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Old 04-19-08, 06:38 PM   #1
Trex
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Quote:
Originally Posted by kurtz
I'm talking off the top of my head here, but I believe US and UK ordnance of WWII used seperate Shot/propellant rather than the German (and the 105s) single shell system...maybe that's just the bigger guns though?
The Germans always seemed to prefer cases, even for very large guns. I've seen some which must be 16" or better.

In current useage, the 105mm is semi-fixed, meaning that it has a brass or steel case with a number of charge bags. Depending on range, type of projectile, etc, the gunners take out and discard a given number of bags according to a firing table before the inserting the projectile into the case. The other three standard NATO ones are 155mm, 175mm and 203mm. The 175 is just about history and few use the 203mm either. None of these use a case - the projectile is inserted into the breach first, then charge bags are added. Finally, after the breach block is closed, a small primer is inserted, much like a small arms cartridge, to ignite the propellent.

Prior to NATO standardization, there were a plethora of different guns, from 37mm on up. Some used semi-fixed, some did not. The standard British field gun, the 25-pounder, was semi-fixed, as was the US 105mm howitzer. The 37mm and 57mm antitank guns used fixed ammo - the cartridge came fully assemled.

Hope that is of some help.

Last edited by Trex; 04-20-08 at 12:19 AM.
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Old 04-19-08, 07:37 PM   #2
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Default gun protection

Hi Trex. Can't really comment with any certainty regarding protection for the gun and crew, but will try to give an overview from my perspective...

we're looking at US troops, and I'm not an American. I served in the RAA (that's Australian artillery). Doctrine is different, but not all that different. If I make an error of judgement that is one potential source of error.

First off, you'd need to know why they were there, and how long they intended staying, and what they thought the threat level was. If you want to entice combat (make them attack you) you set up in a spot that is very inconvenient for the enemy. The Australian deployment at Nui Dat in Vietnam was a deliberate choice (set up on a supply route then tell everyone that anyone seen after dark will be shot without question) to force the VC to act. In that case the arty was dug in with close cover. When the NVA started moving south for Tet they had to pass near the Marine base at Khe Sahn, so the Marines were re-inforced and toughed it out against significant odds (but gave 3 NVA Divisions a bloody nose in the process). They were also dug in, as the NVA had 130mm artillery pieces and rocket artillery.

In the case of the Taliban, they do not have the capacity to focus large arty concentrations. Also, the US probably doesn't want to seem 'rooted to the spot' andprefers to maintain mobility. Finally, they may not want to give the impression that they have a 'defensive' mentality. Realistically, mortars and rockets are not accurate, and while they can throw fragments a long way and make a loud bang, it is better with low numbers of incoming rounds to be in the open (and wear flack jackets... look for them on the crew) so the blast is dispersed rather than risk focussing the energy of a lucky hit.

Like I said, these are all 'spit ball' ideas because I have absolutely no idea of the specific circumstances around the deployment of those guys at the time of the video, but hopefully have been able to give an idea of some of the considerations that may have been in play.

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Old 04-19-08, 08:26 PM   #3
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In my experience mortars are very accurate. More so than artillery if you want to hit a "point-target", i dont know the english term. In a mountain enviroment, attacking firebases, mortars would be very handy. With high rate of fire, 15-20 rounds a minute, and accuracy you could suppress that compound very effectively. Luckily the Taleban training is probably not cut out for this.
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Old 04-19-08, 08:49 PM   #4
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Fair comment. Depends on usage, model and training. Don't forget mortars have been rejected for service because they were too accurate. I am aware that the old British 2" mortar in the hands of a good operator could drop a round onto a point target (like a MG) with only one or 2 shots, but at ranges of around 300yds. The Taliban are nothing like that. Plenty brave enough, but not really the education base for the majority of them to do proper training. The smarter ones are usually employed in other areas like planning, comms, intelligence and making things. I still stand by my comments though, it would have been a risk assessment by the unit commander as to the levels of protection needed, and the man on the spot deemed the risks to be low. If the Taliban had demonstrated a capacity to shoot a tight group at 15rpm and actually hit something I dare say the protection levels would have been higher.

As to being more accurate than artillery, I watched from an OP as my regiment did a demo shoot for some visiting infantry. Their faces turned white as the FOO called in corrections of 10m (the guns were 6km away) and walked a converged grouping (guns firing at a set point rather than as a pattern) over a weapons pit and caved it in. Haven't yet seen a mortar team do that.
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Old 04-20-08, 03:04 AM   #5
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Thanks Trex, Things I never knew. So firing the guns on US and British subs involved handling possibly wet sacks of cordite on deck?
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Old 04-20-08, 07:04 AM   #6
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Recommend the following site:
http://www.navweaps.com/Weapons/WNUS_5-25_mk10.htm

Figure the ROF is high as listed- (fixed charges -vs- separate ). The smaller 4" and 3" guns were fixed ammunition. Trade weight in shot for velocity between the calibers.

Proj weight for 4" gun: 63lbs total, for 5" gun: 80lbs...

Surface action took alot of balls on a submarine. The afforementioned ammo chain, prep the gun from submerged tie down, and just being plain exposed.... hats off to those crews. Back in the day when I was in armor- our 105mm could pop a round every three seconds. That was with a ready rack right behind you, and the loader working flat out.

On a sub the rounds are flying slower (APFSDS was around 5,200+ ft/sec on the tank; 5"-25 listed on the given website 2,155ft/sec) and they'd likely want to observe each round. At roughly five seconds or so to 4,000 yrds.... yeah, ROF would be less. Of course, if that Jap destroyer caught you w/o being able to dive.... that ROF might just be amazing.
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Old 04-20-08, 07:07 AM   #7
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Quote:
Originally Posted by kurtz
Thanks Trex, Things I never knew. So firing the guns on US and British subs involved handling possibly wet sacks of cordite on deck?
Separate charge in this case meant shell and casing (powder in brass). URL in above post states this was specially done to accomendate submarines.
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Old 04-21-08, 09:41 AM   #8
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Quote:
Originally Posted by piersyf
Fair comment. Depends on usage, model and training. Don't forget mortars have been rejected for service because they were too accurate. I am aware that the old British 2" mortar in the hands of a good operator could drop a round onto a point target (like a MG) with only one or 2 shots, but at ranges of around 300yds. The Taliban are nothing like that. Plenty brave enough, but not really the education base for the majority of them to do proper training. The smarter ones are usually employed in other areas like planning, comms, intelligence and making things. I still stand by my comments though, it would have been a risk assessment by the unit commander as to the levels of protection needed, and the man on the spot deemed the risks to be low. If the Taliban had demonstrated a capacity to shoot a tight group at 15rpm and actually hit something I dare say the protection levels would have been higher.

As to being more accurate than artillery, I watched from an OP as my regiment did a demo shoot for some visiting infantry. Their faces turned white as the FOO called in corrections of 10m (the guns were 6km away) and walked a converged grouping (guns firing at a set point rather than as a pattern) over a weapons pit and caved it in. Haven't yet seen a mortar team do that.
I agree on most but the accuracy issue. The practices can differ from country to country but here we can hit a point target with mortars in 1-2 shots atleast 99% of the time, from any range. In a normal situation the target isnt visible from the fring position. This isnt a infantry vs artillery thing for me as i love both and long range artillery/MLRS, is what i usullly have in use in recon missions. We dont have fixed units under one FO, FOs are in the platoon level, he buddies with the platoon commander in the infantry and artillery has some of their own. The units and (tulenkäyttöoikeutta, dont no the term) amount of firepower in your use, is given to you based on the situation by the FO commanders in company, batallion etc. level. So in theory a situation could come that i could be commanding several batteries at one time, as was the case in last war where the Soviet invasion was stopped with massive concentrations of fire. Ofcourse i can only give my word but we have both artillery and mortar units that can do what you described. But if your ever in Finland i can take you to have a look, you being ex military and me having connections it shouldnt be a problem.
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Old 04-21-08, 09:58 AM   #9
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Happy Times - I am a great fan of both guns and mortars. They are, I think, complimentary. In Afghanistan however, lacking the sophisticated survey and rangefinding equipment needed for a first-round hit in rugged terrain, correction would have to be by old-fashioned '50 Up, 75 Left' method - and around built-up ISAF bases, that's unhealthy. Fortunately.

I would love to be able to visit Finland sometime. Beautiful women, a remarkable history and climate that's never 140 in the shade - what's not to like?
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Old 04-21-08, 10:27 AM   #10
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Quote:
Originally Posted by Trex
Happy Times - I am a great fan of both guns and mortars. They are, I think, complimentary. In Afghanistan however, lacking the sophisticated survey and rangefinding equipment needed for a first-round hit in rugged terrain, correction would have to be by old-fashioned '50 Up, 75 Left' method - and around built-up ISAF bases, that's unhealthy. Fortunately.

I would love to be able to visit Finland sometime. Beautiful women, a remarkable history and climate that's never 140 in the shade - what's not to like?
Well said, they ARE complimentary.
Off course we have here first rate maps but i think i could do hit just as well with 3 81mm mortars, some pen and paper stuff i dont know how to translate, GPS for all, optical rangefinder and "käsisuuuntakehä"http://www.mil.fi/maavoimat/kalustoe...pup.dsp?id=320 to get the direction. Comms could be a problem, frequency-hopping radios would be great to have. 30-60 second strike (30-60 grenades)and out, using weather as your friend maybe, if they could do it theyd probably take the risk.:hmm:
Im also happy of their level of current training.
Thanks for the compliment, USA is very high on my list of places to visit, especially the East coast with its rich history.
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Old 04-22-08, 05:38 AM   #11
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Quote:
Originally Posted by Trex
I would love to be able to visit Finland sometime. Beautiful women, a remarkable history and climate that's never 140 in the shade - what's not to like?
Estonia is a better choise, cheaper alcohol and better looking women
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Old 04-20-08, 07:27 AM   #12
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Quote:
Originally Posted by Happy Times
In my experience mortars are very accurate. More so than artillery if you want to hit a "point-target", i dont know the english term. In a mountain enviroment, attacking firebases, mortars would be very handy. With high rate of fire, 15-20 rounds a minute, and accuracy you could suppress that compound very effectively. Luckily the Taleban training is probably not cut out for this.
Line of sight? or direct fire.

I wonder who was spotting for them. They seem to be hitting the target.
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Old 04-20-08, 09:23 AM   #13
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Kurtz - Sorry, it was my impression you were talking land ordnance - you mentioned 105mm. I'm no expert of sub guns, sorry. Unless you are talking of that dead-end concept, the submarine cruiser, with big guns, I would go with thannon's comments.

Howitzers and mortars have a high trajectory, which offers flexibility to the gunners as they can, in effect, shoot over hills. Most land artillery fire missions use indirect fire, in which the round lands in a place where the crew has not a hope of seeing it. Such shoots depend on an observer to correct the fall of shot or else, recently, some highly impressive (and expensive) wiggly-amps kit. To give the flexibility in trajectory, the propellant charges need to be variable, which leads one back to the charge bag concept, allowing the gunners to vary the muzzle velocity. Mortars and howitzer muzzle velocity is generally pretty low.

Standard naval gunnery has generally been more direct fire in nature, with the gunners (or at least somebody in fire control) being able to see the fall of shot. As with tank guns, a high velocity is most useful for this. The main reason for separate ammo would be simple weight (the big boys are heavy enough without having to try to load everything at once) and size (imagine having to design a battleship ammo handling system for 16" fixed rounds, with the projectile permanently fastened into the casing!).

Of course, really big naval guns could fire very long distances and aircraft were often carried as spotters. In a shore bombardment role, observers again might be necessary. In general however, what I said above is, while not universal, almost so.

In short, with smaller-bore high-velocity rounds, fixed ammo is standard as, among other things, it gives you a higher rate of fire. With small-bore howitzer, semi-fixed is the norm. Anything above a certain size (much above 5" or so) tends to be separate due to handling constraints. Again, there are exceptions to every rule.

As to our starting video clip, they were shooting in the direct fire role, something land gunners practice but rarely get to do for real. (In general, this is usually considered a Good Thing as if the gunners can see the target, the Bad Guys have been allowed to get waaay too close. There are exceptions to this too.) Fire a round, watch where it lands, correct your own fall of shot. Lotsa fun.

piersyf - I understand your arguments and have sat in on the odd meeting on whether or not to provide protection. From my point of view however, blast pressure (and thus danger) drops off very quickly (the cube root of the distance) and is thus a very short-range threat, whereas fragments are dangerous to much greater distances. To my way of thinking, if you have the time, it is therefore a no-brainer if you are concerned about your troops and assets. The dangers of containing a blast are far outweighed by the dangers of not containing shrapnel. However inaccurate the bad guys may be, Chicken Little only has to be right once. As an old sergeant instructor once told me (as I was sweating my first trench-digging lesson), all the sweat you expend in your entire career only has to save your life once to be worth all the effort. I 'm not much concerned with trying to maintain appearances - macho posing gets people killed and I'm with Patton on such things. Different case if it's shoot-and-scoot, of course.

WRT the rate of fire of mortars and such. While the Taliban have used them, sitting in one place and firing a sustained barrage against an established base is a good way to meet 72 young ladies in a hurry.
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Old 04-20-08, 09:39 AM   #14
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Quote:
Originally Posted by Trex
Standard naval gunnery has generally been more direct fire in nature, with the gunners (or at least somebody in fire control) being able to see the fall of shot. As with tank guns, a high velocity is most useful for this. The main reason for separate ammo would be simple weight (the big boys are heavy enough without having to try to load everything at once) and size (imagine having to design a battleship ammo handling system for 16" fixed rounds, with the projectile permanently fastened into the casing!).
There is probably also a definite safety risk in keeping your high-explosive rounds in the same room as your powder. Even after the rounds and powder were aboard they were typically kept in seperate magazines.
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Old 04-20-08, 10:58 AM   #15
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Fatty - Very true. One should never store the two together or in any place other than a proper magazine. That does not apply, of course, to fixed ammo. By NATO standards, the risk factor in such munitions is taken as the highest - in the case of a fixed HE round, the entire mag would be rated IAW the HE in the projectile.

Incidentally, one theory WRT the high Royal Navy losses at Jutland is the suggestion that ammo was being stored in places other than magazines so as to be able to carry more. If that happened, it would explain a lot.
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