Artificial Grav

[Grav_Moped]

The tricks I mentioned (whack the forward baseboard, weaponized vertigo) require nothing that's not already assumed in a canon belly-lander ship.

You get fore/aft ping-pong just from using the M-Drive without inertial compensation, alternated with inertial compensation without the M-Drive. It's vertical ping-pong if the ship's a tailsitter/skyscraper (Broadsword, classic Azhanti High Lightning).

Vertical ping-pong on the deck perimeters (bridge, outer edges of the cargo hold, engine room) is just what happens when the grav-field compensates for pitch and roll maneuvers that the ship isn't doing. Might not be 1G each way though -- the math for the actual Gs needed requires assumptions about how fast a ship can rotate on its axes.

The hardware capability is already present. The software controls are probably priced into the Anti-Hijack app.

But this sort of depends on how artificial gravity works, though.

It could also be something that sets the gravity within the space it influences to 1G in a particular direction, regardless of external forces (until it's overloaded and all external forces get applied). That is, it's not actually applying a forward "pull" to counter the maneuver drive and ship rotation, it's just 1G toward the deck no matter what.

In that case, you can only do one-way 1G ping... ping... ping... (down) without the maneuver drive.
With the drives, you can do M-Drive Gs aft, 1G down, then M-Drive Gs aft, repeating -- but basically if the hostiles stay put at the aft bulkhead, it's still just one THUD followed by G-stress and weaponized seasickness.

 

[Proneutron]

It could also be something that sets the gravity within the space it influences to 1G in a particular direction, regardless of external forces (until it's overloaded and all external forces get applied). That is, it's not actually applying a forward "pull" to counter the maneuver drive and ship rotation, it's just 1G toward the deck no matter what.

No, that would mean during continuous acceleration (which is how trav ships operate) the crew and passengers would be pinned against the "rear" walls during travel.

 

[Grav_Moped]

No, that would mean during continuous acceleration (which is how trav ships operate) the crew and passengers would be pinned against the "rear" walls during travel.

I may not have been clear. The idea there is that the volume within the artificial gravity field is isolated from all external forces except the 1G field. It's not selectively changing the artificial gravity vector to compensate for acceleration, it's simply that everything inside the field is ONLY getting the 1G down, and the drives' acceleration doesn't affect anything inside the field while the field is on.

I like it less than "artificial gravity is applied down-and-forward" as a concept, but I'm using it to highlight that it's not the only way one can imagine artificial gravity.

 

[Proneutron]

I may not have been clear. The idea there is that the volume within the artificial gravity field is isolated from all external forces except the 1G field. It's not selectively changing the artificial gravity vector to compensate for acceleration, it's simply that everything inside the field is ONLY getting the 1G down, and the drives' acceleration doesn't affect anything inside the field while the field is on.

I like it less than "artificial gravity is applied down-and-forward" as a concept, but I'm using it to highlight that it's not the only way one can imagine artificial gravity.

Got it. Yes, it could be set up like that and work per the rules

 

[kilemall]

I assume gravitics is hard at work in the materials technology arena.


Metallic Hydrogen used in capacitors for instance from CT:HG. I call them M-Hyd. It's estimated metallic hydrogen can be formed from 490 gigapascals, which fits right in line with gravitics being a key tech for jump and the capacitors' intro at TL9.


Also, all those advanced ship/war vehicle materials, with Superdense and Bonded Superdense. The latter adds in nuclear damper technology for an even stronger hull.


Of course we can have those floating cities, individual elevator tubes (and those at earlier tech if you assume earlier repulsor tech as per CT:HG).


Speaking of which, MgT has those repulsor melee shields. You could scale them up to Dune level if you like, presumably without the lasgun/shield atomic consequences.


It occurs to me that maybe there should be a class of gauss/mass driver/railgun type weapon that doesn't use magnetics at all but gravitics, which would allow for non-metallic projectiles. Could be handy if something like ceramics are better for atmospheric 'reentry' in ortillery bombardment.


Maybe an element used in weather control? I'm thinking less actual repulsion/lifting and more particle dispersal/control.

 

[coliver988]

But this sort of depends on how artificial gravity works, though.

It could also be something that sets the gravity within the space it influences to 1G in a particular direction, regardless of external forces (until it's overloaded and all external forces get applied). That is, it's not actually applying a forward "pull" to counter the maneuver drive and ship rotation, it's just 1G toward the deck no matter what.

In that case, you can only do one-way 1G ping... ping... ping... (down) without the maneuver drive.
With the drives, you can do M-Drive Gs aft, 1G down, then M-Drive Gs aft, repeating -- but basically if the hostiles stay put at the aft bulkhead, it's still just one THUD followed by G-stress and weaponized seasickness.

aha! going back to that version of grav control, with my version of more Star Trek like (from the DS9 tech manual) grav plating, no ping-ponging! My 80's days are back - no ping pong. I really did it this way to make it at least possible to board ships under power; though with the select you could take out the power and therefore grav, which was the alternative method.

 

[Grav_Moped]

Heck, in star trek if you shut down inertial compensation you can kill everyone instantly when you hit the impulse drive.

 

[Proneutron]

Heck, in star trek if you shut down inertial compensation you can kill everyone instantly when you hit the impulse drive.

Yes and no. I've seen at least one episode post TOS where inert comp goes out while using impulse and they continue evasive manoeuvrers which would be useless at 1 -2 G' worth of acceleration. As an aside, in shuttle craft they lose it often and yet have no safety belts which sometimes results in death in the case of a crash. Odd

 

[coliver988]

Heck, in star trek if you shut down inertial compensation you can kill everyone instantly when you hit the impulse drive.

EXCEPT for that coffee cup...perhaps they have perfected the coffee centric inertialess system (CCIS). So - if I drink enough of that coffee, I don't need no stinking inertial compensator!

 

[whartung]

So - if I drink enough of that coffee, I don't need no stinking inertial compensator!

Columbian Inertial Compensation Fluid.

 

[BackworldTraveller]

I assume gravitics is hard at work in the materials technology arena.


Metallic Hydrogen used in capacitors for instance from CT:HG. I call them M-Hyd. It's estimated metallic hydrogen can be formed from 490 gigapascals, which fits right in line with gravitics being a key tech for jump and the capacitors' intro at TL9.

Does this technology allow the fuel in starships to be stored at greater densities than stated in the rules...just don't turn the power off or your tanks explode?

 

[Condottiere]

Can you compress hydrogen or water, or ethanol?

Were they compressed in the default spaceship tanks?

 

[Proneutron]

Can you compress hydrogen or water, or ethanol?

Were they compressed in the default spaceship tanks?

Trav ship fuel tanks hold LHyd if I remember correctly. Which is far denser than hydrogen gas. H2O & ethanol aren't really compressible for ship fuel tank purposes. H2O contains more hydrogen by volume than LHyd. So better for PP fuel storage and additional J-Drive fuel (for the 2nd jump) than LHyd.

 

[aramis]

LHyd is around 13.75 to 14.5 kl per tonne, depending upon exact temp and pressure. It doesn't get much smaller when converted to metallic hydrogen; the papers indicate that the density change is minor.

You can actually store more hydrogen per unit volume in methane or water - CH4 is 0.657 Tonnes/kl and water is 1 tonne/kl...
a molecule of methane is 18 mass, of which 4 is hydrogen.
Heavy methane could be up to 22 mass (and 0.803 density) using ¹⁴C²D4; active radioactive methane to store tritium ¹²C³T4 would be 24 amu, and .876 tonnes per kl...
it takes about 4.5 tonnes of Methane (9/2) to store 1 tonne of hydrogen as component. that takes 6.45 kl. twice as much volume and 4.5× the mass.
Water is 1/9 hydrogen, pure heavy water is 2/10 deuterium, radio-heavy water is 3/11 tritium, and oxygen isotopes are supposedly not that common.

 

[Condottiere]

So you can't compress the hydrogen further, either by pressure or increased artificial gravity, which resolves the issue if you can power the jump drive directly from compressed hydrogen.

Feeding the reactor is slow enough that raw fuel can be processed.

Last up would be reactionary rockets, if they need processed hydrogen, in which case, all you need is a large enough fuel processor.

 

[Straybow]

LHyd is around 13.75 to 14.5 kl per tonne, depending upon exact temp and pressure. It doesn't get much smaller when converted to metallic hydrogen; the papers indicate that the density change is minor.

I read one paper that speculated mH would be about 0.4 g/cc

 

[Straybow]

So you can't compress the hydrogen further, either by pressure or increased artificial gravity, which resolves the issue if you can power the jump drive directly from compressed hydrogen.

Feeding the reactor is slow enough that raw fuel can be processed.

Last up would be reactionary rockets, if they need processed hydrogen, in which case, all you need is a large enough fuel processor.

Cryocompression can achieve 100kg/m³. However, puncturing a tank would result in catastrophic explosion because it will flash in the presence of oxygen at a mere 2 atm pressure (which would be far exceeded). Hello Hindenburg!


By comparison, puncturing an LH2 tank will most likely smother an open flame rather than ignite. (It's the oxidizer that explodes when rockets go bad.)

 

[willtron3030]

When I think about artificial gravity in ships, I get very conflicted.

Take a Type S Scout, where decks are aligned parallel to the long axis from bow to stern, and "up/down", "port/starboard" are at right angles to the axis of thrust (M-Drive is at the stern, and direction of motive force is towards the bow).

With artificial gravity, pax and cargo are subject to acceleration towards the deck. If I load 100kg of material in the starboard side of the ship, artificial gravity (for this example, set at 102% Earth gravity) exerts force on the material, resulting in about 1000 Newtons of force on the deck, at a right angle to "forward". How do forces like that not induce roll or pitch, or affect the course of the ship?

I have a couple of hand-wave solutions, one of which centers around inertial compensation, but I don't like either. Is there a canon explanation?

 

[AnotherDilbert]

How do forces like that not induce roll or pitch, or affect the course of the ship?

I obviously don't know how artificial gravity fields work, but normal gravity fields are two-way, reciprocal. E.g. the Moon exerts the same force on the Earth, as the Earth does on the Moon, through gravity (cf. tides).

If a 100 tonne container press against the deck, presumably the same force (in the opposite direction) will be applied to the other end of the gravity field, presumably the grav plates in the decks. Hence, the ship as a whole will experience no net force and will not start to roll or pitch.


At least if designed and loaded correctly, perhaps if the ship is asymmetric the forces might not entirely cancel out, and produce a bit of rotational acceleration, something the attitude thrusters might have to deal with. But that is way past the level of detail Traveller bothers with.

 

[Condottiere]

Gravity is falling until something stops you, and hoping to have enough structural integrity that your body doesn't get crushed.

One assumes that gravitational plating simply amplifies that locally.

Inertial compensation, on the other hand ...