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Gyro Compass

as of Aug 15, 2010

Most of us have been fascinated,
at least for a minute,
by a child's "top" and/or a gyroscope.

Table of Contents

- Introduction
- My experience
- Interesting On-Line Manuals
- Saturn Guidance .doc - from Charles Carter

Introduction

When the rotor isn't spinning, a gyro is just a floppy thing,
but when the rotor is spinning, the dynamics are so unusual !!
Odd that just making the rotor spin causes such a difference !!

High school physics instructs one how to calculate its reactions, :-))

assuming you can measure the angular velocity and moment of inertia :-((
but I still don't have a physical sense of its behavior.

My experience - not much :-((

In the Army, I was in the Nike antiaircraft missile program which used free and rate gyros as part of the missile guidance control system. However, I was in the radar/guidance area, not the missile area - so never physically saw the gyros.

After the Army, I considered myself a real techie hot shot, and lucky enough got a job at Minneapolis Honeywell Aero Division testing "HIG" and rate gyros. I can wave my hands and kind of explain how those work,
but a gyro

- configured as a compass,
- capable of finding "True North"
- used for navigation,
eluded me.

A friend is an ex-submarine electronic tech who was inpart responsible for maintaining a gyro compass,

and another friend made his bundle selling Litton gyrocompasses.

The purpose of this page is to wave my hands some more

and imagine that I understand the operation of gyro compasses such as used in ships, especially submarines :-))

A bit of a confusion - an aircraft "gyro compass" is frequently a free gyro which must be frequently preset to magnetic north. It is used to indicate "North" during turns and accelerations that cause magnetic compasses trouble. It is not self-aligning (using the earth's rotation) with true north in the sense of a marine gyro compass.

from www4.hcmut.edu.vn/~huynhqlinh/project/Seminars/Gyro.doc
When stabilised the spin axis is maintained in the meridian plane by a precession equal but opposite to the drift at the particular latitude. When there is no tilting effect the marine gyrocompass will lose its directional properties and become useless. This is the case at the poles and also when a vehicle moves due west with a speed equal to the surface speed of the Earth. Because the latter condition can easily exist in an aircraft in the middle and upper latitudes, it cannot be used for air navigation.

Pictures of the SperryRand MK-19 gyro compass installation in the Nautilis Submarine on exhibit at Groton, CT.

NamePlate

Controller

Interesting On-Line Manuals

Elementary Non-technical Introduction to Gyro Gompasses
Good Start A 1944 Sperry (before Rand) GYRO-COMPASS GYRO-PILOT MANUAL
Add gun stablization A navy document MK-19 and MK-23 gyro compass. 6.5 MByte
Wonderful ;-)) THEORY OF THE GYROCOMPASS ( www.maritime.org/fleetsub/elect/chap17.htm ) 1,2 MByte Local copy)