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Subject: FFG-500 Fletcher Class -- Advanced Frigate
dwightlooi    10/20/2007 12:34:28 PM
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Herald1234       10/20/2007 12:43:16 PM
What kind of gonzo radar system are you using? ESSM requires an illuminator.

What about navalized PAC 3 instead?

Herald

 
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dwightlooi       10/20/2007 1:53:27 PM

What kind of gonzo radar system are you using? ESSM requires an illuminator.

What about navalized PAC 3 instead?

Herald

(1) AN/SPY-3 -- same as the X-band component of the DDG-1000 USS Zumwalt's (formerly DDX) Dual Band Radar. Instead of 4 planar arrays covering 90 degrees each, the SPY-3 covers 120 degrees each and only three are used for 360 degree coverage. The DDG-1000 also has an S-band Volume Search Radar (VSR) to support very long range detection in excess of 1200km for high altitude targets such as ballistic missiles and warheads.

(2) Being an X-band AESA, the SPY-3 serves as both the air/surface search and track array as well as the illuminator. The ESSM was designed from day one to be used with either Continuous Wave (CW) illumination or Interupted Continuous Wave (ICW) illumination. With ICW, the ESA radar multitasks and hits the target with the illumination pulse many times a second while also performing other tasks.

(3) The German F124 Sachsen class frigates for instance uses ESSMs and SM-2s fired from a 32-cell Mk41 VLS with the European X-band APAR radar (AESA). ICW is used to support semi-active homing in this all-purpose AESA radar. The APAR radar assembly can be seen on top of the main mast of the F124 class in the photo. The SPY-3 is similar except that the aperture size is roughly 7.2 times larger and the output is a lot higher.
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Herald1234    ICW on the ESSM, huh?   10/20/2007 2:06:06 PM
Learn something new every day.

Herald.
 
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earlm    One issue with your design   10/20/2007 3:12:53 PM
I don't think steam is a good idea.  It will save money on fuel but increases noise and maintenace costs.  RACER was rejected for the Arleigh Burke class for maintenance reasons.
 
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andyf       10/20/2007 3:27:12 PM
certainly looks stealthy
 
 
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andyf       10/20/2007 3:28:57 PM
what about diesel electric?
you get none of the noise problem and the effieciency of a diesel
 
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dwightlooi       10/20/2007 4:38:41 PM

what about diesel electric?

you get none of the noise problem and the effieciency of a diesel

(1) Turbines are in general quieter than Diesels because they are not reciprocating piston engines have none of the vibrations associated with slugs going up and down.

(2) Let's put some numbers in the comparison shall we? Large marine gas turbines are around 37~43% in terms of thermal efficiency -- this is a measure of how much of the calorific value of the fuel is extracted as mechanical work done. The best piston engines are in the neighborhood of 50~55%. Note that I did not use the word "Diesel". This is because "diesel" is a fuel type and not an engine confiugration. BOTH the so called "diesels engines" and "gas turbines" used in ships run on diesel distillate fuel. The disadvantage of piston engines is their much worse power density -- much more machinery space and weight is needed for the same power output. The diesel engines also require more maintenance and servicing. The disadvantage of gas turbines is that while the make much more power per unit space and weight (significantly more than nuclear powerplants BTW), they have inferior fuel economy, especially at part loads compared to diesels. This is why gas turbine installations tend to favor multiple turbines and the shutting down of half or 3/4s of the turbines during cruise while running the remaining at near peak output.

(3) Currently, the MOST EFFICIENT propulsion technology available is the combined gas and steam arrangement (COGAS-E). The gas turbine exhaust is used to provide "free" heat to boil water to run an auxiliary steam turbine. In this manner, the total thermal efficiency of the powerplant can reach about 60%. As a side benefit (for a stealthy ship), because most of the turbine exhaust's heat is recuperated to boil water for the steam turbine(s), the exhaust temperature of this power plant arrrangement is very low. Traditionally, gas turbines and steam turbines are used together in land based power generation but not in ships because it is extremely difficult to make a gearbox to couple everything together to drive propellers due to the non-linear relationship between the output shaft speeds of both turbine types across the operating range. This however is not a problem if the only thing driving the propellers and both the gas and steam turbines do nothing but turn generators to produce electricity. With the advent and maturation of turbo-electric drives, COGAS-E (COmbined Gas And Steam - Electric Drive) propulsion has emerged as the ultimate powerplant arrangement for large marine vessels offering both the power density and the best fuel economy in the business. It is for instance used in the latest Cruise Ships and succeeds very well at penny pinching for the cruise lines -- See the Celebrity Millenium Class (91,000 tons; 2 x GE LM2500+, 1 x Steam turbine) and the Royal Caribbean Radiance of the Seas (90,000 tons; same) for examples of COGAS-E (aka COGES) installations in the cruiseline industry.

 
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YelliChink       10/20/2007 5:43:59 PM
Amazing idea. Northrop Grumman or Lockheed Martin  should hire you as weapons concept designer.
 
Though I don't think USN is interesting in this design. Some other smaller navies will definately be interested. However, there are some operational requirement that needs to be changed:
 
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
 
2. Move the harpoon launchers some where else to free the space for towed-array sonnar, VDS or towed-jammer.
 
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.
 
4. Free the original hanger space for CIC, crew compartment, storage, or operation compartment for anti-sub/mire warfare UUVs.
 
5. Jet propulsion is good, but it requires high maintainance and frequent cleaning. You gotta love those sticky sea creatures. Good old fasion two shaft is thus suggested.
 
6. Anything that I forget? Oh yes! Those Harpoons. Forget about them. Put some SM-6 ERAMs into Mk.41 if there are surface threat.
 
Other things:
 
a. Since NLOS-LS is just the size of a few portable toilet, they don't need to be integrated weapons system on the ship. They can still be operated as "add-on" or "plug-and-prey" systems on still available space on the ship.
 
b. Though Bofors 57mm gun is great, options for bigger guns, especially Oto Melara stealth 76mm or 127mm, should be available. The configuration with bigger gun will compromise stealthiness, therefore RAM must be mounted somewhere on the ship.
 
But, honestly, frigates are something like chicken wing. It's good eats but not very much meat on it. For serious punch, you need to bring out destroyers and cruisers (if they are somehow not extinct by then). Frigates are good augmentation for fleet or concentrated ASW/escort missions, they are also top choice for sea-safety missions to counter terrorists/pirates.
 
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YelliChink       10/20/2007 5:44:58 PM
Again, why Fletchter, not Summer or Gearing?
 
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randomjester    Seakeeping   10/20/2007 10:39:01 PM
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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