Medium Flexible Short-Range Transport

[AnotherDilbert]

Inspired by wbnc I had to make a lighter version.
http://forum.mongoosepublishing.com/viewtopic.php?f=89&t=119916


Medium Flexible Short-Range Transport
TL12, 120 dT, MCr 81, flexible external payload system, can jump a total of 1000 dT.
J-1, M-1 with total volume 1000 dT (external payload 780 dT + a tank)
J-2, M-2 with total volume 500 dT (external payload 280 dT + a tank)
J-1, M-1 with total volume 333 dT (external payload 113 dT + a tank)
Jump fuel provided by a 100 dT drop tank that is generally dropped.
External mounts:
....Two drop tanks á 100 dT
....800 dT external cargo mounts
....800 dT jump net
....4 clamps for 30 dT crafts
....1 clamp for a 300 dT craft
Spacious quarters for 5 crew: Pilot, Astrogator, 2 Engineers, Admin/Purser with a hydroponic garden negating the life-support cost.

The ship is designed to distribute cargo to minor systems. If less developed systems are to be served, cargo/fuel shuttles can be carried. Passengers can be carried in a separate hull. Small starships can be carried (e.g. for repairs).

TL 12             Hull  38                                                     90,2    
                                       Desired    ∆TL    Rat    #    dTon    Cost    Power
Hull                                      120                         120               24
Config            Dispersed                 5             5                     2,3    
Hull strength     Light                     1             1                
Repair Drones                               1             1             1,2     0,2    
                                 
JumpD             Budget                    1     -0      1     1      30,0    33,8    130,0   EneIneff
ManœuvreD         High Technology           1      3      1     1       7,0    21,0    100,0   RedSize
PowerP   (TL8)    High Technology                  4            1      10,0     7,5    142,5   RedSize
Batteries         60 Power                  1                   1       1,0     0,2    

External Load     880 dT                    1                        
Drop Tank Collar  100 dT                    2                   2       0,8     0,4    
Drop Tanks        100 dT                    8                                   2,5    
Fuel, Jump                                
Fuel, Power                                 4           4 w     1       1,0        
Fuel Purification                        60 h          60 h     1       2,0     0,1      2,0
                                
Bridge                                      1                   1      10,0     1,0    
    Holographic                             1                   1               0,3    
Comp              m/15                      3            15     1               2,0    
    Backup Comp   m/10                      2            10     1               0,2    
                                
Sensors           Military                  2             2     1       2,0     4,1      2,0

Staterooms, High                            1                   1       6,0     0,8    
Staterooms                               100%             5     4      16,0     2,0    
Escape Capsules                             1                  10       5,0     0,2    
Hydroponic Garden                           3                   3       3,0     0,6      3,0
Common Areas                              14%           14%     1       3,0     0,3    

Cargo                                                                   0,0
External Cargo Rack                       800                 800               0,8    
Jump Net                                  800                 800       8,0     2,4    
                                
Docking Clamp     300 dT                    1                   1      10,0     2,0    
Docking Clamp     30 dT                     4                   4       4,0     2,0    

Fixed Mount                                
Missile           Standard                  1           TL7     1               2,4    
                                
                                
                                                                
Software                                                                        1    
Jump Control/3                                           15                     0    
Virtual Crew/0                                            5                     1    
                                
                                
                                                                
Crew                     5                        
    Command                                       
    Bridge               2    
        Pilot                  1
        Astrogator             1
        Sensor & EW        
    Engineer             2    
        Engineer               1,3
        Maintenance            0,12
    Service              1    
        Admin                  0,06
        Medic                  0,03
        Steward        
    Gunner        
    Flight        
    Troops

 

[wbnc]

definitely a different take on what I was working up

Not a bad idea. small and light with some useful features. I can see it running between mining facilities hauling bulk ore and supplies since it's very light it wouldn't be expensive to run.

 

[PsiTraveller]

What do folks think the limit of ship to external mount might be? Or of ship to Jump Net since the same issue of Jump engine size to desired load to be moved is similar. X amount of Jump engine moves y tonnage z parsec distance.

For cargo mounts is there a point at which the external framework gets too long to be manageable? Or is some sort of freight engine scenario with the ship up front towing a huge chain of cargo modules to a Jump Point going to show up as artwork?

 

[AnotherDilbert]

We clearly didn't abuse the external payload system enough during beta, so we have no limit in the rules.

The CT Jump Tug in FS limited external cargo to 100% of the ship, we might use that as a house rule?

 

[wbnc]

What do folks think the limit of ship to external mount might be? Or of ship to Jump Net since the same issue of Jump engine size to desired load to be moved is similar. X amount of Jump engine moves y tonnage z parsec distance.

For cargo mounts is there a point at which the external framework gets too long to be manageable? Or is some sort of freight engine scenario with the ship up front towing a huge chain of cargo modules to a Jump Point going to show up as artwork?

I had that idea a couple of years ago...it's in my "Ships Of Gold" book...

The limits would really be up to the REF, it's not n outright hack of the rules. There are significant tradeoffs for hauling external cargo. It does limit the types of cargo the ship can carry and requires some significant support to work efficiently.

 

[DivineWrath]

I have tried to push external cargo mounts to the extreme. I was able to make a 5000 ton J-3 ship that had half its tonnage in external mounts. In practice, it felt like I was trying to design a J-6 ship. It needed to store twice the tonnage in fuel in internal storage, and it needed a J-Drive and M-Drive that was twice the usual size. Over 75% was reserved. Cost savings... external mounts costed 1000 Cr per ton while the internal was 50,000 Cr per ton, so I saved 49,000 Cr per external ton, so 122.5 MCr. As for power, I was only able to cut the internal hull power demands in half, leaving the J-Drive and M-Drive power demands untouched.

In exchange to making half the ship external cargo mounts, I lost the ability to safely land on planets and harvest fuel from gas giants. Unless you jumped to somewhere that had a good starport or good ship support, it would be hard to trade goods. Even trying to include ships that could to do the trading was hard. I would have to get rid of some external storage to make room for more ships, otherwise it could take up to 2 weeks to finish all business. There also wasn't much in terms of rules how to use external mounts, such as how to unload and reload the external mounts yourself (mind you the rules don't seem to cover how to handle cargo under normal circumstances either).

It also relied on significant amounts of automation to keep the crew size low.

 

[PsiTraveller]

Scoundrel Page 87: The example they give is a 400 ton ship with 800 tons of external cargo mounts for 1200 ton total max load

"For example, a 1,200 ton ship would normally have a hull
costing 120MCr. By designating 800 tons of that as external
cargo, the ship only needs a 400ton hull costing a mere 16MCr.
(plus another Cr. 800,000 for the cargo frame). Into that 400
ton hull, the designers cram the drives, bridge, fuel and other
components for the freighter."


The External Cargo Trader on page 93 of Scoundrel also has a 300 ton ship with 500 tons of external cargo area. But no actual limit is given.

 

[AnotherDilbert]

Light Cargo Shuttle

30 dT, Man-3, Grav drive, 20 dT cargo, MCr 10.

The entire cargo hold is an airlock, to allow the bridge to remain pressurised while loading in space.
We also have collapsible tanks (20 dT) and some folding acceleration benches (10 dT, Seats 40)
A cargo crane allows us to load and unload.

It has a grav drive, like a grav vehicle, to allow it to land anywhere. (I estimated the grav drive with a Man-1 drive.)

TL 12             Hull  10                                                   11,0    
                                       Desired    ∆TL    Rat    #    dTon    Cost    Power
Hull                                       30                        30                 6
Config            Streamlined               2             2                   1,35    
Hull strength     Light                     1             1                
Armour            Crystaliron               1             1           0,38    0,07    
                                
ManœuvreD         Very Advanced             3      2      3     1     0,72    1,80      9
GravD             Very Advanced             1      2      1     1     0,24    0,60      3
PowerP   (TL8)    Very Advanced                    2            1     1,44    0,90     18
Fuel, Power                                 4           4 w     1     1,00        

Bridge                                      1                   1     3,00    0,50    
    Holographic                             1                   1             0,13    
Comp              m/10                      2            10     1             0,16    
    Backup Comp   m/5                       1             5     1             0,03    
                                
Sensors    Basic                                                1            

Cargo                                
Collapsible Tanks                          20                  20     0,20    0,00    
Acceleration Bench, Foldable               10                  10             0,50    
Cargo Crane                                 1                   1     3,00    3,00    
Cargo Airlock     20 dT                     1                   1    20,00    2,00

 

[steve98052]

Is there really a big savings on cost of a ship for external cargo? It looks like there's this choice:

Build a smaller main hull with external cargo clamps, and a set of external cargo pod hulls, and load cargo containers into the external pods.

Or

Build a larger hull, but no external pods, and load cargo containers directly into the hull.

In other words, every credit saved on the main hull means a credit spent on the external pod instead. That makes sense if the pods can do things the main hull can't (surface landings, for example), but I don't see any advantage unless the external pods are really cheap (light materials, no need for pressurization, etc.).

---

What's the capacity of an external clamp?

I'd say that it's dependent on mass more than dton volume. One dton of liquid hydrogen is one ton of mass, by definition. One dton of water is 14 tons of mass. One dton of iron is about 110 tons of mass. One dton of air is just over 17 kg. Somewhere I read that "typical" cargo is about 5 tons of mass per dton -- which suggests that there's a lot of air space between things in typical cargo.

If an external clamp were hauling fuel, no problem. A load of iron? Better limit maneuvers to maybe 0.05 G.

 

[AnotherDilbert]

Is there really a big savings on cost of a ship for external cargo? It looks like there's this choice:

Yes there is a large saving. With external cargo mounts the cargo is basically lashed to the hull, no external pods needed. Only the drives are the same, everything else is smaller and cheaper.

A basic conventional ship of 1800 dT (J-1, M-1) can carry 1419 dT cargo costs MCr ~245.
A basic 150 dT ship that can carry 180 dT drop tanks and 1470 dT external cargo (total 1800 dT) costs MCr ~144.

Of course external cargo is exposed to vacuum and temperature extremes, I assume most cargo will not like that.

What's the capacity of an external clamp?

Like the rest of the design system both volume and mass is estimated by "displacement tons". External cargo mounts for 1 dT can handle 1 dT of cargo, regardless of mass.

 

[wbnc]

Just doing a mental summary of advantages and disadvantages..tell me if I missed any

External cargo clamps
Advantages:
cheap, allows the ship to carry anything that has a volume within its drive capacity.regardless of shape or configuration...even other ship. Tonnage carried on clamps do not add to upkeep costs. or require extra crewmen.
Disadvantages:
limits cargo types to those that can survive exposure to open space, or are sealed in containers/modules suitable for open space. prevents a ship from skimming fuel or landing on a planet with anything but the thinnest atmospheres.

modules carried on docking clamps:
Advantages:
allows the ship to carry anything that can fit within the modules.Allows for life support and protection fro open space for the cargo.Allows for passenger modules as well as cargo module.Any vessel ith docking clamps can carry any module regardless of manufacturer
Disadvantages:
more expensive, and requires a reactor and computer for each module and may require crewman to attend to the modules internal systems. Internal systems can not be accessed or controlled by the carrying vessel.

Breakaway Sections:
Advantages:
Same as module, but each section can act as an independent vessel if properly equipped and breakaway sections can be streamlined allowing for skimming and atmospheric operations. Each sections internal systems can be combined with the carrier vessels internal systems allowing reactors drives and other systems to be accessed by the main hull.
Disadvantages: most expensive option, adds to upkeep costs, and requires a crew for internal systems. sections can only be used with ships specifically designed to couple with the section in question. genericoff te shelf sections not possible.

 

[AnotherDilbert]

Just doing a mental summary of advantages and disadvantages..

I mostly agree, but disagree on a few points, purely based on prejudice.

Prejudice: Externally carried payload extend from the hull. If it extends too much it will extend out of the jump bubble and be lost. A large ship carrying a little payload has no problem, a small ship carrying a lot of payload has a problem. The solution is Jump Nets, which, I assume, extends the jump network in the hull, so that the jump bubble is blown up around the hull and the jump net. If we wrap any external payload in jump nets, it will not have any problem with the jump bubble.

Prejudice 2: External cargo mounts can be used to mount "cargo", e.g. small standardised containers, that can be evenly distributed around the hull. To mount large heavy objects we need sturdier mount points, e.g. docking clamps.

So, I would disagree that External Cargo Mounts can mount anything and everything. For a small ship to carry a large vessel or module I would require both a Docking Clamp and wrapping it in a Jump Net.


On the other hand I would be more liberal with connecting hulls carried in docking clamps. Airlocks have extensible docking tubes that can mate with another airlock, so we can access the interior of the exterior modules. A power coupling providing the external module with power should be easy enough, and can perhaps be simulated with UNREP equipment.

 

[PsiTraveller]

The locomotive linkage design that WBNC has on his ship offers an interesting concept in 'ship' building. Assume the Engineering Core of the ship houses the M Drives, Jump Drives,and crew quarters and a modular connection to add on additional modules. The ship could be extended with additional modules for whatever mission or job it was needed for. The limits would be the M Drive capacity to move the total tonnage and the Jump Drive capacity to Jump the ship to its destination. M Drives might not be a factor if it sat at a Jump Point and had a large number of modules attached to it. If the M Drive tonnage was too low to move the Jump Drives could still Jump the ship.

The breakaway hull rules could be used for the additional cost of the docking and clamping mechanisms. This would satisfy structural integrity concerns. I might rule that if the module is not going to be moving on its own it does not require a bridge and additional M Drives as a separate ship, the module loses 2 percent of the volume for structural integrity.

This makes cargo moving more expensive over external cargo mounts. Nothing is cheaper than a rack of Octet Truss and some mooring clamps, but with the breakaway modules you get protected cargo space and environmental controls.

That brings up another issue. If you have a module attached to a ship that could hold people, does the cost of life support go up?

 

[wbnc]

The locomotive linkage design that WBNC has on his ship offers an interesting concept in 'ship' building. Assume the Engineering Core of the ship houses the M Drives, Jump Drives,and crew quarters and a modular connection to add on additional modules. The ship could be extended with additional modules for whatever mission or job it was needed for. The limits would be the M Drive capacity to move the total tonnage and the Jump Drive capacity to Jump the ship to its destination. M Drives might not be a factor if it sat at a Jump Point and had a large number of modules attached to it. If the M Drive tonnage was too low to move the Jump Drives could still Jump the ship.

The breakaway hull rules could be used for the additional cost of the docking and clamping mechanisms. This would satisfy structural integrity concerns. I might rule that if the module is not going to be moving on its own it does not require a bridge and additional M Drives as a separate ship, the module loses 2 percent of the volume for structural integrity.

This makes cargo moving more expensive over external cargo mounts. Nothing is cheaper than a rack of Octet Truss and some mooring clamps, but with the breakaway modules you get protected cargo space and environmental controls.

That brings up another issue. If you have a module attached to a ship that could hold people, does the cost of life support go up?

I'd say that Modules with passenger spaces would add to life support. but cargo space not so much. al they need is a heater and pressure doors to keep the air inside. It doesn't have to be breathable just there.