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Questions regarding "director firing" video

 
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lflelli



Joined: 09 Feb 2008
Posts: 3
Location: Lithgow, Australia

PostPosted: Sat Feb 09, 2008 6:41 pm    Post subject: Questions regarding "director firing" video Reply with quote

In the video you see the gun-layer's elevation receiver with the red pointer oscillating. Am I correct in assuming that the oscillation is due to the rolling motion of the ship and that the pointer oscillation is the result of the director-layer keeping his telescope fixed on the target?

If so, does this mean that the motion of the director-layer's telescope is somehow superimposed on the elevation data transmitted from the plotting room?

It's my understanding (I'll admit - somewhat limited understanding) that (in the WW1 period) the elevation data was transmitted from the plotting room to the turrets and that the gun-layers would follow the pointer and elevate the guns to the commanded elevation. The guns were then left at this elevation setting. Since the ship is rolling, the elevation would only be correct for firing when the deck was level. The director's telescope was set parrallel with the deck and when the ship rolled level the target would "roll onto" the cross-hair at which point the director would fire the salvo.

My view on how things worked is a little different to what I saw in the video. Any clarification on this issue would be very much appreciated.

This is my first post, having just discovered this site - and what a fantastic site it is!

Lou
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tone
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Joined: 29 Oct 2004
Posts: 478
Location: Boston

PostPosted: Sat Feb 09, 2008 10:52 pm    Post subject: Re: Questions regarding "director firing" video Reply with quote

lflelli wrote:
In the video you see the gun-layer's elevation receiver with the red pointer oscillating. Am I correct in assuming that the oscillation is due to the rolling motion of the ship and that the pointer oscillation is the result of the director-layer keeping his telescope fixed on the target?


Yes, but this was actually an error on my part. The oscillation shown was a consequence of the director layer applying continuous aim against the roll of own ship. In reality, he would not do this, as the guns' hydraulics were not agile enough to track this.

digression: additionally, the maximum rate of angular data transmission in this system was fairly low -- a high roll rate for the ship could easily require the guns to have to elevate or depress at speeds greater than the transmitter/receivers could reliably communicate. A failure would likely be a misstep -- a mode of failure that cannot be detected until someone notices one or more guns are firing noticeably off in range.

Generally the director layer would fire "on the roll", and so the receivers would show only occasional movements as the director sightsetter applied changes or the director layer perhaps bumped the sights up or down to save a few seconds on the next salvo.

Quote:

If so, does this mean that the motion of the director-layer's telescope is somehow superimposed on the elevation data transmitted from the plotting room?


Well, yes and no. The transmitting station ("plot" in American parlance) doesn't actually compute elevations, but ranges, which it sends to the director where it is received on pointers on the director's sightsetter range dial. The sight mechanism in the director converts these range inputs into elevations that will loft the shells to the range, and it DEPRESSES the scopes on the director by that angle. The director layer then raises them back up, and THIS angle is the one transmitted to the guns.

Quote:

It's my understanding (I'll admit - somewhat limited understanding) that (in the WW1 period) the elevation data was transmitted from the plotting room to the turrets and that the gun-layers would follow the pointer and elevate the guns to the commanded elevation. The guns were then left at this elevation setting. Since the ship is rolling, the elevation would only be correct for firing when the deck was level. The director's telescope was set parrallel with the deck and when the ship rolled level the target would "roll onto" the cross-hair at which point the director would fire the salvo.


You are substantially right except for the elevation/range confusion. You know enough of this to have identified a mistake I made. If I recall correctly, I had programmed both modes of firing in the AI of the director layer, but most or all of my use of the prototype is done in continuous aim.

Lou, you should certainly post more, as you are a keen observer who brings a strong basic understanding in the door!

tone
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