Author Topic: Grav Decks & Jumping  (Read 3426 times)

hammer6r

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Grav Decks & Jumping
« on: 27 May 2016, 17:33:23 »
Just out of curiosity - because I can't remember seeing a reference to it - can Jumpships with rotating grav decks Jump while the deck is spinning? Or, do they need to cease rotation before engaging their K-F drive?
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worktroll

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Re: Grav Decks & Jumping
« Reply #1 on: 27 May 2016, 18:21:26 »
Don't know about "need", but from Dropships & Jumpships p95

"Because the deck's drive motors and bearings are delicate, several locking rms must brace the deck in position before the JumpShip performs any maneuvering more complex that station-keeping."

While this can be interpreted to exclude K-F operations, I'd strongly suggest that a competent captain will do this just in case there's a need to move on arrival to clear incoming/outgoing traffic.

On a headcanon level, I just can't see why you wouldn't do this anyway, just to remove yet another potentially complicating factor. I mean, most subs don't ram mountains the moment they submerge, but it's common practice to close all the watertight doors internally beforehand.
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Daryk

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Re: Grav Decks & Jumping
« Reply #2 on: 27 May 2016, 18:52:23 »
Stopping the rotation of the grav deck would just transfer the complicating angular momentum to some other part of the ship, so I'd think you'd just let it continue to rotate.  The jump effect is instantaneous for those jumping, so there shouldn't be any complications.  If we say a grav deck is required to stop, where do we draw the line on stopping other moving parts of the ship, or even the crew?

hammer6r

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Re: Grav Decks & Jumping
« Reply #3 on: 27 May 2016, 21:24:30 »
I ask, because a fan project (not mine) is giving me evil thoughts  >:D  O:-)  ;D

PROJECT ARGO

« Last Edit: 27 May 2016, 21:29:57 by hammer6r »
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Daryk

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Re: Grav Decks & Jumping
« Reply #4 on: 28 May 2016, 05:05:23 »
Right... the idea there is they stop the rotation when the ship is under thrust, not necessarily when it jumps.

Frabby

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Re: Grav Decks & Jumping
« Reply #5 on: 28 May 2016, 06:34:53 »
Keep in mind that jumping doesn't create a thrust vector. It shouldn't affect the grav deck at all.

We're told that JumpShips emerge from a jump "inert", i.e. they lose all angular momentum in jump and arrive with zero velocity relative to their emergence point.
But that cannot possibly apply to moving things within the jump field (like the spinning grav deck) because it would also stop blood circulation in humans, killing everybody aboard immediately or at least equalling a stroke.
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hammer6r

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Re: Grav Decks & Jumping
« Reply #6 on: 28 May 2016, 09:01:22 »
The only thing I've seen in hard-rule form on the subject is the original D's&J 's entry on the Invader, where the ship has to retract its hydoponics pods for Jump, because they would be outside the Jump bubble. But that was it, no other references to restrictions.....
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pheonixstorm

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Re: Grav Decks & Jumping
« Reply #7 on: 28 May 2016, 09:14:14 »
As WT said though, if you plan on moving in a hurry once the jump is complete best to stop the grav deck BEFORE the jump. So stop the deck, jump, and hit full thrust so you don't get zapped by incoming traffic.

Frabby

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Re: Grav Decks & Jumping
« Reply #8 on: 28 May 2016, 09:48:49 »
Good point about the Invader though. I can see a similar reasoning applying to the Argo - pull in those grav deck habitats for jumping, or they'll probably not be inside the jump bubble.
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pheonixstorm

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Re: Grav Decks & Jumping
« Reply #9 on: 28 May 2016, 09:57:50 »
grr no more Argo talk. The wait is already driving me mad  #P [drool]

idea weenie

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Re: Grav Decks & Jumping
« Reply #10 on: 28 May 2016, 23:57:05 »
Stopping the rotation of the grav deck would just transfer the complicating angular momentum to some other part of the ship, so I'd think you'd just let it continue to rotate.  The jump effect is instantaneous for those jumping, so there shouldn't be any complications.  If we say a grav deck is required to stop, where do we draw the line on stopping other moving parts of the ship, or even the crew?

One idea is that there are two rotating components, one for the crew that is fairly massive but slow-rotating, and one for the angular counter-momentum that has lower mass and higher rotation rate.  I.e. a 10 kiloton structure rotating at 1 RPM clockwise is offset by a 500 ton structure rotating at 20 RPM counter-clockwise.  As long as both are slowed down properly there is no net angular momentum.

Kovax

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Re: Grav Decks & Jumping
« Reply #11 on: 03 June 2016, 08:59:32 »
One idea is that there are two rotating components, one for the crew that is fairly massive but slow-rotating, and one for the angular counter-momentum that has lower mass and higher rotation rate.  I.e. a 10 kiloton structure rotating at 1 RPM clockwise is offset by a 500 ton structure rotating at 20 RPM counter-clockwise.  As long as both are slowed down properly there is no net angular momentum.

You'd probably want a pair of counter-rotating weights, one on either side of the rotating habitation ring, otherwise you apply torque in opposite directions and the whole thing begins to spin laterally if there's any imbalance at all.  The counterweights would most likely be liquid storage (fuel, water, liquefied oxygen, etc.), rather than solid blocks of otherwise useless material just for their mass.

victor_shaw

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Re: Grav Decks & Jumping
« Reply #12 on: 08 June 2016, 20:27:08 »
My understanding of a jump is that the engine scans the ship records the info then beams it to the new location to be reconstituted.
this all happens in less then 30 seconds give or take depending on the distances.
now on to the requirements
since the system transports only whats within the field all items that extend outside of the field must be stowed.
1. sail
2. agro domes
3. etc.
dropships must deploy their jumpboom to extend the field around the ship for the field to envelop them.
everything within the field will arrive just as it left so there would be no need to shutdown the grav decks.


 

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