CADH Practice Cards 7 Flashcards
Random questions/statements for exam preparation
The main facstors affecting air density at low speed are …
altitude and temerature, and to a lesser extent, humidity
An increase in density altitude will give you …
reduced rate of climb, increased power required to hover, deareased power available from the engine
Under all flight conditions, Total Rotor Thrust acts perpendicular to …
the tip path plane or plane of rotation
Refer to diagram
The Vector labelled C is …
rotational flow
The diagram is of the autorative drive region
High frequency vibrations are most likely to be caused by …
tail rotor faults
Concerning the rotor blade relative airflow at the rotor hub during vortex ring state …
the rotor blades are stalled
To compensate for the variation in lift production around various sections of the rotor disk during horizontal flight, most rotor systems allow the blades to flap. Flapping means …
the angular movement of the rotor blades above and below the plane of ratation
Refer to the vector diagram -
The letter corresponding to the angle of attack is …
C
The airspeed range for the minimum rate of descent and maximum glide distance is a helicopter during autorotation is …
different for individual helicopters, but is usually between 50 kt and 85 kt
Assuming all other lift formula variables remain constant, lift is …
directly proportional to velocity squared
In regards to the lift formula
If V is doubled, lift will …
quadruple
The effect of exceeding certre of gravity (CG) position limitations on the controllability of a helicopter are …
a forward CG results in difficulty decelerating and controlling the flare
In regrads to the lift formula
If Cʟ is increased, lift will …
increase
A helicopter with an AUW of 3500 lb and a rotor diameter of 45 ft has a Disc Loading of …
2.2lb/sq ft
With a fully articulated rotor system, dragging means …
freedom of the blades to move indipendently in the plane of rotation forward and aft
Refer to Power Curve Diagram
The line labelled by the letter H indicates that …
the helicopter is unable to hover
The result of Coriolis effect is …
acceleration of the blade that flaps up and deceleration of the blade that flaps down
As the density altitude increases, for a given collective pitch setting the rotor RPM during autorotation will …
increase
The corrective action for overpitching is to …
lower the collective
If density is increased, lift will …
increase
During a hover right turn there is an increase in …
main rotor RPM
In a still air hover, the coning angle is the angle between …
the span of a rotor blade and a plane passing through the rotor hub perpendicular to the axis of rotation
When discussing helicopter rotor blade design features, taper refers to …
reducing the surface aera of the rotor blade from the hub towards the tip
When a helicopter with an anti-clockwise rotating rotor system is hovering and moving to the right in nil wind, the advancing blade is at position …
6 oclock, or aft of the aircraft
When discussing helicopter rotor blade design features, twist or washout refers to …
reducing the pitch angle and therfore the angle of attck from the hub towards the tip
With a semirigid rotor system, the blades …
flap as a unit on a teetering head, and are underslung to minamise hunting stresses
In powered forward flight, in the stick fixed position, a helicopter’s dynamic stability in the pitching plane could be described as a …
divergent phugoid
It is necessary to incorporate design features like taper and washout inot a rotor blade to …
equalise the lift produced at different stations on the blade with different velocities
Refer to vector diagram -
The vector labelled O is …
the relative airflow
Hunting or dragging menas …
the leading and lagging of the main rotor baldes about the drag hinge
VNE is …
IAS which decreases with height
In autorotation, friction forces between the main rotor and the transmission …
yaws the aircraft left
The degree of coning depends on …
load factor and rotor RPM
approximately which airspeed, during translational lift, give the helicopter the minimum total power required …
55 kt
In autorotation the rotor exerts friction forces on the transmission tending to …
yaw the aircraft left
In a still air hover, in the stick fixed position, a helicopter’s dynamic stability in the pitching plane could be described as a …
divergent phugoid
Dynamic rollover in a helicopter is most likely when the helicopter is flown …
right skid low, moving right
The force perpendicular to the tip path plane in flight is …
total rotor thrust
