Gyroscoptic Principles And Directional Gyro Flashcards
(27 cards)
What’s a gryo
A spinning rotor with 2 degrees of freedom that keeps its fixed orientation in space
What 2 properties does a Gyro have
Precession and rigidity
What is rigidity
The ability of the Gyro to stay fixed in space
The faster it span with more mass on the outer rim the more rigid
It is dir prop to moment of inertia and angular velocity
What is precession
It is the change in direction of the plane of rotation caused by a 90° force applied
It’s dir prop to force / rigidity
What are the 2 degrees of freedom
The inner gimabl and outer gimbal
It means you can also use the Gyro as an artifical horizon
What is a ring laser gyro
It uses a beam of light that gets split into 2 and the change in frequencies between them translates into a measure of rotation
What is the problem with a ring laser gyro
At slow rotation rate there is minimal frequency changes so both beams are read the same = laser locking
How to stop laser locking
With a dither motor
How is a ring laser gyro powered
By electrics or pneumatics and more than 1 system for redundancy
What are the types of wander
Real wander = instrument error
Apparent wander = earth rate changes due to an observer
Transport wander = when the gyro is physically moved then no longer points at North
What directions can wander occur in
Topple- vertical
Drift - horizontal
What is a directional gyro
It provides a stable directional reference that has better short term stability than a DRC
But needs to be calibrated every 10/15mins in straight and steady flight
What is a caging knob
Allows the gyro to be resynchronised so gives instant re erection of the system
Equation for horizontal situation indicator
HSI = Directional Gyro + Course Deviation Indicator
Equation for apparent wander
15° x sin(lat°)
In the NH then a negative heading changes means then positive heading change means
Gyro drift to the right
Gyro drifts to the left
And opposite in SH
What is drift at equator compared to poles
0 at equator and 15° max at poles
What is the latitude nut
It produces real wander opposite and equal to the apparent wander therefore cancels wander out
What is the remote reading compass
It’s the main compass that uses a flux valve to read accurately the direction
What are the components of a RRC
A magnetic detector unit / Flux valve
A precession amplifier
Precession/ torque motor
What is a bevel gear
It drives the horizontal card
If the gyro remains synchronised what is the error
Zero 0
What is an annunciator
Is a device that shows whether the gyro is synced with the earths magnetic field
What is the flux valve made up of
A primary coil
Secondary coils with 800hz output
3 spokes set to 120° which reduces ambiguity
Collector horns
