Right, ok then. Let's deal with drift nuts first. I'm moving some of your text around to deal with like subjects together - I hope you don't mind - I think I've retained the intent behind it. You've said:
What if the drift nut is there to accommodate constant friction, AND there were something else causing varying deflection on top of that? Of course there are many other possibilities. I encourage you to use your imagination, and to avoid the cul de sac of “what I know, and/or was taught, must be right / is the only possibility”.
...and also:
However, in the process of calibration I am suggesting that the systemic frictions of the mechanical system (when the gyro is mechanical and has a drift nut) as well as another influencer on the gyro are intended to be factored out as well as possible to maintain fixed bearing.
Again, the drift nut provides an adjustable correction depending on latitude. If it was there to correct a friction issue, it would be a one-off calibration that gets left alone. But it isn't. It varies with latitude. You seem to accept the mechanism, and that it works - that's great. But all you're offering is 'something else' and 'many other possibilities'. You can say I'm indoctrinated by my education all you like, but the fact is that this correction factor makes total sense on a globe earth rotating once every 24 hours, and no sense whatsoever on a flat earth. So I'm afraid your repeated dodging of the production of some credible explanation for why this 'other' factor varies with latitude does look very much like you don't have anything credible to offer. You've said 'many other possibilities' - let's hear just one.
I'm particularly curious to understand what you think is special about the equator on a flat earth. Why does the error reduce to zero at that particular latitude? On the globe, it makes perfect sense, as a directional gyro's orientation is such that the rotation of the earth won't effect its heading indication at this position, hence the sine of latitude being the correction term (sin x = 0 when x = 0). But it makes no sense on a flat earth - what's special about the circle us lacking-in-imagination science folk call the equator?
Next, let's talk about gyros on the ground versus gyros aloft or at sea. You've said:
In your belief, yes. In reality, likely not. Even if they did all rotate, they would not (and do not) rotate as one due to the mechanical properties of the medias themselves. The jet stream travels faster than the presumed rotation of the earth, and in the wrong direction. It is very silly to think that everything would rotate as one, but it is one of those fantastically silly things we learn by rote under the guise of education. It is in part to handle/rationalize the paradox that helicopters, balloons, and drones pose to the rotating globe model.
You've also made a similar point to Ron.
To be clear, all my points about directional gyros hold true on land anyway, so this debate is somewhat superfluous, but you are so completely, profoundly wrong on this one I can't let it slide. I think it's probably easier to come at the problem from another angle. Let's try:
1. Consider a simple gyro, with perfect bearings, on a gimbal mount that gives it full freedom to rotate. Let's keep it simple, and imagine we are at the North Pole. Now imagine the gyro's spin axis is horizontal to the ground, just like that in an aircraft's directional gyro. If we were to connect the axle of the gyro to some kind of pointer, we could make a rudimentary DG ourselves - if we spun the gyro up to speed, and held it our hands as we walked around, it would keep pointing in the same direction as we rotated, thereby giving us some way of orientating ourselves.
Agree so far?
2. The reason it does that is the principle of
rigidity. Given the freedom to rotate, a gyroscope's spin axis will continue to point in the same direction in an inertial reference frame. The gyro has no mechanical contact with land, sea, or air - if we have perfect bearings it feels nothing at all. It will just keep on pointing in the same direction. So if the earth is rotating, our gyro will keep pointing in the same direction - towards a star in the distance, for example.
3. This is equally true on the ground as in the sky or sea. If we put our gyro in a helicopter and hover above the North Pole for an hour, whilst keeping the helicopter pointing in the same direction with respect to the ground, our gyro will again remain fixed in space while the earth and our helicopter rotate around it.
4. So if we build a directional gyro, we compensate for drift by the sine of our latitude x 15 degrees / hour - so 100% of 15 degrees/ hour at the pole. It doesn't matter at all whether it's on the ground, in a balloon, or on a boat. The gyro has no contact with those things - it just keeps on pointing in the same direction while the world, boat/plane/truck etc rotates around it.
Hope that's useful.
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