fuel in voyager

[Jark]

That is interesting. But if the sensors are only detecting surface composition and mass, that shouldn't be too hard. You'd get the computer to replicate a load of thin shell-like pieces, using a similar algorithm you use to make a huge printed banner out of lots of A4 sheets (that you tape together). The engineering crew would glue, spot weld or otherwise bond the pieces together and then weight them with ballast so that the mass is accurate. Hard work but doable. OTOH if the sensors are as accurate as Federation sensors are supposed to be, and could detect 'props' like that, I don't know how they managed it.

I'm only going by memory and the transcript here, but it looks like they were just doing a preliminary scan of the debris field and were pissed off because they thought they had accidently destroyed Voyager. A more detailed scan could've seen through the trick.

[Patrick Degan]

The reason why you bother is because there isn't a guarantee that the ship will make it into port on a regular six-month schedule (one area the writers ignored).

This depends on the mission. I get the impression the Intrepid class isn't designed for multi-year deployments the way the Galaxy class is. For Starfleet it's a case of looking at the average and worst case deployment times for their current fleet, looking at endurance costs (all aspects including fuel, parts and phototorp carriage) in terms of tactical performance or cargo capacity sacrificed, and picking an optimal design endurance. 'Being sucked across the galaxy' is such a ridiculously unlikely occurence that it isn't reasonable to expend significant effort designing for it.

To return to the nuclear submarine analogy, an SSN (or SSBN) isn't sent out on multiyear deployments nor is intended to be, but it is designed nonetheless to free the vessel from the requirement for periodic refueling by incorporating a fuel store which will last for a good chunk of the vessel's expected service life (or in the case of the new Virginia-class boats for the USN, its entire service life). If a ship is free from refueling requirements, it can stay out on deployment for as long as the food supply holds out and that is a considerable margin of greater endurance than comparable conventional vessels which have to schedule tanker rendezvous at sea or returns to the nearest base. If a starship can be freed from refueling and can manufacture at least part of its own food supply on board, it can stay out for extended cruises as needed, and this would make for a critical tactical edge even if the vessel in question is a destroyer.

It also reduces a key maintenance problem in that you don't have to worry about the condition of fueling ports, fuel transfer lines and pumps, and containment of anything other than the built-in storage bunkers. You really don't want to have to move bulk antimatter about any more than you absolutely must, and preferrably that's the distance between the tank and the reactor, which should be as short as possible within the ship.

we always knew they'd get back by the time the series expired in seven years

But the characters should've been concerned about where they're going to get antimatter from if they carry less than 80 years worth, which is highly likely.

The situation with the Voyager is entirely a freak occurrence which would not be what the plan for such a ship would be based on. And while it would be facing a fueling problem over the stretch of a 70 year flight back home, this would not be an immediate problem that we would have to have addressed by the writers in any given season other than maybe a throwaway scene discussing long-term planning.

However, it probably isn't a high priority. It's possible that they were looking for deuterium because they were running out of reaction or fusable mass for the impulse engines faster than they were running out of antimatter,

Why would they be running out of deuterium? If you're going to put enough antimatter fuel on board for multiyear endurance, it follows logically that there would be sufficient supplies of matter fuel as well and the logical design solution for powering the impulse engine is to simply run it off the main reactor, which is implicit in the design of the movie-era Enterprise. Or at least drawing from the extant fuel supply.

though that doesn't really square with Janeway's 'there's coffee in that nebula' comments (though her dialogue isn't exactly reliable or even consistently sane). It's possible that combat damage took out the bussard collectors and prevented them from gathering impulse fuel that way, and/or damage in the initial wave event or later combat punctured the main deuterium tank, caused a huge leak and left them low on deuterium (a problem that couldn't have occured with the AM pods, since the ship didn't disappear in a huge explosion).

If I were designing a starship with the capabilities implicit for vessels based on the antigravity/"mass lightening" effect (which lets you off the mass penalty problem for pure reaction-drive vessels having to push all that bulk about to get anywhere), I would have the entire fuel storage in a protected bunker deep inside the ship and compressed to high density if feasible for space-saving considerations. There should be no need to gather fuel from the interstellar medium and any damage which could puncture the internal fuel bunkers would likely be severe enough to destroy the entire ship anyway.

I think I'll go with 'A/M issue didn't get acute enough to be mentioned onscreen, damage caused by the Array included a big deuterium leak that left them hurting for impulse fuel relatively soon, Janeway's ranting about coffee in nebulas was delusional'. It's the least painful explanation.

Actually, the far simpler explanation is that Janeway is just clinically insane.

Thirdly: the physical structure of the pods should be less of a consideration since the interior space has to be a forcefield coocoon to begin with.

According to the TNG TM (as I recall) this is one place where Starfleet was sane and went with KISS; the pods use superconducting electromagnetic confinement only. This is mildly supported by the dialogue in "Contagion". Given how unreliable their subspace tech is, this is probably for the best, as otherwise they might have ships blowing up due to subspace-interference-anomaly-of-the-week.

Well, there it is.

Why might they need to replace a starship's warp coils? Remember the TOS episode "The Paradise Syndrome" when the Enterprise burned out her warp drive system to the extent that they'd need a spacedock facility to repair the engines? That is one possibility.

Good point. Voyager presumably got lucky in that respect, as there's essentially zero prospects for carrying a complete spare set of warp coils or making them without major industrial facilities. OTOH AFAIK we don't know that the coils were the problem in that TOS episode; they should be the most robust bit of the system (being big solid state lumps of metal), it could've been the plasma conduits or some part of the warp core that was burned out.

No, recall that when Spock asked Scotty how long it would take to repair the warp drive, his reply was "Hanging out here in space? Forever! The only thing that'll help these darlings is the nearest repair dock." It's true that the specific problem might not have been the coils, but the damage was severe enough that there was no way they could do a field repair.

And if they essentially scavenged parts from their other shuttlecraft to make the Delta Flyer,

I find this unlikely, given how many shuttles they lost or seriously damaged,

Well, this is where we're running into this silly series' many realism problems. The writers simply couldn't be bothered to think.

More often than not, "more advanced" translates into a more efficient method of doing the same work you needed a much larger and fuel-profligate machine for.

This does not hold for speed. The speed of aircraft increased steadily from 1903 to 1963, largely independently of the size of the aircraft. The limitations were power density, materials strength and the understanding of aerodynamics. Past a certain minimum large Trek ships are no faster than small Trek ships built with the same technology; the Defiant is actually faster than the Galaxy class. The energy cost of moving the ship seems to go up in roughly proportion to size and mass, matching the increase in reactor power output (at roughly constant power density once you get up to capship scales).

Aircraft don't exactly make for a good analogy to a starship. The more likely comparison is with locomotives, submarines, or oceangoing vessels in which you're trying to get better performance out of fairly massive objects. The physical problems connected with getting faster speeds out of aircraft are relatively trivial compared to getting better performance out of a larger machine which is constrained rather than aided by its operating environment.

But starships got no faster in the 100 years between the TOS and TNG eras, at least not in the AQ.

They got steadily faster in Enterprise, from the warp 1 prototype, to the warp 2.5 'NX prototype' we saw, to the NX at warp 5, to the Daedelus stated in 'These Are The Voyagers' to have a maximum speed of warp 7. In TOS the Constitution cruise speed was warp 6 and emergency speed was 8 or 9.

But they eventually hit a wall where speed is concerned. Which is one reason why starship performance has not changed that much between TOS and TNG. To draw another analogy, its sort of trying to compare Robert Goddard's primitive rockets to an Atlas ICBM, and then comparing Atlas to a present-day Delta rocket.

Speeds in TNG also escalated. The Ent-D has a sustained speed of warp 8 and an emergency speed in the 9.2 to 9.7 range (in 'Encounter at Farpoint'). We saw the Defiant holding warp 9.5 for at least several hours on a mission, top speed was not stated. Voyager is supposed to be able to sustain 9.975.

The tough part is the discontinuity between the old warp scale and the new one. We can't directly compare simple warp factors here, and as anyone who's tried to get hard canon numbers for Trek FTL speeds knows the travel times are wildly inconsistent. The fluff suggests warp 8 on the old scale is 512c and warp 9.2 on the new scale is 1649c, so the Ent-D is about three times as fast as the Ent-nil. If the upgraded Ent-D's speed of warp 13 in 'All Good Things' is a reversion to the old scale, that would imply a new scale speed of warp 9.65, which is consistent as an emergency speed for an uprated GCS. Weak canon evidence, but I accept it since a x3 increase in speed between Kirk's time and Picard's time is entirely consistent with the speed increases we see in the ENT-TOS and TNG-VOY timeframes, whereas your 'ships did not get any faster' is both inexplicably inconsistent with this and AFAIK not supported by any evidence.

The valid comparison is observed travel times. None of the warp-scales printed in the literature have really been stated in series or strictly followed, if they were ever followed at all. It still takes a Federation starship the better part of a year to claw its way across the stretch of Federation territory and that's not much of a scalar improvement in a century.

[Starglider]

To return to the nuclear submarine analogy, an SSN (or SSBN) isn't sent out on multiyear deployments nor is intended to be, but it is designed nonetheless to free the vessel from the requirement for periodic refueling by incorporating a fuel store which will last for a good chunk of the vessel's expected service life

I take your basic point, but refueling a nuclear submarine is an extremely expensive and relatively hazardous operation, as you have to disassemble the reactor to do it, which also involves compromising the pressure hull, then reattaching it, then recertifying it. Refueling a surface vessel is somewhat easier but still very expensive. For a Trek starship, you're just unscrewing some hull plates, pulling out the (non-radioactive) AM pods and slotting in new ones. It isn't trivial but it isn't anywhere near as bad as refueling a nuclear submarine.

It also reduces a key maintenance problem in that you don't have to worry about the condition of fueling ports, fuel transfer lines and pumps, and containment of anything other than the built-in storage bunkers.

It's true that the notion of piping antimatter around is pretty silly. Presumably this is still less hazardous than beaming it, otherwise they'd just transport fresh AM into the pods.

Why would they be running out of deuterium? If you're going to put enough antimatter fuel on board for multiyear endurance, it follows logically that there would be sufficient supplies of matter fuel as well

Multiyear endurance yes. Multidecade, probably not. As I pointed out in my earlier post, carrying 100 years worth of antimatter isn't that signifcant in mass/volume terms, but carrying 100 years of deuterium definitely is. Unlike antimatter, deuterium is easy to produce, easy to ship around and quite safe to refuel - plus every single Federation ship has those magnetic scoops on the warp nacelles to collect more in flight, something they would not bother with if they had a multi-decade supply on board. Actually justifying the inclusion of Bussard scoops is pretty hard however you look at it - it's noticeable that the many alien races don't bother with them.

and the logical design solution for powering the impulse engine is to simply run it off the main reactor, which is implicit in the design of the movie-era Enterprise.

I can only assume the logic here is 'we have to have an auxiluary fusion plant anyway, and it's more efficient at producing impulse thrust than using warp plasma, so let's make the impulse engines fusion only and save the need for a big plasma conduit up from the warp core'. Not very good logic, but that's Federation ship design for you. Still, I can't recall a time when the impulse engines were taken out and the warp core was still operational, so they don't seem to have suffered from it.

I would have the entire fuel storage in a protected bunker deep inside the ship and compressed to high density if feasible for space-saving considerations.

It's true that if they powered their impulse drives off the warp core rather than using fusion, they could probably use heavy metals as the reaction mass and cut their bunkerage volume by an order of magnitude.

Actually, the far simpler explanation is that Janeway is just clinically insane.

And no one else noticed or challenged her?

More often than not, "more advanced" translates into a more efficient method of doing the same work you needed a much larger and fuel-profligate machine for.

This does not hold for speed. The speed of aircraft increased steadily from 1903 to 1963, largely independently of the size of the aircraft. The limitations were power density, materials strength and the understanding of aerodynamics.

Aircraft don't exactly make for a good analogy to a starship. The more likely comparison is with locomotives, submarines, or oceangoing vessels in which you're trying to get better performance out of fairly massive objects.

Locomotive speed also increased steadily over time, all the way from the early steam era to the TGV, due to improvements in power density. Ship speed didn't increase quite as continuously, because their were other factors in play (range, wind independence), but the speed of steamships did steadily increase with more efficient machinery and more energy-dense fuels, as well as more hydrodynamic hulls. The basic point is that the power required to move a vessel scales with size, at roughly the same rate that the engine power output scales. Building larger vessels does not help with speed - all you can do is devote a larger fraction of your volume to engines, which works at any scale subject to any limitations in translating that energy into thrust. Speedboats demonstrate this quite nicely.

But starships got no faster in the 100 years between the TOS and TNG eras, at least not in the AQ.

They got steadily faster in Enterprise, from the warp 1 prototype, to the warp 2.5 'NX prototype' we saw, to the NX at warp 5, to the Daedelus stated in 'These Are The Voyagers' to have a maximum speed of warp 7. In TOS the Constitution cruise speed was warp 6 and emergency speed was 8 or 9.

But they eventually hit a wall where speed is concerned. Which is one reason why starship performance has not changed that much between TOS and TNG.

But somehow then started to advance again in the TNG era? Where is your evidence for this? Have you done a comprehensive warp speed analysis somewhere? If crossing the Federation take a similar amount of time, how do you know the Federation hasn't just gotten bigger? I certainly get the impression that it is bigger in Picard's time than in Kirk's time.

[Jawawithagun]

Quick question: How big an effect would weapon use have on their antimatter stores? After all each ptorp gets 1.5kg out (number taken from the TM)

[Starglider]

Quick question: How big an effect would weapon use have on their antimatter stores? After all each ptorp gets 1.5kg out (number taken from the TM)

The tech manual states that the total AM storage capacity is 3000m^3 of deuterium slush. That's 426 tonnes. Worf's dialogue gives the Enterprise 275 photon torpedoes (unlikely to be much below its normal full loadout). Even at max yield/reactant load, PTs would not be a significant drain on the fuel supply. Of course most examples of PTs being use show a rather lower yield than this, lowering the probable AM requirements even further.

[Typhonis 1]

Wouldn`t the antimatter used in torps be kept seperate from the stuff being used for fuel?

[Batman]

Wouldn`t the antimatter used in torps be kept seperate from the stuff being used for fuel?

Whatever for?

[Patrick Degan]

To return to the nuclear submarine analogy, an SSN (or SSBN) isn't sent out on multiyear deployments nor is intended to be, but it is designed nonetheless to free the vessel from the requirement for periodic refueling by incorporating a fuel store which will last for a good chunk of the vessel's expected service life

I take your basic point, but refueling a nuclear submarine is an extremely expensive and relatively hazardous operation, as you have to disassemble the reactor to do it, which also involves compromising the pressure hull, then reattaching it, then recertifying it. Refueling a surface vessel is somewhat easier but still very expensive. For a Trek starship, you're just unscrewing some hull plates, pulling out the (non-radioactive) AM pods and slotting in new ones. It isn't trivial but it isn't anywhere near as bad as refueling a nuclear submarine.

Actually, they swap out the entire reactor unit for a new one, and even this will not be a problem with the Virginias. But insofar as the apparent ease of refueling a starship is concerned, those removable hullplates represent a weak area in the ship's overall structure and swapping out the pods still entails some risk of containment failure or radiation spillage if there's a malfunction during the process. Which is another reason to build your starship reactor/fuel storage as entirely self-contained units which do not have to be removed from the spaceframe except maybe once or twice in the vessel's service life.

Why would they be running out of deuterium? If you're going to put enough antimatter fuel on board for multiyear endurance, it follows logically that there would be sufficient supplies of matter fuel as well

Multiyear endurance yes. Multidecade, probably not. As I pointed out in my earlier post, carrying 100 years worth of antimatter isn't that signifcant in mass/volume terms, but carrying 100 years of deuterium definitely is. Unlike antimatter, deuterium is easy to produce, easy to ship around and quite safe to refuel - plus every single Federation ship has those magnetic scoops on the warp nacelles to collect more in flight, something they would not bother with if they had a multi-decade supply on board. Actually justifying the inclusion of Bussard scoops is pretty hard however you look at it - it's noticeable that the many alien races don't bother with them.

Yes, but as I have pointed out, this really should not be a problem as far as the series is concerned. Since it's a given that the ship is going to find its way home far sooner than 70 years, by way of acts-of-plot so that the series can actually be wrapped up in seven years, the issue of the ship's fuel endurance over a potential near-century long timespan is moot and would only require a throwaway line or two in a couple of episodes in the course of the series run. A twenty or thirty year fuel supply is not at all unreasonable, particularly as this is presently being done with nuclear powered warships and submarines.

You are right in that there is little to justify the inclusion of the Bussard collectors —particularly as there are large areas of galactic space where the density of interstellar hydrogen is very thin indeed, such as within the Cygnus Loop and the Local Bubble. Further, for fuel collection the process would be horribly inefficient since the original concept of the Bussard scoop is to simply shoot the collected hydrogen (undergoing fusion within the ramjet) at high velocity out the back end of a rocket, not diverting it into fuel tanks which would require a means to slow the velocity of the incoming particulate matter which requires energy expended for forcefields. The TNG-era writers simply took the wrong models to base their starship design concepts upon.

and the logical design solution for powering the impulse engine is to simply run it off the main reactor, which is implicit in the design of the movie-era Enterprise.

I can only assume the logic here is 'we have to have an auxiluary fusion plant anyway, and it's more efficient at producing impulse thrust than using warp plasma, so let's make the impulse engines fusion only and save the need for a big plasma conduit up from the warp core'. Not very good logic, but that's Federation ship design for you. Still, I can't recall a time when the impulse engines were taken out and the warp core was still operational, so they don't seem to have suffered from it.

Given the far higher energy density of matter/antimatter annihilation reactions, it's hard to make the "auxilliary fusion is more efficient for rocket power" argument credible. Once again, the writers simply weren't thinking.

Actually, the far simpler explanation is that Janeway is just clinically insane.

And no one else noticed or challenged her?

That bunch? Anyway, the officers who would normally have acted to check the captain's power were all killed in the accident which whisked them off to the Delta Quadrant in the first place, and Chakotay held his position entirely by Janeway's graces. There was no ship's doctor on board anymore so there was nobody to pass a valid medical opinion that the captain was loonier than an Arcturan dogbird and needed the jacket with the wrap-around sleeves. And the sad fact is that given the circumstances, the only way to displace Janeway would have been by mutiny, which might have been destructive to the crew's survival long-term. So they ate it and carried on as best they could. As it happened, Capt. Incompetent got stupidly lucky.

Aircraft don't exactly make for a good analogy to a starship. The more likely comparison is with locomotives, submarines, or oceangoing vessels in which you're trying to get better performance out of fairly massive objects.

Locomotive speed also increased steadily over time, all the way from the early steam era to the TGV, due to improvements in power density. Ship speed didn't increase quite as continuously, because their were other factors in play (range, wind independence), but the speed of steamships did steadily increase with more efficient machinery and more energy-dense fuels, as well as more hydrodynamic hulls. The basic point is that the power required to move a vessel scales with size, at roughly the same rate that the engine power output scales. Building larger vessels does not help with speed - all you can do is devote a larger fraction of your volume to engines, which works at any scale subject to any limitations in translating that energy into thrust. Speedboats demonstrate this quite nicely.

Modern locomotives don't really pull a freight train any faster than a Union Pacific Challenger or Big Boy could. Their advantage over steam is standardised design which can be cranked out on an assembly line and therefore gives you as many units as you need to provide traction power for a far cheaper cost in both manufacture and fuel. And large ocean-going vessels really have hit a wall where speed is concerned, but again their advantage is that they incorporate standardised machinery using a better fuel than the early steam-era and therefore get better efficiency.

They got steadily faster in Enterprise, from the warp 1 prototype, to the warp 2.5 'NX prototype' we saw, to the NX at warp 5, to the Daedelus stated in 'These Are The Voyagers' to have a maximum speed of warp 7. In TOS the Constitution cruise speed was warp 6 and emergency speed was 8 or 9.

But they eventually hit a wall where speed is concerned. Which is one reason why starship performance has not changed that much between TOS and TNG.

But somehow then started to advance again in the TNG era? Where is your evidence for this? Have you done a comprehensive warp speed analysis somewhere? If crossing the Federation take a similar amount of time, how do you know the Federation hasn't just gotten bigger? I certainly get the impression that it is bigger in Picard's time than in Kirk's time.

You're putting the cart before a whole team of horses, here. We do indeed have the evidence of "Encounter At Far Point" in which Deneb (distance from Earth, 1600 ly) is considered the jumping-off point to the "unexplored galaxy beyond". In TOS, Rigel (distance from Earth, 965ly) was considered "a long way out" ("Mudd's Women"). If we go by the expected travel-time for the Voyager's flight back from the Delta Quadrant, that works out to taking roughly one year to travel a distance of a thousand lightyears at warp 9. That doesn't really loan weight to the idea that the ships are faster but the Federation's gotten bigger or that starship performance has really improved all that much in the 100 year stretch between TOS and TNG.

[lord Martiya]

Actually, the far simpler explanation is that Janeway is just clinically insane.

And no one else noticed or challenged her?

That bunch? Anyway, the officers who would normally have acted to check the captain's power were all killed in the accident which whisked them off to the Delta Quadrant in the first place, and Chakotay held his position entirely by Janeway's graces. There was no ship's doctor on board anymore so there was nobody to pass a valid medical opinion that the captain was loonier than an Arcturan dogbird and needed the jacket with the wrap-around sleeves. And the sad fact is that given the circumstances, the only way to displace Janeway would have been by mutiny, which might have been destructive to the crew's survival long-term. So they ate it and carried on as best they could. As it happened, Capt. Incompetent got stupidly lucky.

Actually, in Year of Hell: Part 2 the EMH remove her from the command because she went maniacally crazy (EMH said that he showed symptoms of post-traumatic stress syndrome), and the EMH had the authority to do it, but nobody to force her.

[Starglider]

Given the far higher energy density of matter/antimatter annihilation reactions, it's hard to make the "auxilliary fusion is more efficient for rocket power" argument credible.

The extremely high energy of the M/AM plasma is the problem. The Trek impulse engines apparently work as thermal rockets, possibly with some gravity or electromagnetic acceleration (as I recall the tech manual was not clear if those coils accelerate the exhaust stream at all or just generate the mass lightening effect). Injecting a small amount of extremely high energy plasma into a much larger mass of cold deuterium strongly limits your mass flow (if you want high efficient), because it takes time for thermal equilibrium to occur. Sourcing medium temperature plasma directly out of the fusion reactors heats the entire mass flow evenly, conserving reactant mass (which as I noted in my last post is probably in shorter supply than antimatter). You could probably get around this problem with a much bigger impulse engine with a plasma mixing chamber designed to bring the M/AM plasma and cryogenic deuterium to thermal equilibrium, but that would probably be at least as big as a fusion reactor anyway, so you might as well just make it a fusion reactor, gain more power generation capability and remove the need for the long plasma conduit up from the warp core. Using antimatter directly in the impulse engines (thermally, injecting the AM particles instead of injecting plasma) would be an option, but Fed tech seems to have a problem containing this - thus the safety restrictions on using the AM injection impulse boost only for short periods.

The Constitution refit does seem to have the option of using the warp core to power the impulse engines, but no other Federation starship we've seen does (possibly because it involved routing the warp core through the neck of the ship, which is a structural and battle damage nightmare). As I said the only real benefit to antimatter-powered impulse engines is the option of using more compact non-fusable reaction mass - but you probably want all that fuel anyway for powering your auxiluary generators if you lose your warp core (which Fed ships do on a regular basis).

That bunch? Anyway, the officers who would normally have acted to check the captain's power were all killed in the accident which whisked them off to the Delta Quadrant in the first place, and Chakotay held his position entirely by Janeway's graces... So they ate it and carried on as best they could. As it happened, Capt. Incompetent got stupidly lucky.

Fair point.

Modern locomotives don't really pull a freight train any faster than a Union Pacific Challenger or Big Boy could.

Because there isn't a desire for them to do so; the speed isn't worth the energy costs. Passenger locomotives have gotten faster because it is desirable. Likewise, Federation cargo ships are probably still pretty slow.

That doesn't really loan weight to the idea that the ships are faster but the Federation's gotten bigger or that starship performance has really improved all that much in the 100 year stretch between TOS and TNG.

I grant that it's quite possible that the Federation was focuses on other advances instead, e.g. scaling up their starships by an order of magnitude instead. In the post-TNG era the scaling up trend ceased (in fact arguably starships started to get smaller again) and speeds started going up dramatically, possibly because the Dominion and the Borg taught them how tactically and strategically useful being able to outrun your enemy and chose when and where to engage are (not that the Borg ever made good use of this).

[Jawawithagun]

Quick question: How big an effect would weapon use have on their antimatter stores? After all each ptorp gets 1.5kg out (number taken from the TM)

The tech manual states that the total AM storage capacity is 3000m^3 of deuterium slush. That's 426 tonnes. Worf's dialogue gives the Enterprise 275 photon torpedoes (unlikely to be much below its normal full loadout). Even at max yield/reactant load, PTs would not be a significant drain on the fuel supply. Of course most examples of PTs being use show a rather lower yield than this, lowering the probable AM requirements even further.

Thanks, got that number from a source quoting the TM and didn't find the number for the total capacity

[Typhonis 1]

Speed. To rapidly load up the torpedoes as needed and to keep the stuff oin several small bunkers to kweep an enemy lucky shot from destroying the entire supply.

[Darth Wong]

Speed. To rapidly load up the torpedoes as needed and to keep the stuff oin several small bunkers to kweep an enemy lucky shot from destroying the entire supply.

If an enemy lucky shot hits an AM storage tank, the whole ship is toast. It makes sense to put them in the most well-protected place on the ship, not to spread them around.

[Peptuck]

Speed. To rapidly load up the torpedoes as needed and to keep the stuff oin several small bunkers to kweep an enemy lucky shot from destroying the entire supply.

If an enemy lucky shot hits an AM storage tank, the whole ship is toast. It makes sense to put them in the most well-protected place on the ship, not to spread them around.

Bah. They don't need to hit the antimatter tank to wipe out the whole ship. We've seen the Enterprise be destroyed by glancing impacts to their nacelles!

[Patrick Degan]

The extremely high energy of the M/AM plasma is the problem. The Trek impulse engines apparently work as thermal rockets, possibly with some gravity or electromagnetic acceleration (as I recall the tech manual was not clear if those coils accelerate the exhaust stream at all or just generate the mass lightening effect). Injecting a small amount of extremely high energy plasma into a much larger mass of cold deuterium strongly limits your mass flow (if you want high efficient), because it takes time for thermal equilibrium to occur. Sourcing medium temperature plasma directly out of the fusion reactors heats the entire mass flow evenly, conserving reactant mass (which as I noted in my last post is probably in shorter supply than antimatter). You could probably get around this problem with a much bigger impulse engine with a plasma mixing chamber designed to bring the M/AM plasma and cryogenic deuterium to thermal equilibrium, but that would probably be at least as big as a fusion reactor anyway, so you might as well just make it a fusion reactor, gain more power generation capability and remove the need for the long plasma conduit up from the warp core. Using antimatter directly in the impulse engines (thermally, injecting the AM particles instead of injecting plasma) would be an option, but Fed tech seems to have a problem containing this - thus the safety restrictions on using the AM injection impulse boost only for short periods.

Or, you simply direct the mixed plasma out the impulse chambers as thrust. That is essentially what a matter/antimatter rocket would do.

The Constitution refit does seem to have the option of using the warp core to power the impulse engines, but no other Federation starship we've seen does (possibly because it involved routing the warp core through the neck of the ship, which is a structural and battle damage nightmare). As I said the only real benefit to antimatter-powered impulse engines is the option of using more compact non-fusable reaction mass - but you probably want all that fuel anyway for powering your auxiluary generators if you lose your warp core (which Fed ships do on a regular basis).

It was not an optional function but rather how the impulse engines were powered —directly from the main reactor. This is how it's seen to work in TMP.

Modern locomotives don't really pull a freight train any faster than a Union Pacific Challenger or Big Boy could.

Because there isn't a desire for them to do so; the speed isn't worth the energy costs. Passenger locomotives have gotten faster because it is desirable.

Bear in mind that a fully loaded freight train masses five times the bulk of a passenger train and pulls a far larger number of cars.

I grant that it's quite possible that the Federation was focuses on other advances instead, e.g. scaling up their starships by an order of magnitude instead. In the post-TNG era the scaling up trend ceased (in fact arguably starships started to get smaller again) and speeds started going up dramatically, possibly because the Dominion and the Borg taught them how tactically and strategically useful being able to outrun your enemy and chose when and where to engage are (not that the Borg ever made good use of this).

However, there is an ultimate upward limit for warp drive performance dictated by the laws of subspace physics and the power capacity of their reactors. This doesn't change due to differences in design configuration but is rather a fundamental problem. Which is why a drive based on alternative principles has been sought and discovered by some races.

[Starglider]

Using antimatter directly in the impulse engines (thermally, injecting the AM particles instead of injecting plasma) would be an option, but Fed tech seems to have a problem containing this - thus the safety restrictions on using the AM injection impulse boost only for short periods.

Or, you simply direct the mixed plasma out the impulse chambers as thrust. That is essentially what a matter/antimatter rocket would do.

To generate thrust from any sort of thermal reaction you have to contain it with some sort of nozzle. Federation ships have the additional problem of making their mass-lightening tech work, which seems to involve vectoring the thrust /through/ the coils (possibly to decouple the exhaust from the mass lightening field so they get the full effect of it; the TNG tech manual seems to suggest this). Federation tech doesn't seem to be up to the challenge of making a rocket nozzle that can contain and generate thrust from a direct M/AM reaction - though their impulse engines can apparently take small abouts of antimatter for short periods, in emergencies only. The problem might be all the hard gamma; the bizarrely elaborate nature of the warp core, with a relatively fragile crystal at the focus, seems to be necessary to produce 'tuned plasma' the warp coils can use, rather than hard gamma (and neutrinos) that Fed tech can't deal with.

The Constitution refit does seem to have the option of using the warp core to power

It was not an optional function but rather how the impulse engines were powered —directly from the main reactor. This is how it's seen to work in TMP.

The Enterprise retained impulse capability when the warp engines were offline for recalibration in TMP. This may be because only the nacelles were offline, but in TWoK the impulse engines were still usable when the warp core was offline due to battle damage. 'Scotty's Guide to the Enterprise' clarifies this; the impulse engines can be powered either from the vertical intermix shaft or by five fusion reactors in the aft saucer. Non-canon but pretty reasonable.

Bear in mind that a fully loaded freight train masses five times the bulk of a passenger train and pulls a far larger number of cars.

That fits in with my suggestion that for a few decades the Federation chose to concentrate on increasing starship size rather than starship speed.

However, there is an ultimate upward limit for warp drive performance dictated by the laws of subspace physics and the power capacity of their reactors.

'Threshold' suggests otherwise. Of course that episode was such an utter piece of crap that even many Trek writers consider it non-canon. There is also the 'enhanced warp drive' their liquid metal clones were using - we don't know how close to a normal warp drive it is, but presumably moreso than transwarp or slipstream. Then there's the Traveller propelling the Ent-D at trillions of c using its normal engines plus some kind of bizarre ability - presumably that did involve new physics though.

Which is why a drive based on alternative principles has been sought and discovered by some races.

Slipstream and transwarp cleary go very fast using some different but related physical mechanism - closely related enough that Voyager managed to use both of them with relatively minor modifications to their engines. Ignoring that, there may well be a physical limit to conventional warp, but if so we haven't seen it yet, only limitations of the current technology. Of course Q tosses the Enterprise about at incredible speeds using some entirely unknown (but likely technological) mechanism.

[Patrick Degan]

Using antimatter directly in the impulse engines (thermally, injecting the AM particles instead of injecting plasma) would be an option, but Fed tech seems to have a problem containing this - thus the safety restrictions on using the AM injection impulse boost only for short periods.

Or, you simply direct the mixed plasma out the impulse chambers as thrust. That is essentially what a matter/antimatter rocket would do.

To generate thrust from any sort of thermal reaction you have to contain it with some sort of nozzle. Federation ships have the additional problem of making their mass-lightening tech work, which seems to involve vectoring the thrust /through/ the coils (possibly to decouple the exhaust from the mass lightening field so they get the full effect of it; the TNG tech manual seems to suggest this). Federation tech doesn't seem to be up to the challenge of making a rocket nozzle that can contain and generate thrust from a direct M/AM reaction - though their impulse engines can apparently take small abouts of antimatter for short periods, in emergencies only. The problem might be all the hard gamma; the bizarrely elaborate nature of the warp core, with a relatively fragile crystal at the focus, seems to be necessary to produce 'tuned plasma' the warp coils can use, rather than hard gamma (and neutrinos) that Fed tech can't deal with.

Why would it be a particular problem to generate the antigrav field effect and use the intermix plasma for impulse thrust? A series of EM coils through which plasma is ducted in an MHD setup to draw the electricity needed to power the one allows you to have both operations in the same engineering structure; a concept which is incorporated into several schemes for fusion-powered spacecraft. And I'm not aware of the idea that the warp system needs a particular "tuned" plasma outside of what was suggested in a Canadian fan publication (an interesting idea as far as it went, but there are simpler ideas which are a bit closer in the plausibility dept. than that).

The Constitution refit does seem to have the option of using the warp core to power

It was not an optional function but rather how the impulse engines were powered —directly from the main reactor. This is how it's seen to work in TMP.

The Enterprise retained impulse capability when the warp engines were offline for recalibration in TMP. This may be because only the nacelles were offline, but in TWoK the impulse engines were still usable when the warp core was offline due to battle damage. 'Scotty's Guide to the Enterprise' clarifies this; the impulse engines can be powered either from the vertical intermix shaft or by five fusion reactors in the aft saucer. Non-canon but pretty reasonable.

The Enterprise was powering its impulse system right off the main reactor before the warp engine calibration problem came into play, though.

Bear in mind that a fully loaded freight train masses five times the bulk of a passenger train and pulls a far larger number of cars.

That fits in with my suggestion that for a few decades the Federation chose to concentrate on increasing starship size rather than starship speed.

You're not quite seeing the point. The locomotive unit for a freight train has about the same horsepower capacity as one for a passenger train, around 4000-6000hp. If you were to put examples of both types on the same load they would perform about the same.

However, there is an ultimate upward limit for warp drive performance dictated by the laws of subspace physics and the power capacity of their reactors.

'Threshold' suggests otherwise. Of course that episode was such an utter piece of crap that even many Trek writers consider it non-canon. There is also the 'enhanced warp drive' their liquid metal clones were using - we don't know how close to a normal warp drive it is, but presumably moreso than transwarp or slipstream. Then there's the Traveller propelling the Ent-D at trillions of c using its normal engines plus some kind of bizarre ability - presumably that did involve new physics though.

The effect in the "Threshold" experiment was more or less in line with the practical inability of a starship to surpass warp 10 using known subspace principles (the whole silly angle of it causing you to mutate into catfish notwithstanding). The Traveler's abilities are not relevant to an examination of warp drive as they do indeed represent some entirely different principle which doesn't even compare with transwarp or slipstream mechanics. And as for the alleged "enhanced" warp drive from "Course: Oblivion", it's hard to tell just what is and isn't valid about a wholly one-off device produced aboard an imperfect copy of the Voyager peopled by duplicates who's perceptions (and therefore the data derived from them) may not be wholly reliable.

[Starglider]

If an enemy lucky shot hits an AM storage tank, the whole ship is toast. It makes sense to put them in the most well-protected place on the ship, not to spread them around.

The TNG tech manual does have them spread around a bit; it has AM tanks next to the impulse engines for the 'emergency impulse boost' idea and small tanks in the torpedo launchers for charging the torpedoes. Though AFAIK it isn't mentioned anywhere, there are probably small AM tanks in the shuttlebays as part of the refueling system. 90% of the tanks are in a single cluster at the bottom of the engineering hull; presumably for ease of ejection, as a central position would protect them better.

To be fair WWII warships had a magazine under each turret, rather than a single centralised magazine, so this isn't entirely unreasonable. Though I do wonder why they bother with the impulse antimatter injection system when they never seem to use it (I remember it happening in a couple of Voyager novels and that's it), unless they do it a lot without mentioning it in dialogue.