Helicopter Aerodynamics test part 4

Which, if any, of the following actions is teh most effective way to stop a rolling motion and prevent dynamic rollover

A smooth moderate collective reduction

Which of the following statements is true concerning in-plane drag

Anti-autorotative force in unpowered flight

With the cockpit indication of increased rate of descent, high Ng, high TOT, decaying Nr, the pilot is experiencing

Pr>Pa

Successful autorotative entry does not include...

Up collective to slow rate of descent

Two factors that affect autorotative rate of descent are

airspeed and rotor RPM

What is teh self-induced rotation of a rotor system in unpowered flight--

autorotation

Flapping of the rotor blades in forward flight will--

be directly proportional to airspeeds

Geometric imbalance is alleviated in a rigid rotor head by--

bending of the rotor head

The increased angle of attack, on the retreating blade at high forward airspeed may cause

blade stall

Flapping action of rotor blades while transitioning to forward flight will--

cause blowback

An undesirable structural twisting of the main rotor blade at or near the speed of sound could occur because of-

compressibility

Fore and aft asymetry of lift, or transverse flow, continue in forward flight due to--

coning

Anti autorotative forces will cause the rotor system to

decelerate

Recovery from compressibility may include...

decrease Nr, decrease airspeed, decrease DA

ground effect is caused by

decrease in induced flow and wing tip vortex

What is ground resonance

destructive vibrations

Without flapping in forward flight, the helo would develop what phenomenon

disymetry of lift

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

What will occur when centers of mass in rotor blades are at different radii to the mechanical axis

geometric imbalance

A destructive vibration in the rotor system when the aircraft is in contact with the ground is

ground resonance

When transitioning into forward flight the aircraft will settle because of--

ground vortex

When experiencing Pr>Pa among the cockpit indications

high Ng and decaying Nr

Concerning the height-velocity diagram, what conditions should be avoided

hovering out of ground effect below 100ft

Which of the following may contribute to the rolling tendency during dynamic rollover

increased collective

Less than optimum airspeed during autorotative flight will have which of the following results

increased rate of desent

Anti autorotative force _____ when the pilot ____ the collective in autorotative flight

increases...raises

During unpowered flight, which of the following vectors is reversed

induced flow

In unpowered flight, the ---i s reversed

induced flow

During the flare at the end of an autorotation, the ____ flow vector ___. The resulting increase in angle of attack creates more lift

induced flow...increases

During the transition to unpowred flight, ____ maintains rotor speed until induced flow is fully reversed

inertia

Which of the following action 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

____ frequency vibrations can be caused by a loose aircraft component vibrating sympathetically with the rotor system.

medium

When first transitioning to forward flight, _____ power may be required because of the effect of ____

more...ground effect

Which of the following statments is characteristic of geometric imbalance in the semirigid rotor system.

nearly eliminated by aligning the blade's center of mass with the centerline of the flapping hinge

. Flying in the shaded portions of the height velocity diagram

not recommended in case of engine failure

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

When flying at low altitude, high speed, succesful transition to a safe autorotation is unlikely due to

pilot reaction time

If the resultant aero forces vector of a blade element is forward of the vertical, then the blade element is

pro-autorotative

The ____ which enable the pilot to ____ RPM during autorotative flight

pro-autorotative force... increase

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

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

In the event of vortex ring state the pilot should apply

slight down collective and forward cyclic

When the pro-autorotative forces equal in-plane drag, the rotor RPM will be--

stablized

During an autorotation, the inner section of the rotor system will be ___ due to the ___

stalled....excessive AOA

The internal vibration as a rotor system goes into forward flight (at approximately 10-15 knots) is caused by

transverse flow

The solution to geometric imbalance in the semirigid rotor system is

underslung configurations

When does the vortex ring state take place

when ac settles into its own downwash and rotor vertices

During autorotation rotor speeds below optimum RPM

will cause an increase in rate of descent

The semi-rigid rotor head compensates for dissymetry of lift by--

-horizontal hinge pins.

An autorotative flare will increase rotor RPM and do what to A/S and rate of descent?

Decrease both

An increased induced flow occuring at low rotor heights and approximately 15 knots is

Ground vortex