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Subject: FFG-500 Fletcher Class -- Advanced Frigate
dwightlooi    10/20/2007 12:34:28 PM
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randomjester    Whoops!!   10/20/2007 10:41:18 PM
My bad! I just read the fine print, and those are indeed stabilisers!

My Apologies dwightlooi!

 
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EW3       10/20/2007 11:21:23 PM
The desk jockies that design these things need more time at sea. (I did 2 years on an FF in the North Atlantic)
Your post is right on.  It was my first impression as well. 
I was wondering how likely it would be for the Harpoons to actually work after being kept in their current location.
Seawater will seek out and destroy any connector in short order.  And it gets worse the close to sea level you get. 
We used to get corrosion on antenna connections and waveguides 75 feet in the air. 
One thing I'm just thinking about is seakeeping. I'm assuming the two fins protuding from about 1/3 from the bow are part of an active stabilisation system, because the result of the hull form would seem to be a ship that is very 'wet'. Taking this into a heavy sea would not be fun, as you'd be getting waves just rolling right over your foredeck and hitting your superstructure. The reverse sheer on the bow and tumblehome hull would increase this, but then its pretty much the same as what the Zumwalt design has (Last time I saw that design, anyway). So maybe I know nothing on this......

Stealth is one thing, but can you pop open a VLS hatch with water flowing all over the launcher? Im not sure its a problem with a VLS cell, but I'm pretty sure it was a concern with older rail launchers of getting seawater pouring into your launcher assembly/magazine, whenever you reload the rail. But since is a VLS cell is a 'one-time' launcher (on a given launch), I'm guessing its not such a concern.  But still.

I'm not sure about these points seeing as I'm no naval architect (My sister is though!)



 
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randomjester    Seakeeping   10/20/2007 11:42:03 PM

Actually the more I look at this design, the worse I think the seakeeping issue is. Such a fine hullform, tumblehome hull and reverse sheer just screams submarine! Just think, you take this thing into any sea on the boy, and its effectively combat ineffective, as its just going to dive straight into any steep wave even with those stabilisers, and you'll have your foredeck (including pretty much all your defensive firepower) under a couple of meters of water. And I think the issue is compounded a bit by the fact that western VLS systems are 'hot launch' i.e. the missile fires its engine out of the launcher - you need exhaust piping for the spent gas. While the missile could still possibly launch through the water (I'm no expert on this), if any water gets in your exhaust pipes and flash-boils? I dont think that is a good idea.

A real nitpick: That door you have on the front of the superstructure - You had better make sure thats REALLY strong, because if that fails in a storm, you are going to have massive amounts of water pouring straight in every time you get a wave over the bow. This adds up, I saw a documentery on the Discovery Channel about the loss of the bulk carrier 'Derbyshire' - The critical part of it was that it was half a dozen ventilators less than a foot in diameter that sank it, due to making the bow dive, and then the main hatches failed.
 
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dwightlooi       10/21/2007 1:27:10 AM

1. Still need something like Mk.41 to shoot ESSM and VLSROC, not anything like NLOS-LS. Install 32-cell Mk.41 at raised deck in front of the bridge. This may or may not be needed, but all ships with Mk.41 installed on the gun deck have draft more than 9m. While F-124 (installed on raised deck) has

 ...

3. Extend the rear super structure to helicopter deck and put the hanger in it. The hanger size should be able to operate 2 anti-sub UAVs or a MH-60R. On top os the extended superstructure, there should be concealable UAV control/TACOM antenna, SRBOC and Nukia launcher.


(1) The Mk41 is being replaced by the Mk57 in the DDG-1000 (DDX). This vessel uses the same launcher. 40-cells are carried, 16 ahead of and 24 behind the superstructure. The main difference is that the Mk57 is positioned on the periphery of the ship and is designed to blast outwards in the case of a magazine explosion reducing the chances of the vessel being torn apart in such an event. In addition, the Mk57 VLS is accepts up to 25.4" weapons whereas the Mk41 places a 21"  diameter limit on weapons.

(2) There is a hangar. Instead of fore/aft arrangement, I adopted an over/under arrangement. The ship does not have masts and the superstructure has to be tall enough to place the radars at a decent height. Hence, the hangar simply goes under the bridge decks.

 
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dwightlooi       10/21/2007 1:28:53 AM

1. Still need something like Mk.41 to shoot ESSM and VLSROC, not anything like NLOS-LS. Install 32-cell Mk.41 at raised deck in front of the bridge. This may or may not be needed, but all ships with Mk.41 installed on the gun deck have draft more than 9m. While F-124 (installed on raised deck) has

 ...

3. Extend the rear super structure to helicopter deck and put the hanger in it. The hanger size should be able to operate 2 anti-sub UAVs or a MH-60R. On top os the extended superstructure, there should be concealable UAV control/TACOM antenna, SRBOC and Nukia launcher.


(1) The Mk41 is being replaced by the Mk57 in the DDG-1000 (DDX). This vessel uses the same launcher. 40-cells are carried, 16 ahead of and 24 behind the superstructure. The main difference is that the Mk57 is positioned on the periphery of the ship and is designed to blast outwards in the case of a magazine explosion reducing the chances of the vessel being torn apart in such an event. In addition, the Mk57 VLS is accepts up to 25.4" weapons whereas the Mk41 places a 21"  diameter limit on weapons.

(2) There is a hangar. Instead of fore/aft arrangement, I adopted an over/under arrangement. The ship does not have masts and the superstructure has to be tall enough to place the radars at a decent height. Hence, the hangar simply goes under the bridge decks.

 
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dwightlooi       10/21/2007 1:35:08 AM


Actually the more I look at this design, the worse I think the seakeeping issue is. Such a fine hullform, tumblehome hull and reverse sheer just screams submarine! Just think, you take this thing into any sea on the boy, and its effectively combat ineffective, as its just going to dive straight into any steep wave even with those stabilisers, and you'll have your foredeck (including pretty much all your defensive firepower) under a couple of meters of water. And I think the issue is compounded a bit by the fact that western VLS systems are 'hot launch' i.e. the missile fires its engine out of the launcher - you need exhaust piping for the spent gas. While the missile could still possibly launch through the water (I'm no expert on this), if any water gets in your exhaust pipes and flash-boils? I dont think that is a good idea.

A real nitpick: That door you have on the front of the superstructure - You had better make sure thats REALLY strong, because if that fails in a storm, you are going to have massive amounts of water pouring straight in every time you get a wave over the bow. This adds up, I saw a documentery on the Discovery Channel about the loss of the bulk carrier 'Derbyshire' - The critical part of it was that it was half a dozen ventilators less than a foot in diameter that sank it, due to making the bow dive, and then the main hatches failed.
Actually, I think the whole idea is that the ship will sail and fight like a surfaced submarine. Everything is sealed and made water tight to submarine standards. I don't see this as a big problem, afterall those Trident tubes, VLS cells and torpedo tubes don't leak in the subs and we have been operating them for four decades. And, after the vessel leaves port, nobody goes on deck to stand watch or do anything in general. Electro-optical sensors, radars, EW gears and sonar brings all the situational awareness into the CIC.

 
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hybrid       10/21/2007 3:46:38 AM




Actually the more I look at this design, the worse I think the seakeeping issue is. Such a fine hullform, tumblehome hull and reverse sheer just screams submarine! Just think, you take this thing into any sea on the boy, and its effectively combat ineffective, as its just going to dive straight into any steep wave even with those stabilisers, and you'll have your foredeck (including pretty much all your defensive firepower) under a couple of meters of water. And I think the issue is compounded a bit by the fact that western VLS systems are 'hot launch' i.e. the missile fires its engine out of the launcher - you need exhaust piping for the spent gas. While the missile could still possibly launch through the water (I'm no expert on this), if any water gets in your exhaust pipes and flash-boils? I dont think that is a good idea.

A real nitpick: That door you have on the front of the superstructure - You had better make sure thats REALLY strong, because if that fails in a storm, you are going to have massive amounts of water pouring straight in every time you get a wave over the bow. This adds up, I saw a documentery on the Discovery Channel about the loss of the bulk carrier 'Derbyshire' - The critical part of it was that it was half a dozen ventilators less than a foot in diameter that sank it, due to making the bow dive, and then the main hatches failed.

Actually, I think the whole idea is that the ship will sail and fight like a surfaced submarine. Everything is sealed and made water tight to submarine standards. I don't see this as a big problem, afterall those Trident tubes, VLS cells and torpedo tubes don't leak in the subs and we have been operating them for four decades. And, after the vessel leaves port, nobody goes on deck to stand watch or do anything in general. Electro-optical sensors, radars, EW gears and sonar brings all the situational awareness into the CIC.


Ohios don't spend much of their time on the surface. This baby will spend all of its time on the surface where it will be exposed to pitching and rolling with the sea waves. I'd hate to be on this ship, seakeeping  should be a mandatory requirement for anyone who wants to design anything remotely like a stealthy surface ship.
 
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Shirrush     dwightlooi   10/21/2007 5:17:36 PM
I really like your ideas and designs.
I'd like to know more about you.
Please kindly contribute here on DropBear's thread.

 
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RockyMTNClimber    USS Monitor   10/21/2007 5:20:47 PM




Actually the more I look at this design, the worse I think the seakeeping issue is. Such a fine hullform, tumblehome hull and reverse sheer just screams submarine! Just think, you take this thing into any sea on the boy, and its effectively combat ineffective, as its just going to dive straight into any steep wave even with those stabilisers, and you'll have your foredeck (including pretty much all your defensive firepower) under a couple of meters of water. And I think the issue is compounded a bit by the fact that western VLS systems are 'hot launch' i.e. the missile fires its engine out of the launcher - you need exhaust piping for the spent gas. While the missile could still possibly launch through the water (I'm no expert on this), if any water gets in your exhaust pipes and flash-boils? I dont think that is a good idea.

A real nitpick: That door you have on the front of the superstructure - You had better make sure thats REALLY strong, because if that fails in a storm, you are going to have massive amounts of water pouring straight in every time you get a wave over the bow. This adds up, I saw a documentery on the Discovery Channel about the loss of the bulk carrier 'Derbyshire' - The critical part of it was that it was half a dozen ventilators less than a foot in diameter that sank it, due to making the bow dive, and then the main hatches failed.

Actually, I think the whole idea is that the ship will sail and fight like a surfaced submarine. Everything is sealed and made water tight to submarine standards. I don't see this as a big problem, afterall those Trident tubes, VLS cells and torpedo tubes don't leak in the subs and we have been operating them for four decades. And, after the vessel leaves port, nobody goes on deck to stand watch or do anything in general. Electro-optical sensors, radars, EW gears and sonar brings all the situational awareness into the CIC.


Like the Monitor on high-tech steroids.

 
 
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doggtag    but Rocky,..   10/21/2007 8:24:20 PM
...didn't the USS Monitor founder and sink due to high seas it wasn't designed to handle?
 
I also am someone who questions the wisdom of the wave piercing hull:
is it primarily in the name of stealth,
hydrodynamic efficiency (less drag/water resistance?),
or something else?
The past several centuries of naval achitecture seems to suggest it isn't the most seaworthy of designs, even for a ship with computer-controlled stabilization systems.
 
Also, I'm going to question the validity of the SRBOC and Nulka countermeasures systems:
if the main objective of this vessel is maintaining low observability, why then do I want to broadcast my position by launching high-signature countermeasures systems into the air?
Isn't that the equivalent of wanting to maintain light discipline at night, only to pop a flare to blind an enemy's eyesight temporarily, in effect giving away the fact I'm there to begin with?
Seems more sensible to me, judging by the timeframe in which this ship could be launched  (minimally 5 years out),
we'd be further off adopting a hardkill system, perhaps that Raytheon laser CIWS under development, mounted on the Phalanx' trunnion assembly.
For the most coverage area, it could be mounted high up, on top the ship in a retractable mounting, only popping up when absolutely necessary (last ditch).
I myself prefer the hardkill approach, because if the inbound threat missile somehow has managed to lock on to your lower signature radar or IR silhouette from the surrounding sea surface and other clutter, why then will it actually be fooled away by high-signature countermeasures?
 
If not a laser CIWS (been mentioned on here countless times its vulnerability to sea water corrosion and humidity interference), then at least an aggressive DEW (one of those AESA syystems designed to overload/short circuit enemy electronics).
 
Again, I just don't see the logic in using high-signature countermeasures that will serve more to broadcast my position than actually defeat an inbound threat that, most likely, is programmed/configured to acquire a lower signature target than a higher signature one.
 
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