747400sp
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Could Gas Turbines Been Used In A Super Carrier?

Fri Sep 05, 2008 9:10 pm

With all the bad feelings Japan has about having the GW being base in there port due to it's Nuclear propulsion, I wonder, could a carrier between a Kitty Hawk and Nimitz class carrier sizes or even bigger than a Nimitz class carrier, been design with 8 or more LM 2500 or LM 5000. Eight LM 5000 would be more than enough to keep a 110000 ton ship speed up with a Nimitz class ship. A gas turbine powered super carrier could have easily replaced the Kitty Hawk. I know Nuclear is a better option due to fuel saving, but could there have been a TG powered carrier to replace the Kitty Hawk?
 
rwessel
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RE: Could Gas Turbines Been Used In A Super Carrier?

Fri Sep 05, 2008 10:56 pm

Sure you could. And four or five LM6000s would also be a heck of a lot smaller (and less trouble to live with) than a pair of A4Ws. It'd be a darn sight cheaper to build too.

But you give up a huge amount of range and time on station, since you're now having to lug fuel for the carrier as well as the (very fuel hungry) aircraft. Or accept that you've always got an oiler tagging along.

This was basically what happened with the Kennedy, which is basically a conventionally powered Kitty Hawk. Although the Kennedy used steam turbines instead of gas turbines (that ends up being rather bulkier than gas turbines, but somewhat more fuel efficient).

Given the amount of electricity generated in Japan by nuclear means (about a third now, planned to increase to over 40% by 2015), the opposition to nuclear propulsion is a bit puzzling. Although there's a fair bit of opposition to nuclear electricity generation as well.
 
DfwRevolution
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 12:16 am



Quoting Rwessel (Reply 1):
Given the amount of electricity generated in Japan by nuclear means (about a third now, planned to increase to over 40% by 2015), the opposition to nuclear propulsion is a bit puzzling

Indeed. The U.S. Navy probably has the best safety record of anyone in the world when it comes to nuclear power, civilian utilities included. The Navy has operated over 150 nuclear-powered vessels since 1954 with zero nuclear incidents.
 
BladeLWS
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 2:04 am

For a ship that size to be fueled by conventional means is no efficient for military use. You need to put all that fuel somewhere and they adds weight and takes of space for other stuff.

A super carrier needs to be able to have the range, on station time, and sustainable speed in a battle environment. Having to tag an an oiler behind makes that oiler a sitting duck for anyone wanting to stand a carrier in a hostile operations area.
 
Ken777
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 3:19 am

I served on the USS Long Beach during her first two deployments to WestPac during the Vietnam War. When we left long Beach (out home port) we basically set our course and turned up the speed. It taught me a pretty powerful lesson - a nuclear powered ship can be deployed and can move great distances rather fast, without the burden of refueling.

The only tactical disadvantage is the need for long term planning. On our second deployment is was calculated that if we keep our speed down a bit and limit travel a bit it was possible to get another deployment out of her before re-coring the reactors. That didn't keep us from an R&R trip to Perth (where I met my wife), but it did show the need for long term planning.
 
rwessel
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 3:31 am



Quoting Rwessel (Reply 1):
This was basically what happened with the Kennedy, which is basically a conventionally powered Kitty Hawk. Although the Kennedy used steam turbines instead of gas turbines (that ends up being rather bulkier than gas turbines, but somewhat more fuel efficient).

OK, I'd like to totally rewrite that... Other than a total brainfade, I have no explanation.

The Kennedy is basically an upgraded Kitty Hawk (some people consider it the same class, some not), but it was laid down as a nuke (the rest of the Kitty Hawks are conventionally powered), using four A3Ws. The cost of the Enterprise (and Long Beach) caused the Kennedy to be finished with a conventional steam power plant instead.
 
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moo
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 11:17 am

The new Royal Navy carriers will be powered by Rolls-Royce Marine Trent MT30 36 MW gas turbines - two of them, I think.

Quoting DfwRevolution (Reply 2):
The Navy has operated over 150 nuclear-powered vessels since 1954 with zero nuclear incidents.

Oooh, don't say that!

1972 - 500 gallons of radioactive coolant was accidentally released into the Thames river, near New London, Connecticut, while being transfered from USS Dace to the submarine tender USS Fulton.

1975 - Sturgeon-class submarine USS Guardfish was contaminated with radioactive coolant residue after dumping it overside and having the wind blow it back. This had happened several times before and the dumping of coolant at sea was discontinued.

1975 - Submarine tender USS Proteus discharges radioactive coolant into Apra Harbour, Guam.

1978 - USS Puffer accidentally released 500 gallons of radioactive water into Peuget Sound.

Now, they aren't huge accidents, but they are accidents.
 
zanl188
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 11:40 am



Quoting Moo (Reply 6):
Now, they aren't huge accidents, but they are accidents.

...and more recently this.....

http://www.guampdn.com/apps/pbcs.dll.../20080802/NEWS01/80802023/1002/rss
Legal considerations provided by: Dewey, Cheatum, and Howe
 
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moo
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 11:46 am



Quoting ZANL188 (Reply 7):

...and more recently this.....

Ouch, didn't know about that one! Cheers.
 
curlyheadboy
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 11:55 am



Quoting ZANL188 (Reply 7):
and more recently this.....

http://www.guampdn.com/apps/pbcs.dll...2/rss

" July 17: Radioactive water spills on a sailor working on the submarine after a water leak buildup breaks a valve."

Damn, that's having a bad day! I hope he is ok.....
If God had wanted men to fly he would have given them more money...
 
Kiwirob
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sat Sep 06, 2008 8:16 pm

Think Queen Mary 2, it's 50% heavier than a Nimitz, tops out at 30 knots if you dropped it's proplusion system into a lighter hull it should easily be able to propel it to CVN like speeds. I was told the CVF designers in the UK looked at using the same system as Queen Mary but for some reason decided against it.
 
747400sp
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 3:31 am



Quoting KiwiRob (Reply 10):
Think Queen Mary 2, it's 50% heavier than a Nimitz, tops out at 30 knots if you dropped it's proplusion system into a lighter hull it should easily be able to propel it to CVN like speeds. I was told the CVF designers in the UK looked at using the same system as Queen Mary but for some reason decided against it.

They should gone with it. The CVF much lighter than the QM2, so if the QM2 can reach 30 knots, imagine how fast a ship that is more than two times lighter, could cruise on the QM2 engines.
 
Alien
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 4:48 am



Quoting KiwiRob (Reply 10):
Think Queen Mary 2, it's 50% heavier than a Nimitz,

No it is not. QM2 Displacement apx. 76,000 tons, Nimitz clas apx 95,000 tons.

Quoting KiwiRob (Reply 10):
I was told the CVF designers in the UK looked at using the same system as Queen Mary but for some reason decided against it.

It was dropped for two very good reasons. Much reduced resilience to battle damage and relatively unproven design.

Quoting Rwessel (Reply 5):
but it was laid down as a nuke

No, Congress debated whether it should be a nuke prior to construction. They decided to burn dead dinosaurs rather than split atoms before the JFK was laid down.You don't just plunk boilers into a hull on a whim.

Quoting Moo (Reply 6):
Oooh, don't say that!

Say it. There has never been an incident of any consequence.

Quoting 747400sp (Thread starter):
I wonder, could a carrier between a Kitty Hawk and Nimitz class carrier sizes or even bigger than a Nimitz class carrier, been design with 8 or more LM 2500 or LM 5000. Eight LM 5000 would be more than enough to keep a 110000 ton ship speed up with a Nimitz class ship.

With enough money and enough compromise anything is possible. This is one that you don't to do. If the Japanese don't like it you can always base the fleet, the Marines and the money they pump into the local economy at Guam.

It's not just range. Where do you get the steam to run the catapults? How do you trunk the uptakes, exhausts, insulation and attendant exhaust chillers through the hanger deck and vent it without interfering with flight operations?
 
Stealthz
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 7:48 am



Quoting Alien (Reply 12):
No it is not. QM2 Displacement apx. 76,000 tons, Nimitz clas apx 95,000 tons.

Difference is not so great, QM2 is 76,000 Tonnes and Nimitz class approx 95,000 short tons or aprox 88,000 Tonnes
But other points are valid.
Despite what some think QM2 is not turbine powered but is of a CODAG-Electric design. Combined Diesel and Gas turbines driving electric systems.
The turbines are only used to provide the extra power for high speeds and do not run all the time.
Further to Alien's point of where do you put all the uptakes, exhausts etc for the turbines, this is an issue in liners as well. QM2 solves this in a way not especially convenient to carrier opps, the turbine engines are housed on the top deck at the foot of the funnel.

The proposed RN CVF also use a CODAG-Electric system but they will not have the steam plant requirements that current USN CV ops require.

Cheers
If your camera sends text messages, that could explain why your photos are rubbish!
 
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moo
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 4:55 pm



Quoting Alien (Reply 12):
Say it. There has never been an incident of any consequence.

I certainly disagree with this, every single one of the incidents I highlighted were 'of consequence' because there were high levels of radioactivity released during each and every one of them.

Now, in the context of this thread, each and every one of those incidents strengthens Japans position, especially considering the latest incident may have resulted in radioactivity being released in their own port.

I'd love to hear what you think would constitute an 'incident of consequence' if releasing high levels of radioactivity isn't...

Quoting Alien (Reply 12):
It's not just range. Where do you get the steam to run the catapults?

You boil it. Its not rocket science.

Or you stop using steam - the Royal Navy CVF program has a contigency to be converted to electromagnetic catapults if so required.

Quoting Alien (Reply 12):
How do you trunk the uptakes, exhausts, insulation and attendant exhaust chillers through the hanger deck and vent it without interfering with flight operations?

You direct them up through the islands - as the CVF design does indeed do.

Neither of your issues are exactly show stoppers.
 
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Mortyman
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 5:20 pm

The new Royal Caribbean cruiseship Oasis of the seas has the weight of a Nimitz class aircraft carrier and then some... from what i can understand:


Class and type: Oasis Class cruise ship
Tonnage: 220,000 GRT
Displacement: app. 100,000 tons
Length: 1,181 ft (360 m)
Beam: 154 ft (47 m)
Height: 213 ft (65 m) above water line
Draft: 30 ft (9 m)
Decks: 16 Passenger Decks
Installed power: 8 Wärtsilä V12 Engine @ 17,500 hp each
Propulsion: 3 × 20 MW Asea Brown Boveri Azipod, all azimuthing
Speed: 20.2 kn (37.4 km/h/23.2 mph)
Capacity: 5,400 passengers double occupancy (about 7,300 including third and fourth passengers)


http://en.wikipedia.org/wiki/Oasis_of_the_Seas
 
johns624
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 5:27 pm



Quoting Alien (Reply 12):
If the Japanese don't like it you can always base the fleet, the Marines and the money they pump into the local economy at Guam.

End of discussion-there's the answer. With Japan building up her armed forces, we should let them take over more of our Asian responsibility. Everyone has been dumping on the Germans for not coming to the fore, but the Japanese have been skating for much longer...
 
747400sp
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 7:34 pm



Quoting Alien (Reply 12):
No it is not. QM2 Displacement apx. 76,000 tons, Nimitz clas apx 95,000 tons.

Yes my ship is bigger in net tons, but in gross tons the QM2 whip us buy 44000 ton.
 
curlyheadboy
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RE: Could Gas Turbines Been Used In A Super Carrier?

Sun Sep 07, 2008 10:04 pm



Quoting Moo (Reply 14):
Neither of your issues are exactly show stoppers.

I believe the real show-stopper is strategy.
As correctly pointed out by a poster above, nuclear power means you don't have to refuel.
As a consequence, an immensely valuable strategic asset which a carrier is, can have unlimited range, can sail at high speeds without considering fuel consumption and (possibly the most important thing) doesn't have to rely upon a tanker ship or friendly harbor, so that the enemy can't wipe you out of the operations theatre just by cutting your fuel supplies.
Nuclear has its own disadvantages, and probably is not the most cost-efficient solution, but a supercarrier is a class of its own, and for what it's worth it, nuclear is the best solution.

My 2 cents  Smile
If God had wanted men to fly he would have given them more money...
 
Alien
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 2:16 am



Quoting StealthZ (Reply 13):
Difference is not so great, QM2 is 76,000 Tonnes and Nimitz class approx 95,000 short tons or aprox 88,000 Tonnes

Tons and Tonnes, I always get mixed up, but you get my point.

Quoting StealthZ (Reply 13):
The turbines are only used to provide the extra power for high speeds and do not run all the time.

Consequently fuel economy goes in the toilet and if you don't use exhaust chillers, the heat signature can be spotted from the moon.

Quoting 747400sp (Reply 17):
Yes my ship is bigger in net tons, but in gross tons the QM2 whip us buy 44000 ton.

Agree, but the number for this thread that matters is displacement, not weight. Simply put, how much water do you have to push out of the way to move the ship at a given speed.

Quoting CURLYHEADBOY (Reply 18):
and probably is not the most cost-efficient solution,

Above a certain tonnage for high speed cruising, there is no equal to nuclear propulsion. It provides power to spare to drive the ship at 33 knots, power the ships systems and provide plenty of steam for four catapults. It just cannot be done very efficiently with either diesels or gas turbines.
 
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moo
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 7:29 am



Quoting CURLYHEADBOY (Reply 18):
As correctly pointed out by a poster above, nuclear power means you don't have to refuel.
As a consequence, an immensely valuable strategic asset which a carrier is, can have unlimited range, can sail at high speeds without considering fuel consumption and (possibly the most important thing) doesn't have to rely upon a tanker ship or friendly harbor, so that the enemy can't wipe you out of the operations theatre just by cutting your fuel supplies.

Unfortunately, propulsion is not the only thing an aircraft carrier (or other ship or boat such as a submarine) has to rely on to remain functional - there is also aircraft fuel, food, ordnance and other expendables that have to be replenished to keep the aircraft carrier in operation.

So the opportunity to remove your supply lines still exists, and is still as prudent as before.
 
Kiwirob
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 10:09 am



Quoting CURLYHEADBOY (Reply 18):
As correctly pointed out by a poster above, nuclear power means you don't have to refuel.
As a consequence, an immensely valuable strategic asset which a carrier is, can have unlimited range, can sail at high speeds without considering fuel consumption and (possibly the most important thing) doesn't have to rely upon a tanker ship or friendly harbor, so that the enemy can't wipe you out of the operations theatre just by cutting your fuel supplies.

It's always going to have to rely on a tanker for it's escorts and avgas. Now that the US no longer have nuclear powered escorts the carrier battle group will always need a tanker, which kinda eliminates the advantage of being nuclear powered...

Quoting Alien (Reply 12):
It was dropped for two very good reasons. Much reduced resilience to battle damage and relatively unproven design.

Please explain, I would have thought QM2 powerplant would have been better than having a 100 plus metre long shaft, also by the time Queen Elizabeth is launched QM2 will have been sailing for about 10 years, any problems with the power plant would have been sorted by then.
 
curlyheadboy
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 10:33 am



Quoting Moo (Reply 20):
Unfortunately, propulsion is not the only thing an aircraft carrier (or other ship or boat such as a submarine) has to rely on to remain functional - there is also aircraft fuel, food, ordnance and other expendables that have to be replenished to keep the aircraft carrier in operation.

So the opportunity to remove your supply lines still exists, and is still as prudent as before.

You are correct Moo, but I wasn't trying to say that nuclear propulsion makes a carrier invincible.
If I may add something to what you correctly pointed out, it also has to rely upon its battle group. Can you imagine - for example - a Nimitz-class carrier going to Battle with no AEGIS cruisers providing AA shielding? And those ships need fuel, so that fuel shortage is and will remain a problem even for a nuclear-powered aircraft carrier.
This said, the advantages of not having to refuel the carrier itself remain: you remove a soft spot from the whole concept, the most valuable asset can remain on station for a very extended period of time, and that's a strategic advantage you don't want to miss when you spend 4,5 billion $ for a ship.
So, even though the USN could technically power its carriers with gas turbines, they went and will go for nuclear. If the Gerald R. Ford-class will be eventually built, they will be powered by a couple of Bechtel A1B reactors.
If God had wanted men to fly he would have given them more money...
 
curlyheadboy
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 10:36 am



Quoting KiwiRob (Reply 21):
It's always going to have to rely on a tanker for it's escorts and avgas. Now that the US no longer have nuclear powered escorts the carrier battle group will always need a tanker, which kinda eliminates the advantage of being nuclear powered...


see my above post, sorry but I posted shortly after you and couldn't read your post.
If God had wanted men to fly he would have given them more money...
 
astuteman
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 1:07 pm



Quoting Rwessel (Reply 1):
But you give up a huge amount of range and time on station, since you're now having to lug fuel for the carrier as well as the (very fuel hungry) aircraft. Or accept that you've always got an oiler tagging along.

You'll always have that, IMO.
Propulsion fuel is just one of a whole range of constraints that demand that the US nuclear carriers also have a whole plethora of support ships following them that have to be escorted too, and none of which steams at 30kts+....

Quoting DfwRevolution (Reply 2):
The U.S. Navy probably has the best safety record of anyone in the world when it comes to nuclear power, civilian utilities included.

The RN might dispute that....  Wink

Quoting BladeLWS (Reply 3):
You need to put all that fuel somewhere and they adds weight and takes of space for other stuff.

Wrong and wrong.
Bunker fuel will be stored in double bottom tanks which are required by regulation, and are bugger all use for anything else other than ballast, (which the fuel will also provide)  Smile.

Quoting 747400sp (Reply 11):
The CVF much lighter than the QM2

No it isn't. They are very similar. Don't confuse space with weight.

Quoting KiwiRob (Reply 10):
I was told the CVF designers in the UK looked at using the same system as Queen Mary but for some reason decided against it.

They did. It was rejected for commercio-political reasons mainly (not helped by the fact that the systems engieers were too risk-averse)

Quoting KiwiRob (Reply 21):
I would have thought QM2 powerplant would have been better than having a 100 plus metre long shaft,

 checkmark  Much.
Easier to build.
Easier to maintain.
Much greater layout flexibility
Dramatically better manouevrability.
Maybe next time, eh?  Smile

Quoting Alien (Reply 12):
It was dropped for two very good reasons. Much reduced resilience to battle damage and relatively unproven design.

Those were the reasons published. Neither is a valid reason. Both are misiformation.

Quoting StealthZ (Reply 13):
QM2 solves this in a way not especially convenient to carrier opps, the turbine engines are housed on the top deck at the foot of the funnel.

Mmmm..  scratchchin 
I wonder where the GTG's are on CVF...  biggrin 

Quoting Moo (Reply 14):
You direct them up through the islands - as the CVF design does indeed do.

Not quite.
I'd go so far as to say CVF virtually does away with uptakes, by the positioning of the prime movers....  Smile

Quoting Alien (Reply 19):
Above a certain tonnage for high speed cruising, there is no equal to nuclear propulsion. It provides power to spare to drive the ship at 33 knots, power the ships systems and provide plenty of steam for four catapults. It just cannot be done very efficiently with either diesels or gas turbines.

That's true, but within a day you'll have left behind the fleet of vessels that you still need with it in order to conduct aircraft operations, and provision 6 000 people...  Smile

Quoting 747400sp (Thread starter):
Could Gas Turbines Been Used In A Super Carrier?

Very Easily.

Rgds
 
Alien
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 1:30 pm

When you do not have to feed a 260,000 HP engineering plant that is running at close to full power much of the time your logistics issues just become much more manageable. Further, since the carriers internal volume is not taken up by fuel you have so much more room for aircraft fuel, supplies and munitions.

Quoting KiwiRob (Reply 21):
Now that the US no longer have nuclear powered escorts the carrier battle group will always need a tanker, which kinda eliminates the advantage of being nuclear powered...

Only eight nuclear powered escorts where ever built.This number rarely if ever allowed for an all nuclear task force deployed to be deployed. The advantage however remains for all large military ships. The French use it on CdG. The RN would have used it if cost where not such an issue. The USN will very likely use it on their next class of cruisers. In fact with crude over $100/barrel the life cycle costs of nuclear propulsion on a medium sized combatant become cheaper as well.

Quoting KiwiRob (Reply 21):
Please explain, I would have thought QM2 powerplant would have been better than having a 100 plus metre long shaft,

The difference is that you have a 330 foot shaft buried behind a triple bottom hull with the props and shaft ends protected by skegs. The machinery to drive that shaft is located 330 feet away, deep in the hull of the ship. With propulsion pods you have the electrical motors and attendant equipment located outside of the hull in the pod where it is susceptible to shock. You have power cables and control wiring routed outside of the hull to the pods which can be easily cut or disconnected but not so easily fixed while underway. With pods you have the machinery to steer the ship again located outside of the hull where with a conventionally propelled ship you only have two large rudders which are only large pieces of steel with the controlling machinery located inside the ships hull.

Quoting KiwiRob (Reply 21):
by the time Queen Elizabeth is launched QM2 will have been sailing for about 10 years, any problems with the power plant would have been sorted by then.

How many times will the QM2 have been in battle by then? How do they back fit any lessons learned with the QM2 pods to QE as it is already under construction.

What advantage do pods give a warship? I agree they are great for commercial vessels but they do not make sense for a warship.
 
astuteman
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 1:51 pm



Quoting Alien (Reply 25):
Further, since the carriers internal volume is not taken up by fuel you have so much more room for aircraft fuel, supplies and munitions.

That's not actually completely correct. See my earlier reply.

Quoting Alien (Reply 25):
props and shaft ends protected by skegs.

??? Props and rudders are every bit as vulnerable as a pod IMO.

Quoting Alien (Reply 25):
With propulsion pods you have the electrical motors and attendant equipment located outside of the hull in the pod where it is susceptible to shock. You have power cables and control wiring routed outside of the hull to the pods which can be easily cut or disconnected but not so easily fixed while underway

This is an incorrect interpretation of the pod layout.
All of the machinery is internal to the hull on the pod module. The only thing that penetrates the hull is the drive shaft that powers the pod.

Quoting Alien (Reply 25):
What advantage do pods give a warship?

A number of large advantages.
The two I would consider the greatest are

1. Manouevrability
2. Internal Arrangement flexibility

Makes them a damned sight easier to build too, which is of immense interest to me - perhaps not quite as much interest to the operator.

But they are no more vulnerable than propellers and rudders, of that I am certain.

Rgds
 
Kiwirob
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 4:11 pm



Quoting Alien (Reply 25):
How many times will the QM2 have been in battle by then?

how often has a nimitz actually been in a combat situation where it was in danger of being attacked? I think there is a big difference in being in actual danger than sitting a hundred miles of the coast and launching aircraft than actually being attacked so your point isn't all that valid.
 
Flighty
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RE: Could Gas Turbines Been Used In A Super Carrier?

Mon Sep 08, 2008 6:21 pm



Quoting Alien (Reply 12):
Say it. There has never been an incident of any consequence.

Compared to what? You are ignoring dozens of incidents of interest, most importantly classified incidents, unless you are confident you know those too. Are you?

Quoting DfwRevolution (Reply 2):
The U.S. Navy probably has the best safety record of anyone in the world when it comes to nuclear power, civilian utilities included. The Navy has operated over 150 nuclear-powered vessels since 1954 with zero nuclear incidents.

You are free to say that (which doesn't make it true). But you really shouldn't be putting down the rest of the world with such a broad (and dubious) brush. Is the USN better than the French, Japanese or Korean civilian sector, perhaps. But somehow if you consider our USN to have zero incidents, your judgment is highly suspect in the first place!
 
Alien
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RE: Could Gas Turbines Been Used In A Super Carrier?

Tue Sep 09, 2008 2:26 am



Quoting Astuteman (Reply 24):
You'll always have that, IMO.
Propulsion fuel is just one of a whole range of constraints that demand that the US nuclear carriers also have a whole plethora of support ships following them that have to be escorted too, and none of which steams at 30kts+....

And just imagine how much more often and how many more ships you would need and how often you need to stop for replenishment if you had to feed the carriers engines. Just think about how much less other stores such as jet fuel, ordinance and supplies the carrier could hold. Studies have been done ad nauseaum by Congress, NAVSEA and independent consultants and they all say nuclear power for carriers is the way to go both for lifecycles costs and for combat persistence. In fact you could double the number of oilers you would need for a battle group if the carrier is conventionally powered.

Quoting Astuteman (Reply 26):
Props and rudders are every bit as vulnerable as a pod IMO.

Well you better tell the Navy because they disagree. But that is the easy answer. Think about it. Props and rudders are solid pieces of metal. They have no moving parts and they are not susceptible[tible to shock damage the way a pode is. No gears, no wiring, no electric motors located outside of the hull as there would be with a pod.

Quoting Astuteman (Reply 26):
All of the machinery is internal to the hull on the pod module. The only thing that penetrates the hull is the drive shaft that powers the pod.

Even if you where correct. Which you are not, there would still be gears in the pod. Horizontal(ish) shaft in the hull from motor to approximate pod location, then vertical shaft from hull to pod, then horizontal again to prop. This however is not the design of the QE2's pods. The QE2s pods have electric motors encased in the pods themselves. These motors drive those very same vulnerable props attached to the end of the pod.

Quoting Astuteman (Reply 26):
A number of large advantages.
The two I would consider the greatest are

1. Manouevrability
2. Internal Arrangement flexibility

Neither of which offers a large enough advantage to offset the additional vulnerability and cost. Look, the navy is building a new carrier with all new technology. They are supposed to be incorporating EMALS, reduced manning, new power plant, new flight deck.... Now is the time for pods. Make your case at NAVSEA. They obviously don't see what you see in them.

Quoting Astuteman (Reply 26):
Makes them a damned sight easier to build too, which is of immense interest to me - perhaps not quite as much interest to the operator.

Perhaps because the operator may take them into battle one day?

Quoting Astuteman (Reply 26):
But they are no more vulnerable than propellers

They still have propellers so now you have two systems that can fail. The machinery in the pod and the prop.

Quoting KiwiRob (Reply 27):
how often has a nimitz actually been in a combat situation where it was in danger of being attacked?

That is irrelevant. It is a capital ship and as such is a target for an enemy during wartime. Building warships to civilian standards is a ridiculous proposition and a disaster waiting to happen.

Quoting Flighty (Reply 28):
But you really shouldn't be putting down the rest of the world with such a broad (and dubious) brush.

No one put down the rest of the world except you who took it that way. We are merely stating fact. There has never been a nuclear accident of any consequence by an operational unit of the USN.
 
astuteman
Posts: 6340
Joined: Mon Jan 24, 2005 7:50 pm

RE: Could Gas Turbines Been Used In A Super Carrier?

Tue Sep 09, 2008 5:29 am



Quoting Alien (Reply 29):
In fact you could double the number of oilers you would need for a battle group if the carrier is conventionally powered.

Don't dispute this. But the constraint of a supply fleet is the constraint of aa supply fleet, whatever the size

Quoting Alien (Reply 29):
Props and rudders are solid pieces of metal. They have no moving parts and they are not susceptible[tible to shock damage the way a pode is.

I personally don't fancy going to sea in vessel where the prop and rudder aren't moving parts...  Smile
There are too many examples of vessels that have been disabled by propeller or rudder damage to make your assertion supportable, IMO.

Quoting Alien (Reply 29):
The QE2s pods have electric motors encased in the pods themselves.

Yup. and all that other stuff you mntioned. But the bulk of the pod actually sits inside the hull. The pod is a pre-assembled module.
I'll stand by my assertion that the only bit that sticks ou of the hull is the drive shaft.

Rgds
 
Kiwirob
Posts: 9869
Joined: Mon Jun 13, 2005 2:16 pm

RE: Could Gas Turbines Been Used In A Super Carrier?

Tue Sep 09, 2008 6:14 am



Quoting Alien (Reply 25):
How many times will the QM2 have been in battle by then? How do they back fit any lessons learned with the QM2 pods to QE as it is already under construction.



Quoting Alien (Reply 29):
That is irrelevant. It is a capital ship and as such is a target for an enemy during wartime. Building warships to civilian standards is a ridiculous proposition and a disaster waiting to happen.

What I said is relevant when you take it into context with what you said.

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