Ship design note: liquid hydrogen is not dense

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Master_of_Ritual
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Ship design note: liquid hydrogen is not dense

Postby Master_of_Ritual » Thu Aug 06, 2020 4:18 pm

The setting I am using has ships with rotational gravity. I've been redesigning some of the standard ships from the core book--I've tried to actually arrange the different components in a way that is somewhat realistic, and one thing I found out is that tens of tons of liquid hydrogen takes up a lot of space! It is only about 7% as dense as water. It will probably take up a very substantial portion of any ship. My Scout Ship redesign is probably around 20% hydrogen by volume.
AnotherDilbert
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Re: Ship design note: liquid hydrogen is not dense

Postby AnotherDilbert » Thu Aug 06, 2020 7:18 pm

Yes, obviously, but remember ships are measured in "displacement tons" (volume), not actual tons (mass).

When the description of a ship, say a scout, says that a 100 ton ship has 20 tons fuel it explicitly means that it has 20% of the volume as fuel tankage.

HG, p4 wrote: Ships are measured in ‘displacement tons’ or d-tons: a hundred-ton ship displaces a volume equal to one hundred tons of liquid hydrogen (one d-ton equals roughly 14 cubic metres).
Master_of_Ritual
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Re: Ship design note: liquid hydrogen is not dense

Postby Master_of_Ritual » Thu Aug 06, 2020 8:43 pm

@AnotherDilbert

That is good to know, thanks.
Condottiere
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Re: Ship design note: liquid hydrogen is not dense

Postby Condottiere » Fri Aug 07, 2020 11:42 pm

Lots of fuel sloshing about in the tanks during acceleration can't be good.
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MyndkryM
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Re: Ship design note: liquid hydrogen is not dense

Postby MyndkryM » Fri Aug 07, 2020 11:53 pm

Condottiere wrote:
Fri Aug 07, 2020 11:42 pm
Lots of fuel sloshing about in the tanks during acceleration can't be good.
:lol:

And it would be soooo cold.
Sigtrygg
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Re: Ship design note: liquid hydrogen is not dense

Postby Sigtrygg » Sat Aug 08, 2020 8:59 am

There is no perceived acceleration within a Traveller ship, that's what the acceleration compensators are for, so there is no sloshing about.
Last edited by Sigtrygg on Sat Aug 08, 2020 4:32 pm, edited 1 time in total.
Linwood
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Re: Ship design note: liquid hydrogen is not dense

Postby Linwood » Sat Aug 08, 2020 12:45 pm

I could see tanks designed with interior baffles or maybe with a more cellular structure to limit fluid movement during flight.

Consider - we live in a constant gravity field (so far as I know) but fluids move around inside storage vessels all the time when a vehicle turns, accelerates/decelerates, and/or changes attitude. I haven't had my coffee yet so I haven't through what that would look like in artificial gravity (where the attitude of the vehicle does not change with respect to the gravity it generates internally) and some level of inertial damping but it seems likely that some fluid movement would still occur in certain circumstances.
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Re: Ship design note: liquid hydrogen is not dense

Postby Sigtrygg » Sat Aug 08, 2020 4:34 pm

Either the acceleration compensators work and you have no acceleration effects within the ship and thus no sloshing, or they don't.

Another consequence of a background technology.
Condottiere
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Re: Ship design note: liquid hydrogen is not dense

Postby Condottiere » Sat Aug 08, 2020 9:54 pm

Question has always been what's the source of inertial compensation, manoeuvre drive or hull embedded, and if it's local or a field effect.

Then what happens if latency gets involved.

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ShawnDriscoll
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Re: Ship design note: liquid hydrogen is not dense

Postby ShawnDriscoll » Sun Aug 09, 2020 12:47 am

Crew members turn to mush during jump? I'm guessing jump has been messed with too in your setting.
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Re: Ship design note: liquid hydrogen is not dense

Postby Condottiere » Sun Aug 09, 2020 10:12 am

No sudden turns.
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Re: Ship design note: liquid hydrogen is not dense

Postby AnotherDilbert » Sun Aug 09, 2020 12:01 pm

Condottiere wrote: Question has always been what's the source of inertial compensation, manoeuvre drive or hull embedded, and if it's local or a field effect.
No, that has never been in doubt. LBB5, that first discussed this, said:
LBB5'79, p17 wrote: ... the grav-plates integral to most ship decks which allow high-G maneuvers while the interior G-fields remain normal.
This is inertial compensators, explicitly described as a gravitic component built into ship decks.

It is an artificial gravity field, the same as the artifical gravity field that maintains a standard ~1 G inside, just variable.

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