Poseidon class water tanker (primitive early dropshuttle)

[kato]

This is spun off from LiamGhost's Pathfinder/Ark thread, in some places below referring to that too.

Poseidon class Water Tanker

Code: [Select]

Civilian Spheroid Dropshuttle / 3000 tons / 2124

1170.0 tons - Maneuver Engine (3/5)
  60.0 tons - Structural Integrity (10 SI)
  45.0 tons - Control Systems
  20.0 tons - Quarters (4 Steerage)
   2.0 tons - Armor (primitive - 21 points: 5n/5l/5r/6a)
   0.0 tons - Heatsinks (39 free)
 260.0 tons - Fuel Tank (3900 fuel points, 5.64 tons/burn-day)
   5.5 tons - Fuel Pumps
   7.5 tons - 1.2 tons Consumables and 6.0 tons Spare Parts (for 2 months ea) + 0.3 tons bulk cargo (1 bay door - a)
   1.0 tons - Fluid Suction System (second system for second water tank bay door; first system free with water tank)
1429.0 tons - Water Tank (for 1300 tons of water) (2 bay doors - l/r)
That's the hard cargo limit pre-2130. It can still provide 13.3 burn-days to a jumpship in one go even without converting water - enough for a single jump and a month of stationkeeping, which would fit the lore.

The Poseidon after leaving the planet it operates from would arrive at the jump point with a full fuel tank and about 1043 tons of water left over; in an optimized production cycle the jumpship would already charge its KF drive while both jumpship and dropshuttle convert more water, producing a further 146 tons over a space of 7.3 maintenance cycles to top up the jumpship to a full 391.74-ton supplied fuel capacity and 14.26 tons used for the stationkeeping in this time. Quite commonly, Poseidons would trundle through space at less than 1g thrust in order to give them some fuel remaining for on-station time to wait for a jumpship to arrive.

The 391.74 tons of fuel transferred to a jump ship enable it to perform 2 jumps with a 0.4-day / 940-kg reserve of stationkeeping time. Further reserves for deeper-reaching missions - and for station-keeping in other systems - would be carried along by the jumpship itself, but would not be replenishable unless the jumpship would stay in a system with Poseidon supply for several more weeks.

Poseidons meanwhile excel at requiring minimal land-side facilities restricted to a single specialized support vehicle and a handful men stationed at a seaside outpost which would use the minimum 26-day time that the Poseidon spends on its refueling mission to produce the required 260t fuel for its operations. Their little cargo capacity is insufficient to provide more than a small parcel service to colonies though; in extreme cases they can see up to two people e.g. in medical emergencies taken along to a jumpship, although this requires rather optimal planning time-wise.

They would ultimately be supplanted in the 2130s by refueling space stations at jump points as jumpship operations pick up and newer, even larger dropshuttles become available; these space stations could still be resupplied with water and fuel monthly from Poseidons, keeping available up to 4,800 tons of fuel for jumpships directly at the jump point at any time that way - but even in these operations the Poseidons would soon be replaced by newer dropshuttles that could simply take along higher quantities of fuel which would be produced by expanded capacity on colonies.

Some Poseidons - badly aged with corrosion affecting their inner workings - would later be bought up by budding colonies on arid planets for use in asteroid ice-mining operations, while others would have their water tanks removed and replaced by a generic cargo bay.

The business case for a single Poseidon - 86.34 million C-Bills invested for the dropshuttle, under 125k C-Bills monthly recurring operating cost - is that based upon charging the standard fee per ton hydrogen, it pays off within only 15 fuel deliveries. Operating one for ten years at six deliveries per year will generate about 264 million, or three times the initial investment. Provided credit is available for under 12% annual interest to the amounts required we basically only need to sell the dropshuttle off for around 10 million to turn a profit on the operation.

[kato]

Pontos class Transport

Code: [Select]

Civilian Spheroid Dropshuttle / 3000 tons / 2145

1170.0 tons - Maneuver Engine (3/5)
  60.0 tons - Structural Integrity (10 SI)
  45.0 tons - Control Systems
  20.0 tons - Quarters (4 Steerage - Crew)
  75.0 tons - Quarters (15 Steerage - Passengers)
   2.0 tons - Armor (primitive - 21 points: 5n/5l/5r/6a)
   0.0 tons - Heatsinks (39 free)
  87.0 tons - Fuel Tank (1305 fuel points, 5.64 tons/burn-day)
   2.0 tons - Fuel Pumps
  19.0 tons - 5.7 tons Consumables and 6.0 tons Spare Parts (for 2 months ea) + 7.3 tons bulk cargo (1 bay door - a)
1520.0 tons - Container Storage (2 bay doors - l/r)

The Pontos was a simple redesign from the Poseidon class water tankers to serve as a cargo transport, often for the same colonies that also operated Poseidons for their rather common maintenance requirements and crew handling. Removing the water tank and the bottom two of three fuel tanks made room for transporting containers in a large cargo hold as well as the necessary space for a single deck transporting passengers.

Often used to transport the at the time still in use 40-foot containers ubiquitous in the 20th and 21st century, the Pontos was also classed as a "100 TEU hauler".

[marauder648]

Lovely stuff :D

[kato]

Still pondering the minimal ground force to support the Poseidon.

Current idea is - bear with me - a ca 760-ton cargo train (2 locomotives, 18 cars carrying fuel, 6 crew) that only shunts on a short track between a standby position and a landing field, basically only moving itself back out of the blast zone for landing and liftoff. The requisite discrete construction materials for the track and the landing field would fit alongside the train in a single Pontos without any problems. The train, aside from the fuel, would also carry spare parts and consumables for both itself and the dropship for some 30 months, as well as some exoskeletons to assist loading. Still working on the cost, but it'll probably come cheaper than any permanent base.

[Daryk]

It strikes me installing tracks is tantamount to a permanent base.  Will the locomotives power the necessary electrolysis to make fuel?  Perhaps their "stand by" position should be where they draw the water from...

[kato]

It strikes me installing tracks is tantamount to a permanent base.

For a spaceport it's also one of the easiest ways of moving cargo on dropship scales between the landing site, any storage hangars and other spaceport buildings and perhaps a colony town farther away.

At least if you want to go a simple route, without mobile structure dropship movers and such which sound a bit too advanced and unneccessary complicated for a mid-22nd century colony that sees dropship landings likely only every couple weeks.

Will the locomotives power the necessary electrolysis to make fuel?  Perhaps their "stand by" position should be where they draw the water from...

I was actually thinking reusing the crater created by the initial landing (of the Pontos carrying the train) as a ready water depot. That crater holds up to 30,000 tons of water, both for fuel conversion and for loading on the Poseidon. The landing field should be installed adjacent to this artificial lake; the tracks move away from both landing field and lake, ideally arranged as a siding branching off from preexisting rail line where available. Using the crater keeps construction time for the entire installation to less than a week for installing the tracks and landing field.

The train basically only has to shunt away from the landing field while the Poseidon is lifting off or landing on its dedicated spot - that's perhaps one day in a month. Otherwise it could remain parked next to landing field and lake and fill up its fuel tanks through converting that water.
The two locomotives would be more "powered work cars" - each with a fission reactor (for flavour) powering a 6/9 engine, some quarters for its crew and a relatively large storage/bay section. If Poseidon operations cease they'll still be very usable for other purposes by that colony or just on the spaceport itself.

[Daryk]

Makes sense, thanks! O0

[kato]

Here's some stuff - technically not quite right here, but it's aerospace infrastructure after all...

The initial setup would look like this:



Basically, just branching off that existing rail line running vertical with a siding and a track branching off to our landing field with its water depot next door. Our train would sit next to it, and for the Poseidon to lift off or land would move over to the siding temporarily. And yeah, that blue there is our water depot crater.

Our train would initially only consist of two powered railcars and 18 fuel cars.

Class 275 Power Railcar

Code: [Select]

Tech Level C box rail car, powered, 190 tons

53.0 tons - chassis, tractor
27.0 tons - fission engine (6/9)
  0.5 tons - armour (20 points BAR2 - 5f/5l/5r/5a)
  1.0 tons - communications
21.0 tons - quarters, second class, crew (3)
  8.0 tons - exoskeleton bay (4 exoskeletons nominal)
79.5 tons - bulk storage:
- 11.5t spare parts train (15 months)
- 45.0t spare parts dropshuttle (15 months)
- 23.0t consumables (15 months)

Cost: 1,265,661 C-Bills each

Type-14 Fuel Tank rail car

Code: [Select]

Tech Level C box rail car, unpowered, 21 tons

5 tons - chassis, tractor, trailer
16 tons - fuel tank

The two locomotives would run us 1,265,661 C-Bills each, while the eighteen fuel cars are a steal at only 14,648 C-Bills each. With 18 fuel cars we can 250t of fuel to a dropshuttle.

Our first flight - using a Pontos - would bring in this full train plus construction materials. As a little bribe to the host colony - for using their rail line - we can even bring in a pair of standardized powered passenger rail cars for them, typically bought used (price, new: 485,595 C-Bills) and simply transported there for free:

Pollux 200 Commuter Train

Code: [Select]

Tech Level C, box rail car, powered, 47 tons

9.5 tons - chassis
12.0 tons - fuel cell engine (9/14)
5.0 tons - fuel (2777 km range)
0.5 tons - armour (20 points BAR2 - 5f/5l/5r/5a)
20.0 tons - foot infantry bay (112 people)

These railcars later come in handy as well - because, after all, we're trying to make a business here, and with that we have to expand. So, with only a second Pontos flight, we bring in everything we need to install a small spaceport.



So, basically just a second landing field, extending the tracks there, and a couple buildings. Let's look into those:



The setup of that is actually pretty simple. We've got a control tower, a power generator, a small terminal and a pair of hangars that we can use for both storage and to shift loads over to trucks for those customers who disdain proper transport.

Infrastructure is relatively simple. That control tower - CF16 light building, 1-hex/4-level - basically just hosts 6 tons of communications gear, while the terminal - CF40 medium building, 4-hex/2-level - only hosts a duty-free shop and a small hotel for 20 guests. In addition, between these two buildings, there's accomodation for 29 employees now working on site - 6 for the comms, 21 for the now actually manned landing field and 2 for the shop. We even have sufficient supplies for these guys and the hotel guests for two months on-site. The power generator of course runs fission, and at 90 tons even has sufficient spare capacity to further expand the spaceport later on without needing a new power supply.

The two transshipment hangars - CF45 heavy hangars, 5-hex/2-level - are somewhat special. Effectively, each of them consists of a drive-through pair of (light vehicle) bays for rail cars up to 50t weight, as well as - towards that road - a single (medium vehicle) bay where a truck can be loaded. Each hangar can store some 375 tons on top of that - not quite half the load of a Pontos between the two of them, but sufficient for most dropships of the time.
And when the spaceport's not busy, those hangars make a good site for the local farmers to load their goods for transport to the larger towns at the ends of that rail line.

We'll need something to move some freight around of course. You guess it, we're bringing in a few flatcars on the same flight. Six of them nicely fit our weight budget. Don't need a locomotive, we can just use one of the two already there since it's only standing around.

Container Car

Code: [Select]

Tech Level C, flat car, unpowered, 40 tons (9t empty)

9.0 tons - chassis, tractor, trailer
31.0 tons - bulk cargo storage, external
As they're a bit bigger than the fuel cars these run for 21,533 C-Bills each.

From here on? A few hundred tons, and we can extend both of those rail branches outwards for a pair of extra landing fields. Then we're really in business.

[Daryk]

Nice!  A couple of comments:

1) I've been looking at the rules for damaging barriers, and if you want something to be mostly small arms proof, you really need BAR 5 at a minimum.

2) 6 tons of communications gear?  If you're going above 3, you might as well go for the full 7, I think...


Otherwise, excellent idea!  I really like this...

[kato]

BAR2 works fine against... well, really ugly weather, and not much more. It should work against a saboteur with a hammer in his hands ;)

As for the six tons comms, there's still benefits to not keeping it to three. Mostly that we need 4 tons to use satellite imagers - and 5 tons to really "use" them. There's also the remote sensor benefit, say we're monitoring the rail line with a couple well-placed sensors...
Could still drop one ton and go down to five, adding say a pair of mounted searchlights to the tower. Should fit the theme.

[Daryk]

I was just thinking "building: what tonnage limits?"... :)

[kato]

I was just thinking "building: what tonnage limits?"... :)

I like to keep the building's CF "simple" - while i really dislike "undisclosed equipment". I.e. i either stay at CF16 for that control tower or go straight to CF40 and i would then have to wonder what i pack in there otherwise ;)

7 tons comms is perfectly possible on the frame of that building even with a quarter for the extra crewman. Just lower the bulk storage. That drops our stored supplies down to only 4 weeks though, and i'd like to keep them at a level that's somewhat reasonable between two flights going out from there (and hence some traffic coming in) even for a smaller colony.

P.S. I also use a house rule to find construction materials for logistics purposes for buildings, which is mostly CF-squared dependent. Gotta ship it all in somehow in the early game.

[Daryk]

Put the comms dish in another CF 16 "building" next to the tower? :)

[kato]

See those pale yellow hexes? Those denote where buildings or units would take damage during liftoff :P

[Daryk]

Ahhh, that's what that is... Hmmm... how about running some cable under the rail line (to the green hex on the other side)?

[kato]

Sure, but do we really need that second CF16 building and those 7t comms? Not like we'll need the +2 initiative or the ECCM here, at least for a couple decades. ;)

I'm kinda earmarking those two hexes for a stage 3 expansion to the spaceport, along with the area that road continues for.

[Daryk]

That makes sense... O0

[kato]

Next expansion, a few years in, based on demand, with one more Pontos flight moving things in:

• extending the two rail lines to the landing fields further out and then looping them together with a vertical stretch
• along that vertical stretch installing a full 15x3-hex landing strip for aerodyne dropshuttles, which of course can also be used to land two spheroids in parallel instead

The spaceport itself would now stretch over two mapsheets and is sufficiently sized to support even a mid-sized colony.

A later installation would likely include a small rail shed for the locomotives for maintenance - in one of those green hexes north of the terminal. A single-hex, single-level CF75 hangar with a superheavy vehicle bay suffices.

Beyond that, we can allow some local companies to install a small industry park to the south of our spaceport, though that'll have to be constructed on local means and local money. Existing power supply is good for another 30 hex-heights in buildings, or well beyond 5000 tons of hangar tonnage. For easy commutes we'll want the whole thing to be within 90 km of the next town, which our Pollux railcars can do in under one hour.

[kato]

Just to show something on construction times and costs...

For the initial stage we have just the landing field and railroad. Add an extra team - or a construction vehicle - and you can keep the time at under 5 days. Cost for construction is 185,500 C-Bills. The train as designed adds 2,794,986 C-Bills to that, so we're still staying at under 3 million.

For the second stage those buildings will cost us quite a bit more. All five together come in at around 545.65 days base construction time; the largest component of that is our power generator building at 279 days. Say we're also extending that road further to the next farm some 2 km away just because we're nice. We need some serious support thus to keep this at a reasonable level: Say nine hired construction teams (which turns out twice the personnel strength as will later work on the spaceport) and two construction vehicles; that puts us down to 103 days. Or 3.5 months. Given our rail infrastructure on-site we have enough capacity on-site to house the construction workers too, though for feeding them we'll have to make the occasional supply run into town about every three weeks.
The cost for the spaceport buildings is also quite a bit higher than our initial investment. 5,432,000 for the terminal, 933,800 for the control tower, 4,275,000 for the power generator and 5,110,000 for each of the two hangars Add some 618,000 for the extra tracks, the second landing field and that 2 km road to the farm. Overall we're at 21,478,800 C-Bills for that stage. Add the flatcars and even if we get the commuter passenger railcars used for half their new price we still run an easy 22 million C-Bills here.

[kato]

Sample timetable for tagteaming a monthly jumpship route with an above Stage 2 spaceport, a single Poseidon and a single Pontos:



Our locomotives are used both to convert water into fuel and to deliver the goods from the Pontos to up to five different nearby settlements; nearby being relative since we are talking about 160 miles / 8600-hex distances. The train is not quite big enough to offload all of our inbound goods over those distances; 10% would be delivered locally by truck, in the above table represented by a single TEU delivered from our transshipping hangars every three days.

For scale of what the above supplies to the larger settlements, 40% of this could equal e.g. grain and luxury food imports for typical consumption by 52,483 people. At 3 jumps out from Terra the add-on cost per person for this import (compared to Terran prices) would be about 9 C-Bills per month (!), which makes such imports rather viable.

The spaceport itself could in theory handle twice the above in turnover, provided a second cargo train, a second monthly jumpship route through the system and an additional Poseidon/Pontos pair is available.

The main source of revenue of the space operations - 93% - would always be from the fuel deliveries of the Poseidon, not from the cargo handling of the Pontos. After initial debt servicing the profit margin of the spaceport is large enough to nominally sustain operations even if jumpship routes drop to only one passing by every four years (say after 2236).

[marauder648]

Oh wow! This is a brilliant expansion of this, the starport, the money etc, superb!

[kato]

The funny thing is that the more you play with the numbers the better it fits into the universe. With a total investment of just under 200 million C-Bills the operation even fits the budget constraints of a Campaign-Operations-designed force without problems.

[kato]

Here's a full stage 3 spaceport:

(map clickable for humongous size, this is four mapsheets)


It basically adds:

• an aerodyne landing stretch that can also be used for two spheroids
• a second terminal building to handle larger passenger numbers
• a fuel depot to handle the increased demand, with buried fuel lines to the three spheroid landing zones
• a set of four additional hangars supplied by the spaceport's reactor (in orange), with rail access
• an industrial area to the south externally supplied by other power generators (in blue)
• some additional transport infrastructure (rail and road), in particular expanding our siding into a small marshalling yard
• a bridge across the railway line, possibly to a nearby new settlement

[Daryk]

Awesome!  Are you going to center a game around this idea?

[kato]

It's a bit hard to find the right angle of attack for a game based on this.

It should work well as a backdrop in an ATOW game, perhaps around the Outer Reaches Rebellion on a smaller, less important planet. Economics and negotiations in the starter points, visit the towns and the farms, and for the main campaign: Smuggle some weapons, hack satellites for information warfare, get the opportunity to capture some Alliance heavy gear with a deft risk of exposure, have rebels harass troops using long-ranging weapons in a hit-and-run from the forests in the north, park some fuel train cars next to an Alliance dropship and blow them up...

[Daryk]

That sounds very workable... I'd be interested if you ever decide to do it play by post! O0

[truetanker]

Your Pontos could also drop a single Nolan and LevCar Cargo trailer to do the exact thing! Just 15 tons heavier and easier to produce an use all you'll need is some engineering / work mechs.

TT

[kato]

Maglev would need more infrastructure on-site - not just the rails, but also a discrete power plant somewhere. A Nolan equivalent itself wouldn't be buildable at Tech Level C btw (which i'm restricting myself to as we're in the 22nd century). The chassis and engine alone would already exceed the 475-ton frame of a Nolan - and cost well over 10 million C-Bills.

[kato]

And since the forum's back up here's some fluff for the kind of environment i see this in:


--------------------------------------------------------------------------------------------------

While Epsilon Indi became one of the largest Poseidon sites during the 2160s, operating no less
than 28 dropshuttles of various kinds in the system by that point and maintaining a constant
presence at both zenith and nadir jump points as well as running two of its own spaceports on the
planet, it also became the first such site to be fully replaced by jump point refueling stations
being supplied by newer, larger in-system shuttles that'd tug in blocks of ice cut from asteroids
in the outer system only two decades later in the 2190s. Even earlier than that jumppoint stations
had already been established in the system to facilitate the transfer of cargo and personnel.

Being located at the convergence point of jumpship routes towards both agricultural breadbaskets
such as Ingress and Sheratan and mining worlds such as Kawich, the Epsilon Indi operations became
a corner stone to the colonization of worlds spinwards of Terra, guaranteeing it constant business
and, while not making it a major actor like those capitalizing off the mining business, would
still result in net profits exceeding 10 million C-Bills per week.

--------------------------------------------------------------------------------------------------

Redeploying most its older dropshuttle Fleet after the construction of the jump point stations,
the local operations company of Epsilon Indi managed to expand, supplying the routes towards the
then evolving Tikonov Union and Chesterton Trade League as well as smaller independent planets
such as Poznan or Cynthiania with new ports being built on both established colonies such as on
Woodstock and alongside new colonization endeavours such as on Ruchbah; the number of Poseidons
available also allowed establishing operations even further out on Yangtze and even Demeter - some
115 light years out from Terra.

While "arrangements" with volatile elements in its space sector - in particular the soon expanding
Tikonov Union - kept the Epsilon Indi operations company largely out of the limelight, after a few
incidents around the turn of the century it soon sought to outfit its own small private security
force with some heavier modern weaponry, its ample financial resources and contacts among the
interstellar trade community allowing it to acquire these without much problem.

--------------------------------------------------------------------------------------------------

By the time of the Demarcation Declaration - marking 90 years since local operations began for the
Epsilon Indi Poseidon Corporation - the company would come to still operate some seven original
Poseidons itself, having replaced the majority of its fleet with newer more capable dropshuttles
and having sold off several dozen dropshuttles - mostly of the Pontos and Poseidon classes - to the
colonies that sprung up in the wider sector in the meantime, and, from decades of dominating the
fuel supply market in the sector now even operating four jumpships of its own.

--------------------------------------------------------------------------------------------------

[idea weenie]

If you get a chance, check out Traveller Spaceports books for ideas of other stuff a spaceport might need.  Overall, very nice setup.

[truetanker]

MagLevs use their Engine as a power source, so need for a separate plant. And rails are just one Ferrosteel rail surrounded by ferrocrete sides. BOTH are easy to transport, technically nothing states how may " rails " per ton, but a good amount would be like 50 hexes worth per ton?

TT

[kato]

BOTH are easy to transport, technically nothing states how may " rails " per ton, but a good amount would be like 50 hexes worth per ton?

For maglev, if we use the Transrapid test facility in Germany as a sample, as weight per meter we'd have 6.4 tons concrete, 1.1 tons steel and 0.1 tons other materials (They're currently planning its demolishing, hence why the figures for the 31.8 km track are available. Those figures don't include the 60,000t foundations.). In other words, maglev comes in at 227 tons weight per hex for the track. For supporting a vehicle weight of 75t per hex, not a 475t Nolan.

Including concrete sleepers i calculate the mass for standard rail as axle weight per hex as a nice round figure - i.e. 25 tons/hex. The steel alone is about 4 tons/hex including attachments.

You can arguably in either case cut the concrete down to just cement and use local water and aggregates. That brings standard rail to 6.1 tons/hex and maglev to 55.2 tons/hex.

[truetanker]

I typo'ed

It should have been 50 tons per hex...

But that is sound math.

TT

[kato]

That's the simple math, the hard math is when you try to model trade flows using Poseidon-based infrastructure.

My current sample model uses Epsilon Indi as a hub in which only one million tons per year are transported between Terra and 9 colonies. Already needs 12 Deimos-cored jumpships of pre-2150s times and occupies 80% of the described Poseidon capacity at Epsilon Indi.

[Daryk]

That sounds like interesting math, at least to me...  ^-^

[kato]

My current sample model uses Epsilon Indi as a hub in which only one million tons per year are transported between Terra and 9 colonies. Already needs 12 Deimos-cored jumpships of pre-2150s times and occupies 80% of the described Poseidon capacity at Epsilon Indi.

Had to lower my ambition in that btw.

Preliminary model uses 16 Deimos-cored jumpships in weekly departures from Terra and a Poseidon infrastructure with 12 Poseidon + 2 Pontos at Epsilon Indi (i.e. full capacity as described), four other Poseidon/Pontos bases plus small-station based infrastructure at New Home and Epsilon Eridani - and i've finally found a purpose for dropshuttles at the low end of the size spectrum there this way.
Basically it plots out a set of jumproutes that manage to shuffle some 30,000 tons cargo and 1,350 passengers per month from Terra to ten other worlds - combined, not each.

Rather interestingly, the confining factor - yield per jumproute - is not so much defined by what kind of jumpships or dropshuttles you use - potential gains are marginal, really -, but instead entirely by infrastructure and fuel supply on-site.
In order to raise our yield significantly we either need to get dropshuttles prepositioned on site that empty out our cargo holds - thus also needing proper spaceports - or we position Poseidons literally everywhere in scores to offset the cost of using large jumpships (a 100+kt jumper has a single-jump fuel requirement equivalent to a full Poseidon load, a 200+kt jumper twice that!). The advent of jumpsails then rather quickly makes our Poseidon fleet obsolete as it removes exactly that prohibitive fuel cost.

[Daryk]

At what point does it make more sense to go after ice in orbit vice on the ground?

[Alsadius]

At what point does it make more sense to go after ice in orbit vice on the ground?

That depends heavily on how much fuel you need to take off. Using typical current rockets, >95% of launch weight is lost getting to LEO(e.g., the Space Shuttle could put about 95 tons in LEO, out of a combined mass of close to 3500 tons), but Battletech rockets are far more efficient than that. The implied Isp is so high that sticking a hose into an ocean and then taking off seems more efficient, for most purposes, than trying to find icy asteroids. Abundance and ease of processing winds up being more important than the rather low takeoff costs.

[Daryk]

It's not take off consumption I'm thinking about... it's the fuel burned getting back and forth to the jump point.

[truetanker]

I thought that Iceroids were used in processing and basic drinking, as most planets had little or contaminated sources.

TT

[Cryhavok101]

I watched Ice Pirates recently, and this discussion reminded me of it. People could be harvesting ice from space to replenish water being removed from a planet's ecosphere as fuel... but battletech is probably not far-sighted enough to be bothering with that lol.

[truetanker]

I watched Ice Pirates recently, and this discussion reminded me of it. People could be harvesting ice from space to replenish water being removed from a planet's ecosphere as fuel... but battletech is probably not far-sighted enough to be bothering with that lol.

Did you survive the procedure too?  [blank] lol... Poor 'droids...

TT

[Daryk]

I'm just looking at the economics of the situation.  Kato has done some very detailed work.

[kato]

At what point does it make more sense to go after ice in orbit vice on the ground?

Realistically, from a support/supply viewpoint? Never, as the frost line is always outside the habitable zone by definition.

What would make sense though is dragging an icy asteroid to the jump point.

The kicker in this is mostly the availability of water-ice-rich asteroids. On a cost basis versus a Poseidon installation, we basically for all jump-capable tug installations require water-rich asteroids; in-system tugs in 2150 suddenly double efficiency (to where we can select 6-7% asteroids), and later developments beyond that only mean that by the mid 23rd century we can just as well mine hydrated clathrates for fuel. Like the Poseidon system-wise it would become obsolescent with the advent of jump sails though.

So we basically need to
a) be after 2150 for the technology and before 2200 for obsolescence
b) have the infrastructure to build and support in-system tugs in a system
c) need a certain minimum capacity requirement to make it worthwhile (broadly speaking more than 3 Poseidons in a system)

On point c), given the earlier introduction of Poseidon and thus economic write-off, even medium-sized Poseidon installations would remain worthwhile while the ships remain operational even with the potential of dragging around asteroids unless capacity requirements change.

Arguably, ice asteroid refuelling can become rather worthwhile if one considers Lagrange jump points at gas giants on the edge just behind the H2O frost line but within e.g. the CO2 frost line.

[Cryhavok101]

If you were going to have a version of battletech where belters expanded past the solar system and into other system's oort clouds, would it make sense for them to use this stuff?

[Daryk]

Thanks Kato, that's exactly what I was asking! O0

[kato]

If you were going to have a version of battletech where belters expanded past the solar system and into other system's oort clouds, would it make sense for them to use this stuff?

The ice asteroid tugs? Sure. In combination with a factory that rebuilds the asteroid into a habitat while extracting the water - even ditching the 130,000 tons of olivine and crystals we're still talking 20,000 tons of prime metal for a single asteroid for one of those tugs after all.

[kato]

P.S. Just took the fuel for the tugs themselves into account. Result: Not worth it. Or rather, you need higher water proportions. And you need to go for Lagrange points. And space stations.

Workable scenario A:

- A 7,000 ton in-systems tug works getting asteroids to the L1 point of the local gas giant.
- They basically grab the asteroid and give it a nudge, not thrusting until needing to brake into position.
- These maneuvers burn only 6 burn-days of fuel (36.5t) to move the asteroid over a distance of 7.25 AU over more than 3.5 months.
- A space station at the Lagrange point folds the asteroid into a gantry assembly for disassembly.
- The asteroid - using C1 carbonaceous asteroids - is then disassembled over the next 4 months.
- About 425,000 tons of waste material - olivine - have to be moved away from the Lagrange point every year.
- Result yield for refueling operations is about 12,000t fuel and 1,500t of usable metal for export.

Workable scenario B:

- Two 7,000 ton in-systems tugs tag-team each other getting asteroids to the zenith or nadir jump point of the star.
- They basically grab the asteroid and give it a nudge, not thrusting until needing to brake into position.
- These maneuvers burn 650t fuel per year to move the asteroid over a distance of 10.4 AU within two months.
- The tugs burn another 6,550t fuel per year holding the asteroids in position at the jump point
- The asteroid - using only C1 carbonaceous asteroids - is then disassembled over the next 2 months.
- About one million tons of waste material - olivine - have to be moved away from the Lagrange point every year.
- Result yield for refueling operations is approximately 17,000t fuel per year, additional exports are minimal at 1,000t metal.

Assuming a cost in the region of 140 million for such a in-system tug - primarily in its engine - and an at least comparable price for the space station for scenario A, the above has a benefit-cost-factor of 0.75 for scenario A and 1.04 for scenario B versus Poseidon. Or in other words - a Poseidon can be cheaper, assuming the cost for the ground installations of a Poseidon also needs to be invested in some way for the two scenarios at equal proportion.

Scenario A can be expanded with more tugs feeding the station assuming the inherent capability exists in it; at two tugs we get a benefit-cost-factor of almost 1.0 versus Poseidon, at three tugs we're at 1.1. We'll quickly run into overcapacity issues here though, since with three tugs we already maintain as much capacity as a 8-unit major Poseidon installation. Scenario B has the overcapacity issue from the start, at near-equal costs to Poseidon; it is a viable alternative proposal for 4+ Poseidon sites.

Edited: Revised/recalculated numbers.

[Daryk]

Couldn't the waste material be used as reaction mass to keep the rest at the point of disassembly?

[kato]

Not in a rules-conformant way ;)

I think. We could probably derive something from mass drivers. Those are kinda prohibitive in size and cost though.

[Daryk]

Sad, but true... I saw the idea on a space exploration site that was discussing Von Neumann machines for exploiting the asteroid belt.  Basically, they'd use the waste material from whatever mining they'd do as reaction mass to get to the next asteroids...

[kato]

Above calculation adapted. Scenario B comes out more favourable than before, but runs a basic overcapacity issue for the kind of scale we're talking about. As said i could see such a system in use at Terra on a larger scale for example, though - the 16-jumpship model i'm working with needs around 60,000 tons of fuel at Terra per year.

As regards the olivine waste material, one should note that it does have its use technically, most as foundry sand nowadays. Current production on Earth is about 8 million tons per year.

[kato]

Basically, they'd use the waste material from whatever mining they'd do as reaction mass to get to the next asteroids...

Been tinkering with it a bit, and it can work by attaching a module with a couple Gauss rifles to the asteroid - broadly: 3 firing once every turn (!) for a small asteroid of the same kind of size we can tow.

However, the reaction mass required to be fired off to keep the asteroid in position under the BT-default 0.1g requirement is quite high; effectively, if we assume 80% of that asteroid as potential reaction mass, we exhaust our supply within only 3.5 weeks. To maintain this position for the same time firing the engines of the tug instead we only need about 334 tons of fuel, the equivalent of 8.4% of our asteroid.

Since the waste material is present when we mine the asteroid for its H2O is present anyway, a mixed-mode of firing both these small mass drivers and the tug's engines optimized towards fuel production cycles should be more efficient.

A possible early 2130s model for this could be (for use at Terra):

• eight 3,900-ton tugs employed in a 20-week cycle moving asteroids to a jump point, during which 5 asteroid/tug combinations are present at the jump point at any time
• we move about about 13 asteroids per year to the jump point with that combination.
• each tug additionally deploys a pair of 100-ton support vehicles ("mining rigs") on the surface of the asteroid which each carry mining gear employed in a stationary, anchored position and a single primitive "mass driver" emulating a later prototype gauss rifle that fires off waste material to provide partial thrust
• the tugs in "stationary operations" at the jump point only firing their engines to that point (90% actually) to which their own fusion reactor can be used to produce hydrogen from water supplied from the mining rigs.
• the combination, given the use of 15%+ H2O content asteroids, provides a tap-off of about 772 tons of fuel every week (~40,000 tons per year) to a tanker spacecraft resupplying jumpships at the jump point.

Advantages of the combined propulsion:

• The small mass drivers on the mining rigs are actually worthwhile, as the effective fuel production for tap-off is increased by 25% that way.
• It simplifies loading procedures on the mass drivers - since you're thrusting "down" already anyway you only have to chuck the material in the waste tube where a series of coils then accelerates it out down towards the sun.
• The connection/supply lines between mining rigs and tug can be simplified to mainly a water hose providing water for fuel production on the ship itself. Tap-off by tanker spacecraft could occur directly from the mining rigs e.g. on a daily basis.
• Provided we're "bumping" in two-shot-per-turn cycles, the fusion propulsion from the main spacecraft can adjust to even out thrust to a constant impulse.

The mass drivers used in the above would be primitive gauss rifles that are "dumbed down" to conform more to current coilgun technology in a stationary application. The math used in calculating their requirements is also probably not quite sound.

[Daryk]

Another idea to reduce fuel consumption: solar sails (not the drive charging kind)!  These could actually be the forerunners of the charging kind...

[kato]

Light Sails, available for satellites from 2165, SO p.323.

[idea weenie]

Could you reduce the acceleration?  I.e. traveling at 1G might take 10 days, and use (for example) 1000 tons amount of fuel, but traveling at 1/4 G means you would take 20 days, and wind up only using 500 tons of fuel.  Slower accelerations would reduce the fuel use at the square root of the G rating, while multiplying the transit time by the square root of the G rating.

Then you might also have Hohmann transits for straight cargo, where you perform a low thrust at the beginning, let the cargo coast for most of the trip, and only decelerate it at the destination.  Advantage is vastly reduced fuel usage, the disadvantage is time used.


One idea to even out the thrust rating from the mass driver shots might be springs connecting the firing plate to the mounting craft.  The mass drivers fire, the springs compress, and the craft slowly moves in the opposite direction.  The springs eventually reach their maximum compressing, and the platform starts heading back into position.  At the neutral position the mass drivers fire again, compressing the springs again.  It is a scaled down version of what would be used for an Orion drive.

[kato]

Already doing that, both low-g and Hohmann transit. In the above model when the tug retrieves an asteroid it docks to it and gives it a push at 0.125g (the max it can run) for only 100 hours. It then floats without further acceleration for the next 36 days, before braking again for another 100 hours at 0.125g.

Strategic fuel use in BT is calculated geometric, not squared btw.

It's mostly the fuel to keep the asteroid stable at the jump point that's high; 0.1g required for the combination of asteroid and tug weighing 97,500t means that it's burning the equivalent of 2.4g for the tug only, at a constant rate - and that means you're burning 13.5t per day nominal on fusion only.

Each gauss-rifle-equivalent mass driver reduces that requirement by about one-twelfth, although to "feed" each one employed you need to "convert" about one-72nd of the asteroid per day. If using mass drivers that way you'll also want to pick out C2 asteroids with less H2O content to optimize production-to-waste-material cycles (5.47% would be optimal, at a conversion rate of about 47.6t/hour, thus - with four mass drivers and a tug providing the rest - eating up the asteroid in 3 weeks).

One can optimize tug usage further by using one to push it before disengaging and another grabbing it inflight to brake it and then maintain it. That could be done to yield the "jump point side" tug spending three weeks out of four producing fuel. Using four 3,900t tugs on that side and a single tug for pushing in the asteroid belt would optimize fuel production to about 123t per day continuously (with each of the four using four mining rigs), of which on the jump point side we'll have to reserve about 4t/day for the grab-and-brake maneuvers.

(let's set aside the geometric reduction of the asteroid's size during production btw, that just complicates it further...)

For the economic side, the investment per ton capacity at the jump point is close enough to a Poseidon model that i'd actually have to fully stat out the tugs and gauge their cost; it's in the region of 17,000-18,000 C-Bills per ton capacity for the 2130s either way.

[Daryk]

13.5 tons per day?  I'm looking at StratOps page 147, and it looks like you should only need 0.977 tons per day of fuel for station keeping at 97,500 tons...

[kato]

13.5 tons per day?  I'm looking at StratOps page 147, and it looks like you should only need 0.977 tons per day of fuel for station keeping at 97,500 tons...

Naval Tug Adaptor. TO P.335, while the 6th to 8th paragraph have been erratad the ninth regarding fuel consumption remains valid.

The 3,900 ton tug needs to fire at the equivalent of 2.4g to maintain the whole 97,500 tons at 0.1g. Hence it needs to spend 2.4 burn-days per day, or with a 2130s civilian dropshuttle 2.82*2.0*2.4 = 13.536 tons per day.

Technically for proper rules-compliant fractional accounting in quarter thrust points we actually need to go to the full 3.0g (towing at 0.125g) and for fun calculate through fuel points expenditure; since SFU is a relatively roundabout way of abbreviating that i'd argue we can just go with the above 13.5t per day.

[Daryk]

I think the TO fuel consumption only refers to tactical scale, not station keeping.  Of course, it's your project, so you can interpret it any way you like.

[kato]

Many ways of doing it.

One possible other approach to account for the inefficiency of a moving space station would be an engine size comparison (x 2.6), expanding that factor two-dimensionally for flow rate and multiplying by the relative input requirement (x sqrt(3)) between the tug and a space station that size. Would give us 11.44 tons/day at stationkeeping.

Or we just say that the entire stationkeeping under tow maneuver is tactical, and thus we apply tactical rates at a continuous 360 tons/day. ;)

[RunandFindOut]

Also .1g is WAY above the thrust needed to maintain position for station-keeping at a jump-point.  Gravity at either of the two standard system jump-points is something like .001g if I remember correctly and burning at .1g you'd only need to burn at long intervals.

[kato]

Gravity at either of the two standard system jump-points is something like .001g if I remember correctly

The sun's gravity is about 0.0059267g at 10 AU.

... and maintaining that at pure tactical expense with a x24 factor for the towed asteroid means 204.8267 fuel points per day or - for our 2130s dropshuttle tug - 13.655 tons per day.

[idea weenie]

Already doing that, both low-g and Hohmann transit. In the above model when the tug retrieves an asteroid it docks to it and gives it a push at 0.125g (the max it can run) for only 100 hours. It then floats without further acceleration for the next 36 days, before braking again for another 100 hours at 0.125g.

Good

Strategic fuel use in BT is calculated geometric, not squared btw.

It's mostly the fuel to keep the asteroid stable at the jump point that's high; 0.1g required for the combination of asteroid and tug weighing 97,500t means that it's burning the equivalent of 2.4g for the tug only, at a constant rate - and that means you're burning 13.5t per day nominal on fusion only.

Actually, distance traveled should be based on the square root of the ratio in acceleration,; not sure what you mean by geometric.

The basic distance formula, where you put in starting speed, acceleration, and time is:
D = (starting velocity) * Time + accel * Time^2 / 2

Starting velocity is zero, so that is removed:
D = accel * Time^2 / 2

I now get Time on one side, and everything else on the other:
D = accel * Time^2 / 2
2 * D = accel * Time^2
2 * D / accel = Time^2
Time^2 = 2 * D / accel
Time = sqrt(2 * D / accel)


Proof of time doubling:
setting accel = 1G
Time = sqrt(2 * D / 1)
Time = sqrt(2 * D)
Time = sqrt(2D)

Assuming accel is 1/4 G:
Time = sqrt(2 * D / .25)
Time = sqrt(2 * 4D / 1)
Time = sqrt(2 * 4D)
Time = sqrt(4 * 2D)
Time = sqrt(4) * sqrt(2D)
Time = 2 * sqrt(2D)

So if acceleration is quartered, that means time taken to travel the distance doubles.  Since fuel usage is equal to time * acceleration, that means fuel use is halved.

This is independent of ship mass or other properties.  A tug that is pushing an asteroid at .1G will take half the time and burn twice the fuel compared to the same tug pushing the same asteroid at .025G.

[kato]

ffs to continue this

Code: [Select]

[ Porthos Rig Carrier / Civilian Spheroid Dropshuttle / 3000 tons / 2135 ]

1170.0 tons - Maneuver Engine (3/5)
  60.0 tons - Structural Integrity (10 SI)
  45.0 tons - Control Systems
  20.0 tons - Quarters (4 Steerage)
   2.0 tons - Armor (primitive - 21 points: 5n/5l/5r/6a)
   0.0 tons - Heatsinks (39 free)
260.0 tons - Fuel Tank (3900 fuel points, 5.64 tons/burn-day)
   5.5 tons - Fuel Pumps
   7.5 tons - 1.2 tons Consumables and 6.0 tons Spare Parts (for 2 months ea) + 0.3 tons bulk cargo (1 bay door - a)

(above - all from Poseidon base craft)

400.0 tons - Naval Tug Adaptor incl. add-on internal structure
800.0 tons - Mining Rig Bay (4 small craft bays) (2 bay doors - l/r)
  25.0 tons - Fuel Tank Extension (375 fuel points extra)
168.0 tons - Quarters (24 Second-Level)
  37.0 tons - Consumable/Spares/Bulk extension to 300% / 6 months overall, incl. single mining rig supply


Code: [Select]

Porthos Notes:
- Equipment replaces water tank of Poseidon.
- May carry and deploy in houseruled large bay either:
- four individual small craft / fighters / vehicles / satellites up to 200t
- single mobile structures / space stations / advanced support vehicles up to 800t
  (for rules conformance assume disassembled carriage in cargo)
- Acts as multipurpose deployment and supply tender as well as fuel retrieval tanker for Aramis rig.
- May provide tactical auxiliary stationkeeping for spacecraft up to 90,000 tons for up to one day.
- May provide tactical recovery for spacecraft up to 72,000 tons over distances up to 5 AU (... for anything past one million km count your recovery time in weeks and
  months though).


Code: [Select]

[ Aramis / Mining Rig / 800-ton Mobile Structure / ~50x50m footprint, four-hex / Single-Level (18m height) / 2135 - Tech Level C ]

Chassis Weight : 98.5 tons per hex (CF80 Fortress, nominal)
Internal Armor :  5.0 tons per hex (nominal for CF80)
Sealing        :  8.5 tons per hex (Environmental Sealing)
Motive System  :  4.0 tons per hex
Power  System  :  4.5 tons per hex (1.5 MP, fission)
Equipment      : 80.0 tons per hex

Hex A : Water Tank (28.7t)     : 33.0t
Hex A : 3x Fuel Tank (11.6t)   : 40.0t
Hex A : 8.2 days food/parts    :  1.0t
Hex A : Communications Gear    :  1.0t
Hex A : Backhoe (LCP)          :  5.0t

Hex B : Water Tank (28.7t)     : 33.0t
Hex B : 3x Fuel Tank (11.6t)   : 40.0t
Hex B : 12.3 days food/parts   :  1.5t
Hex B : Dumper (5 tons)        :  5.5t

Hex C : 6x Fuel Tank (11.6t)   : 80.0t
Hex D : 6x Fuel Tank (11.6t)   : 80.0t

Crew : 17 Enlisted + 3 Officers (20 total)
Cost : 20,115,900 C-Bills


Code: [Select]

Aramis Notes:
- CF80 base vehicle costs 17,982,000 C-Bills sans 320t mounted equipment.
- Chassis weight and CF-discrete "internal armor" derived from dual tracked tractor/trailer combination.
- Dumper and Backhoe represent mining conveyor belt system with on/off mass flow capacity of light cargo platform.
- 5-ton minimum does not apply for MS fission engines. For fluff consider single 18-ton reactor spread over all four hexes.

Aramis Production:
- 11.5t fuel - one tank - produced per day (cap-off every 2.5 weeks at 200 tons).
- 28.75% production efficiency relative to available power.
- Asteroid with minimum 6.0% H2O required due to loading requirements.
- Supply reserves for 3 days beyond cycle onboard.

P.S. Operationally serve the L1 point of a gas giant in a system, in particular - due to distances involved - in otherwise already colonized M and K class systems. Aramis would be deployed on moons of the gas giant. For a K2V the L1 point of a gas giant beyond the snow line and proximity limit would be located about 0.184 AU or 27.5 million km from the planet, with a colony on a habitable planet 3.15 AU or around 5 days at 1g away.

[kato]

And for that Lagrange Jump Point:

Code: [Select]

[ Athos Space Station / Civilian Space Station / 6000 tons / 2135 ]

  72.0 tons - Stationkeeping Engine (-/-)
  60.0 tons - Structural Integrity (1 SI)
   6.0 tons - Control Systems
  20.0 tons - Quarters (4 Steerage)
   2.0 tons - Armor (primitive - 21 points: 5n/5l/5r/6a)
   0.0 tons - Heatsinks (39 free)
260.0 tons - Fuel Tank (2600 fuel points, 0.282 tons/burn-day - stationkeeping for 30 months)
   5.5 tons - Fuel Pumps
   7.5 tons - 1.2 tons Consumables and 6.0 tons Spare Parts + 0.3 tons bulk cargo (1 bay door - aft)
1524.0 tons - Cargo

  35.0 tons - Quarters (7 Steerage) [replacing controls]
   4.0 tons - bulk cargo (1 bay door- fwd) [replacing controls]

500.0 tons - Grav Deck (>250m) [replacing engine]
400.0 tons - Small Craft Bays [replacing engine]
  89.0 tons - Consumable/Spares/Bulk extension / 12 months overall [replacing engine]
  15.0 tons - Small Craft Naval Repair Bay, Pressurized [replacing engine]
   0.0 tons - Heatsinks (18 free) [replacing engine]

2023.0 tons - Quarters (289 Second-Level - 58 Crew + 231 Passengers) [add-on tonnage - in grav deck]
617.0 tons - Consumable/Spares/Bulk extension [add-on tonnage - in grav deck]
350.0 tons - Lifeboats (50) [add-on tonnage - in grav deck]
   3.5 tons - MASH [add-on tonnage - in grav deck]
   0.5 tons - Small bulk Cargo [add-on tonnage - in grav deck]
   6.0 tons - Field Kitchens (2) [add-on tonnage - in grav deck]


Code: [Select]

Athos Notes:
- Poseidon hull design in Pontos configuration rebuilt into space station by removing engine
- Replacement aft with stationkeeping engine, paired small craft bays and 270m diameter grav deck producing 0.33g at 1.5 rpm
- Grav deck arranged in three 250m long sections with about 96 quarters and 16 lifeboats each, additional equipment in connecting nodes between sections.
- intended primarily for transshipping, passenger transfer and general distribution purposes at Lagrange jump point
- retains stowage of 100 TEU (20' containers) from Pontos
- space stations do not have primitive engines.