The Chemical Rocket Third Imperium

[mike wightman]

There is a lot of rambling that follows - it is late but this thread fascinates me.

There are a few questions that I keep asking myself about this proposed setting:
why build all these rockets - why do you need to lift stuff into space?

LEO is the only place manned space stations can be put in order to prevent long term radiation damage to the occupants.
LEO stations can assemble stuff for moon and mars missions, trips to mine asteroids.

How much of a space based industry is built before the FTL drive is discovered?

What is in space that is so valuable the expense of doing this will return an investment?
Mining rare earths from asteroids and the moon perhaps? Copper for that matter. Alloys/crystals/semiconductors that can only be manufactured in freefall...

Is the FTL drive a scientific breakthrough by planet bound scientists or space based researchers? Could L points be tasked as jump zones instead of a 10D or 100D limit...

How many years in space before the FTL is discovered?

After a thousand years in space what would it look like?

I keep coming bac to space planes to get to LEO stations, rockets to do the heavy lifting. Rockets and ion drives to move between orbital zones and jump points. I picture the slow transfer ships as looking like great moths in space - wings of solar panels (and radiators) driving ion engines, while rockets are used for much faster transit for manned trips to and from the jump points (the ion drives would take too long and expose the crew to too much radiation over decades perhaps).

Jump ships to carry stuff from jump point to jump point both in system and intersteller. High ports built to service the jump ships.

How do you include PC scale tramp traders, how do you scout new systems?

Like I said - rambling

 

[nobby-w]

[ . . . ]
How do you include PC scale tramp traders, how do you scout new systems.

Like I said - rambling

I think that some of Robert Heinlein's works might be a source of inspiration for this. He did a lot of stuff about civilisation spreading through the solar system and travelling around in interplanetary spacecraft. Granted some of his tropes won't have aged so well, but that's nothing new in Traveller.

 

[aramis]

Chem Rockets won't replace ion for interplanetary...

Ion is faster past a few light seconds.

 

[Thot]

[...]
You assume chemical rockets will keep being the best propulsion, others assume gravitics and yet others warp or whatever it be.

Actually, I assume that fundamental physics equations won't be outdated in a million years. The rest just follows from that.

All are fine, all have their unique challenges and assumptions, and none of us can blame the others for not agreeing with us.

Uh. No one is blaming anybody for anything... still, accepting physics as we know them (mostly) and build our desired SF even with all that in place and have it being cosistent is a fun thing to do.

 

[Thot]

[...]
There are a few questions that I keep asking myself about this proposed setting:
why build all these rockets - why do you need to lift stuff into space?

Because gravity well, in other words: Because of arbitrary limitations that I put on the FTL drive to make actually travelling through space required. (about 0.1 m/s² of local gravity, not more, is my current approach, as the setting is evolving - this is surprisingly close to a simple 5 diameter limit).

LEO is the only place manned space stations can be put in order to prevent long term radiation damage to the occupants.

It is conceivable that strong magnetic fields can be generated on the ship as a means of radiation protection.

[...]
What is in space that is so valuable the expense of doing this will return an investment?

Ore - and the option to do FTL out there.

Mining rare earths from asteroids and the moon perhaps? Copper for that matter. Alloys/crystals/semiconductors that can only be manufactured in freefall...

Not to mention fuel and spaceships themselves, which can be manufactured in high orbits for much lower cost than on the ground.

[...]
I keep coming bac to space planes to get to LEO stations, rockets to do the heavy lifting. Rockets and ion drives to move between orbital zones and jump points.

Using a 5D limit and cheap fuel, ion drives cannot be economical. They do offer superior delta V per reaction mass, but their thrust per weight ratings are so low that all the extra mass from the energy sources and thrusters only pays off on interplanetary journeys or satellites that are not maintained regularly - in other words, for very long journeys.

The same is true for the EmDrive, by the way - even if it works as claimed.

The FTL drive will be used for anything beyond getting to and from the jump point.

How do you include PC scale tramp traders,
[...]

By making fuel and ships cheap, of course.

 

[aramis]

By making fuel and ships cheap, of course.

Which is bigger magic than the lack of heat sinks

 

[Thot]

Which is bigger magic than the lack of heat sinks

Not at all. Energy is freely delivered from the sun. All you need is technology to harvest it in sufficient amounts with few enough resources - which in the case of PV cells, for instance, is a function of the cells' lifetime. The same applies to production facilities, raw materials for which you can have your long-lived robots harvest from asteroids.

 

[Thot]

Further thoughts: One could easily use regular OTU vessels as ships in this ATU setting, but a few considerations would be worth mentioning when building ships specifically for CR3I:

• More than 1 g of acceleration for starships is basically useless.
• It is probably always a good idea to select at least 50% of the vessel's volume as fuel tank size (which translates to about 90% of mass if you use hydrazine, kerosene or methane and assume that 1 dton is about 1 mass ton of the ship without counting the fuel there; that is equivalent to about 10,000 m/s of delta V).
• Fighters do actually make a lot of sense in a CR3I, not because they would be terribly evasive (of course they wouldn't be, as delta V would be limited), but because having more little ships increases one's effective range and coverable area. The same, of course, applies for the larger battle riders.

 

[McPerth]

• Fighters do actually make a lot of sense in a CR3I, not because they would be terribly evasive (of course they wouldn't be, as delta V would be limited), but because having more little ships increases one's effective range and coverable area. The same, of course, applies for the larger battle riders.

I'm afraid I fully disagree in this point. Battleriders make no sense when you need basically the same volume for fuel, as what needs fuel is not the jump.

In OTU, battleriders make sense because they save the volume a jump ship would need for fuel to be better armed/armored. One this is taken out of the equation, they have no advantage over battleships, while they keep all their disadvantage (lack of flexibility, need to be recovered before a retreat, etc...).

Fighters, are more dubious. They must be quite large to be effective:

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 carrier (again, at lower acceleration) to rearm...

 

[Thot]

I'm afraid I fully disagree in this point. Battleriders make no sense when you need basically the same volume for fuel, as what needs fuel is not the jump.
[...]

Well, the idea behind CR3I battle riders would rather be to have a reserve and the ability to position your fleet more effectively. Also, you save the tonnage of the jump drive in your battle riders, so your effective delta V is higher, as the carrier can just stay at the jump point.

Fighters, are more dubious. They must be quite large to be effective:

Well, make a 10 dton payload-fighter carry 90 dtons of fuel for a 100dton-vessel, and you are set.

 

[McPerth]

Well, the idea behind CR3I battle riders would rather be to have a reserve and the ability to position your fleet more effectively.

How will BRs, that have t odetach from the Tender, be more effective tan BBs to deploy?

Also, you save the tonnage of the jump drive in your battle riders, so your effective delta V is higher, as the carrier can just stay at the jump point.

That only represents 2-7% of the tonnage in HG. The true saving for BRs in OTU is For fuel.

Try to build a J4 BB and a BR under those rules, confront them, and then tell me if the difference is worth the Tender and the startegic shortages of the BRs. Even in OTU, where differnece is abysmal, there's doubt. Here I guess it will not be (intuitively, I've not run the numbers).

Well, make a 10 dton payload-fighter carry 90 dtons of fuel for a 100dton-vessel, and you are set.

If the fighters are 100 dton, how large must be the carrier?

 

[Thot]

How will BRs, that have t odetach from the Tender, be more effective tan BBs to deploy?

A battleship has to accelerate the jump drive with it every time it moves. Not so the battle rider: it leaves its jump drive behind and has thus more endurance. At initial fuel-to-mass relations of 75% or more, each additional percent does quite a lot for your delta v.

That only represents 2-7% of the tonnage in HG. The true saving for BRs in OTU is For fuel.

But if you want to have a delta v of 10 km/s, every kg you move requires around 19 kg of fuel. So those 2-7% of the tonnage add up quite a lot.

[...]If the fighters are 100 dton, how large must be the carrier?

Big, which I would call space-opera compatible.

 

[whartung]

A battleship has to accelerate the jump drive with it every time it moves. Not so the battle rider: it leaves its jump drive behind and has thus more endurance. At initial fuel-to-mass relations of 75% or more, each additional percent does quite a lot for your delta v.

The question is whether it's enough to matter.

In the OTU, BRs gained 30-40% hull volume, upon which they gorged them with weapons, armor, and other tidbits to make them more effective in combat.

dV and velocity alone are likely not enough of a significant advantage when it comes to raw combat to make the exercise worthwhile.

 

[Thot]

The question is whether it's enough to matter.

In the OTU, BRs gained 30-40% hull volume, upon which they gorged them with weapons, armor, and other tidbits to make them more effective in combat.

dV and velocity alone are likely not enough of a significant advantage when it comes to raw combat to make the exercise worthwhile.

The least effective ship in combat is the one not getting into range.

 

[McPerth]

About fighters, in OTU, they have several advantages:

1. Small targets
2. Fast and maneuverable
3. They allow for more than 1 weapon mount per 100 dtons (if you need 20 dtons per fighter, hanger and crew accomodations included, you can put 5 weapon mounts per 100 dtons).
4. Interface combat capability
5. Increased range without risking your capital ship.

Comparing those points with your chemical rockets TU:

1. Fighters are over 100 dtons if they intend to have any speed and payload
2. Speed and paneuverability are not too much more (if at all) than for larger ships
3. You need more than 100 dtons per weapon mount in the fighter squadron (and cupled with the small percentage of payload ships have, carriers are likely to be stranded whales.
4. They have the same dificulties to act as interface combat than any other ship
5. this is the only point that, to an extent, keeps valid, but to increase the range they need more fuel, as they must close for the enemy, have some maneuver capability, and return to the carrier.

 

[McPerth]

Returning to your initial question

So, as a resume, and returning again to your initial question about how would this change the OTU (some of the points already pointed in earlier posts, and I know you disagree with my conclusions in some points):

In general:

1. Most ships could not land and interface facilities and orbital stations become quite more important
2. As the fuel is no longer Lhyd, no wilderness refueling exists.
3. Due to points 1 and 2, low quality spaceports (mostly D and E, but also C to some extent) limit the commerce due lo lack of fuel and interface/orbital facilities.
4. As jump needs no fuel, J6 ships are more common, as they lose only 5% payload against a J1 one (of course, that is at TL15, but most ships will have the highest jump their TL allows).
5. Due to the point above and the limited (both in Gs and time) acceleration capability, most intrasystem traffic will be by microjump (at TL 9+, off course).
6. (corolary of the point 5 above) Real space movement would be mostly limited to combat and jump point to planet (incluiding orbital facilities) and vice versa.
7. As no artifical gravity exists, most ships will have spinning sections. Even if you "magic" side-efect-free drugs avoid medical effects, having things floating arround will not be confortable, to say the least...

Commercial effects (aside from point 3 above):

1. Interface costs will make space commerce more expensive
2. As told above too, J1 ships will not exist, so making unimportant planets (low quality spaceports, low to moderat population and no specially unique products) nearly unvisited.
3. Communications will be quicker, as J6 ships will be quite more common

Space military effects:

1. Again, J6 ships will be more common, so 1 jump range larger (and needing to defend more planets)
2. Lack of wilderness refuel will make strategic range shorter (in jumps, not in parsecs).
3. Also due to lack of wilderness refuelling, ships that have already fought one combat will be in severe disadvantage against ships that have not, even if they suffered no damage and have missile supplies.
4. Again for the same reason, Gas Giants will lose their strategic importance. Coupled with the difficulty to move intrasystem by acceleration, this will lead to jumpt directly to the target planet, instead that jumping to the GG to refuel first and move to the target fueled.
5. The 7 days cooling down of the drives will make deep thrusts slower (in OTU they are mostly conducted with wilderness fueling capable ships, so that about 3 jumps per 4 weeks can be performed).
6. Due to this same reason (cooling down need), a fleet jumping into an enemy concentration will be lost (as it would not be able to jump out for 7 days), probably making commanders more cautious.
7. Ships must be larger (as their payload-to-fuel ratio is lower)
8. Fighters and BRs will not be common (if they exist at all), as they lose most of their advantages.
9. As missiles need payload (and, as said, this is scarce in this TU), beams will be the main weapons.
10. As maneuverability will be scarce (at best) combat will become more a matter of pounding each other and resist (by avoiding fire or resisting it) this pounding. Armor will keep being important, despite adding to payload.

Interface/dirtside military effects:

1. Due to the interface problems already told about, landing will be more difficult, and probably with disposable vehicles/drop capsules
2. Of course, the point above makes reembarking nearly impossible...
3. Lack of grav vehicles will make dirtside troop movements quite slower
4. Grav assisted weaponry (e.g. FGMP15) will not exist, becoming support weapons (as they need mount to sustain the recoil) or light artillery.
5. As ships will be low-to-zero gravity, lasers will become the marines' main weapon.

So, again, how will this lack of grav technology and chemical rockets dependance affect the TU: beyond any recognition. Probably it will be closer to 2300AD than to Traveller as such (except for space combat, that will be quie different to both).

Also, again, this does not mean it's not worth of exploring and discussing it, just that it will be a very different universe.

And, of course, YMMV (and sure will in many points).

 

[mike wightman]

About fighters, in OTU, they have several advantages:

1. Small targets
2. Fast and maneuverable
3. They allow for more than 1 weapon mount per 100 dtons (if you need 20 dtons per fighter, hanger and crew accomodations included, you can put 5 weapon mounts per 100 dtons).
4. Interface combat capability
5. Increased range without risking your capital ship.

Depending upon which OTU ship combat paradigm you adopt - let's compare LBB2 and HG'80
small targets - not an issue in LBB2, very useful in HG
fast and maneuverable - no faster or maneuverable than any other properly designed warship, LBB2 6g maneuver, HG 6g,6Ag
more than one weapon mount - this is where fighters shine in LBB2, you can get a mobile turret way above your hardpoint limit
increased range - again this is something very useful for LBB2 combat.

The main disadvantage of fighters at TL15 in the HG paradigm is their limited computer capability and the expense/power requirements of the best computers.
The computer issue can crop up in LBB2 too, so I tend to use the 30t ships boat fitted with a model 5 computer as my heavy fighter.

Comparing those points with yout chemical rockets TU:

1. Fighters are over 100 dtons if they intend to have any speed and payload
2. Speed and paneuverability are not too much more (if at all) than for larger ships
3. You need more than 100 dtons per weapon mount in the fighter squadron (and cupled with the small percentage of payload ships have, carriers are likely to be stranded whales.
4. They have the same dificulties to act as interface combat than any other ship
5. this is the only point that, to an extent, keeps valid, but to increase the range they need more fuel, as they must close for the enemy, have some maneuver capability, and return to the carrier.

fighters being 100t - you could get away with a 50t fighter, 5t payload 45t fuel tank which is the same size as the heavy fighter in S:9
more than one hundred tons for the fighter in the carrier - once you have built your carrier and maxed out its hardpoints every 114t you have spare is an extra mobile hardpoint - sorry - 100t fighter (note the 50t fighter I mentioned would be 69 tons) - tonnages includes one stateroom on carrier in addition to the carried craft.
limited interface ability - this one is tricky - space craft in such a setting are goint to be pretty poor at interface weapons systems, you would be better off with a hybrid engine/SABRE type engine for a vessel designed to operate in orbit and atmosphere.
range - this is where many argue you are better off taking the people out of the fighter entirely and making it a really big missile/drone.

 

[McPerth]

Depending upon which OTU ship combat paradigm you adopt - let's compare LBB2 and HG'80
small targets - not an issue in LBB2, very useful in HG
fast and maneuverable - no faster or maneuverable than any other properly designed warship, LBB2 6g maneuver, HG 6g,6Ag
more than one weapon mount - this is where fighters shine in LBB2, you can get a mobile turret way above your hardpoint limit
increased range - again this is something very useful for LBB2 combat.

The main disadvantage of fighters at TL15 in the HG paradigm is their limited computer capability and the expense/power requirements of the best computers.
The computer issue can crop up in LBB2 too, so I tend to use the 30t ships boat fitted with a model 5 computer as my heavy fighter.


fighters being 100t - you could get away with a 50t fighter, 5t payload 45t fuel tank which is the same size as the heavy fighter in S:9
more than one hundred tons for the fighter in the carrier - once you have built your carrier and maxed out its hardpoints every 114t you have spare is an extra mobile hardpoint - sorry - 100t fighter (note the 50t fighter I mentioned would be 69 tons) - tonnages includes one stateroom on carrier in addition to the carried craft.
limited interface ability - this one is tricky - space craft in such a setting are goint to be pretty poor at interface weapons systems, you would be better off with a hybrid engine/SABRE type engine for a vessel designed to operate in orbit and atmosphere.
range - this is where many argue you are better off taking the people out of the fighter entirely and making it a really big missile/drone.

All good points, but, as the OP did not specify a version.

Personally, I discarded LBB2, as this is clearly not a small ship universe, and mostly thought in MT terms, being the only system that discriminates mass from volume (something I think it's a must in this system) I am familiar with.

more than one hundred tons for the fighter in the carrier - once you have built your carrier and maxed out its hardpoints every 114t you have spare is an extra mobile hardpoint - sorry - 100t fighter (note the 50t fighter I mentioned would be 69 tons) - tonnages includes one stateroom on carrier in addition to the carried craft.

True, if you want to risk the Carrier...

With the need for payload, I gues the carrier will have little (if any) in form of armor or maneuverability, so I don't think that to e a good idea...

range - this is where many argue you are better off taking the people out of the fighter entirely and making it a really big missile/drone.

But if they are big missiles, they are not reusable (so needing to carry more of them, again with the limits for payload you have), and if they are drones I guess they need some remote pilots in the Carrier, so the tonnage saved in the drone is not in the Carrier, and if they fight too far from them communications lag may be a disadvantage (while being too close risks the Carrier).

 

[Thot]

I'll just quote want I want to add something to. I agree with all else.

[...]
[*]As the fuel is no longer Lhyd, no wilderness refueling exists.
[/list]

Chemical rockets could be fueled with LH/LOX, made from water via solar cells and a fuel processor. Likewise, specialized fuel processors could make Methan and LOX, or even Kerosine and LOX, if there is water and CO2 available.

• Due to points 1 and 2, low quality spaceports (mostly D and E, but also C to some extent) limit the commerce due lo lack of fuel and interface/orbital facilities.

I guess one would have to redefine spaceports: If it doesn't have at least one rentable rocket for pushing things into orbit, it does count as X.

• As no artifical gravity exists, most ships will have spinning sections. Even if you "magic" side-efect-free drugs avoid medical effects, having things floating arround will not be confortable, to say the least...

Personally, I find ships that spin in their entirety easier to do, less of a maintenance nightmare and more flexible.

Commercial effects (aside from point 3 above):

1. Interface costs will make space commerce more expensive

1. 
   
   Unless fuel is a lot cheaper, as stated.
   
   

   [...]
   Space military effects:
   

   1. 
      [...]
   2. Fighters and BRs will not be common (if they exist at all), as they lose most of their advantages.
   3. As missiles need payload (and, as said, this is scarce in this TU), beams will be the main weapons.

   1. 
      
      I don't know. A lack of available energy might be an issue there.
      
      

      [...]
      So, again, how will this lack of grav technology and chemical rockets dependance affect the TU: beyond any recognition. Probably it will be closer to 2300AD than to Traveller as such (except for space combat, that will be quie different to both).
      [...].

      
      So let us think this through. For example, would this have changed the outcome of the interstellar wars era significantly? Both sides would be equally limited, so shouldn't the result basically be the same?

 

[McPerth]

I'll just quote want I want to add something to. I agree with all else.

Glad to see we agree in most points

Chemical rockets could be fueled with LH/LOX, made from water via solar cells and a fuel processor. Likewise, specialized fuel processors could make Methan and LOX, or even Kerosine and LOX, if there is water and CO2 available.

Well, it was you who talked about other fuels... In any case, wilderness refueling would need water (so not in GG) and would take more time (though I guess less than the 7 days cooling down)

I guess one would have to redefine spaceports: If it doesn't have at least one rentable rocket for pushing things into orbit, it does count as X.

So going even farther from OTU...

Personally, I find ships that spin in their entirety easier to do, less of a maintenance nightmare and more flexible.

That's also having some spinning sections...(see this thread for my reflections about it in 2300AD universe.

Unless fuel is a lot cheaper, as stated.

Even so, having to rent an interface craft would cost, even if fuel is cheap, the craft itslef would not, neither will crew and support personnel salaries.

I don't know. A lack of available energy might be an issue there.

Again, going further from OTU.

See that if small and relatively powerful power plants do not exist, the fighters would be the ones suffereing the most, as they could not have beam weapons, and missiles need payload and the fighter must return to be rearmed...

So let us think this through. For example, would this have changed the outcome of the interstellar wars era significantly? Both sides would be equally limited, so shouldn't the result basically be the same?

I don't think so...

To put as example FFW, IMHO, the main differences would be:

1. Imperial ships would travel at J6, while Zhodani at J5, giving yet another advantage to the Imperials (in OTU both move at J3-4, with some ocasional J5 cruiser squadrons, as higher jump reduces payload too much). This would have been also important in communications.
2. Imperials, playing defensively, would have a clear advantage on fuel availability, as they would fight mostly in friendly terrain.
3. Reserves coming from elsewhere in the Imperium could no longer perform 3+ jumps a month (I always assumed they fiind the tankers ready in any spot to move as quick as posible), again due to the cooling down time.
4. I already talked about interface/landing problems. The Zhodani reembarcation in Jewell would probably have been quite disastrous.
5. The Imperial ambush to the retreating Zhodani from Rhylanor would probably also have been a true disaster, as most ships could jump out system, while in this universe they would have been out of fuel to maneuver and could not have jumped (again the 7 days cooling down).

Sure there would be some more differences I cannot think about right now.

Would that be enough to change the war? not sure, though I think in overall gives a small advantage to the Imperials, being on defensive.