Should Thruster Plates work on Volume instead of Mass?

[Scott Martin]

Hello

I had a thought yesterday, and it still looks valid today, in the cold light of dawn.

Why not have thruster plates work on volume, not mass?

CG is based on volume, and is the definitive gravitic system in Traveller.


Jump drives work on volume, and the concensus on this board is that they are gravitic in origin.

Why are thruster plates the "odd man out?" Volume based thruster plates would certainly explain why all of the Traveller versions before TNE did ship design *SOLELY* based on volume, and warships had *immense* masses of armour without requiring more volume for drives, or power to run them.

Think of that TL-12 buffered planetoid monitor that you proudly built: 35% planetoid (at a specific gravity of ~6 and 26% "armour" (superdense) at a density of 14. If this was 10,000 dT the *Armour* alone on this thing pushes the average density for the entire hull to 5.75, so if this was just a shell of armour with nothing else in it, it would mass over 800 Kilotons (only a factor of 8 over the "target" for FF&S designs) there is no way that there is enough room in the hull to cram weapons and engines sufficient to get this behemoth crawling faster than about 2 G's at TL-12, and ~5 G's at TL-15. That's without any weapons loadout.

Yet this type of platform was routinely seen in the 3I running around at 6 G's.

A thought for T5: make "thruster plates" work on volume, not mass: this takes mass completely out of the equation, and simplifies design (for thruster plated ships) back towards LBB-2 and HG-like design sequences.

There are some wrinkles that I will throw in if folks are interested in this discussion, but I figured I'd put this out and see if anyone else had a "head slapping" moment like me when they looked at the numbers.

The actual numbers are a *bit* better for the planetoid monitor in Supp9, since bonded SD is more space efficient than SD, but it still gives a base desnity (for just the hill) of 4.34, 6x the "trget" for FF&S, and remember that this is without the drives and weapons, which *all* have a density of ~2, and fill most of the remaining space.

Scott Martin

 

[daltoncalford]

I have always made thrust based upon volume...unless I was doing a 'backward tech' system with multi-stage rockets.

I agree with you on this one.

best regards

Dalton

 

[Fritz_Brown]

Personally, I would prefer planetoids not be zipping about at 6Gs....

 

[mike wightman]

Like Dalton I've always postulated a volume based maneuver drive.

IMTU the maneuver drive produces a field that lowers the inertial mass of objects within the field, such that an ion engine, plasma rocket or the like can push the field's contents from 1-6G.

The same field (probably some sort of cold plasma) also acts as the radiation shield mentioned in Beltstrike.

Within a planets gravity well the maneuver drive also makes use of the same null-grav technology that's used in gravitic craft.

The maneuver drive's inertial reduction is tied into the grav plates and the acceleration compensators.

And no, I've no idea how all this would really be possible either

But I do agree that making the maneuver drive a volume effect rather than a mass based one is much simpler - and closer to how CT did things by the by

 

[daltoncalford]

Hi Sig,

Try this one on for size, maneuver drives up to 15G, inertial compensators set as per tech level. Flight suits and g-tubs used to survive above human tolarences. We currently have planes that will put 7G's worth of stress on us poor digital watch wearing ape decendants.

The big thing about the high G's is the negative modifiers it causes on even simple tasks, like not passing out.

best regards

Dalton

 

[Fritz_Brown]

Actually, Dalton, we have aircraft that will put 9Gs on us poor digital watch shooting apes. Slanted seats, G-suits, and a good M-1 manuever make it doable.

 

[daltoncalford]

Hey Fritz, been a while since I looked at modern plane specs - you aren't one of the flyboys who have been up in one are you?

best regards

Dalton

 

[parmasson]

“Personally, I would prefer planetoids not be zipping about at 6Gs”

That would be rather disturbing now that I stop and think about it

Kinda funny too.

 

[Fritz_Brown]

No, I never got to fly that kind (the F-16). (Though the initial trainer - the T-37 - actually has the fastest G-onset rate of any aircraft in the inventory, including the F-16!) I have been past Mach, though, and spent time watching the world go round ... and round ... and round ..., and loopedy-loop, and all.

 

[daltoncalford]

Hi Fritz,

I always wanted to do some of that, but I would never pass the medical.

oh well, at least I can design the stuff in rpg's (yes, that is a sad statement on life)

best regards

Dalton

 

[ajsg]

to see you back on topic:

even the posters who want M volume based require, and explain, their physics to be mass based.

what you do with M drives is moving masses, not to be confused with J drives, encapsulating a piece of space, volume, in J-space.

 

[TheEngineer]

Hi !

IMTU I usually explain (MT) thrusters as devices, that work on spacetime geometry directly, thus causing a mass-independant gravitational effect. This bending ability might be limited, so that maneuver drive performance is limited that way.
IMHO the explanation of M-drive performance limitation to 6g is a pretty problem to any model, which works thrust/reaction based.

This one is completely volume based and does not depend on included masses.
Its maybe more related to jump drive, which might represent another "consequential" step of technological development...

 

[Pickles]

In contrast to MTY, where I always get guilt twinges over too much handwaving, I agree that the OTU system would be better off sticking with one design system basis, in this case volume. What we're talking about here is easily producing consistent game-stats for spacecraft ... it's not rocket-science, after all.

Willkommen an Bord, ajsg! Hey, waitaminnit - are the Germans taking over the QLI space programme?

 

[GypsyComet]

I prefer something of a hybrid, if only for the fine-tuning implications. Volume-based M-Drive is a useful and fairly consistent *approximation*, particularly in civilian designs with little or no armor. There should be NO SHAME applied to someone who continues to use this approximation, as, frankly, more than a few campaigns lack serious gearheads, and Traveller has used the approximation in all editions.

TNE and T4, however (and possibly GT, as I've never really taken the effort to grok the ship design systems) ALSO provided the actual thrust of the drives, and possessed enough detail to get a good mass for the ships. Result was that the mass-based folks were slightly happier than before (HEPlaR still annoyed them, but there's no helping some people). If you really needed the edge, manuever Gs could thus be calculated to several decimal places, and might change usefully if you dumped your cargo.

As such, you put a "2G" drive in, but you may actually get 2.2G when the hold is empty, and 1.9Gs if you're carrying a load of superdense. A lot of folks won't care: it's a 2G drive. Others will, and for them, the detail exists to go beyond the approximation.

 

[Scott Martin]

I'm really issuing a call for consistency here.

The power requirements for CG lifters are the same for an empty merchant and a loaded, heavily armoured warship of the same volume. The density of the former is often as low as 3-4t per dT, while the latter is often in excess of 20T per dT. As a result of this Traveller already HAS a volume-based "grav drive" unless we decide to *also* make that mass based for consistency. Jump drives are also volume based, and the concensus on this board is that they are also a gravitic based system (or a system that works based on the understanding of the "physical laws" of gravitics)

I'm more than open to good arguments for why this is a bad approach, but removing the link between M-Drives and mass vastly simplifies the design process, and the "approximation" is just that, an approximation. If we can "fix" this once and for all, we shouldn't let inertia stop us from making the "correct" choice. I'm not convinced that this *IS* the correct choice, but there are a lot of arguments for going this route. GypsyComet, I'm afraid that your argument is in the mechanics of how to make the approximation work, not *why* we should use mass-based instead of volume-based drives. (Note 1)

Volume Based drives are simple to explain: you can generate gravity, gravity is a *field* that provides energy based on mass. if you are generating the field, then it doesn't matter if you have a feather or a rock, both accellerate at the same rate.

The mechanics of the simple handwave would be a "drive field" requires "X" power to enclose a volume of "Y" size at "Z" strength. Feel free to embroider and handwave nicer technobabble, but that's the core needed for the rules.

Weber has a nice description of how such a system works in his world. The "Impeller" field is generated to "drop" ships along their direction of accelleration. If you're going to allow reactionless thrusters, then changing to vol-based from mass based is *not* a real issue. You aren't violating any *more* laws of physics with the one than the other.

Scott Martin
____________________

Note 1
A FF&S merchant carrying a load of superdense will quickly drop below the 0.1G range with a "rated" 1-G drive, and can often make 2-3 G's "empty" or loaded with fuel. Of course this is "realistic" using HEPLAR (reaction) thrusters...

 

[aramis]

I would agree that volume based has *SOME* merit; it's harder to buy for many due to the fact that the drive is imparting vector, not displacing a volume.

2300-style stutterwarp makes loads of sense to be volume based.
Similar assumptions render J-drives volume based nature likewise insightful.

The described thrusters, note that word, generate thrust via gravitic means. That's not the ONLY means of generating gravitic acceleration.

Now, if MDrive works by inducing an off-center-of-mass pseudo-grativitic well.... then volume-based would be intellectually workable. Probably frightfully energy-expensive, unless some unusual multi-dimensional theory is invoked to make it cheap.

One can theorize that an object will settle upon a non-tangible gravity well in such a way to render itself so that its center of mass is at the center of of the gravity well. But, given that current gravitic science precludes gravity without interfering masses to generate said gravity, we can not test this directly.

I will leave the simulation to the others...

 

[ajsg]

stutterwarp, as i read it, does not need to know volume, but only the intended accelleration.
then time-space distortion needs to be at a save distance from your object to accellerate, so you need to know the exact dimensions for your ship and have a hell of a computer to calculate your field if you need update your ships relative adjustment. more often you would just go sideways to save cycles for lifesupport.
and, it seems to me, you have no more need to have two drives. if you can warp space, there should be no more need for jumpspace.

 

[aramis]

I was basing my comments off of T2300 Star Cruiser and FF&S.

What I was proposing wasn't Stutterwarp. Stutterwarp in Traveller (2300 and FF&S) ises massive induced quantum tunnelling; not a fuunction of coputer, but a field effect inducing a repeated controled quantum jump, creating pseudo velocity without accelleration.