6G ship acceleration limit

[sabredog]

How I work around the small craft G-limit issue:



Pilot Armor TL-9 25,000CR
Because of the cramped conditions and the lack of full power inertial compensators in craft less than 40 tons without small craft bridges ordinary vaccsuits and combat armor are too cumbersome to wear. Pilots and crews of such craft in the military wear specially designed suits designed not only for protection against spalling and other physical impact damage, but to protect the wearer from injury due to high G maneuvering.
The vacc-tight suit is woven from ballistic cloth with mesh reinforcement in the joints and seals. Overlapping ballistic ceramics further cover the joints and shoulders, with shin, forearms, and thigh protective plates that are inserted in pockets. A clamshell cuirass protects the upper torso (lighter in composition than regular combat armor) and has sockets for plugging in the acceleration reduction systems onboard the craft the wearer is crewed on. The helmet has datalink jacks for connecting to the craft avionics and targeting systems, 100 PWR radio, and contains a combination filter / compressor mask for use when a vacc-tight seal isn’t required.
A manually-variable camo film is standard on the hard surfaces.
The suit provides armor at the level of Combat-1.


Fighters and other combat small craft are assumed to have ejection capsules with rescue beacons for crew life support. Sucks to be a fighter pilot but that's why they get to paint artwork on their ships.

 

[HG_B]

I'd always envisioned shipboard inertial compensation to be an interior feature, an adjunct to the artificial gravity, rather than something encompassing the entirety of a ship's hull, which seems a little too magick-y to me.

Yeah, I guess you're right. It is how they are presented.

 

[jawillroy]

'course, part of the "fast huge ships" thing can be put down to new hull materials at higher techs, I 's'pose...

 

[HG_B]

'course, part of the "fast huge ships" thing can be put down to new hull materials at higher techs, I 's'pose...

Could be. We are ~TL 8. TL 15 is like going from TL 2 - present day. Lots of room for fantastic (to us) metallurgical advances.

 

[Johnny_BoomBoom]

Now, I'm a big bit out of touch with the books, so I'm gonna maybe look a little stupid here....but what the hell!

All this talk of G tolerances got me thinking....how many G's are pulled when you engage the jump drive?

 

[aramis]

Now, I'm a big bit out of touch with the books, so I'm gonna maybe look a little stupid here....but what the hell!

All this talk of G tolerances got me thinking....how many G's are pulled when you engage the jump drive?

None. It opens a rift around you, and you fall along the parabola in effectively a freefall for a week.

 

[Vargas]

The human body can withstand high G forces for short lengths of time - like your fighter pilot enduring minutes at 7G.

Modern aircraft can easily do 9g's, the limitation these days is the pilot. Even in a gee suit a pilot can't do more than a few seconds at 7g's.

 

[Hyphen]

Going back to the G-question briefly: from memory, an old discussion suggested that this was one advantage that HEPLaR had over thrusters; it was not limited to 6Gs. However, your internal grav plates could only compensate up to 6G, so 7Gs was OK, but anything higher meant everyone had to be strapped into G-suits, and it could only be sustained for a limited time (pilots can experience up to 9G's in a suit, but only for a few seconds).

An alternate/additional suggestion was to use both M-drive AND HEPLaR, allowing you to boost your thrust in emergencies (such as combat) without having to carry a full month of HEPLaR fuel.

BTW, my suggestion for grav plates/intertial compensators is that they can only compensate a max number of G's equal to the best M-drive of that TL. That is, if your TL limits your thrusters to 4G, that the best your grav plates can do as well. (This may even be a rule, but I've no idea where it would be...)

Yes, it's arbitrary, but it's neat and easy to remember.

 

[HG_B]

An alternate/additional suggestion was to use both M-drive AND HEPLaR, allowing you to boost your thrust in emergencies (such as combat) without having to carry a full month of HEPLaR fuel.

Or, just use the small craft rules MGT High Guard...

 

[far-trader]

Modern aircraft can easily do 9g's, the limitation these days is the pilot. Even in a gee suit a pilot can't do more than a few seconds at 7g's.

Fair enough, however...

...modern aircraft are not thousands of tonnes in mass and hundreds of meters long with great open spaces tens of meters across capable of jinking at 6Gs for hours repeatedly over a lifetime of hundreds of years with zero stress fatigue on the hull

That's my argument with 6G capital ships in Traveller. Short of there being an enveloping field that cancels all the stress effects on the hull* I find it a stretch to imagine any material capable of such a feat. Small craft (<100tons) sure, small ships (<1000tons) maybe, larger ships... no.

* which is exactly the handwave I use

I've long wanted to ATU a maneuver limit based on hull size. Something like:

• Vehicles (<10tons) 7G (for an edge for fighters)
• Small craft (<100tons) 6G
• Small ships (<1000tons) 5G
• Medium ships (<5,000tons) 4G (max size for std atmosphere ops also)
• Large ships (<10,000tons) 3G
• Huge ships (<50,000tons) 2G
• Gigantic ships (>50,000tons) 1G

...but I'd "have" to do a bunch of work reinventing fleets And I'd probably want a bit less granularity, factoring in hull strength and form, and materials TL, and so on.

I think it'd make a much more dynamic High Guard environment though. Fighters would be more valuable... Capital ships would actually need smaller support craft for ground interface and fuel skimming... and so on.

Picture fighters (<10tons) out-maneuvering and out-running escorts, escorts (<1000tons) dancing rings around destroyers, and destroyers (<10,000tons) making battleships (>50,000tons) look like they're standing still

 

[HG_B]

I've long wanted to ATU a maneuver limit based on hull size. Something like:

• Vehicles (<10tons) 7G (for an edge for fighters)
• Small craft (<100tons) 6G
• Small ships (<1000tons) 5G
• Medium ships (<5,000tons) 4G (max size for std atmosphere ops also)
• Large ships (<10,000tons) 3G
• Huge ships (<50,000tons) 2G
• Gigantic ships (>50,000tons) 1G

...but I'd "have" to do a bunch of work reinventing fleets

This would only be necessary if playing some version of Traveller that didn't use inertial compensators...

 

[far-trader]

This would only be necessary if playing some version of Traveller that didn't use inertial compensators...

As far as I recall no version of Traveller applies inertial compensators to the hull, only to the internals and specifically for crew comfort/safety. And the few that include inertial compensators don't factor the added (momentum?) Gs involved when swinging a few thousands of tonnes about the center of a hundreds of meters long ship. The stresses involved will be far greater than the paltry 6G of inertial compensation the rules presume.

...but as noted above, that is my handwave for ignoring the issue. And like all handwaves it's weak. I'd prefer something else

 

[HG_B]

As far as I recall no version of Traveller applies inertial compensators to the hull, only to the internals and specifically for crew comfort/safety.

Hmm, I don't remember CT separating it out. Maye I missed it. It's been years since I've gone through all that material.

 

[Thunderbolt]

Probably the worst kind of discussion to try an inject the "laws of physics", but whatever the scope of the inertia compensator is, action must be linked to a reaction.

Assuming that the inertial compensator is some sort of highly tuned and variable gravitic field generator, then I assume that it must be mounted somewhere so that it itself is not thrust away with the same force in the opposite direction?

I think I'm with far-trader with the size limits acceleration. The bracing needed to stop a skyscraper sized craft from flexing and breaking its back under 6G must be quite different from a vehicle the size of a fighter plane.

 

[HG_B]

Probably the worst kind of discussion to try an inject the "laws of physics", but whatever the scope of the inertia compensator is, action must be linked to a reaction.

Assuming that the inertial compensator is some sort of highly tuned and variable gravitic field generator, then I assume that it must be mounted somewhere so that it itself is not thrust away with the same force in the opposite direction?

Of course, I agree. How you mount that and where you direct the counter-force in the design has a lot to do with it. The skyscraper is a good example. Do you direct the stress into the outer walls or to the foundation? With inertial comp you could route the force in different directions and take stress off of areas... Thus, with good design and of course, advanced materials, the G level could be MUCH higher than you can envision...

 

[Thunderbolt]

I got thinking about the age old B-Movie problem with giant insects and how you can't just scale things up and expect them to work the same way.

I came across this statement:

"In general, if you scale up an object, its strength will increase with the square of the size multiplier, but its mass will increase with the cube of the size multiplier"

 

[HG_B]

I got thinking about the age old B-Movie problem with giant insects and how you can't just scale things up and expect them to work the same way.

I came across this statement:

"In general, if you scale up an object, its strength will increase with the square of the size multiplier, but its mass will increase with the cube of the size multiplier"

Of course. Basic stuff. So, take material that has 100 times the strength of titanium and the same mass. Gotta think out of the TL 7 box my friend.

 

[hdan]

Unless of course the recent theories about there being multiple "flavors" of Higgs Boson and (possibly related) inertial mass and gravitic mass not necessarily being the same thing turn out to be true.

Add to that the recent calculation that graphene nanotubes could somehow convert electrical fields into mass (apparently there is something odd in the equations that factor out to leave a Mass around - this is supposedly not a new idea, but until recently we couldn't try to test it because of excessive energy requirements).

While it's possible that this is all "quackery" and will be disproved, it's also fun to imagine that a negative electrical field and some nano-mumbo-jumbo could effectively cancel out the gravitic mass of an object without affecting its inertial mass (allowing for "grav lifters").

Sorry, no links. I suspect Google can find some.

 

[HG_B]

Sorry, no links. I suspect Google can find some.

All good sci-fi game fodder.

 

[hdan]

Yep, not as fanciful as "Element Zero" in "Mass Effect", but still good prods for the imagination. I don't take any of those ideas seriously, but they do give good fodder for handwavium.

(BTW, son recently decide that things like "Dilithium Crystals" or the recent Trek movie's "Red Matter" are all "Isotopes of Unobtanium". He makes me so proud.)

BTW: http://www.graphene-info.com/graphene-mass-generation-image is a start on the graphene/mass thing.

I couldn't find any good references to the inertial/gravitational mass difference paper to see if anyone has actually followed up on it. (It's conventional wisdom that they're the same, and all our experiments to date seem to back that up, but it's a fun idea to imagine what we could do if they only APPEARED to be the same....)