# how does a gyro compensate for the problems that result from the influence of the earths rotation?

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• RickH
Lv 6

Gyros do not in any way that I am aware of, respond or react to the Earth's rotation.

All gyros have the property of "rigidity in space." Ever wonder why a spinning top tends to stand upright until it starts to slow down? This is because of that property. Gyros do NOT respond to magnetic fields, are not aligned to True North, but some do respond to gravity albeit very slowly.

This is what allows them to be used to keep the greasy side down when in the clouds. Even in VMC, a DG makes the job of flying a constant heading much easier because it doesn't respond to acceleration and/or bank angle as a magnetic compass will.

A Directional Gyro (DG) is usually aligned to Magnetic North, and has to be reset from time to time because the gyro precesses. A slaved DG will keep constantly aligned to Magnetic North using flux gates which are just fancy remote magnetic sensors usually located in the wing. I've never really thought about it, but I do wonder if DGs in small airplanes operating in the very far North and South, in the area known a the Area Of Magnetic Uncertainty (AMU) are set to True North. In fancy airplanes with IRUs and GPSs, up around 60N or so, the heading reference changes to True.

An Artificial Horizon (AH or ADI) will respond to its perception of gravity by very very slowly realigning itself to "GRAVITY." I quoted "GRAVITY" because in a coordinated turn, GRAVITY is the bottom of the airplane, so the AH will try to align itself to the bottom of the airplane. This effect completely cancels itself out in a 360 degree turn, but at the end of a steep 180 degree turn, the AH will show a slight climb and a turn in the opposite direction for a short period until in realigns itself with the real "GRAVITY"

Actually, now that I have said no way. I do wonder if IRS units have gyros installed that somehow, as a part of their IRSing, detect the Earth's rotation during alignment on the ground.

Conventional gyros are made to track magnetic north, and to give a reading of how many degrees off from that course you are. The only interference issues are from magnetic sources other than magnetic north, which throw off the rotation. Another form of gyros used, mainly on military aircraft are RLG's, or Ring Laser Gyros. These have no spinning parts, but instead, use a laser, a shadow arm, and a photo detector lense. The light is sent in a shape, normally triangle or square, by mirrors, and when the object is in motion, the shadow arm comes from the null position to interrupt the light. The loss of light is then processed to a mathematical reading of degrees. There are normally 3 per aircraft for X, Y, and Z axis,

• Anonymous

As gyros go they are not effected by the Earth's rotation, they are customarily magnetic gyroscopic compasses and do not have any influence from the Earth or the rotation of it. The only thing modern day compasses would be effected by is electromagnetic interference or lightning storms. Spinning and diving would always show true north and there is little other than that which could effect it.

The gyro that determines level however is a weight based gyro it registers the pull of gravity on the plane and shows which way is down for instance so the plane always registers where the ground is.

Gyros percess over time. It is recommended that a heading indicator that is ran by a gyro be adjusted to the magnetic compass to correct for this problem. It needs to be checked in an aircraft every fifteen minutes. I have seen it percess as much as 30 degrees in 15 minutes.

• Anonymous

the IRS systems based on gyros have the corrective element called "Fucault's pendulum", which is used to reallign the gyro to the local gravity vertical.

Artificial horizons either have their own corrective elements (like the air powered one, where a stream of pressured air is blowing against the gimball so that is creates force onto the gyroscope (two vlves at the opposite sides create differential in force (at the side the frame is closer to the valve there is higher force, acting against the frame sot the gyroscope has to react and eventually reallign - to the aircraft vertical i suppose.

most AI systems obviously have a "fast erect" to correct for imperfections in manufacture that would integrate error during the time elapsed, where pilot will manually allign the AI unit in stable, straight flight.