Rotary

Question 1

Define rotor mast

Answer 1

Supports and drives the main rotors

Question 2

Define rotor disc

Answer 2

Area projected by the rotor travel

Question 3

Outline Shaft axis

Answer 3

Axis through the rotor mast, which about the rotors are ALLOWED to rotate

Question 4

Outline axis of rotation

Answer 4

The imaginary line about which the rotars actually rotate

Question 5

Plane of rotation

Answer 5

Plane at right angles to the axis of rotation

Question 6

Tip path plane

Answer 6

Imaginary circular plane outline from the rotor tips during travel

Question 7

Define blade coning

Answer 7

Upward flex of the rotor blades due to pitch and lift increased and centrifugal force is applied

Question 8

Define cone angle

Answer 8

Angle between blades span wise axis and the plane of rotation.

Question 9

Purpose of a transmission system

Answer 9

To transfer power from engine to the main rotors, tail rotor and other accessories

Question 10

Purpose of mgb

Answer 10

Reduce the engines high RPM low torque to high torque low RPM for rotors

Question 11

Components of a tail rotor drive system

Answer 11

MGB, drive shafts, tail rotor gearbox, and tail rotor

Question 12

Main components of a transmission system (4)

Answer 12

MGB
TR Drive system
Clutch
Freewheel

Question 13

4 forces acting on helicopter in hover

Answer 13

Directly upwards forces, thrust and lift, equal to the directly downward forces, drag and weight.

Question 14

Forces in forward flight (2)

Answer 14

Total resultant thrust

Total resultant drag

Question 15

Outline ground effect

Answer 15

When helicopter is hovering within 1 rotor diameter from the ground, it stops induced airflow through disc and the loft vector increases and less power is needed

Also reduces blade tip vortices

Question 16

Define recirculation

Answer 16

When the same air passes through the disc, which is more turbulent and reduces production of lift.

Question 17

Outline gyroscope precession

Answer 17

An input on a rotating mass, will have an output manifest 90 degrees in the direction of rotation. “Lag effect”

Question 18

Define disymmetry of lift

Answer 18

Advancing blade travels faster in relation to the realitive air flow. And the retreating blade travels slower. Blades will flap to equality to reduce this.

Question 19

How is retreating blade stall perceived when evident

Answer 19

Roll
Pitch up
Vibrations

Question 20

Outline coriolis effect

Answer 20

Acceleration and deceleration as the rotor blades flap. When the centre of mass of a rotor blade moves towards the centre of rotation the blade will speed up.

Question 21

Purpose of tail rotor [2]

Answer 21

Counter main rotor torque

Alter fuselage heading

Question 22

Define translating tendency

Answer 22

When helicopter drifts from the thrust cuased by tail rotor to counter the rotors toqure.

To stop this. Manufacturers mount mast at a tilt

Question 23

Translational lift

Answer 23

When helicopter moves forward at about 16 to 24knts it will move out of its downward and into clean air. This gives a boost in lift

Question 24

4 defects of rotor blades

Answer 24

Delamination
Cracking
Erosion
Impact damage