Naval aircraft carrier turning at speed; Really Impressive

[billt460]

A nuclear aircraft carrier turning at full speed. That's a lot of steel moving fast enough to water ski behind. You can't help but wonder how much actual horsepower is turning those propeller shafts?

If the nuclear reactor produces the steam to power it, does the ship desalinate all the water it needs for the boiler? And is that steam recondensed, and the water used over in a closed system? It has to be a complicated system that is somewhat miniaturized, like that of a nuclear power plant.

 

[rekit]

Doesn't do any good to turn so sharp all the planes fall off

 

[OVERKILL]

A nuclear aircraft carrier turning at full speed. That's a lot of steel moving fast enough to water ski behind. You can't help but wonder how much actual horsepower is turning those propeller shafts?

If the nuclear reactor produces the steam to power it, does the ship desalinate all the water it needs for the boiler? And is that steam recondensed, and the water used over in a closed system? It has to be a complicated system that is somewhat miniaturized, like that of a nuclear power plant.

View attachment 178763

I was doing some reading up on Enterprise (CVN-65) last night as I saw its decommissioning appear on an FB military history group. Lots of folks upset it wasn't turned into a museum. Very strong attachment to that ship.

Enterprise had 8 A2W nuclear reactors, which took the place of the standard boilers that were used in traditional steam-driven vessels. She had four shafts, with two reactors per shaft. They used steam generators just like a civilian plant, and Rankine cycle turbines just like any steam-fired power plant.

Two primary propulsion turbines, one HP turbine and one LP turbine. These were mated to the screws via a gear reduction.

Electrical turbines were just like a civilian power plant, and the steam was also used to drive other things on board, like the catapult.

The primary and secondary heat transport loops were closed cycle, the condensers were cooled by sea water, just like a conventional plant.

She's listed as being 210MW, which is around 280,000HP.

 

[Astro14]

Doesn't do any good to turn so sharp all the planes fall off

This is sea trials. Full rudder deflection. Maximum performance testing.

The Air Wing wasn’t embarked.

“Like that of a nuclear power plant”. Yep. Basically, that’s it. Two Westinghouse AW-4 reactors. 1200 PSI steam turbines. Condensers with heat exchangers to the ocean.

Desalination plants. Electric power plants. Catapult steam. All driven by reactor heat.

 

[Astro14]

I was doing some reading up on Enterprise (CVN-65) last night as I saw its decommissioning appear on an FB military history group. Lots of folks upset it wasn't turned into a museum. Very strong attachment to that ship.

Enterprise had 8 A2W nuclear reactors, which took the place of the standard boilers that were used in traditional steam-driven vessels. She had four shafts, with two reactors per shaft. They used steam generators just like a civilian plant, and Rankine cycle turbines just like any steam-fired power plant.

Two primary propulsion turbines, one HP turbine and one LP turbine. These were mated to the screws via a gear reduction.

Electrical turbines were just like a civilian power plant, and the steam was also used to drive other things on board, like the catapult.

The primary and secondary heat transport loops were closed cycle, the condensers were cooled by sea water, just like a conventional plant.

She's listed as being 210MW, which is around 280,000HP.

I‘ve seen the plant aboard Enterprise. Been in reactor control. They chose the 8 A2W submarine reactors because it was a proven design. Development of the A4W was still on going.

As a data point, on the capability/capacity of that particular ship, we were doing 25 knots and launching and recovering airplanes during carrier qualification. So those eight reactors, which were organized into four reactor plants, were providing steam to drive the ship, steam to provide electric power, and steam for the catapults.

With all that load, they were running at roughly 25% of max capacity. Loafing along.

Big E had a slightly narrower hull than the Nimitz class, and a tremendous surplus of power.

So, she was fast.

Very, very fast.

 

[thastinger]

68 class can make up to 400K gallons of water per day.

 

[OVERKILL]

I‘ve seen the plant aboard Enterprise. Been in reactor control. They chose the 8 A2W submarine reactors because it was a proven design. Development of the A4W was still on going.

As a data point, on the capability/capacity of that particular ship, we were doing 25 knots and launching and recovering airplanes during carrier qualification. So those eight reactors, which were organized into four reactor plants, were providing steam to drive the ship, steam, to provide electric power, and steam for the catapults.

With all that load, they were running at roughly 25% of max capacity. Loafing along.

Big E had a slightly narrower hull than the Nimitz class, and a tremendous surplus of power.

So, she was fast.

Very, very fast.

I was surprised to read that she was overhauled only a couple of years before being retired, at a cost of almost $700 million. One would think that would have made the case for keeping her around longer. There seemed to be a tremendous amount of love for that ship.

 

[Astro14]

By the way, the gear reduction is planetary gears. The housing for them is a bit over two stories tall.

So, steam turbine spins, turns gears, gear output is a shaft several feet in diameter. It’s roughly 300 feet from the gearbox to the propeller itself.

When power plant is developing maximum torque, that shaft has a full 360° twist in it.

Put another way, if you drew a big pencil line along the top of the shaft when it was at rest, and then looked at under full torque, that line would spiral around the shaft, one full revolution.

Ever seen a socket extension twist under torque?

Now, imagine the torque it takes to twist a shaft several feet in diameter 360°.

The propellers themselves are a bit over 20 feet in diameter, they are moving a lot of seawater.

 

[ripcord]

The IT director at a company I worked for earned his PHD in nuclear physics while working on a CVN... wouldn't say which one. He did admit that the published top speeds were "estimates" and not "really accurate."

He also said that one of the biggest technical issues on the ship that limited how hard they would go underway was keeping the huge drive shafts balanced. They had massive power but only really put the hammer down during combat emergencies or trials as it was a massive strain on the drive train and could require extra maintenance and down time.

 

[Astro14]

I was surprised to read that she was overhauled only a couple of years before being retired, at a cost of almost $700 million. One would think that would have made the case for keeping her around longer. There seemed to be a tremendous amount of love for that ship.

There was a balance there, it takes several years to buy a nuclear carrier, you have to pay for the reactors upfront, and you’ve got to start laying down steel years before you want to ship delivered.

When Enterprise went in for the overhaul, it was because we couldn’t fill the gap fast enough with a new carrier, we needed her refitted and back in service. So, while $700 million is a lot, we got a couple of years out of her, and her replacement cost about 20 times that.

The design life for a new carrier is 50 years. And Big E was already there. You can upgrade some things, like combat systems - those things get removed and replaced with better, more upgraded parts. But there are some things that are so extensive that you simply can’t fix it without taking years.

The plumbing, for example, or the habitability of spaces.

Interestingly, in the past several years, we’ve had to upgrade the air conditioning systems for all the carriers.

When the ships were first designed and built, everything was done on paper. Now, there are computers in nearly every space aboard the carrier, so, the total load of hundreds of watts of heat, from each one of thousands of computers, that is added to the air conditioning load is substantial. Particularly when we operate in warm parts of the world, for example, the Persian Gulf, we simply needed better cooling throughout the ship.

 

[ripcord]

...paticularly when we operate in warm parts of the world, for example, the Persian Gulf, we simply needed better cooling throughout the ship.

I can only imagine how miserable something like the Admiral Kuznetsov would be in those conditions.

 

[Just a civilian pilot]

There was a balance there, it takes several years to buy a nuclear carrier, you have to pay for the reactors upfront, and you’ve got to start laying down steel years before you want to ship delivered.

When Enterprise went in for the overhaul, it was because we couldn’t fill the gap fast enough with a new carrier, we needed her refitted and back in service. So, while $700 million is a lot, we got a couple of years out of her, and her replacement cost about 20 times that.

The design life for a new carrier is 50 years. And Big E was already there. You can upgrade some things, like combat systems - those things get removed and replaced with better, more upgraded parts. But there are some things that are so extensive that you simply can’t fix it without taking years.

The plumbing, for example, or the habitability of spaces.

Interestingly, in the past several years, we’ve had to upgrade the air conditioning systems for all the carriers.

When the ships were first designed and built, everything was done on paper. Now, there are computers in nearly every space aboard the carrier, so, the total load of hundreds of watts of heat, from each one of thousands of computers, that is added to the air conditioning load is substantial. Particularly when we operate in warm parts of the world, for example, the Persian Gulf, we simply needed better cooling throughout the ship.

Curious how effective the air conditioning is when deployed to really hot and humid ( more humid lol ….ocean ) places?

 

[sw99]

There was a balance there, it takes several years to buy a nuclear carrier, you have to pay for the reactors upfront, and you’ve got to start laying down steel years before you want to ship delivered.

When Enterprise went in for the overhaul, it was because we couldn’t fill the gap fast enough with a new carrier, we needed her refitted and back in service. So, while $700 million is a lot, we got a couple of years out of her, and her replacement cost about 20 times that.

The design life for a new carrier is 50 years. And Big E was already there. You can upgrade some things, like combat systems - those things get removed and replaced with better, more upgraded parts. But there are some things that are so extensive that you simply can’t fix it without taking years.

The plumbing, for example, or the habitability of spaces.

Interestingly, in the past several years, we’ve had to upgrade the air conditioning systems for all the carriers.

When the ships were first designed and built, everything was done on paper. Now, there are computers in nearly every space aboard the carrier, so, the total load of hundreds of watts of heat, from each one of thousands of computers, that is added to the air conditioning load is substantial. Particularly when we operate in warm parts of the world, for example, the Persian Gulf, we simply needed better cooling throughout the ship.

Ah the good ol' Persian Gulf... Did a tour covering the mighty 68. Nice and toasty in those parts.

 

[Astro14]

Curious how effective the air conditioning is when deployed to really hot and humid ( more humid lol ….ocean ) places?

Basic physics - the difference between heat exchanger temperature and ocean temperature determines the rate of heat transfer.

So, sailing in hot water limits the heat transfer.

The ships were designed for those operating conditions - but that extra heat load from all the PCs was enough to push the internal temps up.

Summer in the Gulf, we used to see near 80F inside the ship. Not great, but a whole lot better than the 100F+ outside.

We upgraded the cooling systems, don’t know the details, so someone with more recent experience would be beater able to answer your question.

 

[sw99]

Curious how effective the air conditioning is when deployed to really hot and humid ( more humid lol ….ocean ) places?

Or not effective... Embrace the suck comes to mind.

 

[4WD]

Doesn't do any good to turn so sharp all the planes fall off

That’s what I’m wondering

 

[4WD]

We were coming in on a vessel heading to Halifax. Captain tells us to come up to the bridge … “You’ll want to see this” … The Roosevelt was about to depart - we listened to the crisp radio clearance - watched choppers inspect the lanes - then she turned on a dime to move on quickly … amazing display of power …

 

[R_W_M]

Doesn't do any good to turn so sharp all the planes fall off

The deck is always moving, so aircraft are always chocked and chained down, unless the aircraft is actually moving.

 

[Owen Lucas]

Reading threads like these makes me wish I had chosen a different path in life sometimes.

I can imagine being in that reactor room is the closest experience you can get to being on Star Trek.

"Jordy, we need to maintain warp 9.8 for a few hours"

"Aye sir!"

 

[andyd]

I can only imagine how miserable something like the Admiral Kuznetsov would be in those conditions.

Adm,K is presently in a Murmansk shipyard. AC is not a major issue there. S'posed to be back in service next yr. The ways things for Russia right now...