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In some episode (I can't remember the name), Voyager makes planetfall, the crew has some merry adventures, and they continue on their way.

Since it has to return to space, we can determine what it had to generate to get free of the planets gravity.

The figures I found say that Voyager was 342 meters long, 55 meters high, and 144 meters wide. Assuming 10% solidity and iron density for the hull, we get a mass of 2.13*10^9 kg. Since it must generate 6*10^7 joules per kg to reach orbit, this means it must be capable of generating 1.28*10^17.

As far as I know, Voyager does not have an unusual or exceedingly advanced reactor at this time. So if someone could provide dimensions for the warp core, we could get PD and use that to get generating levels of other ships.

Any comments or errors or that information would be welcome.

The only comment I would make is that the ship would not conceivably be using its warp engines. It would logically be using the ships impulse engines and atmospheric thrusters.

Chris OFarrell wrote:The only comment I would make is that the ship would not conceivably be using its warp engines. It would logically be using the ships impulse engines and atmospheric thrusters.

It could still be using its warp core. It obviously wasn't using reaction drive to fly up, because we've seen it lift off and the volume and velocity of ejecta required for that would have been noticeable.

True enough.

However (and I'll have to check this) in either 'Basics' or 'Deamon', two episodes where Voyager landed or took off from planets, there was explicate orders to shut down the warp core and eject all of the drive plasma from the warp naceles as part of the landing procedure. Also in one of the episode as they landed (I'm preaty sure this one WAS basics), there was an explicate mention of 'Atmospheric Thrusters' (as opposed to the regular thrusers), possibly some kind of antigrav?

Warp drive to be best of my knowedlge is only for FTL travel, not for sublight travel. There isn't realy any clear way it would or could be used for taking off from a planet. But its not unprecedented in Trek. Remember the BOP in ST4 as it took off from Vulcan? Or Earth? There was something like a thruster firing, but clearly not enough (and cutting off after a few seconds) to make the ship hover like it did.

And as a final point, one of the season 1 (or very early season 2 I'm not sure) episodes of DS9 had Kira and Dax flying a sub impulse Bajoran scout and come under attack from a pair of Bajoran impulse ships. Kira and Dax talked about how they were too outclassed in space against a ship with an impulse drive, so they screamed down into Bajors atmosphere, forcing the two ships to also switch to their thrusters rather then impulse engines. And the Bajoran impulse ships IIRC are said onscreen in another episode to not have any warp capibility.

I'll go and see if I can dig this all up.

Given that the ship wasn't appearing to use reaction drives as it left for orbit, I would suggest it was capable of using its mass-lightening fields, even in the atmosphere.

Master of Ossus wrote:Given that the ship wasn't appearing to use reaction drives as it left for orbit, I would suggest it was capable of using its mass-lightening fields, even in the atmosphere.

How does that prove the presence of mass lightening? Even lightened, it still would not cause the ship to float free on it's own merits. It suggests an antigravity field, or perhaps we just didn't see it use the impluse drive, but it doesn't show that AMRE was in effect.

Ender wrote:

Master of Ossus wrote:Given that the ship wasn't appearing to use reaction drives as it left for orbit, I would suggest it was capable of using its mass-lightening fields, even in the atmosphere.

How does that prove the presence of mass lightening? Even lightened, it still would not cause the ship to float free on it's own merits. It suggests an antigravity field, or perhaps we just didn't see it use the impluse drive, but it doesn't show that AMRE was in effect.

For the purposes of this particular scenario, a mass-lightening field and an antigravity field are the same thing. They are arguably near-synonymous from a conceptual standpoint anyway.

Ender wrote:

Master of Ossus wrote:Given that the ship wasn't appearing to use reaction drives as it left for orbit, I would suggest it was capable of using its mass-lightening fields, even in the atmosphere.

How does that prove the presence of mass lightening?

Mass lightening has been shown in other episodes, and is a known phenomenon within the ST universe. I don't particularly see a reason to add an additional term.

Even lightened, it still would not cause the ship to float free on it's own merits.

True, but it would also make the conspicuous lack of reaction-drive type effects more understandable.

It suggests an antigravity field, or perhaps we just didn't see it use the impluse drive, but it doesn't show that AMRE was in effect.

For the purpose of the thread, both terms are roughly equivalent, since we're trying to determine power generation capabilities as a lower limit, and either system would invalidate the calculations that we generate (although neither system is remotely explained).

Mass lightening could allow the ship to be lighter then the air it displaces, so Ender it could indeed float on its own. But once in space you'd need to use thrusters.

You're right that at best it can give us a minimum power output, but there's so much treknobabble involved even a definitive answer there will be hard to impossable to reach.

Figuring the power required for planetary lift off won't give you an upper end power limit either. Somehow I doubt taking off from a planet uses more power than weapons, full combat shields, warp manuvering, etc etc.

kojikun wrote:Mass lightening could allow the ship to be lighter then the air it displaces, so Ender it could indeed float on its own. But once in space you'd need to use thrusters.

We have seen by how much it can reduce the mass in "Deja Q". It appears to be that a lightened mass has ~ .013% of he original mass. This is insufficient to be lighter then air. In fact, it's not even close, it's still something like 2*10^5 kilos.

Master of Ossus wrote:

Ender wrote:

Master of Ossus wrote:Given that the ship wasn't appearing to use reaction drives as it left for orbit, I would suggest it was capable of using its mass-lightening fields, even in the atmosphere.

How does that prove the presence of mass lightening?

Mass lightening has been shown in other episodes, and is a known phenomenon within the ST universe. I don't particularly see a reason to add an additional term.

Adding in mass lightening is ADDING a term to account for.

Even lightened, it still would not cause the ship to float free on it's own merits.

True, but it would also make the conspicuous lack of reaction-drive type effects more understandable.

The only thing we know is Chris's vague recollection of no reaction drives. Nobody has posted anything from the episodes in question saying one thing or the other.

It suggests an antigravity field, or perhaps we just didn't see it use the impluse drive, but it doesn't show that AMRE was in effect.

For the purpose of the thread, both terms are roughly equivalent, since we're trying to determine power generation capabilities as a lower limit, and either system would invalidate the calculations that we generate (although neither system is remotely explained).

How does an anti gravity field negate it? It still has to apply the energy to push agaisnt the planet.

Mass lightening may well have been used, but I am confused as to why this would invalidate power claims:
Surely engaging the fields required to reduce local mass requires power? If a vessel with a certain mass has x power then it can accel at y g/sec, right? After engaging the drive it would have less mass, but as I understand physics it should still be capable of only y g/sec, as the rest of the power is needed to maintain the field...
If not then a perpetual motion machine with a positive power output may be built--right? Imagine a simple one: an arm with two weights-one on each end-is mounted on a horizontal bearing. Each weight has its own mass lightening field generator, "A" and "B". "A" kicks up, and B is pulled toward the ground, then "B" kicks up, continuing the rotation....... The only way to rationalize this is to make the field require the same power as the machine puts out--does this make sense?

If so, then Voyager still requires about 1.28E17 J to achieve orbit, but it might have been able to shunt much of this to the warp core to create the mass reduction fields, giving the thrusters a lighter load. Or, alternately, if the warp core was indeed shut down for planetary operations, then it would imply that secondary power can handle 1.28E17 J output in whatever time-frame it took.

The Silence and I wrote:Mass lightening may well have been used, but I am confused as to why this would invalidate power claims

It doesn't. Regardless of "mass-lightening" technobabble, the change in gravitational potential energy must be made up at some point. However, it does affect the question of how this power was applied (thrusters vs fields).

Darth Wong wrote:It doesn't. Regardless of "mass-lightening" technobabble, the change in gravitational potential energy must be made up at some point. However, it does affect the question of how this power was applied (thrusters vs fields).

Thats a good point. What would happen if a ship were to move from planet to interstellar space then return to normal mass? I can see an orbiting craft would deorbit, but what about a craft all the way in interstellar space?

kojikun wrote:

Darth Wong wrote:It doesn't. Regardless of "mass-lightening" technobabble, the change in gravitational potential energy must be made up at some point. However, it does affect the question of how this power was applied (thrusters vs fields).

Thats a good point. What would happen if a ship were to move from planet to interstellar space then return to normal mass? I can see an orbiting craft would deorbit, but what about a craft all the way in interstellar space?

If I'm reading the situation correctly, cutting off the field would release the energy that you originally used to "lighten" the ship. Presumably you would have to radiate it away as heat.

Ted C wrote:If I'm reading the situation correctly, cutting off the field would release the energy that you originally used to "lighten" the ship. Presumably you would have to radiate it away as heat.

Youre not reading it correctly. Mike said that you need to make up for the change in GPE eventually. If you didn't you would deorbit. But if the ship is in interstellar space, wheres it gonna go? towards the planet? The Star?

I don't understand how mass lightening would make a difference. Acceleration in a gravitational field is independent of mass. If the argument is that it would require less exhaust momentum from the thrusters and so less energy expenditure, then I suppose my question would be; why isn't the thruster fuel made less massive and its momentum when expelled correspondingly reduced?

ClaysGhost wrote:I don't understand how mass lightening would make a difference. Acceleration in a gravitational field is independent of mass.

Gravitational acceleration is independent of mass when the other body is much more massive than you are. However, your acceleration as a function of thrust is most decidedly not independent of mass.

If the argument is that it would require less exhaust momentum from the thrusters and so less energy expenditure, then I suppose my question would be; why isn't the thruster fuel made less massive and its momentum when expelled correspondingly reduced?

Even if it is made less massive, it simply becomes easier to hurl out the back end at extreme velocity (presumably, it would spontaneously slow down upon leaving the field). The difference in energy requirements remains: the GPE difference between a 10 kg object at ground vs 100km altitude and a 10 ton object at ground vs 100km altitude remains.

If the ship used some kind of repulsorlift to go to orbit, it would still be applying the same force as it would via thrust, only it would be doing it with its repulsors. However, if the ship actually reduces its effective mass (an idea which floats throughout the Trek official and canon world but is never really explicitly made clear in terms of function), then in theory, it would be easy to push up to orbit. However, the question then becomes: what happens when you turn off the field? You can't have a situation where the mass-lightening field could be used as a perpetual motion machine, so the missing GPE must be stored somewhere.

Darth Wong wrote: Gravitational acceleration is independent of mass when the other body is much more massive than you are. However, your acceleration as a function of thrust is most decidedly not independent of mass.

No, but wouldn't the thrust available be reduced by mass lightening (below)?

Even if it is made less massive, it simply becomes easier to hurl out the back end at extreme velocity (presumably, it would spontaneously slow down upon leaving the field).

But does that help? The warp core reactants have just got a lot less massive, so power output is going to be reduced, and then so is thrust. That's aside from the supply requirements of the field itself, whatever they may be.

The difference in energy requirements remains: the GPE difference between a 10 kg object at ground vs 100km altitude and a 10 ton object at ground vs 100km altitude remains.

If the ship used some kind of repulsorlift to go to orbit, it would still be applying the same force as it would via thrust, only it would be doing it with its repulsors. However, if the ship actually reduces its effective mass (an idea which floats throughout the Trek official and canon world but is never really explicitly made clear in terms of function), then in theory, it would be easy to push up to orbit. However, the question then becomes: what happens when you turn off the field? You can't have a situation where the mass-lightening field could be used as a perpetual motion machine, so the missing GPE must be stored somewhere.

I'm stilll trying to work out how cancelling most of the rest-mass of an object isn't a violation of conservation of energy. The energy can't be made up by supplying the field, because it's the ship that would have to do that.

ClaysGhost wrote:No, but wouldn't the thrust available be reduced by mass lightening (below)?

Given the same amount of energy, you could still produce the same amount of thrust despite "mass-lightening" by simply firing it out the thrusters at greater velocity.

But does that help? The warp core reactants have just got a lot less massive, so power output is going to be reduced, and then so is thrust. That's aside from the supply requirements of the field itself, whatever they may be.

Unfortunately, that is where the technobabble starts. Most Trekkie tech-geek types argue that the missing mass is "stored in subspace", so that when it gets annihilated, it's pulled back into realspace and its energy is all in realspace.

I'm stilll trying to work out how cancelling most of the rest-mass of an object isn't a violation of conservation of energy. The energy can't be made up by supplying the field, because it's the ship that would have to do that.

As usual, the Trek solution is to simply mumble "subspace".

What if the field can ignore the impulse engines and fuel? Wouldn't it then be like the engines are pushing an object thats alot less massive?