Rotor Aerodynamic & flight controls Flashcards
Define: Chord or Chord Line
Chord line — a straight line intersecting leading and
trailing edges of the airfoil.
Define: Blade Pitch Angle (or Angle of Incidence)
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.
Define: Relative Wind
Defined as the airflow relative to an airfoil and is created by movement of an airfoil
through the air.
Define: Angle of Attack
Angle of attack (AOA) measured between
the resultant relative wind and chord line.
Define: Center of Pressure
The point along the chord line of an airfoil through which all aerodynamic forces are considered to act.
Define: Blade Coning
During takeoff, the combination of centrifugal force and lift cause the rotor disk to cone upward.-
Main rotor heads movements
feather or pitch
flap
teetering
lead and lag or hunt
main types of rotor head
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)
Semirigid rotor head ac
bell47 / bell206
fully articulated rotor head ac
S-58/Huges 500c/S76
Limits how far
down a blade will settle
droop stops
types of teeter stops
- dynamic stops (teerer limit that changes with rotor dpeed)
- static stops (max teeter limit)
type of Main rotor head lubrication
oil and grease
Self Lubrication ( teflon bearings)
life lubricated
What does mean to lead and lag a main rotor blade
horizontal movement about the hinge
function collective pitch control
a simultaneous and equal increase in pitch angle of all main rotor blades
function of the Throttle Control
The function of the throttle is to regulate engine rpm.
function of Governor/Correlator
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
function Cyclic Pitch Control
The purpose of the cyclic pitch control is to tilt the tip-path plane in the direction of the desired horizontal direction.
function Anti torque Pedals
control the pitch and therefore the thrust of the tail rotor blades or other antitorque system
what does the mast nut do
hold the rotor head
a semi rigid head allows what movements
flap and teering
hydraulic system purpose
provide flight control boost and eliminated rotor system feedback
Hydraulics are drive by?
main gear box
does the hydraulic system bypass?
no- if the system plugs it will shut down system
what is the min pressure that the hydraulic servo should be able to funtion at?
200 psi
what pressure should the hydraulic test stand be set to when doing a functional test system?
600 psi
A torque tube transmits what kind of motion?
angular or twisting
Rod-end bearings on a push-pull tube are some times riveted in place or ?
threaded
Push rods with a bearing end often will have a large washer installed under the retaining nut. Why?
This retains the rod on the bolt in the event of a bearing failure)
What allows rotation of the swashplate outer ring without putting undue stress on the control rods and pitch links?
drive link
A bell cranks in flight control systems can be used to change direction and provide:
mechanical advantage
what is the filtration rating of the hydraulic filter
15 micron absolute
how can be the hydraulic system adjusted
adding washers
if the hydraulic system has a red indicator button means that ?
block filter
will pulling the hydraulic circuit breaker shut off the hydraulic system?
no- because the solenoid needs power
