CADH Practice Cards 3 Flashcards
Random questions/statements for exam preparation
You are departing a confined area, at 100ft AGL your low rotor RPM horn sounds this means…
the helicopter is over pitching. Increase forward airspeed while simultaneously rolling on the throttle and lowering the collective.
In cruise, with the aircraft being flown outside its operating limits, it pitches up and rolls to the left. What is occuring …
retreating blade stall
Over pitching is caused by …
high pitch angles and low rotor RPM
A design feature used to minimise the effect of tail rotor roll during the hover is …
offsetting the mast in relation to the centreline of the helicopter
The control that is responsible for the increase or decrease of rotor thrust is….
the collective
In a fully articulated rotor system, blades have the ability to flap up or down independently. As the advancing blade flaps up its centre of gravity will….
move out, speeding up the blade and causing it to advance forward in the plane of rotation.
The aircraft you are flying has a GW of 2500lbs. It has a rotor disc diameter of 28ft. The disc loading for this flight would be…
4 lb/sq ft
Goss Weight / Disc Area = Disc Loading
If atmospheric pressure remains constant, and temperature increases, the effect on density altitude and helicopter performance will be …
density altitude increases, performance decreases
Refer to vector diagram
The letter H represents …
torque
As you transition from the hover to forward flight, the helicopter will experience effective translational lift. The aerodynamic principals involved are …
the reduction in induced flow through the rotor disc, resulting in an increased angle of attack and a reduction in drag.
The relative wind angle that will produce weather cocking is…
180 °
Phase lag is…
the angle between the pilot control input and the direction the disc tilts
The rotor blade is a symmetrical aerofoil becuase …
it has a relatively stable centre of pressure
The region that has the total reaction force aft of the axis of rotation is…
Driven region
Ref: Principales of Helicopter Flight, Chapter 18
Refer to Power Curve Diagram
The line labelled by the letter G indicates that …
the helicopter can only hover in ground effect
Some semi-rigid rotor systems employ a hinge as part of the blade root to reduce excessive bending of the blade during flight, keeping pitch changes more in line with the centreline of the blade. This hinge is called the……
Coning hinge.
Examples of this can be found in the R22 & R44
The vector that is perpendicular to rotor drag is the….
Total rotor thrust.
A relative wind from between 285° and 315° could produce….
main rotor vortex interference.
What will cause a decrease in the airspeed at which retreating blade stall occurs?…
Higher gross weight
Blade twist refers to….
the reduction of the pitch angle from the root to the tip of each blade, reducing the angle of attack (AoA) along the feathering axis
The angular displacement between the movement of the cyclic and the reaction of the pitch links is called…
the advance angle.
During autorotation, what causes the three regions to move towards the retreating side?….
Forward airspeed. This causes the advancing blade to flap up reducing lift, and the retreating blade to flap down increasing lift. The increased angles of attack on the retreating side create a larger stalled region.
Ref: Principles of Helicopter Flight, Chapter 18
Flying from A to B, you have an increasing headwind. How will this affect your range?
Your range will be decreased.
The effects of raising the collective in a helicopter with no governor control will ….
produce higher torque, rotating the fuselage right. A reduction in rotor RPM will also be noted if engine RPM is not increased.
The 3 main regions of the rotor disc during autorotation are the…
stalled region, driving region and the driven region.
In a semi-rid rotor system, the design that minimises lead-lag tendencies and reduces vibrations is to..
attach the blades to the hub below the highest point on the mast.
Torque effect of the main rotor (in a conventional helicopter) will tend to…
rotate the fuselage to the right
The chord line of an aerofoil is …
a straight line drawn from the centre of curvature of the leading edge of an aerofoil to the centre of the trailing edge of an aerofoil
Part 61 MOS Scedule 3 Unit 1.3.1 CADC 2.1.1 Chord Definition
Centrifugal force acts …
Outwards parallel to the plane of rotation
Part 61 MOS Schedule 3 Unit 1.3.3 CADH 2.1.2 Centrifugal Reaction
The mean camber line of an aerofoil is …
sometimes the same straight line as the chordline
Part 61 MOS Scedule 2 unit 1.3.1 CADC 2.1.1 Camber Line
Angle of attack with increase if …
pitch is increased
Part 61 MOS scedule 3 Unit 1.3.3 CADH 2.4.2 Vectors Acting on a Rotor Blade in Forward Flight
The lift formular is written as …
LIFT = Cʟ x ½Rho x V² x S
Part 61 MOS Schedule 3 Unit 1.3.1 CADC 2.2.1 Bernoulli’s Theorem
During autorotation, best range is achieved by …
low rotor RPM, high collective pitch at best range speed
Part 61 MOS schedule 3 unit 1.3.3 CADH 2.6.1 Effect on Autorotative Flight of RRPM and Airspeed
During autorotation the pilot cotrols the rotor RPM by using …
the collective
Part 61 MOS Schedule 3 Unit 1.3.3 CADH 2.6.1 Autorotative Flight - RRPM
In the lift formular, Cʟ represents …
angle of attack
Part 61 MOS Schedule 3 Unit 1.3.1 CADC 2.4.1 General Helicopter Aerodynamics - Lift
Any decay in main rotor RPM will result in …
both blades flapping to equalise lift production across the disc area
Part 61 MOS Schedule 3 Unit 1.3.1 CADC 2.3.1 Flapping
Refer to the Power Required Curve below.
Compared it its position at MSL, as density altitude increases, the overall position of the curve will move …
upward and to the right
Part 61 MOS Schedule 3 Unit 1.3.1 CADC 2.3.1 Power required
Refer to vector diagram
Vector M acts perpendicular to …
the relative airflow
Hunting in a fully articulated rotor head is …
movement of the blades in the plane of rotaton due to coriolis effect
The coning angle is the result of the balance of the forces ….
centrifugal force and rotor thrust
