Aero Gouge (New) Flashcards
What aggravates compressibility?
Decrease in air temperature
What are the main forces on the rotor blades?
Centrifugal and aerodynamic
If you input a cyclic control to lower blade pitch at 90 degrees, what happens?
TPP pitches back (aft)
What aggravates dynamic rollover?
Increase in collective
On a fully articulated rotor head…
Blades can flap and feather independently
Once per rotation vertical vibration is due to what?
Blade out of track
How can a CH-46 have two main rotors and no tail rotor?
The two rotors spin opposite of each other.
Transverse flow effect is felt when…
Only at lower airspeeds. (Approximately 10-20knts)
Ground effect is affected by airspeed? (T/F)
False, Ground effect is not effected by airspeed.
What is density altitude on a cold, dry day?
Low density altitude due to high air density.
Increased gross weight affects what?
a) Increase in power available
b) Increase in power required
c) Decrease in power available
d) No effect
What is true about retreating blade stall?
Turbulent air and abrupt maneuvering causes aircraft to pitch up and roll left
How does a rigid rotor flow allow for flapping?
Bending of the rotor head
A fully articulated rotor head does not incorporate
Flapping dampeners
Flapping causes the advancing blade to flap up and the CG to shift to the center of rotation causing?
An increase in Vrot, known as the Coriolis effect
On a semi rigid system, the tip path plane is a line through the tips of the rotors and?
a) Chordline
b) Rotor hub
c) AOA line
d) Pitch plane
What is true of a helicopter in a 30 degree AOB turn?
The total lift vector must increase causing increased G loading.
Linear velocity is parallel to the tip path plane and induced velocity is
Perpendicular to the tip path plane
In an auto-rotation flare, the rate of descent and _____ decrease and the ______ increases.
Airspeed; rotor RPM
Max glide airspeed in an auto-rotation is….
Higher than maximum endurance airspeed.
What are the characteristics of in-plane drag?
Anti-autorotative force in unpowered flight
When the pilot moves the cyclic forward, what happens to the mechanical axis with relation to the fuselage?
It remains stationary.
If not compensated for, a decrease in power will result in?
Yaw to the left due to anti-torque pedals
Ground effect is caused by?
Decrease in induced velocity, decrease in wingtip vortices
An increase in translational lift is due to?
A decrease in induced velocity
Flapping is caused by?
Dissymmetry of lift.
Flapping is…
Directly proportional to airspeed.
Flapping causes…
Blowback.
In an autorotation, higher than optimum main rotor RPM leads to?
Increase in rate of descent
On density altitude charts, 1000 ft, 20 degrees C, 80% RH leads to what DH?
2200 feet (looks like 2300 feet)
Contributing factors to retreating blade stall?
High gross weight, low rotor RPM, turbulent air
Lead and lag are used to compensate for what?
Coriolis effect
Profile drag is…
parallel to relative wind, perpendicular to lift.
T/F: Rotational velocities are faster at the root than at the tip.
False.
T/F: With 50% RH, air is half as dense.
False.
In a dynamic rollover situation, what must be true?
Lift produced must be close to weight.
Rotor blade vortices are…
The same as wingtip vortices.
What are the four regions of flow in an autorotation?
Prop, autorotative, stall, reverse flow
When the nose of the aircraft suddenly pitches up in high speed flight…
The pilot should NOT pull aft cyclic/ up collective.
For autorotation entry, what is required?
Reduce in-plane drag (lower collective), reverse induced velocity, maintain/regain Nr
Too much cyclic movement in the flare can cause what?
Increased Nr up to the windmill brake state.
In a semi-rigid rotor system, what allows flapping?
Horizontal hinge pin
In a conventional helicopter, the tail rotor can produce thrust to the left to
Counter transmission drag (DISPUTED)
In forward flight, in comparison to each other, the rotor blades have
Unequal lifting velocity, equal lifting moment, and unequal AOA
On airspeed vs. power required chart, a line from the origin that is tangent to the curve determines
Max range airspeed
Helicopter drift in the direction of rotor thrust in a hover is called what?
Translating tendency
As the AOA on a symmetric airfoil increases, what happens to the center of pressure?
Remains constant
During the flare portion of an autorotation, what causes the increase of rotor RPM?
The increase in lift due to the change in angle of attack on the main rotor blades (think about the change in induced flow)
For a constant RPM rotor, what causes upward bending of the rotor blades?
Increased lift is greater than increased centrifugal force.
What causes a slight descent in the first stages of forward flight?
Too much forward cyclic.
A _____ in Nr will cause a _____ in airspeed needed to enter retreating blade stall.
decrease; decrease
Air density will increase when temperature and humidity _____ and pressure _____
decrease; increases
To tip the tip path plane aft, where must the blade pitch be the greatest?
3 o’clock/ 90 degree position
What is the most effective method to stop dynamic rollover?
Steady smooth downward motion of the collective.
What limits Vne in straight and level flight?
Structural limitations and torque available.
At 100% humidity, how much water occupies the air by volume?
4%
Which of the following is not a requirement to enter an autorotation?
Left pedal trim.
During a steep approach at low airspeed you experience an uncommanded increase in the rate of descent. You may be experiencing what?
Vortex ring state.
On the H-V diagram, where would you not want to be?
Out of ground effect hover at 400 feet. Low altitude, high airspeed.
What are indications of entering retreating blade stall in order of occurrence?
Low frequency vibrations, nose pitches up, uncommanded left roll
During an autorotation, the inner section of the rotor system will be _____ due to _______.
stalled; excessive AOA
Your aircraft is power required greater than power available. Placing the collective down will…
increase the rate of descent
High frequency vibrations/ buzzing could be caused by?
The Barbell Shaft
What effect will a headwind have on max range airspeed?
It will increase the airspeed for max range.
What is true regarding rotor blade vortices?
They are similar to wingtip vortices produced by an airplane in forward flight.
The virtual axis…
Perpendicular to the tip path plane.
Moving the cyclic will do what to the rotor blades?
Cause an equal change in blade pitch but in opposite direction.
If settling occurs with a reduced airspeed at max power, what should be done to ensure level flight?
Return to the original airspeed
If experiencing vortex ring state, what actions should be taken?
Forward cyclic and slight reduction of collective.
During the initial phase of dissymmetry of lift, the advancing blade feels increased linear flow, thus increasing ____ and increasing aerodynamic force causing the blade to flap ____.
AOA; up
A destructive vibration occurring in the rotor system when the aircraft is in contact with the ground is?
Ground resonance.
If flying in the low/fast portion of the height/velocity diagram, why is this dangerous?
Plot reaction time. (a distractor is severity of maneuver, this is NOT the correct answer. Also this is not the exact
wording of the question…)
While in unpowered flight if _____ increases, ______ also increases.
induced flow; AOA
Hydrogen (not nitrogen) makes up how much of the atmosphere?
Less than 1%
During the flare of an autorotation, rapid cyclic input may cause?
Rotor overspeed
In high velocity forward flight, decreased induced velocity and increased AOA may lead the retreating blade to?
Stall
On a cold, dry day, one would expect the density altitude to…
Decrease and air density to increase.
In a fully articulated rotor system, blades are able to…
Flap, feather, and Hunt (Lead/Lag) independently
Cockpit gauges indicate high TOT, high Ng, high rate of descent, and decaying Nr. You are experiencing
________?
Pr>Pa
Cockpit gauges indicate high TOT, high Ng, high rate of descent, and normal Nr. You are experiencing
__________?
Vortex Ring State
Mast Bumping occurs in what type of rotor system?
Semi-rigid
Primary cause for mast bumping…
Low G’s
Recovery from mast bumping…
Aft cyclic then center (According to the test, this is a more appropriate initial step than a collective input)
Geometric imbalance is compensated for using…
Underslinging.
Max Ng and TOT at a constant forward airspeed with Nr decreasing is an indication of what condition and what
should the pilot do?
Pr>Pa and the pilot should accelerate/decelerate to max endurance airspeed.
Air density increases as temperature and humidity _____ and pressure_____.
Decrease…increase.
Air at 50% humidity is half as dense as Dry Air.
False.
As outside air temp increases, what will happen?
Air density decreases.
A plane defined by tips of rotor blades is…
Tip path plane.
In a rotating system the linear flow is greatest at blade root and least at the blade tip.
False.
Induced drag is created as a result of the production of _____ and in-plane drag is the sum of the _____ in the
plane of rotation.
Lift; decelerating forces.
T/F: As density altitude increases, the power required will increase because the rotor blade is/are less efficient.
True.
A decrease in air density will…
decrease rotor efficiency.
Which of the following factors affects density altitude?
Humidity and temperature.
Density altitude is pressure altitude corrected for
Humidity and temperature.
On a cool, dry day one would expect…
the density altitude to be low and the air density to be high.
Rate of descent in autorotation is affected by which of the following…
Nr.
As temp increases above standard day conditions, density altitude will decrease.
False.
Pressure altitude is based upon which of the following elements…
Standard atmosphere.
What is pressure altitude?
Altitude corresponding to particular static air pressure in standard atmosphere
Aircraft altimeters are constructed for the pressure-height relationship and can determine the pressure altitude by dialing in ______.
29.92
By volume, hydrogen is approximately what percent of the earth”s atmosphere?
Less than one.
Water composes approximately ____ of air by volume at 100% humidity.
4%
High twist angles on a rotor blade are limited due to which of the following
High speeds.
Constructing a rotor blade so that it’s pitch angle increases as you go from the tip to the root is called
Geometric twisting
Which of the following results are characteristic of geometric twisting:
Improves helicopters performance by making lift distribution along the blade more uniform.
Using a ____ airfoil will eliminate rotor blade pitching moments
Symmetrical.
Two major forces acting on the rotor head arc are:
Centrifugal and aerodynamic
Power required to rotate a rotor system is directly proportional to
In-plane drag.
In powered flight, when linear flow increases, which of the following changes will occur
AOA increases.
In powered flight, as induced flow increases, the AOA
decreases.
As you increase density altitude, the power required/power available chart will show a/an
Decrease in max power available.
AOA is found between the chord line and the:
Relative wind.
On the blade element diagram, the relative wind vector is the result of ___ and ___ vectors
Induced flow; linear flow.
What component counteracts main rotor torque in a hover:
Tail rotor.
Which of the following functions does the tail rotor serve:
Controls aircraft about vertical axis.
In a single rotor helicopter, movement of the directional control pedals will:
vary the pitch of the tail rotor blades.
During ground resonance, if unable to takeoff, the pilot should:
shut down the engine and apply the rotor brake.
Rotor tip vortices:
are created by high pressure air below the airfoil flowing to low pressure air above it.
Helicopter A weights 23,000 lbs and helicopter B weighs 22,000 lbs. Which produces more intense rotor tip vortices:
Helo A.
What two forces determine coning angle:
aerodynamic force and centrifugal force.
Linear flow is parallel to tip plane path while induced flow is…
perpendicular to tip path plane.
Within it’s envelope, when there is a ______ in AOA, there is a corresponding increase in the _____
increase; lift
Using a ____ airfoil will increase rotor blade pitching moments
non-symmetrical
What is the extension of the centerline of the rotor mast called…
mechanical axis
Which of the following is a description of the virtual axis?
an apparent axis about which the rotor system appears to turn
What is the actual axis of rotation in forward flight?
mechanical axis
More power is available for the main rotor system in forward flight because of the:
vertical stabilizer
Tail rotor loading is decreased in forward flight by which of the following effects?
vertical stab lift, weather vaning effect
Since the tail rotor is a thrust producer, in what direction does the tail rotor cause the helo to drift?
Right.
A system having an even number of rotor systems of the same design rotating in opposite directions:
is effective since both torque effects balance each other out.
In multi-rotor systems, the torque effect is compensated by having an ___ number of rotor systems rotating in ___ directions
even; opposite
During hovering right turn, you may experience a sudden uncommanded right yaw caused by:
main rotor vortices.
In the TH-57 torque effect created by the main rotor system causes the fuselage to rotate:
clockwise
What will happen to the fuselage when you add power:
Yaw to the right due to torque effect.
Increase in helo weight causes what reaction?
Increase in power required.
Power required is always increased by both:
Increase in DA and weight.
What is the lowest point on the power required versus airspeed curve?
Max rate of climb.
During reaward flight the TPP is perpendicular to the:
virtual axis.
When the pilot of a th-57 helicopter moves the cyclic stick forward, the mechanical axis will ___ with respect to the fuselage.
remain stationary
In a single rotor helicopter, moving the center of gravity forward will:
require aft cyclic control movement to maintain original attitude.
With an engine loss in a hover, the pilot must move the ___ to the___ when the failure occurs to compensate for the reduced tail rotor thrust
cyclic; right
The main rotor must be tilted to the ___ in order to counter the affect of the tail rotor, thus the helicopter will tend to land on the ___ skid first
left; right
The virtual axis of a rotor system always remains perpendicular to the:
tip path plane
When making a vertical takeoff, what will happen to the tail rotor power requirements:
increase
In a no-wind hover, a pedal turn to the ___ in the th-57 would cause the tail rotor to demand ___ power.
left; more
The fully articulated head allows lead lag by ____ and flapping by ___.
vertical hinge pin; horizontal hinge pin
In order to tilt the rotor disc to the left, blade pitch must decrease at the ___ and increase at the ___ positions
12 o’clock; 6 o’clock
Which of the following characteristics is associated w/ best range airspeed…
increases with a headwind
The additional performance produced by the rotor system because of forward flight is called…
translational lift.
One phenomena which decreases power required while hovering in ground effect is:
reduction of induced flow.
Max power for climb:
is available at max endurance airspeed.
An increase in density altitude:
has no effect on max endurance airspeed.
Best range airspeed in a no-wind situation is:
is located at the point where a line drawn from the origin becomes tangent to the power required curve.
In a single rotor helo, a change in fuselage center of gravity location will result in:
opposite proportional change in cyclic position to maintain a hover.
If while in a hover, the helo enters uncontrolled flight to right even though pilot has applied full left cyclic, the helo may:
have exceeded right center of gravity limits.
With an aft center of gravity shift on helos, the nose attitude will move ____ and the pilot must compensate with ___ cyclic:
up; forward.
What effect does airspeed have on rotor blade flapping?
increased airspeed; increased flapping.
What statement reflects blade flapping in forward flight?
Varies the angle of attack on the blades.
Because of the effect of blowback while accelerating in forward flight, what must you do to maintain level flight?
Trim cyclic forward
To compensate for dysemetry of in a semirigid rotor system in forward flight, the blades will do which of the following actions:
advancing blade flaps up and retreating blades flap down
Disymetry of linear flow experienced by the rotor blade in forward flight causes the blade to do which of the following motions?
Retreating blade flaps down and induced flow decreases
During the initial phase of disymetry of lift and the resulting flapping effect, the advancing blade feels increasing linear flow, thus increasing ____ and increasing aerodynamic force causing the blade to flap ____
induced flow; up
Translational lift increases available lift due to:
decrease induced flow
Translational lift is increased while:
increasing forward airspeed
Which of the following characteristics is related to a semirigid rotor system?
flapping is accomplished by a horizontal hinge pin (trunion)
Max range airspeed of a helo in an autorotation:
higher than maximum endurance TAS
Which of the following characteristics best describes powered flight best range airspeed?
lower with a prevailing tailwind
Powered flight best range airspeed will:
increase with a headwind
Ground effect increases lift when the rotor system is operating within approximately one rotor diamter surface by:
decreasing induced flow
Ground effect
is not effected by airspeed.
Fore and aft asymmetry of lift, or transverse flow, continue in forward flight due to…
coning
Flapping action of rotor blades while transitioning to forward flight will…
cause blowback.
What will occur when centers of mass in rotor blades are at different radii to the mechanical axis?
geometric imbalance.
The solution to geometric imbalance in the semirigid rotor system is…
The underslung configurations.
Flapping of the rotor blades in forward flight will…
be directly proportional to airspeeds.
Without flapping in forward flight, the helo would develop what phenomenon?
disymetry of lift
The semi-rigid rotor head compensates for dissymetry of lift by:
horizontal hinge pins.
When the pro-autorotative forces equal in-plane drag, the rotor RPM will be:
stabilized.
The ____ which enable the pilot to ____ RPM during autorotative flight
pro-autorotative force; increase
Anti autorotative forces…
will cause the rotor system to decelerate
When transitioning into forward flight the aircraft will settle because of…
ground vortex.
When first transitioning to forward flight, _____ power may be required because of the effect of ____
more; ground effect
What is the self-induced rotation of a rotor system in unpowered flight
autorotation
Ground effect is caused by:
decrease in induced flow and wingtip vortices
Geometric imbalance is alleviated in a rigid rotor head by:
bending of the rotor head
Which of the following statements is characteristic of geometric imbalance in the semirigid rotor system:
Is nearly eliminated by aligning the blade’s center of mass with the centerline of the flapping hinge
The internal vibration as a rotor system goes into forward flight (at approximately 10-15 knots) is caused by
transverse flow
Less than optimum airspeed during autorotative flight will have which of the following results:
increased rate of descent
When flying at low altitude, high speed, successful transition to a safe autorotation is unlikely due to:
pilot reaction time
Flying in the shaded portions of the height velocity diagram:
is not recommended in case of engine failure.
During the flare at the end of an autorotation, the ____ flow vector ___. The resulting increase in angle of attack creates more lift.
induced; increases
An autorotative flare will increase rotor RPM and:
decrease A/S and decrease rate of descent.
Which of the following statements is true concerning in-plane drag…
Anti-autorotative force in unpowered flight
Anti autorotative force _____ when the pilot ____ the collective in autorotative flight.
increase; raises
Successful autorotative entry does not include which of the following requirements
Up collective to slow rate of descent.
In unpowered flight, the ____ is reversed.
induced flow
During unpowered flight, which of the following vectors is reversed?
induced flow
If the resultant aero forces vector of a blade element is forward of the vertical, then the blade element is:
pro-autorotative
When does the vortex ring state take place?
when a/c settles into its own downwash and rotor vertices
If vibrations and loss of control response occurs during a steep approach of less than 40 knots and rate of descent greater than 800 fpm, the helo is probably
Entering a vortex ring state condition.
Concerning the height-velocity diagram, what conditions should be avoided?
hovering out of ground effect below 100ft.
In forward flight, retreating blade stall causes a nose up pitching moment because of:
phase lag action on the stalled sector of the rotor diameter.
The increased angle of attack, on the retreating blade at high forward airspeed may cause…
blade stall.
During an autorotation, the inner section of the rotor system will be ___ due to the ___.
stalled; excessive AOA
Two factors that affect autorotative rate of descent are:
airspeed and rotor RPM
During autorotation rotor speeds below optimum RPM…
will cause a increase in rate of descent.
During the transition to unpowered flight, ____ maintains rotor speed until induced flow is fully reversed
inertia
IOT transition from powered to unpowered flight you must do which , if any, of the following actions?
reduce inplane drag, reverse induced flow, regain and maintain RPM
The constant RPM of a rotor system in autorotation will stabilize at a constant value when which of the following actions take place?
pro-autorotative forces are equal to the anti-autorotative forces
An increased induced flow occurring at low rotor heights and approximately 15 knots is:
Ground vortex
An undesirable structural twisting of the main rotor blade at or near the speed of sound could occur because of:
compressibility
Recovery from compressibility may include the following steps…
decrease Nr, decrease airspeed, decrease DA
____ frequency vibrations can be caused by a loose aircraft component vibrating sympathetically with the rotor system
?
Which of the following may contribute to the rolling tendency during dynamic rollover?
increased collective
Which, if any, of the following actions is the most effective way to stop a rolling motion and prevent dynamic rollover
a smooth moderate collective reduction
Which of the following actions contribute to mast bumping
Low G maneuvers
If settling is encountered, with a reduced airspeed at maximum power, what should be regained to insure level flight
Maximum endurance airspeed
What is ground resonance?
Destructive vibrations
A destructive vibration in the rotor system when the aircraft is in contact with the ground is:
ground resonance
In the event of vortex ring state the pilot should apply:
slight down collective and forward cyclic
With the cockpit indication of increased rate of descent, high Ng, high TOT, decaying Nr, the pilot is experiencing
Power required exceeding power available
When experiencing Pr
high Ng and decaying Nr
