The Chemical Rocket Third Imperium

[McPerth]

Well, let us agree that "side-effect-free" is what the label sais. :rofl:

And por naive customers believe it :rofl:

With chemical rockets, the actual acceleration isn't much of an issue, it can easily be 30m/s² without much ado. The delta vee, however, would be vital, and in the 10-20km/s range, not more. Relation from payload to fuel mass will probably be around 1:20.
Weapons should probably be standard Traveller stuff of all kinds.

Well, acelration is more important in space movement than pure speed, as is what allows you to maneuver, and the time you can maintain your acceleration is the time you stay manuverable...

A paylod to fuel ratio of 1:20 means that to have a turret (1dt) you need 20 dtons of fuel. Adding to this the rocket itself, power plant, cockpit, etc...

And all of this raises the mass, needing for a larger rocket (and so more fuel) if you want to have any acceleration...

See this MgT1E light fighter, but assuming the 1.5 dtons of the drone core is the cockpit (tonnage is quivalent in MgT1E HG), so that we don't enter in AI issues (as you asked).

It is 10 dton and has a payload (power plant, cockpit and turret, excluding MD as I guess it is included in the fuel for your rocket) of about 6 dtons (so about 60% of it is payload). To have this same 6 dtons payload, wiht your ration 1:20 you'd need a 125 dton, and its endurance and acceleration will be quite lower...

You could reduce the PP if you want to arm it with missiles instead of beams, but misiles also need payload, and it lowers still more the endurance, due to ammo problems, needing to return to the carier (again, at lower acceleration) to rearm...

That's true. Fortunately, for this little chemical rocket thought experiment, we can just adjust the behavior of the jump drive.

I'd prefer not to touch the JD behavior (fuel needs and jump distance aside, as those were in the OP), so, at least, we have some common point understood (in gmae terms) be everyone (or nearly so) here.

This aside, if you change the jump and take off gravitics, then I must agree with those that claim this is no longer Traveller, as much interesting as it may be. Probably, it will become closer to 2300AD (BTW, as a side note, ITTR this was the reason its name was changed from Traveller 2300 to 2300 AD, vecause those same changes made it nothing like Traveller and the name created confusión).

Well, my country doesn't.

But more to the point, a nuclear power plant is a minor risk compared to a beanstalk. Fukushima made a single county uninhabitable, a beanstalk disaster would at the very least kill one ore two continents when the construction collapses and is wrapped around the Earth by planetary rotation..

The fact your country doesn't have nuclear power plants does not mean it is safe from any accident. Chernobil had some efects in most Eastern Europe.

In 2300AD it is specified there were plans to let loose BC beanstalk before Kaffer attack just to avoid this kind of damage. Once done, the whole beanstak would be left adrift, with the hope of being able to recover it latter (this will be an epic and daunting task, we agree, but I guess easier than building it anew. But this is another question for another thread...).

And rockets may also be used as weapons, if a terrorist band takes a lanuching site, for what's worth...

If you don't send down equivalent mass, then the upper part of the beanstalk becomes slower when you send something up, to the point where the Earth starts to rotate faster than the upper end of the beanstalk. As a result, it will be pulled towards the surface, and collide with it disastrously. You could use some kind of thruster to compensate for that, sure. But it would have to be quite some thruster.

I guess (from my engineering ignorance) that having similar masses going up and down at once would sufice, not needing to be exact the same mass in each travel (as it is assumed several capsules are at once going up and down).

Probably you could achive it by making the capsule more massive than its payload, but I'll leave this discussion for those more knowledgeable on those details than myself...

But that's something where higher tech levels can conceivably help.

Claiming higher tech advances when trying to limit its effect :devil:?

Of course, higher tech may help in this, as it may reach FTL or countergravity, who knows? It may even achieve side-efect-free drugs .

As long as they just keep drifting in space (or in some solar orbit, or even just falling towards the local star very slowly), they'd probably last for as long as the crew likes. But I guess food supply might become an issue, so that danger would probably be manageable.

As said in my former post, I have serious Doubs at this being the standard doctrine of any military fleet, as if there's something no military want to do is sitting still.

Density of liquid hydrogen: About 70 kg/m³.
Density of liquid oxygen: 1,141 kg/m³.

So the oxygen is much easier to store than the hydrogen. Also, its mass is included in all the delta V calculations, so that's not a problem.

Water is H₂O, so its atomic weight is 18, 16 from the oxygen atom and 2 from the 2 hydroen ones. So, to convert your fuel to water (if I understood well that's wht the rockets do) you need a mass realtion of 8:1 among oxygen and hydrogen. So, per every metric ton of hydrogen (14 m³, or 1 dton), you'll need to carry 8 metric tons of oxygen (accepting your numbers, as I don't know, about 7 m³, or 0.5 dton). So you need 1 dton of oxygen per each 2 dtons of hydrogen in your fuel tanks, with a total mass of 18 metric tons for the 3 dtons.

f course, as you don't need the fuel for the jump, relations in OTU are not valid here, but, OTOH, as you fuel will be about about 6 times more massive, your thrust will be about 6 times less efficient in generating acceleration...

Agreed. One thing to think about though: Launch catapults are quite an interesting thing under such circumstances, both for the carrier and the fighter.

I guess recovering them will be more a problem than launching them (thoug some initial sped may help). The maneuvers for it will be closer to the Soyutz attaching to the ISS than the Nimitz having its F18 landed (I guess in Travelelr repulsors help the fighters to hit the entry to the carrier, but this need grav tech).

I guess that mostly depends on the new safe jump distance compared to spinal weapon ranges.

I'm afraid we don't talk about the same thing here...

I meant strategically. Let's see 5FW operations (be it a deep thrust or moving reserves behind the lines):

In OTU:

• In day 1 a Zhodani fleet jumps to a GG in a hostile but undefended system.
• In day 7 they exit jump, send fighter cover and begin refuelling opperations (let's say 2 days to refuel the fleet)
• In day 9 they jump again, repeating the opperation for a deep drive into Imperial territory
• This way they can jump about 3 times per month (4 weeks), and they reach their target (if they do) with several days endurance to fight

In your setting:

• in day 1 a zhodani fleet jumps to a hostile but ndefended system
• In day 7 they exit jump. Sending fighters will cost precios fuel, so it's up to the Fleet commander to decide if it's worth it. They cannot refuel, but they must stay there for 7 more days to cool down.
• I nday 14, they resume opperations.
• In the end, they perform 1 jump each 2 weeks, so being 25% slower in those strategic moves. This also gives more advantage if any scout detects them and jumps to raise tha alarm, as they probably can relly on already cooled down ships i neach system to spread the news...

Also, as they canot refuel without friendly facilities, they are likely to reach their targets low on fuel, taht wil lbe consumed quite quickly once combat opperations begin.

Other Space Military changes:

While in OTU you can asume that if ships reach the system with fuel enough for a jump (having juped under they maximum capacity), retreat is posible by jumping away if forces in system are strnguer than expected (after all your intelligence is at least 2 weeks old). In your setting, the need to cool down for 7 days means no retreat is possible.

[The fact of jump not needing fuel makes the whole BT/BR concept unfit for the setting, as the main advantage of BRs is that they don't devote most of their tonnage to fuel, something they must do in this setting if they intend to be more than space pillboxes.

 

[McPerth]

People who are sure to win or people who have no choice but to try.

Being so sure to win usually invites to disaster, sooner or latter (and having no reatreat, disaster means true disaster), and I don't envison many (if any) situations where you have no choice but to invade aplanet. After all, having orbital supremacy (a must for the invasion) yuo always have other choices, even if other reasons (usually political ones) make invasio nthe preferred one.

I would propose that attacks on planetary systems are a thing you only do when outnumbering the defenders vastly anyway. Even in the OTU. After all, attacking with at least 3:1 is a good old and proven rule of thumb. Another one is: You don't attack when you're not sure to win, unless you are very desperate.

Its not always needed to have the 3:1 overall superiority, just force concentration may raise an overall 1:1 to a local 10:1, while your fleet may make difficult for the enemy to so concéntrate their forces...

In Invasion Earth game, the Imperials have about 4000 battalion force to invade a planet with about 4250 battalions defending (800 more appearing as reinorcements for the defenders), and TL advantage is rarely more than 1-2 TLs...

Drop pods. If your Navy has space superiority, it can bring in more troops and vehicles (both air and ground, possibly even seagoing components) with troop transports that travel from the jump point to planetary orbit. Once the planet is secured, the relaunch rockets land, refuel and bring everything up again.

Yes, the scale of such operations is mind-boggling. But so is the size of the Imperium.

As said above, Space supremacy (not just superiority) by your Navy is a must for such opperations. and you can drop some vehicles, but, again, without gravitics (that make all your forces de facto aeromobile and with very high non-combat strategic speeds), any such a conquest will take quite long only to move forces.

Aside form some aeromobile units (whose ranges will be quite shorter than grav vehicles'), most troops will move by conventional means, probably among damaged transport infrastructures, and this will make movements very slow.

And to reembark some units for quicker moves will not be eeasy, as interface movement is not...

Again quoteing Invasión Earth, just for sake of completeness it explicites that motorized units would move in this scale at 5 hex per turn (against the 10 hex per turn grav units move), with the penalties for terrain that grav units forfeit.

All in all, as you initial question was (among others) how will it affect warfare?, I must keep saying that the answer is: beyond any recognition.

QUOTE=mike wightman;570310]I'm enjoying this thought experiment - it makes for an interesting setting.[/QUOTE]

Agreed here

 

[aramis]

You are talking about the OTU's tech levels, I presume.

No, Im talking rules assumptions. Traveller is NOT the OTU; it's a set of tech assumptions.

What I want is valid arguments. If I believe they are not valid, I will point that out. If that is unwelcome here, then just say so, and I'll leave for good.

The ""Shooting down everything rules based as «That's OTU»" is a hostile, borderline trolling, activity. It is NOT welcome here.

You've been given valid arguments. You've been hostile to every one.

[m;]Yes, this is a public warning: Change the tone of responses or I will close the thread[/m;]

 

[Thot]

[...]
You may have missed the part about Metallic Hydrogen where the theory is once it's formed as a metal, it's metastable and will not require excessively expensive continuation of pressure.

As far as I know, that hypothesis has been theoretically disproven - quantum tunneling prevents metastable metallic hydrogen from existing, apparently.

The bigger problem might be that it is a highly energetic fuel that might be that much more explosive when struck by lasers or missiles.

I would not worry about that. In a lightly built spacecraft, you are dead when your energy supply is hit either way, be it LH/LOX or some other energy source. No rocket can survive a battle if it cannot avoid being hit somehow. Any hit is a kill, with rare exceptions, I would expect.

So we have at least these types of ships:

• FTL vessels. A mothership, if you will, that stays at the jump point and has only small amounts of dV. Unstreamlined existing Traveller OTU vessels can perfectly fill that role if their jump fuel is at least sufficient for up to 3 parsecs. (that means 30% volume % and probably around 3 mass %, translating to a dV of around 500 m/s. They are, once built, pushed into a jump position by a rocket tug, and then never leave it intentionally, using their own rockets merely to correct their position if required.
• Rocketships for takeoff and landing, and transfer to the FTL mothership.
• Debateable: Space planes for covering the lower part of getting into orbit, so the first 2-4 km/s².
• Likewise debateable: If space planes are used, low-to-high-orbit rockets that cover the remaining 8-10 km/s².- These are basically the same as takeoff and landing rocketships, albeit with higher payload because the spaceplanes have done a part of the required work.
• Dropships that are basically unable to move in space, shot into landing position from the mothership using a catapult and aerobrake the speed away to land. Possibly with minor chemical propulsion to make slight course corrections when approaching the planet. Mostly for cases when immediate return is not planned. Might actually double as planetside aircraft if built accordingly.

 

[Thot]

No, Im talking rules assumptions. Traveller is NOT the OTU; it's a set of tech assumptions.




The ""Shooting down everything rules based as «That's OTU»" is a hostile, borderline trolling, activity. It is NOT welcome here.

You've been given valid arguments. You've been hostile to every one.

[m;]Yes, this is a public warning: Change the tone of responses or I will close the thread[/m;]

Ah, so this is not a place for open debate. Goodbye.

 

[mike wightman]

Please don't leave. It has been a good discussion thus far, McPerth and I agree on that.

This is the IMTU sub-forum, so your universe with no grav technology is well worth exploring.

I have run near future solar system campaigns in the past (based initially on the Cyberpunk space supplements and GURPS Terradyne) , and there is the Orbital setting for Mongoose Traveller that is well worth looking at too.

Your setting is a lot harder than even those and is therefore interesting.

 

[aramis]

Ah, so this is not a place for open debate. Goodbye.

You've not engaged it debate, merely a string of personal attacks for citing rules mechanics to explore the ideas. For which you have not been infracted.

 

[Brandon C]

You've not engaged it debate, merely a string of personal attacks for citing rules mechanics to explore the ideas. For which you have not been infracted.

I think what the original poster did not fully appreciate was that he was handwaving questionable science in favor of handwaving questionable economics. It's okay if you do this intentionally but when it happens by accident and you refuse to see it being pointed out to you, it can be a problem for you later in the campaign when your players see the problem.

I'm sorry if my posts came off as confrontational but I think they were issues his players would likely raise later in play.

 

[atpollard]

As far as I know, that hypothesis has been theoretically disproven - quantum tunneling prevents metastable metallic hydrogen from existing, apparently.

LiH6 is expected to form a metastable alloy at a fraction of the pressure needed to maintain metastable metallic hydrogen. This suggests that with research, other more exotic catalysts might be discovered and a means perfected for storing Hydrogen as a metastable alloy and releasing the hydrogen from the alloy to use as reaction mass.

Other metastable alloys of LiH were predicted.

This is certainly no less plausible than Fusion Power (which has yet to pass break even in a lab), or any of the super ISPs from your rocket performance. This is a game, after all.

 

[mike wightman]

I was looking forward to discussing waste heat management in such a setting.

 

[Brandon C]

I was looking forward to discussing waste heat management in such a setting.

The two settings I suggested to the OP (Transhuman Space and 2300AD) both give a nod to ship heat radiators, although they probably underestimate the problem for playability.

 

[mike wightman]

This thread has definitely renewed my interest in a hard sci-fi setting.

What's more intriguing is to take the hard stuff and add the jump drive and then have three thousand years or more - with some of the tropes of the OTU thrown in such as the encounter with the Vilani Imperium, Ancients, the Long Night.

What if ship scale fusion proves to be impossible too - unless it is a really big ship of course?

 

[Brandon C]

What if ship scale fusion proves to be impossible too - unless it is a really big ship of course?

Whoa, now, let's fully explore the lack of any gravatics technology before we start in on another branch of the superscience tree

 

[McPerth]

What if ship scale fusion proves to be impossible too - unless it is a really big ship of course?

They you'll get even closer to 2300 AD setting, where this is exactly what happens (most ships are powered by MHD plants there) .

 

[atpollard]

One thing Thot gave a nod to was that Reaction Drive ships (absent some replacement handwave like HEPLAR as presented in TNE) will be FRAGILE craft, not the heavy armored gunships of the OTU. Mass REALLY is your enemy when 80-90% of a ship (by MASS) is going to be LH2 ... which is where the deep space, long endurance high ISP drives are going to lead you.

Like for patrolling a star system.

I think it will look more like a Space Air Force than a Space Navy. Start to think USS Shenandoah or USS Los Angeles (Rigid Airships) as a starting point rather than the HMS Dreadnought.

 

[mike wightman]

TL 8 mature spaceplane technology, reusable rockets, fission powered space ships, space industry established including moon base, LEO refueling stations, fusion power plants (too large for ship or vehicle use), ion engines (nuclear powered and solar powered)

TL 9 skyhooks, mach 24 spaceplanes, colony on moon, colony on mars, jump drive

TL10 fusion engines for ships

TL11 solar powered antimatter production

 

[atpollard]

TL 9 skyhooks, mach 24 spaceplanes, colony on moon, colony on mars, solar powered antimatter production facilities near the sun, jump drive

Why antimatter at TL 9?
Sure, it can probably be created as a curiosity in minuscule quantities (like metallic hydrogen in 2017), but as an economical energy storage medium that can be safely contained and converted back to usable energy? Will it require a storage unit even larger and heavier than the Fusion reactor?

It just seems a radical departure from the Traveller TL timeline and a huge leap forward for a civilization that can't even control gravity. :rofl:

 

[mike wightman]

One thing Thot gave a nod to was that Reaction Drive ships (absent some replacement handwave like HEPLAR as presented in TNE) will be FRAGILE craft, not the heavy armored gunships of the OTU. Mass REALLY is your enemy when 80-90% of a ship (by MASS) is going to be LH2 ... which is where the deep space, long endurance high ISP drives are going to lead you.

Like for patrolling a star system.

I think it will look more like a Space Air Force than a Space Navy. Start to think USS Shenandoah or USS Los Angeles (Rigid Airships) as a starting point rather than the HMS Dreadnought.

The military would be using nuclear fission engines for their spacecraft - if we can put them in submarines, cruisers and carriers then using nuclear powered spacecraft for military purposes is a given.

What's needed is the establishment of space based manufacturing, either station, moon base or asteroid. Once you have your high technology industries in space and you can build nuclear engines off world rather than risking the fall out from a failed rocket launch
(I wonder just how far you can scale up the Space X Falcon heavy lift - a couple more boosters looks doable).

 

[mike wightman]

Why antimatter at TL 9?
Sure, it can probably be created as a curiosity in minuscule quantities (like metallic hydrogen in 2017), but as an economical energy storage medium that can be safely contained and converted back to usable energy? Will it require a storage unit even larger and heavier than the Fusion reactor?

It just seems a radical departure from the Traveller TL timeline and a huge leap forward for a civilization that can't even control gravity. :rofl:

We can make and trap antimatter now.

In 2 TLs time a mature space industrial society could easily build the facilities for the mass production of antimatter.

 

[atpollard]

The military would be using nuclear fission engines for their spacecraft - if we can put them in submarines, cruisers and carriers then using nuclear powered spacecraft for military purposes is a given.

What's needed is the establishment of space based manufacturing, either station, moon base or asteroid. Once you have your high technology industries in space and you can build nuclear engines off world rather than risking the fall out from a failed rocket launch
(I wonder just how far you can scale up the Space X Falcon heavy lift - a couple more boosters looks doable).

Let's run some numbers through a B.O.T.E. calculation and see what we get. Any idea on the mass and power output of a complete Fission Reactor?