Gyro Errors
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Joined: Sep 2005
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From: los angeles
Gyro Errors
Real Wander, Apparent wander and transport wander. I have read them all several times and don't quite understand it. I am not quite understanding the "direction of the gyroscopes spin axis actually moves from its alignment in space." anyone?
Joined: Apr 2004
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From: London, GB
Some video clips here for you to build the mental picture of rigidity and precession, http://www.gyroscopes.org/1974lecture.asp
If you're absolutely stuck after this, PM me.
If you're absolutely stuck after this, PM me.
Joined: Aug 2005
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From: fairly close to the colonial capitol
Wander is the loss of relational reference - to the horizon (for example in the ADI) - where the gyros spinning axis does not maintain a perfect 90 degree angle to the horizon.
Real Wander is caused by mechanical imperfections which can cause the axis to 'wander' from true vertical. Most modern mechanical gyros exhibit a very small amount of this error.
Transport Wander comes about due to the earths converging meridian lines.
In a N or S latitude, when your course carries you anything but directly N or S, the DGs output relative to the actual heading will change. The instrument to display an inaccurate reference - the magnitude of which varies according to direction and distance traveled and the degree of latitude you are in.
Apparent Wander is due to the rotation of the earth. The gyro maintains its spatial position - however due to the earths rotation - it will appear that the gyros indication is inaccurate.
While a laser gyro exhibits no appreciable real wander as does its mechanical counterpart, without compensation, both transport and apparent wander do occur within all gyro systems.
There are formulas for both transport and apparent wander compensation. Anyone recall them - I don't have this data on me ?
Real Wander is caused by mechanical imperfections which can cause the axis to 'wander' from true vertical. Most modern mechanical gyros exhibit a very small amount of this error.
Transport Wander comes about due to the earths converging meridian lines.
In a N or S latitude, when your course carries you anything but directly N or S, the DGs output relative to the actual heading will change. The instrument to display an inaccurate reference - the magnitude of which varies according to direction and distance traveled and the degree of latitude you are in.
Apparent Wander is due to the rotation of the earth. The gyro maintains its spatial position - however due to the earths rotation - it will appear that the gyros indication is inaccurate.
While a laser gyro exhibits no appreciable real wander as does its mechanical counterpart, without compensation, both transport and apparent wander do occur within all gyro systems.
There are formulas for both transport and apparent wander compensation. Anyone recall them - I don't have this data on me ?
Psychophysiological entity
Joined: Jun 2001
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From: Walton on the Naze Essex.
Originally Posted by selfin
Some video clips here for you to build the mental picture of rigidity and precession, http://www.gyroscopes.org/1974lecture.asp
If you're absolutely stuck after this, PM me.
If you're absolutely stuck after this, PM me.
Joined: Apr 2004
Posts: 734
Likes: 10
From: London, GB
Dplus$, check PM.
App. topple is 15 · cos(lat) per hour.
App. drift is 15 · sin(lat) per hour.
Transport wander is (E/W GS · tan(lat))/60 per hour.
(GS being groundspeed)
Simple table I was taught is:
NH SH
RW ±° ±° [as given]
ER - + [15 · sin(mean lat)]
LN + - [15 · sin(lat as set)]
TWE - + [E GS/60 · tan(mean lat)]
TWW + - [W GS/60 · tan(mean lat)]
PER HOUR.
--
[edit]
LR, for all his shortcomings Eric was a brilliant teacher and a very inspiring fellow. Article he wrote in '74 here, http://www.gyroscopes.org/papers/The...0umbrellas.pdf
App. topple is 15 · cos(lat) per hour.
App. drift is 15 · sin(lat) per hour.
Transport wander is (E/W GS · tan(lat))/60 per hour.
(GS being groundspeed)
Simple table I was taught is:
NH SH
RW ±° ±° [as given]
ER - + [15 · sin(mean lat)]
LN + - [15 · sin(lat as set)]
TWE - + [E GS/60 · tan(mean lat)]
TWW + - [W GS/60 · tan(mean lat)]
PER HOUR.
--
[edit]
LR, for all his shortcomings Eric was a brilliant teacher and a very inspiring fellow. Article he wrote in '74 here, http://www.gyroscopes.org/papers/The...0umbrellas.pdf
Last edited by selfin; 31st July 2006 at 16:46.
