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Old 04-11-2020, 04:11 PM   #26
Fidd
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Join Date: Apr 2005
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I can't tell you how it worked on a ship, but I do have a better understanding than most of how aircraft instrument gyro's work, as a retired ATPL/IR and QFI.

I would imagine, (and this is surmise) you'd have a box of 2 or more gyros on the ship, which generate electrical currents proportional to the movements of the ship around the gyros, and these signals are used to drive electric or electro-hydraulic motors, more probably, to stabilise the hedgehog to local-earth vertical (according to the gyros) regardless of the movement of the ship. I doubt this was on all the time, but rather was enabled once an ASDIC contact was made, and disabled to aid reloading, when ideally you'd want the unit remaining to ship vertical, rather than earth-vertical during the reload.

The other way to do it would be to put a large weight as far below the hedgehog as possible, with a connecting structure. Although less accurate, this would have the benefit of being more reliable. A Flower Class is as about a hostile environment for a gyro as you could devise.

The Yanks used a similar system on remote-barbettes on B29's, so that the gunner in a blister could align his sight with a target, generating a signal which the turrets then attempted to bring to 0 difference electrically. This occurred far faster the greater the deviation, so once in the right area the corrections became progressively more accurate.
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