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Fascinating look into a Mechanical Computer

When I toured the USS North Carolina battleship about 10 years ago, the tour materials said that they tried matching the mechanical range-finding and bearing setting computer used to aim the 16" guns against a modern digital computer. Guess which one won? (Don't know if it is true or not, but it was a nice story ... and a fascinating tour.)
 
Very interesting.

I have a book from the 1940s concerning analog mechanical computing devices. having read (but not fully iunderstood) it, I immediately thought of the perfect practical example, which was indeed the TDC, since I have always been interested in the submarines. I put my chances of ever getting any data on a real TDC as less than zero..... This was outstanding, to be shown the manual, and to be able to snag the files. Big thank you.

Looking at the first sections of the TDC manual, I was immediately able to identify the resolver and integrator sections..... Now comes the detailed reading through (I saved the PDFs) to see what they were doing.

Just packaging that stuff.... yeesh.... That TDC was better than anything the opponents had, German engineering notwithstanding, according to the sources I have seen. And then to pack it that tightly.............

it detracts not at all from the accomplishment to mention that the entire thing could be done with a hand-held computer these days....
 
When I toured the USS North Carolina battleship about 10 years ago, the tour materials said that they tried matching the mechanical range-finding and bearing setting computer used to aim the 16" guns against a modern digital computer. Guess which one won? (Don't know if it is true or not, but it was a nice story ... and a fascinating tour.)

I'd bet it's true, the degree of mechanical perfection sought in pre-computer days far exceeded the nebulous goals of today.....That's all they knew about and they took it to the utmost.....

The 16" guns on the IOWA class battleships using the OPTICAL gunsights were incredibly accurate.....Of course, if haze, smoke, night or other visual impediments were in play, it was byguess or bygosh.....That is, until accurate radar came into use.....After that it was a case of run and hide NOW.....

Jim
 
Yes, very accurate rifles, because that is what they were. Sixteen inch rifled cannon barrels. A good barrel could hold "about" one minute of accuracy just like a good hunting rifle. One minute of accuracy at 100 yards is one inch.

Range of these guns was from 20 to 24 miles depending on which shell was being fired. There have been accounts of accuracy to 100 yards at 20 miles, but in one test firing of fifteen shots from different turrets, the maximum spread was more like 250 yds. Not someplace you would want to be when fifteen 2,700 lb projectiles were incoming.

16"/50 caliber Mark 7 gun - Wikipedia, the free encyclopedia
 
Modern digital fire control systems are more accurate than the old mechanical systems if only because they are more stable. Analog stuff drifts off and needs constant TLC to keep it within spec. A well tuned analog system could maintain 2 minutes accuracy in a rolling sea.

The main deficiency with US Navy guns was the ammunition. There was a significant variation in the speed that the rounds leave the barrel. The Royal Navy has much less variation in muzzle velocity.

During the Falklands war, the Naval guns were landing shells onto the same spot just making the shell hole bigger. They had to introduce random glitches into the software to spread the shells.
 
Conrad,
Thanks!
I remember seeing those for sale as a kid, but never seeing one up close.
I was Fascinated! Never could remember the name of it, or how to search for it...
 
Thanks for posting. Dose anybody know who built them?

Todd

"Both the Mk III and Mk IV TDC were developed by Arma Corporation (now American Bosch Arma)."

From this page:

Torpedo Data Computer - Wikipedia, the free encyclopedia

Go to the original link, and back up a few steps.
LOTS of fascinating stuff to learn!

As a youngster I was totally fascinated with submarines, and couldn't get any details about all the systems and how they worked.
Now, it is old enough to be part of history, and mostly all available.
 
attached are pictures of part of an aiming computer from the Canadian navy. As I understand it this device drove a projector which projected an image onto a frosted glass plotting surace from the under side.
 

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