From what I understand there is just one Enterprise class aircraft carrier. Now I am sure these things are not cheap or easy to design. Why invest in the design if you are only going to build one. Was there some type of flaw that they saw to not build anymore?
According to the Wikipedia entry
At the time of the Enterprise’s launch, there were still lots of other carriers in service, such as the Kitty Hawk and Forrestal classes.
They started making the Nimitz class carriers around 1975.
Well, one factor is that the Enterprise has eight smaller reactors compared to the two larger ones that the Nimitz-class vessels have. (8 A2W vs. 2 A4W plants) AIUI when they drew up the plans for the Enterprise they simply replaced the boiler rooms from a Forrestal-class hull with reactor plants. And that’s not a very efficient loading.
Another factor going to the reactor plants - the Enterprise, and other early nuclear-powered USN vessels were on what is now considered a fantastically short fuel cycle. IIRC the Nautilus had it’s first core removed after less than two years. And the Enterprise, Long Beach and Bainbridge all were on similar fuel cycles for their first cores. When talking about the Virginia-class CGNs we went from commissioning in 1976 to decom in 1994 all on one core. AIUI that’s a more normal fuel cycle for modern carriers, too.
ETA: Wikipedia on the modern A4W plants claims that they have a fuel loading for 23 years.
I just realized I didn’t explain very well why eight reactors weren’t very efficient. obviously there are going to be inefficiencies of scale involved with building eight smaller reactors, vice two larger ones: more shielding needed, more watchstanders leading to higher personnel costs, increased maintenance costs. Just to name a few. But the biggest one, IMNSHO, goes to the less-obvious major benefit for nuclear power for aircraft carriers.
Contrary to common belief it’s not improved range and cruising duration. Or at least not directly. Because of how carrier battlegroups are deployed one will never see a carrier on its own. And since the escorts available to the carriers are all conventionally fired (and mostly GT powered ships) the range and endurance that the carrier has is not shared with its escorts. Which means that the carrier battlegroup is still tied to the logistics chain on a pretty short leash.
But because the carrier itself has (effectively) no need for bunkerage for its own fuel, it can dedicate its onboard bunkerage to storing fuel for the airwings. AIUI, too, since the GT powered ships run on the same fuel as the air wings, in case of emergency the carrier can supply a bare bones escort group, allowing it to operate in advance of the logistical chain I mentioned above.
ETA: Therefore, by reducing overall reactor volume by consolidating the 8 reactors into just two, later carriers can carry more fuel onboard.
It was my understanding that the reactors on Enterprise were the same as on a nuclear sub so they needed eight for more power a carrier would need. Is this true?
No.
You’ve got a couple of errors in your thinking.
At the time (1958-1965) the reactors being used on subs were the early and mid-range S-series reactors, and the S5W plant was becoming the standard plant, which it would remain until the Los Angeles-class boats shifted the standard sub plant to the S6G plant. The S5W plant is very different from the A2W plants in the Enterprise. So, the plants in the Enterprise are not simply sub plants moved into a surface hull.
I’m not going to talk power numbers (Sorry, I don’t care to spend time in Levenworth.) but my understanding is that the A2W plants were more comparable in power output to the C1W plants aboard the Long Beach, than to smaller sub plants. Now, a C1W plant has more power than a contemporary sub plant would have had, but a carrier would have had more power demand, too, than even the Long Beach did. In addition to the increased complement (and increased hotel loads, and power demands) modern carriers are built around the steam catapult system which I understand to be a huge steam hog. And, of course, the bigger a ship is, the more resistance to movement it will have, so more power is required for propulsion.
It’s fair to say that Enterprise would have more power demands than Long Beach. But I don’t think that it had four times the requirements. Twice the power of Long Beach, i.e. four A2W plants, probably would have been enough to keep her properly powered, and AIUI three times would match the power loading aboard Nimitz-class ships.*
You’re right to think that the Enterprise would have needed more than just two reactors of the size she had to meet power requirements. But I’ve never heard anyone who had experience with the ship ever say anything but that she was ridiculously overpowered. And they were even birdfarm sailors!
*Why am I not placing matching Nimitz-class power requirements as my idea for a reasonable design power level? First off, in general the most that onboard power demands will take from a reactor’s theoretical power output are about 15-20%, and that’s generous. Since I have no experience with steam catapults, we’ll bump that up to 30% of max power is needed to supply all the steam and electric needs aboard ship, using all systems at max rates. That leaves 70% of the ship’s power output for propulsion. Naval propulsion is one of those fields that really demonstrates the expression: diminishing returns. The first 20% of reactor power dedicated to propulsion is usually enough to get a ship moving at what’s called “Standard” speed. Which is probably about 1/2 to 2/3 of the ship’s maximum speed. Above “Standard” is “Full”, which uses another 20% of reactor power to push the ship’s speed up to about 80-90% of the maximum theoretical speed. It’s that extra 30% power I have left from my calculations that’s left to push the ship from “Full” to “Flank.” Based on the numbers publicly available for Enterprise’s speed in the Wikipedia article referenced above, that extra 30% power will increase the speed about 4 knots. :rolleyes:
Given that you wouldn’t have wanted Enterprise to out pace her escorts, and until the 70s and the adoption of the GT ships, they were steam powered escorts, they were already slower than the Enterprise. Dialing back her max power would have simply made sense, I think.
Of course, I’m not a birdfarm sailor, nor a naval architect. Both those sorts of people tend to think that even a tenth of a knot is worth sacrificing anything up to the Admiral’s wife** to get. 
**Me? I’d just sacrifice the Admiral, instead. Who cares about speed benefits - there’d be no more Admiral on board! Yah! 
Are nuclear carriers designed with substantial bunkerage with this in mind?
AIUI, yes, sqweels. I don’t know that it’s often that the carrier will unrep fuel to her escorts. I can’t find confirmation of this right, now, though. Of course, finding hard numbers about any in-service vessel is hard, and I’m not going to use anything I can’t find off a public source. If a carrier sailor wants to come in and tell me my head is up my arse again, I’ll have to eat my words.
ETA: There are a lot of capabilities on naval vessels that are built in for what any rational person would call a corner case. This is one such, I believe. (And more likely to be useful than many more obvious ones.)
Wait, the escorts run on jet fuel, not diesel? Interesting.
Diesel full = Jet fuel = Kerosene = Home heating oil
There are slight differences in terms of additives but they are all essentially the same thing.
A nitpick or two.
Unless it was changed completely during a retrofit, the Enterprise used the A1W reactor core. Also, many of the steam ships ran on jet fuel, too (JP4 or JP5).
eta: Which smelled just like diesel (thanks, Shagnasty).
I’m wondering why they didn’t make more of the smaller ships nuclear. Is there a smallest practical size for a reactor that limits it to the largest vessels?
Rhubarb, do you have a cite for the A1W vs. A2W reactor plants? Everything I can find online has the A1W being the prototype in Idaho Falls, and A2W being the shipboard version. But, I can’t find anything official, for some reason. 
On preview: Sunspace, they did make some nuke escorts. The reasons there were only a few built, and those decommed in the 1990s were discussed here. The short answer is a combination of higher costs, both initially and operationally, and (I believe) a dislike of nuclear power in the eyes of the public. The benefits to nuke propulsion for subs and carriers outweighs those costs, but since so many non-nuke ships were being built anyways, there really was no way to avoid the conventional escort for nuke carriers issue.
An imponderable is this: Navy Nuke training has about a 50% wastage rate. That is, for every two people who start the training only one will be deployed to a sea-going command. I’m not sure that there was the manpower pool to meet the demands of an all nuke fleet. Even if the public could be sold on it.
I trained at the S1W (Nautilus) prototype, next door to A1W. I was always told it was the Enterprise reactor prototype. You could be right about the A2W plant, but I never heard anything about it.
Regarding the number of nuke surface ships, the bubbleheads (submarine sailors) would say it’s because skimmers (surface ships) are just too easy a target.
Also, IME, the nuke program has closer to a 75% washout rate. Even higher if you count the ones who are bumped out after they reach the fleet. Of course, that may have improved since Rickover joined the great mothball fleet in the sky.
ETA: On further thought, I recall that there was a major retrofit of the E involving new reactors. Maybe the switch was made then (late '70s, early '80s time frame)?
I don’t believe this is strictly correct.
Jet fuel is kerosene (ref). Both are obtained from the fractional distillation of crude oil between 150 C and 275 C.
Diesel fuel is very similar to home heating oil (ref) and either fuel can be used in a diesel engine. Both fuels are obtained in the fractional distillation of crude oil between 200 C and 350 C.
There is considerable overlap. So, one could define a mixture which would work in both applications. The Navy may specify a single fuel for both. However, filling up your jet with ordinary diesel is asking for trouble.
I always enjoyed passing on every tuber joke I ever heard. Every scurrilous story about the lack of moral fiber of the bubbleheads. And I’d always cap it by pointing out that in the insult game, the bubbleheads always won the insult game: No matter what we called them, “target” was just that much worse.
It’s possible, but given that apparently the plants on the USS Triton were labeled S4G, even though they were the direct counterparts to the S3G prototype, I think that it’s fair to say that it’s possible they did make the prototype then put in the nearly identical plant with a different designation aboard the ship. Why they then wouldn’t do the same thing for the S6G plant, I couldn’t say.
I asked a lot of questions during training about the various bird farms, because I am borderline claustrophobic - and wasn’t going sub for any reason. I heard and read what I could about the Enterprise and the Nimitz-class ships, because I was afraid I’d end up needing that knowledge. In the end, I qual’ed at S3G, then spent the rest of my time aboard USS Virginia. I have about as much direct knowledge of the current nuclear navy as I do of Farragut’s navy.
I drop in a quart of STP with every tankful, and my F/A-18E doesn’t seem to mind.
Of course, I only drive it on the weekends when the weather’s good.
Hey, Otaku! We ran across each other a while back in a different submarine-related thread. I served onboard the ninth USS Virginia (SSN 774).
The information you shared about diminishing returns WRT nuclear propulsion was interesting. I’ve never heard that, but then again, I wasn’t a nuke.
One thing I am curious about, though. . . were surface nukes as disgruntled and curmudgeonly as their subsurface counterparts? Admittedly, those guys often got a raw deal, and typically put in a LOT of time. Of course, being cruel and easily amused, I took great joy in reminding them that’s why they get that fat pro-pay.* :dubious:
(I was too old when I enlisted to go nuke, although my recruiter assured me we could get that waived. After discussing the training pipeline, I pretty much told him to stuff his waivers. If I’d wanted to spend that much time in school again, I would have gone back to college.)
- Of course, without fail, every time I taunted them I’d find we had a weapon shipping evolution to carry out, which kept me onboard from dawn to dusk.
Hey, yourself!
Completely anal nitpick: Actually, you served on the seventh USS Virginia, thought the ninth American warship of that name. One that was counted for the stars in our ship’s crest was the CSS Virginia, the former USS Merrimack. The other one counted for our crest was the CSS Virginia II.
It’s not just nuclear power. That sort of power/speed relationship is true no matter what the source of the power to the screws might be.
I can’t offer any direct confirmation. The only bubblehead nukes I’d met were people in the training pipeline who were putting in their shore rotations in one of the training commands. As such I think they’re under “strong recommendations” to be upbeat and positive. But, if you look around at the few other submariner nuke sailors who post on the Dope, most of them share the same general level of bitterness I can attest was present aboard my Virginia.
Though I’ve yet to hear someone else boasting about being complimented on their ability to share hate and discontent. I said some rather unwise things in the discussion session following the reading of a sexual harassment incident during the first post-Tailhook sexual harassment training* stand down.
One of the incidents was about how an LCDR had been ordering a female seaman to kiss* him. When the complaint was acted on, the LCDR had a letter of reprimand put into his jacket. Now, you and I know that would effectively kill his career, but considering some of the other incidents and punishments we had been discussing it was a bit jarring. And I categorized it as: “Sounds like another khaki got a slap on the wrist for something a blue-shirt would have fried for.” There was a moment of awed silence from the rest of my division. And pained silence from my DivO and LCPO. But, to give them their due, they didn’t actually contest that interpretation.
Oddly enough that incident was not part of any of the other sexual harassment training I ever saw in the Navy.
**Of course we were never told where the kiss was ordered, nor what the standard for completion might have been. I certainly have my suspicions that while the word kiss might be accurate from some views of the event, the more honest description would have been far more damning.
Hey, I’m nuc fallout, part of the 75%.
I spent my time on the carrier Kitty Hawk. It isn’t regular for a carrier to fuel other ships. It can be done and is practiced once in a while to keep everybody trained, but not often.