Rotor Aerodynamic & flight controls

Question 1

Define: Chord or Chord Line

Answer 1

Chord line — a straight line intersecting leading and

trailing edges of the airfoil.

Question 2

Define: Blade Pitch Angle (or Angle of Incidence)

Answer 2

Angle of incidence is the angle between the chord line of a main or tail rotor blade and the rotor hub. It is a mechanical angle rather than an aerodynamic angle.

Question 3

Define: Relative Wind

Answer 3

Defined as the airflow relative to an airfoil and is created by movement of an airfoil
through the air.

Question 4

Define: Angle of Attack

Answer 4

Angle of attack (AOA) measured between

the resultant relative wind and chord line.

Question 5

Define: Center of Pressure

Answer 5

The point along the chord line of an airfoil through which all aerodynamic forces are considered to act.

Question 6

Define: Blade Coning

Answer 6

During takeoff, the combination of centrifugal force and lift cause the rotor disk to cone upward.-

Question 7

Main rotor heads movements

Answer 7

feather or pitch
flap
teetering
lead and lag or hunt

Question 8

main types of rotor head

Answer 8

rigid-(feather)
semi-rigid (feather and teering)
tri-hinge or semi-articulated (feather,teeter,flap)
fully articulated (feather,flap lead and lag)
bearingless or soft in plane(feather, flap, lead and lag)

Question 9

Semirigid rotor head ac

Answer 9

bell47 / bell206

Question 10

fully articulated rotor head ac

Answer 10

S-58/Huges 500c/S76

Question 11

Limits how far

down a blade will settle

Answer 11

droop stops

Question 12

types of teeter stops

Answer 12

• dynamic stops (teerer limit that changes with rotor dpeed)

- static stops (max teeter limit)

Question 13

type of Main rotor head lubrication

Answer 13

oil and grease
Self Lubrication ( teflon bearings)
life lubricated

Question 14

What does mean to lead and lag a main rotor blade

Answer 14

horizontal movement about the hinge

Question 15

function collective pitch control

Answer 15

a simultaneous and equal increase in pitch angle of all main rotor blades

Question 16

function of the Throttle Control

Answer 16

The function of the throttle is to regulate engine rpm.

Question 17

function of Governor/Correlator

Answer 17

A governor is a sensing device that senses rotor and engine rpm and makes the necessary adjustments in order to keep rotor rpm constant
A correlator is a mechanical connection between the
collective lever and the engine throttle

Question 18

function Cyclic Pitch Control

Answer 18

The purpose of the cyclic pitch control is to tilt the tip-path plane in the direction of the desired horizontal direction.

Question 19

function Anti torque Pedals

Answer 19

control the pitch and therefore the thrust of the tail rotor blades or other antitorque system

Question 20

what does the mast nut do

Answer 20

hold the rotor head

Question 21

a semi rigid head allows what movements

Answer 21

flap and teering

Question 22

hydraulic system purpose

Answer 22

provide flight control boost and eliminated rotor system feedback

Question 23

Hydraulics are drive by?

Answer 23

main gear box

Question 24

does the hydraulic system bypass?

Answer 24

no- if the system plugs it will shut down system

Question 25

what is the min pressure that the hydraulic servo should be able to funtion at?

Answer 25

200 psi

Question 26

what pressure should the hydraulic test stand be set to when doing a functional test system?

Answer 26

600 psi

Question 27

A torque tube transmits what kind of motion?

Answer 27

angular or twisting

Question 28

Rod-end bearings on a push-pull tube are some times riveted in place or ?

Answer 28

threaded

Question 29

Push rods with a bearing end often will have a large washer installed under the retaining nut. Why?

Answer 29

This retains the rod on the bolt in the event of a bearing failure)

Question 30

What allows rotation of the swashplate outer ring without putting undue stress on the control rods and pitch links?

Answer 30

drive link

Question 31

A bell cranks in flight control systems can be used to change direction and provide:

Answer 31

mechanical advantage

Question 32

what is the filtration rating of the hydraulic filter

Answer 32

15 micron absolute

Question 33

how can be the hydraulic system adjusted

Answer 33

adding washers

Question 34

if the hydraulic system has a red indicator button means that ?

Answer 34

block filter

Question 35

will pulling the hydraulic circuit breaker shut off the hydraulic system?

Answer 35

no- because the solenoid needs power