Adding a third nacell?

[Jim]

I put this in TNG as the Refit future Enterprise-D is the only ship that I know of that added a nacell. I admit that I know nothing about Warp core efficency nor nacell/warp foeld dynamics.

What exactly does adding a third nacell do? If you use the same warp core, does the speed increase or decrease? Does the third nacell draw power just to run and therefore decrease the power:speed ratio, or would adding the nacell increase efficenty (or what have you) and therefore increase the power:speed ratio?

[Mikey]

Well, we've seen a few canon ship designs with a third nacelle. However, a third nacelle should technically do nothing but make the ship break in some fashion - Roddenberry's own rules of starship design state that nacelles must appear in pairs (among other design requirements.)

This is not from a pseudo-scentific basis - Roddenberry created those rules merely to flip off Franz Joseph, with whom Roddenberry fell out and who had puiblished some starship designs, including the three-nacelle Connie variant.

So, we can't have a ship with three nacelles, yet we have ships with three nacelles. Even if we discount AGT as an artificial future, there is the evidence from BoBW, etc. Maybe we could pretend that there were advances in warp field geometry that allowed for the concept in between TOS and TNG.

As far as what it does, I like the Kennedys' idea - that reducing the load on any one coil extends the coils' operational life and increases the long-term average speed. However, we've seen four-nacelled ships, that should be able to do this even better, and they don't seem to have been very successful (judging by the lack of numbers.)

Maybe the third nacelle restructures the warp field in a particular way so as to increase maneuverability at warp?

[Blackstar the Chakat]

I second the manuverbility theory. From my understanding of how manuvouring at warp works, by altering the firing rate of the individual warp coils you can alter course without dropping out of warp. Four nacelles seem to be ideal for maximum manuverability.

Why then, don't more ships have four nacelles? Simple. According to the TNG Tech Manual(I'm not sure if this information is canon, as I haven't seen every episode) a pair of coils, and by extension the set of nacelles' coils, are supposed to be withen six months of age. The more nacelles, and more coils you have the harder it is to keep them withen that age limit. It creates manufacturing issues for nacelles as well, and you can only deploy about half as many warp-capable ships.

[Mikey]

Each additional nacelle/coil also requires an additional plasma feed mechanism. No matter how advanced, adding an extra drain or tap from the warp core will invariably lead to a loss of efficiency. This migh be nominal, but is certainly multiplicative.

[Blackstar the Chakat]

I belive Picard did say the Stargazer was underpowered, and it was a four-nacelled ship. Maybe the AGT Enterprise's warp core was upgraded to the point it could handle the drain without losing efficiancy. Considering the other additions it had, it wouldn't be much of a stretch in belivability.

[sunnyside]

I put this in TNG as the Refit future Enterprise-D is the only ship that I know of that added a nacell. I admit that I know nothing about Warp core efficency nor nacell/warp foeld dynamics.

That's OK, neither do the writers.

However people tend to like to go with Roddenberry's design requirement. (Well except for the exposed bridge that has some people here frothing at the mouth).

Personally I like the idea that the third nacelle is redundant. Allowing you to comfortably enough run on any two. This would allow you to do maintenence on the third without dropping out of warp, should increase the time before you need to go into spacedock, and would allow you to go to warp despite more substantial damage.

As an added plus you get some move coverage of your warp core from enemy fire.

[Mikey]

The problem I have is that there is no canon as far as I know which explains the ability to disregard Roddenberry's design rules.

[sunnyside]

Well the design rules say that the nacelles can only be used in pairs. Not that the ship self distructs if you add a third. Hence the popularity of the "the third nacelle is at rest" theory since it doesn't violate the design rules while still providing an advantage in adding the third nacelle.

It also explains why the third nacelle isn't popular as it doesn't improve top speed just endurance and reliability, and may actually reduce speed while requiring more resources.

[IanKennedy]

Of cause it is canon that you do not require two nacelles to operate correctly.

• Take a look a the Prometheus sections, the top section has only one nacelle.

• The Niagara class had three nacelles, and was seen in the wreckage of Wolf 359

• Challenger, although it has two nacelles they are not arranged in line with the Rodenbury rules. This class was also seen in the Wolf 359 debris field

• Freedom Class, has but one nacelle and was very clearly seen in Wolf 359

• The controversial Hermes Class and Federation classes, which have 1 and 3 nacelles respectively

• Defender Class has four nacelles and was also seen at Wolf 359

All this and the political background of the reason for the rules (ie to p*ss off Franz Josef) lead me to discount the rules. Even ignoring the two nacelle rule there are other rules that say you must be able to see the front of the nacelle clearly in a front view of the ship. This is broken by a few ships.

[Mikey]

So, assuming there hasn't been a breakthrough which would allow violation of the design rules, you're saying that three-nacelle ships rotate nacelle usage, while keeping them in paired operation? In other words, have a rotating schedule, keeping on off and two on?

Very interesting, but wouldn't having an operating pair of nacelles with an off-axis or asymmetrical alignment (which is bound to happen in a rotation like that) have a VERY negative effect on warp field dynamics?

[sunnyside]

I kind of like the ex astris Scientia article on this (I just read it)
http://www.ex-astris-scientia.org/articles/design.htm

The idea that two nacelles are optimal not required is appealing.

I didn't know the rules were purely made as a shot at Franz Josef, but I could see that.

However the look of the Freedom and Challenger classes seems to be a good reason why the rules should be followed if for no other reason.

[Mikey]

Yep. It's a little disappointing that Roddenberry could act that way, but he made those rules purely to discredit Josef's work - specifically, the Hermes, Saladin, and Federation classes.

[Sionnach Glic]

Out of curiosity, why did he want to discredit him?

[sunnyside]

I started a new thread just on that in hopes of getting the straight dope

viewtopic.php?t=838

[Captain Picard's Hair]

Personally, I don't aesthetically like ships with odd numbers of nacelles; I can only guess this is because 2-nacelled ships are the standard?

On the mechanics of the things, it is clear that two nacelles are quite capable of propelling the ship. Since there are few ships with more than two nacelles, I gould surmise that there is a cost associated with extra nacelles that outweigh any benefits, perhaps extra power demands or the cost of so many more warp coils. Then there are the single-nacelle ships Ian mentioned. I can only guess that these designs may be limited in their warp capabilities, or that running on one set of warp coils places very high stress on the coils, reducing durability.