That still doesn't explain why the Soyuz class was retired so early. If they could upgrade the Mirandas internally, why not do the same for the Soyuz?
Possibly because the Soyuz was a dead ringer for the Miranda anyway that SF decided it wasn't worth the bother to keep it in service because Miranda's (especially with upgrades) proved they can do everything the Soyuz could. Its also possible that some admiral wisened up to the fact that having a nearly identical starship with some separate bits designated as a completely different class of ship (instead of saying its a simple variation belonging to the Miranda class) was nonsensical and terminated production because it didn't make any sense?
But there were already several variants of the Miranda class still in service by TNG. I’m not seeing why, say, the Saratoga variant from Emissary was still being used, but the Soyuz class wasn’t. See above. I’m simply not seeing any rational reason why the Soyuz was retired so early while other contemporary classes such as the Miranda, Constellation, Sydney, etc. were still in service during TNG.
There was nothing on screen indicating the USS Saratoga was not a Miranda class starship. If there were other starships of the identical class (Miranda) running around that had slightly different configurations, they probably would have been left in service and upgraded. The Soyuz was a separate class and probably didn't offer anything a Miranda couldn't and was retired decades prior. The Sydney and Constellation have virtually nothing in common with the Miranda class starship or each other in terms of how they are arranged. Also, the Constellation may have been of a newer production line (late 23rd century) and upgraded over time internally. Per the dialogue in TNG, Soyuz was a separate class of starships compared to the Miranda. As I said, its possible the Soyuz was retired from active service because they were essentially identical to the Miranda class and had nothing new to offer compared to the Miranda class starships... so instead of having several starships that are for all intense and purposes identical to each other but classified differently, the Soyuz might have had a brief overall existence because it was also made in smaller numbers compared to Miranda's... and in order to prevent 'overcluttering' the fleet with useless class differentiations even though the ships were virtually identical, the one with the smaller numbers (Soyuz) may have been axed from production.
I’m not really buying that rationale. And the configuration of the Constellation and the Sydney classes doesn’t really matter. They are contemporaries to the Soyuz, and yet they are still in service a century later while the Soyuz was retired for that long. And saying that the Soyuz had ‘nothing new to offer’ makes little sense to me when the USS Lantree, a contemporary to the Soyuz, was still functioning as a supply ship by TNG. So why couldn’t the Soyuz class have been converted to supply ships like the Lantree was? There’s nothing inherently different between the Lantree and the Bozeman to warrant one ship being refurbished to transport supplies and the other one being scrapped.
I've always found it interesting the Soyuz apparently had a short service life, but I don't agree either it was virtually the same as a stock Miranda. It doesn't visually look that way and I can imagine plenty of reasons why it had a briefer career, but my own headcanon would probably be different. The Lantree is kind of a weird case, as some sources have treated it as a separate variant/subclass of the Miranda family due to it lacking the rollbar and being a fairly mundane supply ship with a small crew. The production reality is that it was intended to be a stock Miranda but the rollbar was temporarily removed because they were having issues with the wiring to light it properly. So, in this context, should it be considered a Miranda that was simply modified uniquely for supply runs? Should it be considered a separate variant that older Mirandas were modified into (as in some fan sources)? Is either option good depending on someone's personal preference?
Actually, the Lantree wasn’t supposed to be a TMP movie ship at all. The scriptwriter envisioned a small ship with a minimal crew, probably thinking that the VFX personnel would be building a new model. Instead they just reused the Reliant. The Tsiolkovsky was the same story: that ship was supposed to be a contemporary to the Enterprise-D, having been launched the same year. Instead they used the Grissom model (labeled as the Copernicus from its previous use in The Voyage Home.)
Perhaps Starfleet ship designers are the kind of people Sir Pterry Pratchett was talking about when he wrote this line?
Personally I think the Soyuz class was based on the Miranda but with a lot structural changes, more so than just removing yhe tollbar or adding a couple of side mounted sensors. The large additional structure behind the extended hull might have had unforeseen affects on the ship's performance, enough to prevent this class from being produced in greater numbers. Starfleet does mass produce reliable ship designs but there are some ships we have only seen once, even with "all hands on deck" situations like the Dominion War battle groups.
Jackill's entry suggested the Soyuz was primarily an attack frigate variant, with four multiphasing megaphaser turrets that were intended to add more tactical flexibility to the heavy frigate design frame. It's a bit vague as it's implied these turrets are less powerful than the normal megaphasers seen on other designs, but it doesn't specify exactly how they differ. It does mount torpedo systems but does have standard phasers and particle accelerators, although they might not actually be a tactical system. The Soyuz also incorporated some experimental tactical systems like improved ECM, at least when it was first introduced, and a fairly large complement of small craft. The schematics show three shuttlebays (with the third being at the end of the aft tactical boom), but the text only references two.
I have seen those four turrets also described as long range sensor arrays similar to what was mounted on Sisko's Saratoga
Given we never saw them side by side, is it possible the Soyuz was supposed to be smaller than the Miranda, similar the Sombra class to the Constitution class? If that were the case, I could see the logic in retiring the smaller, more niche vessels for the more do it all Miranda variants.
Looks like. The Sombra just had a smaller crew. Maybe not even that much smaller, if they haven’t started doubling-up the bunks and gone up to 430 crew on the Enterprise (hey, maybe that’s why Kirk doesn’t have a suite with a chef’s kitchen and California-King bed). I’d forgotten about the Sombra, otherwise I was thinking Starfleet would take an expansive view of ship-classes. For instance, if we ever saw a concept-Reliant, it could still be a Miranda class, since the core hull is still the same, just the nacelles and rollbar are swapped. Same with the Constitution-refit desk model we saw in TNG with the sideways nacelles and open saucer (maybe a one-off variant testing out components for the Constellation).
Yes, as I've mentioned before, Starfleet seems to be arbitrary in determining whether a ship is a variant of one class, or an entirely different class.
I've tended to prefer subclasses in some cases, so variants like the Bonhomme Richard and Achernar in SotSF would be subclasses of the Constitution family but not necessarily distinct classes in a broad sense. The Ascension class dreadnought is a variant of the Belknap strike cruiser family (themselves variants of the Constitutions), and a separate class because it has unique modifications and a separate mission profile.
I think the idea of the ‘subclass’ has gone out of favor in modern Trek. I would have been just fine had the dialogue stated that the Sombra was a subclass of the Constitution rather than a whole different class that happens to be an exact duplicate of the Discotution.
It really is too bad that the production had to reuse the Excelsior, Reliant and Grissom models in early TNG. I think it would have served the universe better if the 1701-D had some contemporaries right off the bat. Instead we get a Starfleet that has one brand new looking ship slumming with a bunch of 80-year old designs.
One thing having the Excelsior class appear in TNG's Encounter at Farpoint. We know how big that ship is, having the USS Hood flying in formation next to the new Enterprise gave us a relatable feel how big the Galaxy class was https://www.ex-astris-scientia.org/articles/excelsior/excelsior-galaxy-encounteratfarpoint.jpg
Yes, especially since most of the times they showed up, they were meant to be completely different ships entirely. The Fearless from "WNMHGB" was supposed to be a Probert Ambassador class and they ended up reusing stock footage of the Excelsior from "Encounter at Farpoint." The aforementioned Tsiolkovsky and Lantree were supposed to be different ships. The Stargazer would have been a reuse of the TMP movie Enterprise had Greg Jein not built a new model on time and under budget. They could have built a new science vessel for the Brattain in "Night Terrors" but instead just reused the Reliant. And the Pegasus was definitely supposed to be a different ship but they reused the Grissom model. The thing is, when TNG premiered, the producers didn't want to build more Starfleet ships because they were worried that the show wouldn't be popular and would get canceled after the first season, thereby wasting money. But once that proved not to be the case, the producers would still balk at spending budget money on new models. Heck, they didn't even want a new model built for the Enterprise-C, even though the entire episode of "Yesterday's Enterprise" wouldn't have happened without it (or at best, they would have had to reuse the TMP Enterprise or the Excelsior model and change the script to make it an older Enterprise.)