Bertil:
> From 'The Effects of Nuclear Weapons' and other sources:
> Complete fission of 57g of fissionable material produces 1kt (1.45).
> The three most likely fusion reactions are (weighted for probability)
>three times more effective (1.69) pound for pound.
> Thus 1kt of energy (4.18e12J) requires complete fusion of 1/3 of 57g
>ie 19g of hydrogen.
> A Type S at 2G uses 25m3 of hydrogen per hour. That weighs 1750kg, so
the
>per second figure is 486g.
> 486g of hydrogen, undergong complete fusion, produces 25.6 kt of
energy.
> Still claiming that the type S has an engine output of 33kt per
>second, Steve?
Fascinating. Of course, I have been claiming a Free Trader (not a
Scout) had an output of 30Kt (not 33Kt). And I was speaking in round
figures, also...
But beyond the fact that you got most of my arguments wrong, this is a
wonderful rebuttal.
> Just for the hell of it I started to make calculations on the
>pressure of the jet. This might be the wrong method, but what the heck.
This is the wrong method. Using a reasonable approximation (ideal gas),
the pressure of a gas is about (1/3) * N * v^2 * molecular mass, where N
is number of atoms (molecules) per unit volume.
Bertil:
>> I see no reason why fusion rockets would fail to operate in an
>> atmosphere. The ejection velocity is far greater than sonic
>> velocities, thus the exhaust will not impinge on the ship itself
>> unless something reflects it.
> I was thinking that there might be problems in getting the thing to
> ignite in the first place if the ignition chamber or whatever isn't in
> a vacuum. You could rig some contraption that 'opens the door' after
> ignition trusting to the pressure to keep the air out, but there is
> a risk of 'disposable doors' here if the ignition/opening isn't
> handled exactly correctly. And if they are gone your engine won't
> start.
Steal from Niven again, and use a squirt of vaporized fissionables to
jump-start the reaction. The fission reaction will clear the air out of
the chamber REAL FAST, and provide the excess of neutrons needed to
start the fusion off with a bang...
Wildstar:
>Steve Higginbotham writes:
>The name of the game is science FICTION role-playing. Getting the
>science right is important; don't doubt that I take some good care in
>getting the science believable. However, at some level of detail,
>absolute scientific accuracy has to take a backseat to storytelling.
>I described (and clearly labelled) what I would do if I had to make the
>call as a referee *right then*. I *know* it's not scientifically
>accurate, but it should be good enough for the story to continue.
>As opposed to raising a problem and then heckling everybody while we
>puzzle it out, what would you do? I realize that you're in a bad mood
>(probably from reading too much Star Viking background in T:TNE), but
>try to be constructive here.
What would I do? If my PCs tried to toast a spaceport? Say "Ok, it
breaks up nicely when the blast hits. Now what's the plan?" I don't
see any reason to restrict the guys (and girls) from wrecking things,
except where internal logic decrees that they can't (you know, the
places where there are like 3000 missile launchers waiting for you to
look at it wrong, or the places (like my first game) where there are
nuclear dampers focussed on your ship whenever it is within range of a
spacestation, or on the ground at a spaceport)...
Wildstar:
>I certainly can't speak for Hans and Bertil, but what I an trying to do
>is explain the following observations:
<lots of stuff>
So what does this all have to do with my original post, which started
all this? My original post was to the effect that keeping nukes out of
the PC's hands (which you, Hans, and Bertil were trying to justify) was
pointless, since the destructive capability of the DRIVE was far more
extreme than any combination of nuke det-lasers they could carry. This
has pretty much been ignored by you, and by everyone else, in the rush
to demonstrate how harmless a fusion drive is, or how things should be
changed to make them harmless..
>However, all of the available Traveller (Classic, MegaTraveller, and
>New Era) points to a very different model of ship operations.
These are the same models that consider gas giant refueling a wonderful,
cost-effective, idea, right?
>While you have managed to produce a post virtually ensuring a
>significant flame-fest, you haven't managed to comment on any of my
>recent proposals in any serious manner.
That's because I have little if any interest in how starships land. I
can see a lot of ways, you can see a lot of ways, everyone else can see
a lot of ways (well, a few for each of us anyway). So? I consider the
LETHALITY of the drive, and its usefulness as a weapon to be a FAR more
fundamental problem that needs resolution than the question of how ships
land...
>As far as thge possibilities of operating a fusion drive near a
>planetary surface or close to a large solid object in deep space, I've
>had a chance to do some more thinking. I still feel that there is a
>chance (depending on the amount of damage the starship wishes to do,
>and the degree of success rolled by the pilot attempting the task) of
>damage to the ship. THe closer you are, the better the damage done,
>but the higher your chances of being accidentally engulfed in the cloud
>of very hot, radioactive gas. Even for an instant, that could cause
>damage.
Unlikely. If the ship was designed to operate in space, where other
ships like this exist, then it is (SHOULD be) designed to deal with a
hit like that as long as the hit was less than, say, 0.01 seconds (the
time required for the ship to travel ten times its length at "normal"
speeds). Assuming the "hit" was at long range (several hundred Km), or
just a brush with the edge of the drive flame, of course.
>Secondly, while the temprature of the fusion exhaust is very high, the
>mass flow is very low; I don't know enough about plasma physics to even
>begin to calculate what that would do in an atmosphere of any density.
>It seems to me that it's possible that the drive would "choke"
>and fail to function properly or at all; possibly with damage to the
>drive mechanism.
If this were true, then it would be even more true for fusion guns,
which have MUCH smaller mass flows, and (probably) operate at lower
temperatures and pressures to boot...So you are supposing that fusion
guns do not work?
>Unless and until someone can come up with some better physics; as a
>game ruling (based on referee's judgement of possible effects,
>playability, and general story needs) I would *still* say that running
>a fusion drive in an atmosphere will cause serios damage to the drive
>and/or ship.
Your privilege. It seems I won't ever be playing with Trav with you as
GM, so I doubt it would ever matter, but if you decided that, I would
decide to quit playing, since I consider that a cop-out...
>At some point, additional scientific (or economic, or social, or
>anything) accuracy becomes detrimental to the game.
No, it doesn't. At some point it becomes to difficult to calculate.
>> PS. My, I'm getting acid these days...
>You are. You really should make the effort to be less so; it doesn't
>help you make your point, and it certainly doesn't help raise my
>opinion of you. Maybe you should put less battery acid in your
>coffee? ;-)
Quite frankly, after the last month of the TNE pocket, and the last few
days of the TML, I really don't give a flip what you think of me. I
only care for the opinions of people I respect...
Baranski:
> Second Idea: What happens if we try to approximate a much higher
>energy fusion exhaust, with thinking about what a lower energy exhaust
>does in a denser medium, IE what happens when you try to run a rocket
>under water?
Lousy approximation. Better one would be to keep RELATIVE pressures in
similar ratios, so the question then becomes "what happens when we run a
rocket in a vacuum?" A chemical drive under water compares to a fusion
drive through rock, in other words...
> Idea three: Is it possible to tune the shape of the exhaust from
>the fusion drive.
Yes, but you sacrifice efficiency in a major way if you try...
Since relatively few people seem interested in addressing the question I
brought up (why worry about nukes when you have a fusion drive?), I
suspect that I can make the best use of my time by signing off now...
---Steve Higginbotham