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Shipright
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 3:01 pm
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Yatsumi, there is no realistic danger of a liferaft that far aft and that high being hit by a wave period let alone ripped off by one. This board is obssessed with wave action damage for some reason. The stealth issue, however, is valid.

If you have a dedicated search radar that has a low power settting you do not need anything for helicopter guidance, you can just use that. I am not sure about APAR but SPY-1 definetly does and thats how the Burkes roll. You do need two nav radars as already stated though, so you can keep the one on on the helo hangers or mount another it higher for greater range, just make sure they are offset so they have different cutouts.

You are missing UNREP stations for both stores and fuel. You will want at least one of the first and two of the second on each side.

How many VLS cells is this sporting? Do you have the depth of fire needed for an AAW centric ship given it looks like you expect to devote significant magazine space to strike weapons (and I imagine ASROC since you have the cell lenght for them)? If you are thinking self defense or short range defense only then quad packed ESSMs will give you plenty, if you are looking at group defense at range then SM2s are needed more and those are one for one as you know. You are looking at 2-4 missiles per target, so calculate accordingly.


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heuhen
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 3:33 pm
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Shipright wrote:
Yatsumi, there is no realistic danger of a liferaft that far aft and that high being hit by a wave period let alone ripped off by one. This board is obssessed with wave action damage for some reason. The stealth issue, however, is valid.
you haven't been to Norway, and the North sea.... here things get ripped of quiet easy.

on the radar side, Oslo class had heating cables to prevent it freezing in the extreme weather, special during winter. for me personally, why build an ship that can only withstand weather in that local area, and not in the rest of the world, specially for Navy ships that have the task of being every where.


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Shipright
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 3:59 pm
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No one but the Norwegians spend much time in Norway so unless he is designing this thing specifically for Norway there is no reason to criticize the design for that niche environment. But even in Norway these life rafts are high enough and aft enough. You can't be perfectly invulnerable to every hazard all the time.


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heuhen
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 4:58 pm
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Shipright wrote:
No one but the Norwegians spend much time in Norway so unless he is designing this thing specifically for Norway there is no reason to criticize the design for that niche environment. But even in Norway these life rafts are high enough and aft enough. You can't be perfectly invulnerable to every hazard all the time.
Even the Americans have the same problem, on a Burk it's nor an problem because the hull of an Burke is so big, but when you get smaller as an frigate, that have much bigger motion in the sea, and also tend to be driven much harder in bad weather than a destroyer. so where ever you are in the world you will every year come over weather bad enough to rip of the life raft on a frigate sized hull. An Destroyer is Big thus some of the problem is gone. if you take an look at an OHP class some are an frigate, then you will notice that the Americans have mounted there life raft on deck due to the risk as I mention earlier.

the same to the British Type 23 frigate. frigates from Netherland, Germany. But as soon they get bigger than a frigate, they tend to just hang it over the board.

But there is also and thumb rule: If you have space for it on deck, mount it on deck.
and If you draw an modern frigate like he have her. mount it on deck, the only reason Burk have mounted on the side, is to open up space for special operation, and that they need the space for extra equipment. Specially when you have an ship with 300 men on a ship that is just 40 meter longer, thus you need more deck space for them. on a frigate that have 120-130 men on a hull that is 40 meter shorter have the space, because the crew is smaller.

so get those life raft on deck. it's better protected there, it's more accessible, specially when you going to service it from time to time. specially on a ship that will be used every day. In a fleet with a Burk-spam, you can easily have one go into port for just controlling it's life-rafts, and in that period the ship can't be used. while the frigate with his life raft on deck...

Of the life raft system on Burk works, it give extra cost in production (no need for that), it's reinforced, to handle the weather, it have an sort of wave/spray brake (prevent water on to the raft and salt damaging it's systems), and many other things that just make it all more expensive than needed.


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Yasutomi
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 5:12 pm
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heuhen wrote:
not a good place at all. the best place for Torpedo tubes is next to/in front/behind the hangar, so it can share the torpedo magazine with the helicopter, thus save up space.
I can't fault that logic...but neither can I find the space! The ship's boats are stowed forward of the hangar (behind a sliding screen) and forward of that is the funnel, with all those uptakes and intakes. I could probably have slotted the tubes in abreast of the funnel in my first design, but that's simply not an option with side mounted funnels- and relocating the funnels essentially means binning the design and starting again, which is really only a last resort!
Shipright wrote:
Yatsumi, there is no realistic danger of a liferaft that far aft and that high being hit by a wave period let alone ripped off by one. This board is obssessed with wave action damage for some reason. The stealth issue, however, is valid.
Well...if I proceed with the AU background forming in my mind, this ship will be serving in the seas off Borneo; not the North Sea. ;)

Having said that...I was aiming for uncluttered lines (for reasons of personal aesthetics as much as stealth) so the idea of stowing the rafts behind solid railings has a definite appeal.
Shipright wrote:
You are missing UNREP stations for both stores and fuel. You will want at least one of the first and two of the second on each side.
I'm not at all certain what those look like, so I shall have to do some research first! As a general rule, I haven't added anything to the image without having at least some idea of what it actually does...
RP1 wrote:
Having both motors in one space is a vulnerability issue. Even if they are in two separate space spaces right next to each other, the chance of loosing both is halved, in simple terms (although the chance of loosing half is doubled).
True...how far apart do they need to be, then? I mean realistically, there are limits in a ship this small. It's also worth pointing out that the main turbines are grouped, as are the GTGs. I could separate these out more, but than means more funnels and a more cluttered topside...which is something I'm really trying to avoid.
RP1 wrote:
APAR+LRR, SPY-1xyz+ Illuminators or APAR+Seamaster 400 are all valid options for a system based on SM-2 & ESSM. The choice would come down to the precise details of strategic partnerships with the suppliers, industrial support, ship impact, cost and the design engagement scenarios.

For instance, if you are concerned about defence against multiple, simultaneous, high performance SSMs then the APAR systems will have the edge. For absolute long range surveillance, one would expect the SMART-L to edge out SPY-1F or Seamaster 400, but both those will have better performance at the ranges they do cover.

The APAR+SeaMaster 400 makes upperdeck integration much simpler, but it will not be cheap. Offhand I suspect the US system would be the cheapest, (unless you cut a deal with the Dutch ) But it's difficult to tell as the price of weapons sold internationally is "variable" to say the least, as so much politics and offsetting is included.
If SeaMaster 400 can stand in for SMART-L, then why have the British, Dutch and Danish navies all opted for variants of the latter? Is it just because they are looking for longer-range performance? Apologies if this is a daft quetsion, but I'm just trying to get a better sense of the options.

Eliminating a separate volume search radar would definitely help my task, as it would mean reverting to a single funnel arrangement which would in turn provide space for the torpedo tubes. However, I don't want to sacrifice significant performance purely for an easier time. :)
RP1 wrote:
How many VLS cells is this sporting? Do you have the depth of fire needed for an AAW centric ship given it looks like you expect to devote significant magazine space to strike weapons (and I imagine ASROC since you have the cell lenght for them)? If you are thinking self defense or short range defense only then quad packed ESSMs will give you plenty, if you are looking at group defense at range then SM2s are needed more and those are one for one as you know. You are looking at 2-4 missiles per target, so calculate accordingly.
The design has space for 48 cells, so I'd probably have 32 SM2s and 8-16 quad pack ESSMs with the remainder used for ASROC or Tomahawks. Having said that, this is very much the maximum load of the class and (particularly in my speculative AU scenario) the ships wouldn't need anything like that number.


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Shipright
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 5:48 pm
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heuhen wrote:
Even the Americans have the same problem, on a Burk it's nor an problem because the hull of an Burke is so big, but when you get smaller as an frigate, that have much bigger motion in the sea, and also tend to be driven much harder in bad weather than a destroyer. so where ever you are in the world you will every year come over weather bad enough to rip of the life raft on a frigate sized hull. An Destroyer is Big thus some of the problem is gone. if you take an look at an OHP class some are an frigate, then you will notice that the Americans have mounted there life raft on deck due to the risk as I mention earlier.
Yes, if your ship requires them to be lower and farther forward then thats what you do or put them on deck, but this is not the case here. They are over four decks above the waterline. In fact if you are worried about waves ripping off lift rafts at that level you need to worry about waves sweeping people off the bridge wings.

I get your experiance is with extreme North Sea weather but that is and always will be a niche enviroment.
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the same to the British Type 23 frigate. frigates from Netherland, Germany. But as soon they get bigger than a frigate, they tend to just hang it over the board.
Compare the position of the life rafts as drawn with that on the Burkes. They are actually higher.
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But there is also and thumb rule: If you have space for it on deck, mount it on deck.
and If you draw an modern frigate like he have her. mount it on deck, the only reason Burk have mounted on the side, is to open up space for special operation, and that they need the space for extra equipment. Specially when you have an ship with 300 men on a ship that is just 40 meter longer, thus you need more deck space for them. on a frigate that have 120-130 men on a hull that is 40 meter shorter have the space, because the crew is smaller.
Yes for steath it is a superior position and Burke has a lot of stuff competing for deck space. I would agree that making space for chaff launchers, boat davits and the like are a major driver of their slung position. That and not spoiling the LOS of SPY.

People, however, are NOT one of those things competing for deck space. Seriously in what situation are you imagining where the entire crew needs to be on deck? Are we expecting to grapple and board the opponenent? Not only that, you can fit all 300 people on just a part of the fight deck or focsle with no problem. We do it all the time for award ceremonies.
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so get those life raft on deck. it's better protected there, it's more accessible, specially when you going to service it from time to time. specially on a ship that will be used every day. In a fleet with a Burk-spam, you can easily have one go into port for just controlling it's life-rafts, and in that period the ship can't be used. while the frigate with his life raft on deck...
1.) You don't "use" these life rafts as in manually handle them. You release the cannisters (or they self release, see below) into the water and then they self inflate. Its a zero maintenance system as far as the crew is concerned thought he mounts like to create running rust like any hull attachement.
2.) You don't service them either. They are in self contained enclosures specifically designed to basically explode out of their shell instantly when triggered or when at a certain depth if sinking with the ship. Because of this there is no way to open them and then repackage them. All similar systems work the same way.
3.) These things can be moved on and off a ship by crane in a matter of hours for all of them. Same with putting them back on. You don't generally have ships using all their life rafts and then returning for a reload for obvious reasons, so this maitenance is no different than any other a ship needs and scheduled alongside other in port maintenance.
4.) Life rafts on deck have the exact same shelf life and maintenance needs of life rafts anywhere else.
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Of the life raft system on Burk works, it give extra cost in production (no need for that), it's reinforced, to handle the weather, it have an sort of wave/spray brake (prevent water on to the raft and salt damaging it's systems), and many other things that just make it all more expensive than needed.
They are literally racks made out of welded I-beam, probably little to no difference in cost to whatever craddle your deck mounted ones use. It is not reinforced (why would dit be?), they have no wave/spray brake and as I have said before salt builds up regardless of direct wave action or not, and there is nothing about them that make them more expensive than something mounted on deck. You obviously have never seen or know anything about these rafts in particular, so why make this stuff up?


Last edited by Shipright on August 8th, 2014, 5:55 pm, edited 1 time in total.

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RP1
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 5:53 pm
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If SeaMaster 400 can stand in for SMART-L, then why have the British, Dutch and Danish navies all opted for variants of the latter? Is it just because they are looking for longer-range performance? Apologies if this is a daft quetsion, but I'm just trying to get a better sense of the options.
Well, for the British and Dutch, SeaMaster 400 didn't exist when the decision was made. Also it would not work on Type 45. I should probably give some background:

SAMPSON, SPY-1xyz and SeaMaster 400 are both S-band, which is a compromise wavelength providing a mix of long range, high accuracy, weather resistance and so forth. They also have reasonably large, square/circular-ish faces so are well suited to fully 3D operations. In all three cases this trade-off is acceptable because either some other radar exists to illuminate the target, or the missile has it's own seeker.

APAR (and the little strips on the top of the Thales i-mast) are X-band, which is a high frequency radar, providing greater accuracy at the expense of range. This is also the frequency used for missile illumination (and, IIRC the active seeker in ASTER). As this is a shorter wavelength the arrays can be smaller, or, in the case of an equally sized array, the accuracy can be greater. The little strip on the i-mast is for horizon search, as it will generate a beam narrow in azimuth but wide in elevation. APAR is roughly circular, so it will generate a so-called "pencil" beam that can be pointed wherever.

SMART-L is L band, which is low frequency, offering long range and weather resistance at the expense of accuracy. This type of radar is best for covering very large volumes of space at a lower refresh rate.

Now, as to why SMART-L exists... well, the Dutch didn't have a choice. With APAR as the fire control radar something else was needed for surveillance and possibly for industrial reasons, possibly for a requirement for long range, they went for L-band.

Type 45, however, is a bit more controversial. *technically*, to achieve the missile-defence role, Type 45 doesn't need SMART-L. SAMPSON is capable of sufficient surveillance on it's own. BUT, the best defence against a missile is to shoot the enemy aircraft first (shoot the archer not the arrow), and the best thing for that is fighters, which need controlling, which needs a large surveillance radar... so Type 45 has the SMART-L for a wider situational awareness / fighter control role.

Now of course there are many variables in this... a huge array will be good in pretty much any frequency, processing can do a lot, having more than one radar allows one to be sneaky in sneaky ways, and that SMART-L can be tasked to do other things, such as ABM surveillance, without detracting from the capability of the SAMPSON or APAR (which is of course more capable than a simple fire control radar).

EDIT: For reference, Type 45 Key User Requirement (KUR) 2: Type 45 shall be capable of providing anti-air warfare situational awareness covering 1000 airborne objects against a departure/arrival rate of 500/hour and KUR 3: Type 45 shall be able to provide close tactical control to at least four, fixed wing or groups of, aircraft

http://books.google.co.uk/books?id=TXzS ... ts&f=false

RP1

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Last edited by RP1 on August 8th, 2014, 6:09 pm, edited 1 time in total.

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Shipright
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 6:03 pm
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I hadn't heard about aircraft control being a driving force in SMART-L for the Brits, that is interesting. Even more so because they build these ships when they had no aircraft to control and more so again because they won't for probably another five years realistically (factoring airwing procurement and training). Thats a decade between the first Daring coming into service and getting to use its systems as intended. Its amazing that the RN could be so far sighted and disciplined in procurement given its recent history.


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RP1
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 6:04 pm
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True...how far apart do they need to be, then? I mean realistically, there are limits in a ship this small. It's also worth pointing out that the main turbines are grouped, as are the GTGs. I could separate these out more, but than means more funnels and a more cluttered topside...which is something I'm really trying to avoid.
Literally just move it forward one compartment and you'll eliminate several damage cases that can take out both shafts in one go. Ideally it would be separated by at least one compartment, but that's probably not possible on a ship this size.

Are you using IFEP- i.e. can the forward GTAs be connected to the propulsion bus? Even if the system is normally run in an isolated mode but can be connected you will have some propulsion.

The objective here is to stop single hole in the waterline removing the entire propulsion capability - the "cheap kill". And beware of claims about things running submerged. Yes, some equipment does, briefly, but the best waterproofing is a bulkhead.

RP1

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RP1
Post subject: Re: AAW Frigate (not a kitbash this time!)Posted: August 8th, 2014, 6:05 pm
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Its amazing that the RN could be so far sighted and disciplined in procurement given its recent history.
Actually the usual argument is that it was ill-disciplined, as the capability wasn't strictly required! :lol:

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