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acelanceloet
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 12th, 2017, 8:43 pm
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Well, the paper gives information that you can take over my word over that stuff, if my scanning trough it saw the right things :P

Note that a heavier ship will be deeper in the water, longer, or have a fuller hull, or be slower, or wider (or a combination of those things) to actually allow that additional weight without the ship going over safety limits. The impact of additional weight will be impacting the rest of the design of the ship, hence why Erik said it could not be done on the current hull: the ship would require changes to allow for this additonal weight.

Anyways, as for not being able to present much of an argument: this is the chance for you to learn :P We all learn from experience, both on shipbucket and in other places, and I think you are on these forums as much to learn and improve your work as I am, if I read your reactions correctly. There are quite a few people here who like to help with that ;). Also, your ability to answer questions and problems with 3D models actually showing the result is something few people can actually do out here, actually!

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NepsterCZ
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 12th, 2017, 9:10 pm
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Okay, honest question. The jump from Flight II to Flight IIA added about 800 tons to the ship. But from what I can understand they didn't increase the beam at all, the only length. Does the 1 meter, 1/154 of the ship, actually make such a difference? I mean, if it helps, I can make the hull longer by one meter, and nobody will probably even notice. That extra hangar space would sure come useful if I'm to fit those Ospreys there :D Come to think of it, It would probably also help with those VLS too

I'm actually kinda sure, that I'm on some sort of government watchlist, after all the information I googled about Burke class destroyers :D. The way I see criticism is really simple. Its either good criticism and I should learn from it, because its, well, good. Or its bad, and I can just ignore it because it's, well, bad. So I'm always glad when people criticise my work. Anybody can "like/favorite" something, but when someone criticizes it, it actually shows they put some thought to it.

The thing is, I just can't say basically anything. For example, putting more VLS tubes, obviously, A, Reduces the internal space B, Makes the ship heavier - which in turn makes the ship slower etc. But when someone asks me, "How am I able to fit them there". I cant answer. I cant google the inside layout of Arleigh Burke-class destroyer (believe me, I tried), so the only answer I can give is generic "The space was reorganized", "Due to advance in technology, the other systems got smaller" or "The automation lowered the requirement for the crew size, so rearranging internal bunks freed up some space" you know. Technically, probably not wrong, I mean, we do talk about ships that are 6-26 years in the future, there's bound to be some miniaturization, some automation etc... But it's not a great answer. I mean, the "enclosed bay" actually does increase the space somewhat, so I can account for at least some of the "missing space".

Okay, It makes the ship slower, I still can't say anything about this either. The wiki states that the speed of Arleigh Burke-class destroyer is "in excess of 30 kn". Great, so the speed is somewhere between ∞ and 30 kn. So I can't even say "The ship is slower" right? I don't know the speed, to begin with.

So yeah, there just not much I can say without going deeper and deeper into the rabbit hole :D

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acelanceloet
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 12th, 2017, 9:30 pm
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I actually am not certain how they modified the burkes hull. The hull design should have remained the same, so I think the block coefficient would remain about the same, as do the beam and waterline length. One likely solution is just increasing the draft by half a meter for those 800 tons. It is possible that the design was build with the reserve size, strength and stability to be heavier on the same hull (the same was done on the spruances) but I would have to look up what exactly they did.

I am pretty sure the lengthening of the hull was just to allow the length of the hangar deck, and might have been a modification done only above the waterline. I estimate that lengthening the stern with one meter would bring 20 tons of additional displacement lifted, or about a hundred if added amidships. so that is at the very least not the whole story.

btw, there are quite a few systems (especially electronics) which have currently shrinked to the point where the size is mostly based on the need for people to reach and service them. automation and miniturization are, on modern ships, no magical space saving mechanisms :P

Anyways, there are indeed things which are unknown to most if not all of us, such as exact internal arrangements. There is a lot you can estimate from experience though, by looking at similar ships or looking at alternate proposals for ships (for example, the DDV designs here http://www.shipbucket.com/drawings/sear ... =&drawing= , which were in between Flight 2 burkes and Flight 2A burkes) and by reading books, websites and articles on the subject. Keep asking questions ;) they make me look up those books and articles and make me learn new stuff too haha

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erik_t
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 12th, 2017, 10:20 pm
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There have been a number of studies about shortened and lengthened Burkes. If the increase in capability is demanded, I'd just insert a parallel-sided additional compartment amidships and slide everything to fit.


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NepsterCZ
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 13th, 2017, 11:24 am
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Well, the displacement difference from first Flight I, and First Flight III is about 1485 tons. From flight IIA to Flight III its 600 tons, so yeah, they for sure planned for some future upgrades.

Well, I truly have no idea about the miniaturization etc, so I'll have to take your word for it :D

I'm honestly not sure if I really wanna go *that* deep into the rabbit hole you know? Especially reading books :D Not exactly my favorite thing to do :)
erik_t wrote: *
I'd just insert a parallel-sided additional compartment amidships and slide everything to fit.
I'm not sure I understand. Are you suggesting extending the hull somewhere mid-ship, or just adding additional compartments to the sides? Possible above the deck? I'm bit confused, sorry.

Would you guys agree tho, that lengthening the hull by two meters, like in the image below, would actually help the design? Or does it make it even worse?

[ img ]

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Tobius
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 13th, 2017, 2:36 pm
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What about reframing issues? Lengthening a ship is virtually a redesign from the keel up if you stick a new section in the middle. I'm thinking of some of the American Spruances and the Italian Cavours.


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acelanceloet
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 13th, 2017, 4:49 pm
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Tobius wrote: *
What about reframing issues? Lengthening a ship is virtually a redesign from the keel up if you stick a new section in the middle. I'm thinking of some of the American Spruances and the Italian Cavours.
Which American Spruances or Italian Cavours? As far as I know, neither design had a lengthened variant build, definitely not the Spruance.

Anyways, reframing? what is that supposed to be? I suppose you refer to the longitudinal frames in a ship, which are oversized enough that 1 or 2 meters additional length would have no significant effect on the stresses in them. In addition, the largest stresses are in the midship area due to bending moments in the hull, which enables you to reinforce exactly those sections you are modifying anyways to fit the new section there.
While a lot of things have to be recalculated when a ships hull is modified (such as stability, strength, weight and systems placed in the hull) the frames need very little if any modifications, and all of those calculations are more checks then a full redesign. In short, I completely disagree

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Voyager989
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 13th, 2017, 4:56 pm
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I... what?

http://www.bbc.com/future/story/2015111 ... ps-in-half
Quote:
The process involves slicing through the ship’s structure and hull, gently pulling the two sections apart on rollers and then slotting the new piece in between. Finally, all three sections are welded tightly together again so the whole ship can be repainted. At Blohm+Voss, the project takes just two months.


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NepsterCZ
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 13th, 2017, 5:00 pm
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I found this dissertation work , from 2010 done by Naval Postgraduate School student about "Hydrostatic and hydrodynamic analysis of a lengthened DDG-51 destroyer".

He even talks about inserting 18 meters long midbody section. And even tho I won't pretend that I can fully understand everything said there, his conclusion seems (if I understand it correctly), that it should be theoretically possible. If "solution to reduce the roll characteristic" is developed.

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Thiel
Post subject: Re: Arleigh Burke Flight III - 3D conceptPosted: October 13th, 2017, 10:44 pm
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Yeah, long narrow hulls can have some really nasty wave interactions. Especially if the bow and stern flares significantly.
Parametric rolling is no joke

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