Notes Flashcards
Atmospheric conditions favorable flight
High pressure = high density = low density altitudes
Atmospheric conditions less than favorable flight
Low pressure = low density = high density altitudes
One half of weight atmosphere is contained at ____________ ft within
18,000
90% of weight atmosphere is contained within ________ ft
53,000
Left side of the chart
- 92 inches of mercury or Hg (hotel golf)
- 2 mb or Hp
1 inch per 1,000 ft
Right side of the chart
15 C
59 F
2 degrees per 1,000 ft
Three components of atmosphere density
Temperature, pressure, humidity
Air density favorable increase
Pressure high
Temperature low
Humidity low
Air density not favorable decrease
Pressure low
Temperature high
Humidity high
Two pressures related to atmosphere
Static and dynamic
5 names of pressures related to pitot
Static, impact, ram, total, pitot
Indicated altitude
Is read of the face of an instrument with the current kollsman setting
True altitude
Is the height above MSL
Absolute altitude
Is height above surface or terrain
Pressure altitude
Is height above standard datum plane
Density altitude
Is density corresponding to a given altitude in standard atmosphere
Two errors
Instrument and installation
IAS
Read directly off instrument and is un corrected
CAS
IAS corrected for instrument and installation error
TAS
CAS corrected for density error
Ground speed
Is an airspeed resultant based on headwind and tailwind assistance.
ASI diaphragm vented
Pitot
ASI case vented
Static
VSI diaphragm vented
Direct static pressure
VSI case vented
Calibrated leak
Calibrated leak causes a lag delay of
A few seconds
What is the difference between VSI and IVSI?
Accelerometer
Airfoil
Surfaced body or structure which produces a lift or thrust
Chordline
An invisible line that protrudes through airfoil on which all angles and winds are measured
Chord
Provides longitudinal dimension of the airfoil and is self contained
Camber
Is shape or curvature of the airfoil expressed as the upper or lower
Span
Measured from root to the tip of the blade
Center of pressure
Aerodynamic forces are considered to act most critical part of airfoil
3 types of airfoil
Symmetrical, non symmetrical, unsymmetrical
As the blade passes the tail and enters the right side
Blade advances into relative wind, blade begins to speed up, the blade begins to flap up
Left side of rotational disc
Retreats from relative wind, slowdown and flap down
Rotational wind
Is parallel and in the same direction as the blades.
Rotational relative wind
Is parallel and opposite the flight path of the blades
Induced flow
Air flowing vertically through the center of the rotor system.
Resultant relative wind
Rotational relative wind modified by induced flow
What is the only way to reduce the effects of induced flow?
Forward airspeed
Angle of incidence
Is measured from the chord and the plane of rotation
Mechanical angle
Angle of attack
Is measured from the chord and the resultant relative wind
Aerodynamic angle
What is the cause of all aviation stalls?
Exceeding the critical angle of attack
What happens to angle of attack as induced flow increases?
Angle of attack decreases
Two components of TAF and it’s related term
Lift and drag
Resultant force
4 types of drag
Induced, parasite, profile, total drag
Induced drag
Induced flow and Rotor tip vortices
Most critical in hover
Profile drag
Caused by frictional resistance of the lift-producing surfaces (rotor blades) passing through the air relatively unchanged in flight
Parasitic drag
Decrease or increase proportionally with airspeed created by non-lifting comp everything else including skin
Total drag
Used to compute some airspeed limitations
Sum of induced, profile, and parasite drag
How does the disk tilt in a semi-rigid rotor system?
Relative to the mast
Articulated or rigid rotors tilt
Relative to the hub
Centrifugal force
The most dominant force is the the turning rotor; other forces act to modify this force.
Outward force on curve path of the body
Provides rigidity to the rotor system
Conning
Is an upward flexing
What is the compromise of the rotor blade coning?
Lift and centrifugal force
Four causes of excessive coning
Low RPM
High gross weight
High G-maneuvers
Turbulent air
3 adverse effects of excessive coning
Loss of disk area - inverted umbrella
Loss of total lift
Stress on blades - cracks, fractures, separation
Why do we twist the blades in standard American helicopter?
Blade twist is necessary to distribute the lifting force more evenly alone the blade. (Verbatim)
How do we twist the blade?
Higher pitch angle at root of the blade
Lower pitch angle at tip of blade
What is the torque effect on a single rotor helicopter?
A counter-clockwise turning rotor turns the fuselage clockwise
3 ways the helicopter compensates for translating tendency
Rigging the cyclic to the left
Tilt the mast to the left
Left cyclic input by the pilot
Rotation produces
A relative wind
Total force acts
Perpendicular to the tip path
2 components of TF or total force
Lift and thrust
You are in ground effect up to what altitude?
One rotor disc diameter measured from the rotor disc to the surface (verbatim)
Translational lift
Additional lift obtained because of the increased efficiency of the rotor system
How can a helicopter obtain ETL?
Through horizontal flight or hovering in a head wind
16 - 24 KTS
Transverse flow effect
10 to 20 KTS
Forward half induced flow is decreasing and angle of attack is increasing
aft half induced flow maintained
Settling with power
A vertical or near vertical descent rate of at least 300 ft/ min
Engine must be using at least 20% to 100%
Speed less than ETL
First two physical responses to entering settling with power?
Increase airspeed with cyclic
Reduce collective pitch as altitude permits
One recovery procedure for Dynamic rollover?
Smooth moderate collective reduction
Primary cause for retreating blade stall?
Excessive airspeed
Symptoms of RBS?
Violent pitch up of the nose
Failing to the left side
Recovery of RBS?
Reduce collective
Regain control of aircraft
When variant used
variant is used when varies 60 deg or more and the wind is >6 KTS
Sky coverage
SKC/CLR = refers to unlimited vis around the horizon circle above and up 12,000 feet FEW = Trace to 25% SCT = 50% BRN = 75% OVC = 100% VV = Vertical Visibility used as the ceiling in metar when skies are considered totally obscured.
RVR
runway visual range, effective runway and 100’s of feet
Only given when less than one SM and less than 6000 ft
Autorotation
The flight condition during which no engine power is supplied and the main rotor is driven by the action of relative wind
3 causes of Dynamic rollover
Establish a pivot point
Initiate rolling motion
Exceeding the critical angle
Two factors for entering dynamic rollover
Human and physical
FAA ceiling definition
Lowest layer a loft which is broken or overcast, or VV is used when considered to be totally obscured.
Purpose of the kollsman window?
Corrects for barometric pressure changes
Max mechanical altimeter error?
+ or - 75 feet
To determine the accuracy limit in a new aircraft what must you do?
Maintenance or reference manuals
In reference to the max mechanical altimeter error give me the two steps you do when entering a cockpit
Set altimeter to field elevation look at the kollsman window. Then get current altimeter setting and compare it by subtracting them to see if your within limits.
Newtons 1st law of
Inertia
All flight forces are equal
Newtons 2nd law of
Acceleration
Change to any outside force
Newtons 3rd law of
Action/reaction
Torque effect- takeoff to hover
Practical definition of ETL?
Rotor system completely outruns the recirculation of old vortices and begins to operate in clean air.
During autorotation aerodynamic equilibrium
Maintain rotor rpm within acceptable limits
Altimeter is a aneroid barometer with adjustable barometric scale which is visible in what part of the cockpit?
Kollsman window
What happens to IAS if the pitot pressure increases?
Airspeed increases
Pitot static system dumps
All three are effected
Increase of airspeed of over a airfoil?
Dynamic increases and static decreases
Relative wind speeds
Add on the right
Subtract on the left
Lifts relationship to the resultant relative wind?
Perpendicular
Drags relationship to the resultant relative wind?
Parallel and in the same direction
Diss of lift
Unequal lift on the advancing and retreating sides of the disc
In regards to induced flow
On the advancing side of the blade what happens to the angle of attack?
Decreases
In regards to induced flow
On the retreating side of the blade what happens to the angle of attack?
Increases
What attitude will the rotor be in if we had blowback
Fwd-angle up
Aft-angle low
Diss of lift for blowback
Fwd cyclic feathering
What other event based on it’s causes pertains to retreating blade stall?
Excessive coning
In autorotation what will happen to rpm in a turn
They will increase
Weather proximity stations
On station (OS) - from center of runway complex within 5 sm
Vicinity (VC) - between 5-10 sm
Distant (DSNT) - beyond 10 sm
