headwind decreases max glide range (decreased ground speed)
- -Tailwind increases max glide range (increased ground speed)
- -Wind has no effect on rate of descent or glide endurance.
- Propeller Feathering
- -for props, windmilling occurs when the blades stay flat to the relative wind, which would adversely affect glide performance.
- Blades can be turned to prevent this (known as feathering the propeller).
DESCRIBE the locations of the regions of normal and reverse command on the turboprop power curve
- Normal Command
- The region above the maximum endurance velocity.
- Characterized by airspeed stability.
- -A decrease in airspeed (ex headwind gust) results in a thrust or power excess that will eventually accelerate the airplane back to the original airspeed (and vice versa) at point B.
- Reverse Command
- The region below maximum endurance velocity.
- Characterized by airspeed instability.
- -A decrease in airspeed (ex headwind) will result in a thrust or power deficit that will eventually slow the plane to the point of stalling (assuming level flight is maintained).
- -An increase in airspeed (ex tailwind gust) from point A will eventually speed the airplane up and reach equilibrium at point B.
EXPLAIN the relationship between power required and airspeed in the regions of normal and reverse command
- Normal Command
- Velocity and throttle setting for level flight are directly related.
- To fly in equilibrium at a faster airspeed, more TA/PA is need (vice versa).
- Reverse Command
- Velocity and throttle setting for level flight are inversely related.
- Once stabilized at a faster airspeed, TA/PA will be lower than when stabilized at a slower airspeed.
- The slower an airplane flies, the more thrust and power is needed.
DEFINE nosewheel liftoff/touchdown speed
The lowest speed that a heading and course along the runway can be maintained with full rudder and ailerons deflected when the nosewheel is off the runway.
Lifting the nosewheel below the minimum nosewheel liftoff/touchdown (NWLO/TO) speed may cause the airplane to weathercock or weathervane into the wind and possibly run off the runway
STATE the pilot speed and attitude inputs necessary to control the airplane during a crosswind landing, in a classroom
- The rudder is the primary means of maintaining directional control during crosswind landing/takeoff. Push the rudder into the wind.
- Ailerons are not used to maintain directional control, but to maintain lateral stability that is trying to roll the airplane away from the sideslip relative wind. Deflect the in wind aileron up to lower the wing
STATE the crosswind limits for the T-6B
- Causes the airplane's tires to skim atop a thin layer of water on a runway.
- May occur in standing water in excess of 0.1 inches.
STATE the factors that affect the speed at which an airplane will hydroplane
- Speed for normal dynamic hydroplaning (mph)
- For knots, divide Vhydorplane by 1.15.
- Weight has no effect on hydroplane.
- The higher the tire pressure, the higher the speed of hydroplaning. (Lower pressure allows for a bigger "footprint" of the tire)
DESCRIBE the effects of propeller slipstream swirl, P-factor, torque, and gyroscopic precession as they apply to the T-6B
- Propeller Slipstream Swirl
- The propeller imparts a corkscrewing motion to the air. The corkscrewing air flows around the fuselage until it reaches the vertical stabilizer.
- When at a high power setting and low airspeed (such as take off), the increased angle of attack creates a horizontal lifting that pulls the tail right and the nose yaws left.
- Right rudder and lateral control stick inputs are required to compensate for slipstream swirl.
- The yawing moment caused by one prop blade creating more thrust than the other.
- The angle at which each blade strikes the relative wind will be different, causing a different amount of thrust to be produced by each blade.
- If the relative wind is above the thrust line, the up-going propeller blade on the left side creates more thrust since it has a larger angle of attack with the relative wind.
- This will yaw the nose to the right.
- -Note: this will result at high airspeeds due to the slight nose-down attitude required in level flight.
- If the relative wind is below the thrust line, such as flight near the stall speed, the down-going blade on the right side will create more thrust and yaw the nose left.
- The reactive force based on Newton's Third Law of Motion.
- A force must be applied to the propeller to cause it to rotate clockwise.
- Torque is the opposite and equal force in the opposite direction (counter-clockwise) of the propeller (clockwise).
- Gyroscopic Precession
- A consequence of the properties of spinning objects.
- When a force is applied to the rim of a spinning object (such as a propeller) parallel to the axis of rotation, a resultant force is created in the direction of the applied force, but occurs 90° ahead in the direction of rotation.
- Input - GP
- Pitch ↑ - Yaw →
- Pitch ↓ - Yaw ←
- Yaw ← - Pitch↑
- Yaw → - Pitch↓
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
- Propeller slipstream swirl
- Right rudder and lateral control stick inputs are required
- If the thrust line is above the relative wind line, the nose will yaw right. Left rudder is needed.
- If the thrust line is below the relative wind line, the nose will yaw lest. Right rudder is needed.
- Rudder and the automatic Trim Aid Device (TAD) are the primary means of compensating for engine torque in the T-6B.
- A turbojet will not experience torque from its engines.
- Gyroscopic precession
- Rudder and stick control to counteract
DESCRIBE the effect of lift on turn performance
- Lift vector is divided into two components:
- Horizontal componenet (LH)-aka centripetal force
- -accelerates the airplane toward the inside of the turn.
- Vertical component (LV)
- -the component of the lift vector that opposes weight.
If the pilot does not increase the total lift vector, the airplane will lose altitude because weight will be greater than LV
- When banked, increasing lift will:
- -Decrease Turn Radius
- -Increase Turn rate
DESCRIBE the effect of weight on turn performance
- Turn rate and Turn Radius are independent of weight.
- As long as the aircraft can fly at the same velocity and same angle of bank at different weights, turn radius and rate will remain the same.
DESCRIBE the effect of thrust on turn performance,
- Thrust may limit turn performance.
- Induced drag is directly proportional to lift squared (an airplane pulling 5 Gs in will produce 25 times as much induced drag in level flight)
- If the plane can only overcome 16 times as much induced drag, then the plane can only maintain level flight at 4 Gs
DESCRIBE the effect of drag on turn performance
- Drag is directly proportional to lift squared.
- 5 Gs would result in 25 times as much induced drag in level flight.
DEFINE turn radius and turn rate
- Turn Radius
- a measure of the radius of the circle the flight path scribes.
- Turn rate
- the rate of heading change
DESCRIBE the effects of changes in bank angle on turn performance
- If angle of bank is increased for a given velocity, turn rate will increase and turn radius will decrease
- An increase in angle of back also increases the accelerate stall speed, and vice versa.
DESCRIBE the effects of changes in airspeed on turn performance
- Increase in airspeed = Increase in turn radius
- Increase in airspeed = Decrease in turn rate
DESCRIBE the effects of aileron and rudder forces during turns
- Applying ailerons to bank the aircraft causes the plane to yaw adversely.
- Rudders are needed to correct the plane into a coordinated turn (step on the ball)
EXPLAIN the aerodynamic principle that requires two G's of backstick pressure to maintain level, constant airspeed flight, at 60 degrees angle of bank
- When an airplane rolls into a bank turn, lift is divided into two components: horizontal (LH)and vertical (LV)
- LH is centripetal force, accelerating the plane toward the inside of the turn.
- LV is the force that opposes weight.
- The total lift vector must be increased to prevent the plan from losing altitude.
- To calculate the number of Gs: n=1/cos Φ
- for 60 degrees angle of bank, n=1/cos 60=2
- The pilot must pull back on the stick to increase the angle of attack in order to create the required lfit
DESCRIBE the relationship between load factor and angle of bank for level, constant-airspeed-flight
- Load factor (n) is the ratio of total lift to the airplane's weight.
- It is also know as Gs since it is measured as the number of times the earth's gravitational pull felt by the pilot.
- To find the load factor based on the angle of bank: n=1/cos Φ
- The greater the angle of bank, the more the total lift vector shift from the vertical component to the Horizontal component.
- More lift is required to ensure the vertical component generates enough lift to maintain level flight.
DEFINE load, load factor, limit load factor, and ultimate load factor
- a stress-producing force
- Load Factor
- the ratio of the load applied by an airplane's lift to the load applied by its weight.
- It is a multiple of the acceleration of gravity, commonly called "Gs".
- Limit Load Factor
- The maximum load factor an airplane can sustain without any possibility of permanent deformation.
- It is the maximum load factor anticipated in the normal operation of the airplane.
- Ultimate Load
- The maximum load factor that the airplane can withstand without structural failure.
- It is 1.5 times the limit load
DEFINE static strength, static failure, fatigue strength, fatigue failure, service life, creep, and overstress/over-G
- Static Strength
- A measure of a material's resistance to a single application of steadily increasing load or force
- Static Failure
- the breaking or serious permanent deformation of a material due to a single application of a steadily increasing load or force.
- A pencil breaking after being snapped in half
- Fatigue Strength
- A measure of a material's ability to withstand a cyclic application of load or force.
- Fatigue Failure
- the breaking (or serious permanent deformation) of a material due to a cyclic application of load or force.
- Wire hanger breaking after bent back and forth repeatedly.
- Service Life
- the number of application of load force that a component can withstand before it has the probability of failing.
- Metal stretching or elongating due to high stress and temperature
- Condition of possible permanent deformation or damage that results from exceeding the limit load factor.
DEFINE maneuvering speed, cornering velocity, redline airspeed, accelerated stall lines, and the safe flight envelope
- Maneuvering speed (Va)
- IAS at the maneuver point.
- It is the lowest airspeed at which the limit load factor can be reached.
- Airplane can achieve its maximum turn rate and minimum turn radius.
- It is usually the recommended turbulent air penetration airspeed.
- Cornering velocity
- aka maneuvering velocity
- Redline Airspeed (VNE)
- the highest airspeed that an airplane is allowed to fly.
- Flight at speed above VNE can cause structural damage.
- It is determined by one of several methods: MCRIT, airframe temperature, excessive structural loads, or controllability limits.
- Accelerated Stall Lines
- Lines of maximum lift on the V-n diagram.
- represent the maximum load factor that an airplane can produce based on airspeed.
- Safe Flight Envelope
- the white portion of the V-n diagram. The area that an airplane can safely maneuver for a particular weight, altitude, and configuration.
DESCRIBE the boundaries of the safe flight envelope, including accelerated stall lines, limit load factor, ultimate load factor, maneuver point, and redline airspeed
DEFINE asymmetric loading and state the associated limitations for the T-6B
- Asymmetric loading
- Refers to uneven production of lift on the wings of an airplane.
- Can be caused by a rolling pullout, trapped fuel, or hung ordinance.
- T-6B max load factor during asymmetric loading is +4.7 to -1.0 Gs.
DEFINE static stability and dynamic stability
- static stability
- the initial tendency of an object to move toward or away from its original equilibrium position.
- dynamic stability
- the position with respect to time, or motion, of an object after a disturbance.
DESCRIBE the characteristics exhibited by aircraft with positive, neutral, and negative dynamic stabilities, when disturbed from equilibrium
- The object oscillates from the point of displacement, through the original point of equilibrium, and to another point of displacement.
- The object will roll back and forth, each time with less magnitude, until it comes to a rest at the original point of equilibrium.
- The object is displaced, then oscillates through the original point of equilibrium. The oscillations never dampen out, keeping the object moving through the equilibrium point to the original points of displacement.
- The object will never rest at the point of equilibrium without outside force.
- The object is displaced, then moves back through the point of equilibrium to a point of displacement further from the point of equilibrium.
- The object will never rest at the original point of equilibrium without outside force.