Modular Freighters: Concept Proposal

[Rigel Stardin]

Modular Freighters are a design that has been around for quite some time in Science Fiction. Gene Rodenberry even proposed a design for the original Star Trek. You have seen them in Babylon 5, Space 1999 and Avatar. Yet when it comes to Traveler, we see little or no use of this design.

The concept consists of a Command module, cargo (passenger) module and a drive unit. In some concepts the command module and drive unit are combine.

The reason I am toying with this idea right now is the concept of modern freight hauling. If a corporation could stage freight and only have to switch out the command module, the turn around time for a cargo vessel would be reduced by 7 days. Just like modern day truckers all they would have to do is pick up a trailer at their destination and return it to their home base. You would only see these types of freighter along well established Jump 1 routes.

The following concepts are posted in the art gallery, which are quite good. Seriayne Colony Transport, DaveChase Shotgun Modular Transport and lucasdigital Hector Class Module Transports in the Art Gallery.

I have a few concerns about the design. First is jump drive, maneuvering drive and reactor size for the drive unit which is capable of handling different size loads while being cost effective. Second, is the size of the load for profitability? And third, is it possible to design the ship using traveler rules.

I’ve posted it spaceships since I haven’t figured out the modular Jump Drive that could handle different tonnage…

 

[robject]

is it possible to design the ship using traveller rules?

Yes.

Regarding the jump drive. Although it constrains how much you can move, it jumps the ship within a bubble-shaped field, and thus can support dispersed-structure hulls. That means irregular payloads can be gathered to a main hull and the whole thing will jump.


There are at least 4 Traveller designs arguably using LASH-type concepts:

(1) the Jump Shuttle (CT, Traders & Gunboats), intended to transport System Defense Boats, but theoretically can move anything up to 400 tons;

(2) the Jump Ship (CT, Fighting Ships), capable of moving from zero up to 5,000 tons of payload (presumably modular, such as 30t cutterform payloads, but can haul anything, including irregular raw materials);

(3) the Ghalalk-class Cruiser (CT, Fighting Ships) is supposed to be a modular design, with 6 modules removable in pairs;

(4) the Clipper (from TNE).


There are probably others.

Note that three of these are military designs. And the Jump Ship, while not explicitly military, is found in a military supplement. As with most Traveller ships, these designs work best in niche "markets".

The trick to ship design of any kind is to set the mission parameters. In any case, you can "integrate" the command module with the engine module into a single "core" module.

For minor routes with less infrastructure, figure out the largest payload to carry, and install drives to required specs -- in your case, make sure the ship can pull Jump-1 and 1G at full capacity.

For major routes, use drop tanks to match fuel requirements at each leg of a ship's journey, and keep a supply of different "core modules" on hand, and use whichever is needed for that leg of the jump.

 

[atpollard]

Since ships of 100 to 1000 dTons (in Classic Traveller) or 201 to 1000 dTons in Mongoose Traveller use the same size bridge, you could install a standard Bridge Unit (designed for a 1000 dT ship) that should be perfectly capable of 'controling' any ship of lesser size. If the JD/PP/MD 'Engineering Units' were sized for a 200 dTon ship, then up to 5 engineering units could be attached to the common 20 dT Bridge Unit. The ship could expand or contract in performance to fit the need by just adding or removing Engineering Units.

 

[Rigel Stardin]

What I'm trying to wrap my head around, goes like this:

The max load for each section, that I have depicted is approximately 240 tons. There are 8 load points on a cargo section for cylinder style cargo modules on the fuel tank (30 ton cargo modules).

At planet A, he picks up a load for Planet B with only 6 containers (180 tons). When he arrives at Planet B, he picks up a load for 720 tons (3 cargo sections). The only thing that changes between each of these loads is cargo sections. The drive section and command module remains the same.

In my mind, Fuel starts getting tricky because the larger the load, the larger the engine and Jump Drive needed to push the cargo modules you add to the ship subtract from the ship's performance when the load is decreased. The only way for this system to work in my mind is if there is some majic number where Manuver, Jump Drive and reactor can work on several different load combinations without detracting from the ship's performance.

The design posted is not set in stone and will most likely change depending on how realistic I can solve the fuel comsuption problem...

 

[dean]

What I'm trying to wrap my head around, goes like this:

The max load for each section, that I have depicted is approximately 240 tons. There are 8 load points on a cargo section for cylinder style cargo modules on the fuel tank (30 ton cargo modules).

At planet A, he picks up a load for Planet B with only 6 containers (180 tons). When he arrives at Planet B, he picks up a load for 720 tons (3 cargo sections). The only thing that changes between each of these loads is cargo sections. The drive section and command module remains the same.

In my mind, Fuel starts getting tricky because the larger the load, the larger the engine and Jump Drive needed to push the cargo modules you add to the ship subtract from the ship's performance when the load is decreased. The only way for this system to work in my mind is if there is some majic number where Manuver, Jump Drive and reactor can work on several different load combinations without detracting from the ship's performance.

The design posted is not set in stone and will most likely change depending on how realistic I can solve the fuel comsuption problem...

You simply design the drives and crew needed to allow for the MAXIMUM possible capacity of the ship.

Then, recalculate the range, maneuverability, etc of the ship when it is "lightened" by each successive module. Recall that "dtons" are a volume measure, and is not a mass (per se) so how "heavy" the cargo is is irrelevant.

If you wanted to go completely insane, you could also simply make the fuel tankage modular as well, and then the cargo load vs. range (even if in successive J-1 hops) is fully customizable (although personally for this kind of ship I might put in a J-3 capable drive for max tonnage, and then increase payload in favor of range when it is profitable to do so).

It would also be possible to add modular passenger sections as well, and while these could be very "smart" from an anti-hijacking point of view, I suspect passengers accustomed to High Passage might not use them even if available ("Sir, we're under attack!".."Right! Jettison the High Passenger Module! It's all they are after!").

Book 5 "Dispersed Structure" configurations are probably ideal for this sort of thing and this idea is likely a big part of why that set up is included (that and fleet riders).

 

[DaveChase]

First, thanks for the mentioning of my one (of 3) Modular Transport ships.

Second, it is possible to make module engines (Jump and Maneuver along with Powerplant ones)
The key is working in 30 ton increments.

When you build any Modular Transport ship, try to build it in multiplies of what ever the module will be, 30, 50, 100 or 1000 ton modules. Or a the very least to keep the headaches to a min, the largest ship mass (volume) should be a number evenly divided by the module type.

My 3 Modular Transports ships are designed to hand the 30 ton (CT version) module so their complete mass is 600, 900 and 2100 tons. The Jump engine is a bubble (if YTU makes a difference in this or grid with the modules requiring a grid built into the hull. I use bubble because it will allow a 30t module that standard built but fits the outside dimensions to still allow the ship to jump).

When building module drives you have 5 engines that will fit. A, B, C, D and E size ones. I allow that A and B size engines are as cost, C and D engines are 110% the standard cost due to the modules shape and E is a custom built Jump Engine so cost 140% the standard E.

Examples

Jump Module Engine pod
15 ton 	Jump B
10 ton 	Power Plant C
5 ton	Maneuver C
Cost (CT) 56MCr

This module requires a fuel source but it can Jump upto 400t ship 
(assuming you have the computer and fuel and at least 100 ton mass). 
It is also very Maneuverable but is not very cost efficient 

Jump Module Engine pod
30 ton	Jump E (Custom drive)
Cost (CT) 70MCr

This module is Engine only but can Jump upto 1000t of ship
Requires everything else connected to it to function.

Jump Module Engine pod
15 ton	Jump B
3 ton	Maneuver B
7 ton	Power Plant B
1 ton 	Control space
4 ton 	Computer space for either Model 1, 2, 3 or 4 computer
Cost (CT) Model 1	 46MCr
	Model 2		53MCr
	Model 3		62MCr
	Model 4		74MCr

Now something else to consider in YTU is if you allow multiple Jump engines
to work together to allow bigger loads in Jump.
I do not think that was the idea originally in CT, but your mileage may vary.

There are lots more things I could mention but ….

Dave Chase

 

[Dragoner]

FASA DPM-2

ISCV: Leander

Leander is a 600 ton drive unit and up to ten 200 ton cargo barges.

From the FASA CD by FFE.

 

[rancke]

The reason I am toying with this idea right now is the concept of modern freight hauling. If a corporation could stage freight and only have to switch out the command module, the turn around time for a cargo vessel would be reduced by 7 days.

More like 16 hours. What you save is the time it takes a ship to travel from the jump limit to the surface and back again. Possibly also a bit on the loading and unloading. The people who wrote GT:Far Trader have said that they worked out the costs and savings of LASH setups and that it wasn't any cheaper. Don't ask me what precisely the factors they included in their calculations were.

Just like modern day truckers all they would have to do is pick up a trailer at their destination and return it to their home base. You would only see these types of freighter along well established Jump 1 routes.

Talks of jump-1 mains to the contrary notwithstanding, jump-1 only makes sense economically in very limited circumstances (Basically back and forth between adjacent systems one parsec apart). When your goods have to travel more than one parsec, jump-2 or jump-3 becomes cheaper than two or three jumps-1.


Hans

 

[Winterwolf]

I have a question for Rigel Stardin where do you get the great starship layouts I know you design them where do you get the parts.
As to a modular freighter design. use say a 3 to 5 thousand ton hull mass and a jump rating of say 3 and a manuever rating of 1. With the design that you posted I like it but I would add a 3meter dia. passageway down the center of the fuel tank area and a control room to the engine module

 

[Rigel Stardin]

Winterwolf to answer the easy question first. I designed the ship under the concept of a command module, fuel tank/cargo module rack and manuver/jump drive, reactor module. In this way, you can stack the fuel/cargo modules together to form a longer ship. The manuver/Jump module for easy maintance. There is no need for a tube leading from the command module to the engine compartment.

As far as my ship interior parts, years of designing them. I design starships as a hobby. One day, I'll post one of my real early design and show you how far I have come...

 

[Rigel Stardin]

Here are some ruff figures on the design I posted. I use 1.5 by 1.5 by 3 meter square in all my designs. Tonnage in all my designs is corret according to Traveler. I rounded up all my figures to be on the safe side.

Command Module: 90 tons
Cargo module: 50 tons
Fuel tank/Cargo rack: 80 tons
Drive Section: 75 tons.

 

[Vargas]

There was a design in the IISS Ship Files book Game's Workshop did for CT. It was noted there that container carriers were more numerous than regular cargo ships.

 

[McPerth]

HT (page 69) talks about the concept of jump carriers.

Similar to BT/BR concept, they are an irregular jump capable ship able to carry several STL barges through jumpspace. I don't see any reason fot those STL ships not being replaced by containers.

Even you can use some containers as 'fuel pods' instead of having fuel tanks, adjusting them to the fuel needed for each specific jump (unless using MT, where fuel is determined by the size of the JD, not for the jump distance/mass combo), allowing you to carry more containers if less fuel is needed.

 

[Dragoner]

Even you can use some containers as 'fuel pods' instead of having fuel tanks, adjusting them to the fuel needed for each specific jump.

The Leander talks about having both fuel pods and a shuttle pod.

 

[iron warrior]

Well, jump drive is affected by volume without regard to mass.

Thrusters are affected by mass without regard to volume.

In general, as long as the modules are the same volume you have no worries on the jump engine. If you go for that level of detail you'll need to calculate the ship's acceleration and delta v (if using such types of sublight engines) for the various masses of the pods.

I have some questions for myself and you to consider on this issue. You say a modular freighter. Please clarify. Does this mean cargo modules that are pre loaded before a freighter arrives so the module can be used to replace the one the ship arrives with so the ship can turn around without waiting to offload/reload? OK, but consider this: the modular system will be at least somewhat more expensive than a regular system, and will the time saved make up for the cost? Also will that much time be saved? I mean, you have to carefully detach the module, then attach a new one, and then make DAMN SURE! the connections were done right as if any aren't you may lose the ship, cargo and crew, which will cancel out any savings in time and then some.

Really, I'm not sure that you'd save a lot of time with a modular freighter, and maybe not enough to make up for the cost. Why not just load the cargo into pods inside a bay, then upon arrival simply open a large cargo door, slide out the old pod and slide in a new, pre loaded one.

Now that may seem like I'm dumping on your idea, but not so! A modular ship could be useful if the modules were more than just standard cargo pods. If the modules were notably different in effect then the concept gets a new lease on life. You could have modules for cargo, passengers, live cargo, special needs cargo, hazardous materials and so on. A module could be dedicated to survey or scientific research, turning a freighter into a research vessel.

Some modules might have military applications, turning a freighter into a serviceable auxiliary warship or at least an anti piracy vessel that might escort other ships. A large enough module might allow a freighter to serve as an improvised carrier for fighters, if you use fighter craft.

The concept of a modular freighter isn't bad, but I think you need to justify it a bit to make it suitable for a serious SFRPG. Trying to make in anomalous to an 18 wheeler swapping trailers might be stretching things as I'm not sure docking a modular spacecraft and attaching it will be as simple as swapping trailers on an 18 wheeler, and in space a cargo pod could just be pushed out the cargo bay and a new one pushed in and secured, allowing the carried cargo pods to be loaded before the freighter arrives and unloaded without delaying the freighter.

Also, who might use such ships? A power with limited resources might need the efficiency they offer, a vast polity with a strong economy might not consider them worth the bother.

I hope these thoughts help you out.

 

[Dragoner]

To me it just sounds like a containerized freight ship, which is how 90% of cargo is moved today, something like a tramp freighter is actually not done anymore, afaik.

 

[FreeTrav]

Nobody seems to have mentioned the LSP Modular Starship, which was originally a QLI PDF release, but is now included in the Mongoose release of Golden Age Starship Compilation 1-5.

 

[coliver988]

not sure if it was mentioned either, but the GURPS Modular cutter book also has a modular freighter in it, based on 30Dton cutter modules. As pointed out, it is not very efficient at that scale.

 

[Rigel Stardin]

Explaination in depth:

A concept my brother had in our writing, History Channel Ice Road Truckers and an Episode of Cowboy Bebop were inspiration for this idea. But to keep it simple, Ice Road Truckers will be the model for this explaination.

Concept: You have a depot close to the Jump point where cargos are prestaged ready for the return trip or to a new destination. The command module detatches from the load it just brought in from planet A and recieves orders to return to planet A with a new load from the staging area. The container are already mounted on the fuel tank/Cargo rack. They don't have to do anything but drive the load back to Planet A or any other destination the dispatcher chooses.

Problems with this design: One Manuver/Jump Drive/Reactor (MJR) module doesn't fit all. The way around that is to build different MJR Module for different loads. Ruins the idea of having a single MJR that would fit all sizes. But it does allow MJR to be created for different size loads....

will get back to you on this wife having computer issues....

 

[Rigel Stardin]

I'm back...

Problems with this design: One Manuver/Jump Drive/Reactor (MJR) module doesn't fit all. The way around that is to build different MJR Module for different loads. Ruins the idea of having a single MJR that would fit all sizes. But it does allow MJR to be created for different size loads. One way to get around this is set a max load limit for the number of Fuel/Cargo Modules that can be moved at one time. Right now, I'm looking at that number as being 3 because modern day truckers are only allow to run 3 tandum trailers in some state. Which makes the max load minus command and MJR modules as being 1440 tons (240 of that being fuel using present design).

One way around the Jump drive issue is to make modules containing jump drives.

Manuver Drive has the same issues as already discussed.

Pluses to Design: The crew doesn't have to worry about maintance of MJR or command module since they are owned by the corporation running the Modular frieghters. Crew makes a salary for each run. Thou it could get boring. Inner system runs are possible allowing the crew to visit the planet or mining operations, and habaitats.

Just a few idea I'm batting around here but you get the point...