Gyro Flashcards
Drift
Rotation in horizhontal direction
Rigidity
Maintains its orientation in space
(Second law of newton)
Requirments:
~dense material
~outer rim which increase radius
~high rotational speed ,RPM 15000 to 25000
Precession
The force applied is been applied 90 degrees further the gyro rotor
Gimbals
The mounting system comprises bearing and supporting frames collectively known as Gimbals
Vertical gyro
Horizhontal gyro
Vertical : when the axes is in vertical
Horizontal : when the axes is horizonthal
2 degress of freedom wiht two gimbals
The spin axes is never counted as degree of freedom
Rate of gyro
Rate gyro when the gyro has one degree of freedom (one gimbal)
Space gyro
When it has 2 degrees of freedom ( 2 gimbals)
Directional gyro
2 gimbals
Attitude indicator
2 degrees
Turn indicator
1 gimnbal and spring
Wander summary
~Wander : topple, drift
~real/random wander: mechanical imperfections, latitude nut
Apparent wander:earth, transport wander
All gyros suffer from real wonder (mechanical imperfection)
ERECTION SYSTEMS
To cope with topple we need an errection system
Earth rotion 600kts
15.04 degree per hour
Earth rate
Varies with latitude for directional gyro
15.04 x sine lat
Vertical gyro
Like in the equator
No drift ,max topple
Horizontal.
Like in the poles
Max drift ,no topple
Apparetn topple /drift
At the pole
~vertical gyro appear not to drift or topple
~horizontal gyro appear to drift
At the equator
~vertical gyro appear to topple
~an east aligned horizontal gyro appears to topple backwards to the vertical
~a north aligned horizontal gyrp will not topple or drift if it remains on th equator
Real wander
~Random wander: due to mechanical imperfection
~latitude compesation :(gimbal input) influence by gravity erection system
Horizontally tied
Latitude nut
Operational latitude ,small nut is adjusted on the gryo’s spin axis which inputs a real wander effect to correct its positon using the principle precession
Vetical tied
To keep the instrument gry ospin axis vertically tied a sub system causes a deliberate wander effect
Principle of precession
Precession used to correct for apperent wander (earth rate drift) in the direcrion gyro
The pirnciple of precession is used
For correct apparent wander ( topple) in the attitude indicator
Pneumatic driven
The air in requires filtering
Vacuum gauge indicates vacuum pressure
Electrically dirven
Advantages :
~higher rpms
~more accurate
~more reliable
~DC power supplying a DC motor
~Dc power to an inverter to supply constant frequency ac from an acmotor
~contanstan frequecny ac power to drive an ac motor
~frequency wild CANNOT be directly used
Electrically driven
Micro electro mechanical sesnors
~ring laser
~smaller lighter
~more reliable
~more accurate
~chea[er to purchase and maintain
Redundancy
Light a/c will have
Air driven pump for AI and DI ,and electrically driven for the turn indicator ,if the generators fails the turn coordinator will be still powered until battery dies
