That is a most interesting insight, Agor.agor95 wrote:Now that is a point.
The centre of gravity of earth/moon is just under the earths crust.
As a result we have two tides 1. the moon's attraction 2. caused by the earth's rotating around this Centre of Gravity.
Now is the second effect causing the iron core to rotate [technical term alert - sloshing around]?
Moreover, the sloshing doesn't have to be large in feet and inches because the material is so stiff.
I'll explain what I mean in relation to the offset gyro.
To all external appearances the gyro disk is completely orthogonal to the axle connecting it to tower. To appreciate the internal strains one would either have to cut it up into individual masses as Laithwaite did - thanks for drawing attention to that, maybe you subconsciously realised the significance ;-) - or make the disk out of perspex or some other suitable transparent material, and view the dynamic disk with polarised light.
As an alternative one might mount sensitive strain gauges on the disk and measure the strains while the gyro is running. The forces generated by these strains will account for the moments opposing the horizontal and vertical moments.
Laithwaite was certainly hot on the trail and might have got there in the end had he lived long enough.
The consequence of the internal strains is that the gyro is orbiting the tower in a very shallow spiral (think of a flattened slinky). The free orbit that the disk would like to take, an open spiral virtually orthogonal to the orbit around the tower, is squashed nearly flat by the dynamic forces on the disk.
Thus the strain energy in the disk can correctly be seen as precession (3rd derivative) energy.
Just as with a yo-yo the Linear Kinetic Energy of vertical fall, LKE, is transmuted into the Rotational Kinetic Energy of the yo-yo, RKE, so also with the offset gyro the Linear and Rotational Kinetic Energies, LKE + RKE are transmuted into the Precession Kinetic Energy, PKE, of the offset gyro.
One might even think of it as an offset yo-yo. :-)