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Weapons & fire control on troopships, AMCs

 
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Ralph Currell



Joined: 15 Aug 2007
Posts: 7

PostPosted: Wed Aug 15, 2007 8:10 pm    Post subject: Weapons & fire control on troopships, AMCs Reply with quote

Hello all,

I'm looking for information on the armament used on the large British troopship liners in WWI, particularly RMS Olympic. I know Olympic had six 6-inch guns during the latter half of the war, but I've been unable to find photos or drawings that show them in any detail. I assume the same type of guns would have been used on other liners such as Mauretania and Aquitania. Looking at http://www.navweaps.com/Weapons/WNBR_Main.htm, it seems the British used several types of 6 inch gun and mounting during this period; knowing exactly which model was used would be a great help.

I'd be very interested to know about fire control arrangements on these ships too. Olympic seems to have had at least one rangefinder mounted aft, and range clocks both forward and aft. Would these have been 'networked' to the guns for passing data? There are electrical cables that may be used for this but the photos I have are not very clear.

Any information on these topics (or suggestions as to sources) would be most welcome.

Best regards,
Ralph Currell
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tone
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PostPosted: Thu Aug 16, 2007 1:45 pm    Post subject: Reply with quote

I'd have to guess these ships all used low-velocity (early) variants of these guns... particularly when 6-in was being used.

e.g., this 26-cal weapon used on a similar (?) converted ship:

http://www.navweaps.com/Weapons/WNBR_6-26_mk6.htm

High velocity guns usually required special framing to resist their recoil and weight.

Quote:
I'd be very interested to know about fire control arrangements on these ships too. Olympic seems to have had at least one rangefinder mounted aft, and range clocks both forward and aft. Would these have been 'networked' to the guns for passing data? There are electrical cables that may be used for this but the photos I have are not very clear.


I'm actually surprised to learn of the presence of a rangefinder, and any "range clocks" (by which you probably mean consort range indicating clock faces... "range clock" being a term often used but fraught with ambiguity) totally perplex me.

While those surprises might reduce my confidence in a general guess as to arrangements for FC, I'll offer one nonetheless (I'm a maverick!)

The rangefinder would have been accompanied by a dumaresq and some very good spotting glasses, and a clockwork Vickers range clock. I'll presume these would have been kept right near the rangefinder, but they might have moved this belowdecks.

The rangefinder would have been used early in the encounter, and then (my guess) almost ignored. I doubt plotting would have been performed anywhere. An initial range or two would be taken, and a guess at target speed an inclination entered onto the dumaresq to derive a range rate for the target. The Vickers would be wound up and set to the present range and rate and started off.

Communication to the guns would be by telephony, with two circuits wending their way to all gun positions (main and auxiliary for fault tolerance). The team with the range clock would call out ranges to sightsetters at the guns (who would be wearing telaupads ... headphones in modern parlance). The guns would be fired on command, and a range for the next salvo would be talked out a few seconds in advance of when the salvo should take place. When the Vickers clock passed this pre-talked range, a "fire!" command would be shouted out on the phone (or, less likely, a separate gong circuit triggered). Deflection would similarly be telephoned out to the guns (being looked up on a graph from range and speed-across on the dumaresq). Spotting corrections to range would be applied to the Vickers clock, and those to deflection would merely be tallied on a note card, and likewise fed out to the guns for the next salvo.

This is a guess, of course. The primary factors in my making it are that there would have been little interest and/or resources available in equipping and maintaining these vessels with range/deflection/order transmitter/receiver pairs, and certainly not follow-the-pointer sights for helping the sightsetters keep their sights in ship-wide harmony.

There clearly would be no director firing.

I have to return to my puzzlement on the presence of a rangefinder and range indication equipment. Was the RF around 4.5 feet or 9 feet in length? Can you send/post some large scans of the range signaling devices? Might they have been something as modest as rough gauges to indicate the line of bearing for a sighting of submarine/mine/torpedo? They hint at a surprising attempt at ambitious firing. I have to wonder what that was all about.

In contrast, a book I have from American ships of the "District Naval Force" indicates that the guns on these vessels were employed to ward off submarines, and it has NO indication of much advanced control being on the table. It is all a matter of "rules of thumb", such as that gun sights should be left at 800 yards at all times. It appears that rangetaking was not in any way a part of the gunnery method of this ersatz naval force (whose composition is sadly unknown to me).

tone
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Ralph Currell



Joined: 15 Aug 2007
Posts: 7

PostPosted: Thu Aug 16, 2007 7:36 pm    Post subject: Reply with quote

Tone,

Thanks for a very detailed and informative reply!


Quote:
I'd have to guess these ships all used low-velocity (early) variants of these guns... particularly when 6-in was being used.

e.g., this 26-cal weapon used on a similar (?) converted ship:

http://www.navweaps.com/Weapons/WNBR_6-26_mk6.htm

High velocity guns usually required special framing to resist their recoil and weight.


Possibly. I know Mauretania and Lusitania were actually designed with 'hard points' to carry guns (the Admiralty payed in part for their construction) but I'm not sure if that was the case with Olympic.

Quote:
I'm actually surprised to learn of the presence of a rangefinder, and any "range clocks" (by which you probably mean consort range indicating clock faces... "range clock" being a term often used but fraught with ambiguity) totally perplex me.


This is the stern of Olympic. The rangefinder is something of a guess on my part; I can't think of what else this object might be (it's visible in the upper left of the attached pic). It seems to be about 7 or 8 feet across, but of course that depends on the angle it's being viewed at.


This is one of the stern guns, with an odd curved crane or davit projecting from the rear.


A view from aft (just behind and below the suspected rangefinder) showing the clock faces. There were four of these at this location, two apparently measuring range and two bearing.


This a view from forward, showing the clock faces and one of the forecastle guns. There's a screened area on the bridge roof (just behind the clocks) that would be a logical place for a forward rangefinder, but I have no photos that would confirm or refute this.


<very informative speculation snipped>

Quote:
I have to return to my puzzlement on the presence of a rangefinder and range indication equipment. Was the RF around 4.5 feet or 9 feet in length? Can you send/post some large scans of the range signaling devices? Might they have been something as modest as rough gauges to indicate the line of bearing for a sighting of submarine/mine/torpedo? They hint at a surprising attempt at ambitious firing. I have to wonder what that was all about.


In his memoirs, Olympic's captain mentions that the 6-inch guns came with about 40 naval ratings and a mate gunner, if that is any help in judging the scale of the operation. I do know that Olympic often travelled alone rather than in convoy (there were few escorts who could keep up with her) and perhaps they wanted to give her the ability to handle something like a surface raider.

Regards,
Ralph
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PostPosted: Fri Aug 17, 2007 3:31 pm    Post subject: Reply with quote

Ralph -- you have many good pictures. Those are clearly substantial, long barrel weapons, not at all what I imagined, and I'd suspect this is the benefit of the special provisions in the construction your research has illuminated.

The little davit near the breech of the gun is associated with the regular operation of the gun. I have seen similar items before, but I have to confess I am not sure what they are.

The image showing a "cable" is interesting. It might be a flexible voice pipe. Are you so familiar with the vessel's ordinary rigging that you'd confidently guess that this line is part of the war fittings?

One more guess about these clock faces is that they are actually a means of communicating rough ranges and bearings NOT to consort ships, but to her own sightsetters. This would certainly be low-tech!

I'd have to see the dial faces in higher clarity to be sure that they are not all the same, and intended to be range-only, with 2 hands together communicating the value.

Consulting a drill book, a 6 inch BL or QF gun ordinarily had 9 men in its crew, but this might have been altered for this sort of mounting due to differences in the ammunition supply or limited manpower. I'd think this would leave few men for any other task than servicing the guns unless non-gunners were employed in assisting roles.


tone
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Ralph Currell



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PostPosted: Fri Aug 17, 2007 8:06 pm    Post subject: Reply with quote

Quote:
Ralph -- you have many good pictures. Those are clearly substantial, long barrel weapons, not at all what I imagined, and I'd suspect this is the benefit of the special provisions in the construction your research has illuminated.


In Olympic's case I suspect the reinforcing took place when the troopship conversion was done at Harland & Wolff, the original builders. But yes, they look like pretty big guns. I wonder if Olympic received the guns originally earmarked for Lusitania after the latter sank.

Quote:
The image showing a "cable" is interesting. It might be a flexible voice pipe. Are you so familiar with the vessel's ordinary rigging that you'd confidently guess that this line is part of the war fittings?


I'm pretty sure it was a wartime addition. Here's another shot showing the item (looking aft, running past a searchlight or signal lamp from the lower right). I confess I hadn't considered the voice pipe option, but it is certainly possible.


Quote:
One more guess about these clock faces is that they are actually a means of communicating rough ranges and bearings NOT to consort ships, but to her own sightsetters. This would certainly be low-tech!

I'd have to see the dial faces in higher clarity to be sure that they are not all the same, and intended to be range-only, with 2 hands together communicating the value.


The pic I posted was a capture from a video that can be seen online here:
http://www.nfb.ca/enclasse/ww1/en/film.php?id=531546
One of the dials seems to be graduated from 0 at the top to 40 at the bottom (same markings left and right) if that suggests anything.

Quote:
Consulting a drill book, a 6 inch BL or QF gun ordinarily had 9 men in its crew, but this might have been altered for this sort of mounting due to differences in the ammunition supply or limited manpower. I'd think this would leave few men for any other task than servicing the guns unless non-gunners were employed in assisting roles.


Yes, ammunition storage and supply is another big question mark. I'll have to keep digging in the hope that more photos or other documents show up.

By the way, I've been looking at some of the simulator videos you have on your site. Fascinating stuff! I've worked with fire control instruments in the field artillery, but we didn't have to worry about the guns and targets moving in different directions. :)

Regards,
Ralph
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tone
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PostPosted: Fri Aug 17, 2007 9:48 pm    Post subject: Reply with quote

Ralph Currell wrote:

One of the dials seems to be graduated from 0 at the top to 40 at the bottom (same markings left and right) if that suggests anything.


That suggests to me that this is knots of deflection, left and right. But 40 knots deflection is an awful lot. I can imagine it, however, as this is a fast ship and the fire would likely be at short ranges.

The video shows that the thing you interpreted as a cable entering the gun shield is just a davit -- there are two shown in the video between 0:50 and 1:05

tone
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Ralph Currell



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PostPosted: Sat Aug 18, 2007 5:23 pm    Post subject: Reply with quote

Quote:
That suggests to me that this is knots of deflection, left and right. But 40 knots deflection is an awful lot. I can imagine it, however, as this is a fast ship and the fire would likely be at short ranges.


That sounds quite likely. I wonder why there would be two pairs of clock faces aft but only one forward. Perhaps the main mast or the ship's cranes interfered with visibility, requiring one pair for each aft gun.

Quote:
The video shows that the thing you interpreted as a cable entering the gun shield is just a davit -- there are two shown in the video between 0:50 and 1:05


Possibly, though the davit would have to fold down or be removed for the gun to traverse fully. I wish I had a better photo of the guns.

Tone, thanks again for your explanations and informed speculation. I hope some day to find better photos or documentation of Olympic's armament but at least I now have a good idea of the technology and practices of the era. If I come across any other evidence I'll post it here.

Regards,
Ralph
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Ralph Currell



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PostPosted: Wed Sep 05, 2007 1:23 pm    Post subject: Reply with quote

Here are a couple of new photos of Olympic's guns:

http://rpmshipboat.fotopic.net/p2802780.html
http://rpmshipboat.fotopic.net/p2802779.html

The first one shows that davit above the breech, with an odd conical device hanging down. Any ideas what that might be? I can't recall seeing anything similar on other ships.

Regards,
Ralph
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PostPosted: Wed Sep 05, 2007 8:15 pm    Post subject: Reply with quote

I will ask knowledgeable friends. One thought that has occurred to me is that it is a light with a shade for night use. Does that sound corny?

tone
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Ralph Currell



Joined: 15 Aug 2007
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PostPosted: Wed Sep 05, 2007 8:52 pm    Post subject: Reply with quote

tone wrote:
One thought that has occurred to me is that it is a light with a shade for night use. Does that sound corny?


Tone,

No, not corny at all. It makes as much sense as any other explanation I've thought of. It would illuminate the breech area, and presumably other small lights would exist for the range and deflection scales.

Regards,
Ralph
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PostPosted: Thu Sep 06, 2007 8:52 pm    Post subject: Reply with quote

Still awaiting word on my inquiry, but I can say with complete confidence that the sightsetter dials had small lamps to illuminate their indices. Ditto, the telescopes had lamps fitted to cast their beams on the crosshairs.

I can easily imagine these were lamps meant to light up the working area, possibly red tinted.

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Ralph Currell



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PostPosted: Sun Sep 09, 2007 2:06 pm    Post subject: Reply with quote

Here's a couple of related pics that seem to support the light fixture explanation. The lamp in the second picture apparently swivels to allow illumination of the breech and either of the gunlayer's positions.

http://cas.awm.gov.au/photograph/a00100
http://cas.awm.gov.au/photograph/130004

And a photo of the liner Aquitania with a 6" gun (probably similar to Olympic's, but without the shield).
www.hospitalshipbritannic.com/images/Aquitania_gun_web.jpg

Regards,
Ralph
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