Well, from the TNG Tech Manual, it carries 3 years of fuel and cruises at Warp 9.2. Warp 9.2 uses roughly 10^9 megajoules per chochrane, and is, according to the encyclopedia, 1649 cochranes, so that's 1.649*10^12 megajoules. Warp 7 is 656 cochranes, and warp 8 is 1024 cochranes, but the power per cochrane goes down too. Roughly 10^7.2 for Warp7, 10^8 for warp 8. Which suggests that the fuel would last more than 1000 times as long at warp 8 as it does at warp 9.2. Edit: slipped a decimal: only 10 times as long. But that's just fuel. The DS9 Technical Manual says that no Federation ship has ever covered 1000 lightyears in a single year. That would mean that the Galaxy Class cruising at Warp 9.2 must spend about 1/3 of the time with the engines shut down, at least. While running the engines continuously at warp 7, or almost continuously at warp 8, would still be slow enough to not break that barrier, odds are they still require significant down-time even at slower speeds. I'd be surprised if you could travel at warp 8 continuously for more than a few months, or for more than 11 months out of 12. Time spent out of warp doing repairs/maintenance would save fuel, of course. But the estimate of "3 years" fuel probably took that into account for projected warp 9.2 travel, so at warp 8 the ship would actually be using more fuel than my projections above, because it would be spending less time with the engines off. Mostly guesswork, and depends on which books you want to count as "canon". Hope this helps.
I think warp 6 is sorta the normal cruising speed for most Federation starships, and a vessel could probably cruise at that velocity indefinitely as long as it has enough fuel. Beyond warp 6, however, I think the greater the strain on the engines and the shorter a ship can maintain those speeds before something burns out. Warp 7 and warp 8 are probably still within the safety zone, but are still likely considered high warp speeds, IMO. How long a Galaxy-class ship can maintain those speeds (before suffering engine damage) is anyone's guess, IMO...
Well if you look at it from the stand point of Enterprise, warp 6 is beyond the strain of the engines, i think it depends on the type of engine you have, also with the equipment on board...i know that the Enterprise-D went through countless upgrades, small ones at difforent times, but they increased the spee, so as C.E. Evans said, it is anyones guess.
I think those fancy warp cores with the intermix rates high enough to actually begin degrading the dilithium crystals that had Scotty so worked-up in TNG:Relics helped make a sustained warp 9 drive possible. The time limiting factor here would be the point at which the crystal assembly was undermined to the point of requiring the re-crystallization process Geordie referred to, which I'm assuming would involve a temporary core shutdown.
I wouldn't be surprised if the maximum cruising speed for long periods of time would range in high Warp factors. To my recollection, Enterprise-D at the start of TNG was able to max out it's warp to 9.2 if I'm not mistaken, which got increased to 9.7 over the 7 years, with 9.9 being absolute maximum before the ship experienced stresses. Voyager was slated to have a maximum cruising speed of warp 9.975. Of course, with the state Voyager found itself in at the beginning of it's run (low resources and a battered ship from being transported 75 000 ly's away), it's no wonder the ship hadn't had enough fuel to run continuously on such high speed. It wasn't until after season 2 that they started doing more in terms of resources for themselves. There was also an episode of Voyager where Neelix was telling a story to the Borg children ('the haunting of deck 12) in which supposedly, Tuvok stated they gathered enough deuterium to power the Warp engines for another 1000 ly's. Taking into consideration the instability of the nebula itself and a variety of other factors that forced them out of it prematurely, it's possible the ship could have acquired much more fuel. Plus, Janeway mentioned in early seasons to the Drayans that the Warp core on Voyager was designed to go on for 3 years without a re-fuel. So it's possible similar thing goes for the Intrepid (given it's size and technological advancement). I think the writers dropped the ball in various aspects of things. If TNG warp scale was accurate and Data mentioning it would take them about 2 years (at their then max. Warp) to reach the nearest star-base from the J system (when being flung 7000 Ly's away), Voyager's maximum warp factor should have allowed the ship to traverse the whole Galaxy within around 21.5 years. At the very least, it could have made for some interesting story-telling when running away from the Borg (and the Collective could be interested in learning that SF was able to increase their warp factors by that much in only 5 years). They still could have taken short-cuts home, but the situation would hardly be dire as saying they needed 75 years to get back at max. warp. And heck, even the novels established that SF ships at high warp frequencies (9.7 or 9.9) would cross 24 .5 ly's in 1 day. That essentially translates into 8 232 ly's in 1 year (which makes travelling through the Federation a bit more conceivable if it's 8 000 ly's across). At that speed, it would take Voyager just over 9 years to reach the Federation ... and given it's max. cruising speed at 9.975, going at it at 9.9 would not really strain their engines (heck, the cruising speeds are supposed to be sustainable speeds for long periods of time anyway, so strain isn't supposed to enter the equation for a very long time).
The Enterprise-D actually experienced engine damage due to prolonged flight at Warp 9 in "The Chase," so cruising at that velocity for very long periods of time would likely be unwise for a Galaxy-class ship unless you plan to stop over somewhere later for repairs. And the Voyager's Warp 9.975 likely refers to its maximum rated velocity more than its normal safe velocity (I think we generally saw her cruising around Warp 6 in most episodes though). Generally, the various tech manuals have claimed that ships can only hold their top cruising/emergency speeds for 12 hours or so, but I think there's been various onscreen instances in which it was even less than that because the ship was either going to fly apart (as in TOS) or the engines was going to automatically shut down (as in TNG) if they were pushed too hard after only a few minutes apparently...
I guess Stadi would be prone to exaggerating in "Caretaker", whereas assorted manuals (including both the ones written for fan enjoyment, and the ones supposedly written for or by Scotty) would be prone to playing it safe... Timo Saloniemi
But the Galaxy class has NOT been slated to have a maximum cruising speed of Warp 9. It's cruising speed is/or was lower because at the time it wasn't possible for the design to handle higher warp velocities. Voyager was obviously different. Both Stadi and Janeway mentioned Voyager's capabilities of top cruising speed 9.975. Why would either of them be exaggerating? they weren't. Sloppy writing and poor use of tech for the time period the shows were set in were the main culprit because 'drama' (in the sense of being elevated to a higher status by ignoring the setting itself) was more important.
I really don't think there's a problem here because it probably comes down to an issue of semantics or using different terminology to describe the same thing. "Sustainable cruise velocity" = "maximum velocity" Regardless of how you call it, it pretty much means "pedal to the metal" and not something any ship can maintain indefinitely, but definitely useful for covering relatively short distances--which could be anything up to a couple of sectors--very quickly.
What we know for a fact is that Voyager was always on the verge of falling apart when attempting speeds past warp 9 - and that she virtually never attempted those (probably because of the above fact). "Threshold" is a good example of this. This leads me to think that the "sustainable cruise speed" of warp 9.975 is some sort of a semantic misunderstanding that does not translate to an ability to sustain warp 9.975 for any appreciable length of time. That is, warp 9.975 for Voyager is what warp 9.8 is for the Enterprise-D - something the designers consider achievable, but the onboard engineers consider suicide if sustained past a few minutes. Timo Saloniemi
Say what? Sustainable cruise is a long term speed that is efficient and doesn't cause damage. Max velocity is exactly what is sounds like. In no way are they the same thing nor could they be construed to mean the same thing. Let's look at a Cessna 182 shall we? Max cruise is 150 kts which gets you max range for a given weight. Vne (velocity-never exceed) the classic red line is around 172 kts. Those are not the same thing.
Not necessarily. A ship's normal cruising speed (which I earlier suggested was warp 6) would fall under that category, but Stadi could be (and probably is) referring to the fastest velocity the ship can sustain period. And a "sustainable cruise" could be as short as 12 hours as far as a Federation starship is concerned.
I'd probably not use TOS as a comparison point as they've ran the Enterprise 990 to a 1000 ly in a single episode...
"Threshold" episode WAS on the other hand booted out of canon, so that doesn't count any more. I can understand if the writers wanted to strand Voyager for example ... but they could have essentially said that certain systems were damaged beyond repair in the initial transfer to the Delta Quadrant (which seriously damaged the ship and the warp core anyway), not to mention being under constant attack of the Kazon for the first 2 years. Having the ship limited to lower than Warp 9 velocities during that time and explaining it away as unrepairable damage 'on the go' (at least until they would get technology to repair their engines seasons later or to a friendly space-dock where these repairs could be conducted). The writers intentionally crippled the technology for the sake of the drama. At the very least, staying at Warp 9 would not be damaging to the engines in the long run as running at 9.9 or 9.975 (even if it is top cruising speed). If the ship is not performing up to specs, then it has no business being launched in the first place.
Oh, every episode counts. Forever. And in any case, the part where the hero ship falls apart when trying to do warp 9.7 was in no contradiction of earlier or later material, nor a particularly poor part of the episode treknologically or dramatically... In real life, ships tend to be launched whether they perform up to the originally dreamed-of specs or not. Sometimes an effort is made to at least falsify a few figures so that the project doesn't appear to be falling too short of original promises. Or perhaps an originally intended "operational" dash speed for a warship is achieved by leaving all the guns and half the fuel ashore for the duration of the dash speed tests. Perhaps the Intrepid class was originally intended to sustain warp 9.975 for some meaningful length of time, but this got quietly rewritten as sustaining said speed for 2.2 minutes in ideal conditions when there's no crew or cargo? Timo Saloniemi
But Star-Fleet ships tend to perform up to specs all the time. At least they did before Voyager aired. And we also know that the only reason Voyager never really performed up to specs in terms of Warp speeds is because of the writers. As for Threshold ... don't get me wrong, I personally liked the episode in question, but fact remains it wasn't acknowledged later in Voyager and was booted out of canon. There are plenty of ways to explain away this episode and what transpired within it, all within the confines of Trek universe ... trouble is, when counting 'canon' facts, that episode unfortunately doesn't count anymore as credible.
Not the Defiant... Nor the refitted Enterprise in TMP. At least their failings didn't get anybody killed (that we know of); the failure of the Pegasus killed an entire crew minus a handful of mutineers. But that's the only reason for everything in Star Trek. "Day of the Dove" was never acknowledged later on in TOS, or in any TOS-related adventure, or in any other piece of Star Trek for that matter. Doesn't mean it was "booted out of canon". And terminology introduced in "Threshold" was reused in several later VOY episodes, which is more than, say, the reuse of Kang in a single DS9 episode (which didn't acknowledge "Day of the Dove" in any way, btw, despite using one of its key characters). Timo Saloniemi
VOYAGER traveled 738 light years a year according to the Star Charts and it's normal cruise veolicty was warp 6. But 738 light years in a year is approximately warp 7.24 pretty consistent... In the episode that Enterprise was going from one planet to another very rapidly attempt to beat the klingons and Cardassians to a great archeological find the Enterprise reported to a starbase for repairs because Picard says operating at high war for long period of time.
You mean 438 light-years per year, according to Star Charts. That would place her cruising more around Warp 6.2 according to the TNG scale. That would average out about right given the times in which the ship took sidetrips or even doubled back to revisit certain worlds, as well as the occasional times she did go briefly to higher or lower warp speeds.