CADH Practice Cards 3

Question 1

You are departing a confined area, at 100ft AGL your low rotor RPM horn sounds this means…

Answer 1

the helicopter is over pitching. Increase forward airspeed while simultaneously rolling on the throttle and lowering the collective.

Question 2

The control that is responsible for the increase or decrease of rotor thrust is….

Answer 2

the collective

Question 3

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….

Answer 3

move out, speeding up the blade and causing it to advance forward in the plane of rotation.

Question 4

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…

Answer 4

4 lb/sq ft

Goss Weight / Disc Area = Disc Loading

Question 5

As you transition from the hover to forward flight, the helicopter will experience effective translational lift. The aerodynamic principals involved are …

Answer 5

the reduction in induced flow through the rotor disc, resulting in an increased angle of attack and a reduction in drag.

Question 6

The relative wind angle that will produce weather cocking is…

Answer 6

180 degrees

Question 7

Phase lag is…

Answer 7

the angle between the pilot control input and the direction the disc tilts

Question 8

The region that has the total reaction force aft of the axis of rotation is…

Answer 8

Driven region

Ref: Principales of Helicopter Flight, Chapter 18

Question 9

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……

Answer 9

Coning hinge.

Examples of this can be found in the R22 & R44

Question 10

The vector that is perpendicular to rotor drag is the….

Answer 10

Total rotor thrust.

Question 11

A relative wind from between 285 degrees and 315 degrees could produce….

Answer 11

main rotor vortex interference.

Question 12

What will cause a decrease in the airspeed at which retreating blade stall occurs?…

Answer 12

Higher gross weight

Question 13

Blade twist refers to….

Answer 13

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

Question 14

The angular displacement between the movement of the cyclic and the reaction of the pitch links is called…

Answer 14

the advance angle.

Question 15

During autorotation, what causes the three regions to move towards the retreating side?….

Answer 15

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

Question 16

Flying from A to B, you have an increasing headwind. How will this affect your range?

Answer 16

Your range will be decreased.

Question 17

The effects of raising the collective in a helicopter with no governor control will ….

Answer 17

produce higher torque, rotating the fuselage right. A reduction in rotor RPM will also be noted if engine RPM is not increased.

Question 18

The 3 main regions of the rotor disc during autorotation are the…

Answer 18

stalled region, driving region and the driven region.

Question 19

In a semi-rid rotor system, the design that minimises lead-lag tendencies and reduces vibrations is to..

Answer 19

attach the blades to the hub below the highest point on the mast.

Question 20

Torque effect of the main rotor (in a conventional helicopter) will tend to…

Answer 20

rotate the fuselage to the right

Question 21

The chord line of an aerofoil is …

Answer 21

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

Question 22

Centrifugal force acts …

Answer 22

Outwards parallel to the plane of rotation

Part 61 MOS Schedule 3 Unit 1.3.3 CADH 2.1.2 Centrifugal Reaction

Question 23

The mean camber line of an aerofoil is …

Answer 23

sometimes the same straight line as the chordline

Part 61 MOS Scedule 2 unit 1.3.1 CADC 2.1.1 Camber Line

Question 24

Angle of attack with increase if …

Answer 24

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

Question 25

The lift formular is written as …

Answer 25

LIFT = CL x half Rho x V2 x S

Part 61 MOS Schedule 3 Unit 1.3.1 CADC 2.2.1 Bernoulli’s Theorem

Question 26

During autorotation, best range is achieved by …

Answer 26

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

Question 27

During autorotation the pilot cotrols the rotor RPM by using …

Answer 27

the collective

Part 61 MOS Schedule 3 Unit 1.3.3 CADH 2.6.1 Autorotative Flight - RRPM

Question 28

In the lift formular, CL represents …

Answer 28

angle of attack

Part 61 MOS Schedule 3 Unit 1.3.1 CADC 2.4.1 General Helicopter Aerodynamics - Lift

Question 29

Any decay in main rotor RPM will result in …

Answer 29

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

Question 30

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 …

Answer 30

upward and to the right

Part 61 MOS Schedule 3 Unit 1.3.1 CADC 2.3.1 Power required