T5 Only: Liberty Ship Development Discussion

[Major B]

I am seeking help in developing a transport ship design based on the Liberty Ship created by Clay Bush for MT and published in Vol 1 No 1 of Starships, Starports, and Vehicles.

I want to make some designs that are common if not ubiquitous in the Spinward Marches. I have plans now to work up a T5 version of the Onderneming since Flykiller was good enough to resurrect that thread and remind me how much I liked Seriayne's original. But first I want to make a T5 re-imagining of the Liberty Ship and I need support to make it fit well within the OTU.

In Clay's original writeup, the Liberty Ship was described as a 10,000 ton transport capable of 1G and J3 with the following notes:

The design was ordered to replace commercial losses during the latter portion of 
the Third Frontier War. Because the Imperial Navy made the plan public domain (to 
encourage standardization), it can be found anywhere.
In 1116, many Imperial and colonial auxiliaries were of this class. While too slow to 
accompany combat units, the class was adequate for transport of regular supplies and 
parts to established bases and garrisons.
Yes, this is similar to WWII's Liberty boat, a mass produced bulk transport.

For more background, the little that I know about the 3FW (copied from where I can't remember) is here:

Third Frontier War:
•	979-986 (7 years)
•	ended 126 years ago (as of 1112) or 121 (as of 1107)

The Third Frontier War was less characterized by the planetary sieges of previous 
wars, and more by commerce raiding, deep thrusts by cruiser squadrons to disrupt 
shipping, and by harassment of civilian shipping.

Finally, here is some of the descriptive text (draft) that I have come up with:

First prototype completed in 983. The design specifications were provided 
free of charge to numerous shipping and construction companies. Intended only 
for the Spinward Marches, the cheap and fast construction features of this design 
made it popular across the Imperium and in some locations outside Imperial 
Borders.

The design uses standard and generic parts and is intended not to be good but to 
be good enough. The ships have continued to be produced in small numbers for 
over 120 years now. Models in service are invariably modified to at least some 
extent.

Some modifications have become popular enough to be standard production 
models for some companies in the Spinward Marches.

So, enough background. From here I want to start posting questions and ideas for discussion as I move along (slowly - I have a day job still) with the development of this design.

For anyone who provides input - thanks in advance.

 

[Major B]

Economics

My first question is probably a can of worms that has to do with economics. The original Liberty ship was a J3 design but I wonder if a J3 transport is an economically viable design in the time frame we are talking about (3FW).

My experience is with combat designs rather than merchants so I am very interested in feedback about the plausibility of a J3 versus a J2 merchant transport in the 10,000 ton category.

I have some data that I can't format for posting tonight so I will try to get it on tomorrow but in the meantime please opine on the idea I just outlined.

And thanks again.

 

[Condottiere]

Jump one or two may tie up too many escort vessels.

 

[Whipsnade]

Fascinating project, Major B, and, given your track record, there isn't anyone better to tackle it.

Sundry Comments & Observations:

• That description of the 3FW is in SMC. It could be in other products, but I know for certain that it is in SMC.
• Was Clay's design meant to be an "ancestor" of the 20K dTon, jump3, 1gee, TL 15, Common Imperial Transport found in MT's Rebellion Sourcebook?
• Regarding jump3 economics, Wil routinely posts operating costs vs. revenue analysis for different jump ratings in different systems. Perhaps he could share his jump3 numbers with you?
• Liberty Ship designs were deliberately "conservative" and used "older" technologies to speed construction and simplify/reduce maintenance. You could mix & match component TLs for the same reasons. ForEx: While jump3 requires TL 12, the ship could use a TL 8 2bis computer. While it costs the same as the TL 9 code 3 computer, it's smaller and needs fewer EPs.
• Similarly, the ship's configuration, capabilities, and even operation could be the result of cost saving/simplifying design choices. ForEx: the design relies on thrust for internal gravity and/or lighters/shuttles for loading/unloading in orbit.

 

[Condottiere]

For the concrete hull variant, there's nothing cheaper nor easier than a hollowed out planetoid.

 

[aramis]

• Regarding jump3 economics, Wil routinely posts operating costs vs. revenue analysis for different jump ratings in different systems. Perhaps he could share his jump3 numbers with you?

I've never done them for MT; I don't have a good spreadsheet to quickly crank the bulk boxes.
I haven't done them for TNE nor T4 for the same reason.
I've not done them for T5 as I can't grok the ship design system therein.

I have done them for both editions of CT, plus for T20 and MGT 1E. I did a partial for MGT 2E...

I can find/disclose the CT and MGT 1 versions.

 

[Enoki]

I'd say a J3 merchant would be more of a "Victory Ship" than a Liberty Ship. While the Victory ship was only a bit larger than a Liberty ship, it was much faster. The Liberty ship was really a bare bones design using obsolescent technology for much of its engineering plant.

A J1 or 2 would be far more appropriate to a Liberty ship while a J3+ being more of the Victory ship design.

 

[Timerover51]

I'd say a J3 merchant would be more of a "Victory Ship" than a Liberty Ship. While the Victory ship was only a bit larger than a Liberty ship, it was much faster. The Liberty ship was really a bare bones design using obsolescent technology for much of its engineering plant.

A J1 or 2 would be far more appropriate to a Liberty ship while a J3+ being more of the Victory ship design.

I would agree with this. The WW2 Liberty was designed to carry the maximum amount of cargo as cheaply as possible, using readily available off-the-shelf technology, and capable of being operated by minimally trained crews. It has less than 1/3 the horsepower of a Victory ship, but 2/3 of the speed. The cost was lower and speed of building faster because reciprocating engines were cheaper and faster to build than turbine engines. Turbine blade cutting equipment as at a premium in World War 2, and turbines were primarily used for warships, although there were still a fair number of reciprocating-engine warships built, and to get around the turbine-blade cutting problem, the US got quite creative with power plants for the Destroyer Escorts.

If you have to worry about the economics of operating a ship, then you are not in the Liberty Ship category.

 

[Selandia]

I'd say a J3 merchant would be more of a "Victory Ship" than a Liberty Ship. ....

A J1 or 2 would be far more appropriate to a Liberty ship while a J3+ being more of the Victory ship design.

for reasons explained by timeover51 never truer words were spoken.

For the economic, T5 is into ACS ships, (max 2,500) and use free trading cargo/passengers tables suited for the small ships characters gets at mustering out. So, T5= no 10K dT; no bothering about the micro economic of liners or the economy of global tramping: if the macro economic provide an adequate load factor for large cargo, somehow, the lowest cost carried will get a share. You just presume that the operators meet by your PC are efficient enough to be in business because there is a market segment for them.

Liners tend to be more efficient than Tramps because they are made for a specific J-1, J2, J3, route. Because they must cover a wide range of options, tramps will gain from being J2, although on the J-1 Main, J-1 will beat the crap out of the J-2 if the extra space could be filled.

Therefore, I would allow for J-2 engineering but make the J fuel in permanent tankage limited to PP & J-1, fit Transfert Pumps in the main hull, with connection to "Fuel pods" for the additionnal fuel storage to acheive J-2. Fuel tanks of Cargo pods being fitted accordint to circumstance.

One of the key consideration is planetary landing. The J-3 (strategic mobility overide cost concert) that would have been built as auxiliary "assault" logistic may be required to be a lander for the state of high port in the target area is dubious. Then, you may decide to rely on lighters anyway and accept innexpensive & versatile dispersed structure as an "auxiliary assault tender". A 2,500 dt involved in "high volume" trade may trust the presence of high port of lighter at destination. BTW a 2,500 dT main hull may be the base for a 10,000 dT fully loaded tender.

have fun

Selandia

 

[Major B]

Was Clay's design meant to be an "ancestor" of the 20K dTon, jump3, 1gee, TL 15, Common Imperial Transport found in MT's Rebellion Sourcebook?

There is no mention made in his notes about that ship. When I can dig my copy out I will compare publication dates to see which came first. In the meantime, I will follow up this post with another carrying his full ship description.

Regarding jump3 economics, Wil routinely posts operating costs vs. revenue analysis for different jump ratings in different systems. Perhaps he could share his jump3 numbers with you?

Thanks for mentioning this. I was hoping for some of that type of analysis.

Liberty Ship designs were deliberately "conservative" and used "older" technologies to speed construction and simplify/reduce maintenance. You could mix & match component TLs for the same reasons. ForEx: While jump3 requires TL 12, the ship could use a TL 8 2bis computer. While it costs the same as the TL 9 code 3 computer, it's smaller and needs fewer EPs.

Similarly, the ship's configuration, capabilities, and even operation could be the result of cost saving/simplifying design choices. ForEx: the design relies on thrust for internal gravity and/or lighters/shuttles for loading/unloading in orbit.

All true and you have hit on some of the things I want to replicate. However, there was one innovative aspect of the Liberty ships and that was their construction technique. Remember that they were built to address a strategic problem and while I have seen them described as a measure to replace shipping lost to U-Boats I think instead that their purpose was to expand shipping at a rate higher than projected losses in order to reach a throughput level that met the logistic requirements for future strategic plans.

So they had to use readily available components and be built fast so they were not built in a traditional fashion from the keel up but rather in sections that were welded together. I want to capture this aspect of the design too.

I remember that the construction technique caused some problems too. I think that at least one ship broke on a weld on a convoy to Murmansk but I don't remember the details. There is a Liberty Ship museum here in Tampa and I am going to check it out in a few weeks to see what else about the original I might be able to replicate.

Thanks for the response and the compliment Whipsnade.

 

[Major B]

Original Design Specifics

Here is the original design by Clay Bush in SS&V Vol 1 No 1:

Formatting may be difficult here but I'll do my best.

Liberty class Transport© By Clay Bush
CraftID: Liberty, Type MI, TL 13, MCr2,014(d)
Hull: 9,000/22,500. Disp= 10,000. Config= 7USL. Armor= 40 F.
Unloaded= 59,499 tons. Loaded= 138,058 tons.
Power: 160/ 320, Fusion= 21,600 MW, Duration= 30/90.
Loco: 450/ 900, Manuever= 1. 360/ 720, Jump= 3. Cruise= 750 kph, Top= 1000 kph. Agility= 0.
Commo: RadioComm= system x2 LaserComm= system x2
Sensors: PassiveEMS= Interstellar x1, ActiveEMS= FarOrbit x2,
NeutrinoDect= 100 kw x 1, Densitometer= HighPen/100m x1
ActObjScan= Routine, ActObjPin= Routine
PasObjScan= Difficult, PasObjPin= Difficult
PasEngScan= Routine, PasEngPin= Difficult
OFF: Missile= xx3
Batt 10
Bear 10
DEF: DefDM= 3, Sandcaster= xx4
Batt 10
Bear 10
Controls: Computer=Model/4 x3, Panels= HoloLink x7,148, Special: LgHoloDisplay = 30
Basic env, basic and ext ls, grav plates. NO inertial comp.
Acomm: Crew= 72 (10 x7), stateroom= 72
(Bridge= 12, Engrng= 23, Maint= 4, Gunnery= 2, Flight= 2,
Troops= 9, Command= 9, Steward= 3, Medical= 3)
HighPass=6, LowPass= 50, LowBerths= 50
Subcraft: one Air/raft, two 50ıton cutter
Other: Fuel= 35,640 kliters, Cargo= 76,065 kliters
Purification Plant (24 hours)
ObjSize= Large, EMLevel= Moderate.
Design Notes: Battery round is 30 missiles. No magazine.
Irregular hull design allows up to 10 small craft to dock at once.
The design was ordered to replace commercial losses during the latter portion of the Third Frontier War. Because the Imperial Navy made the plan public domain (to encourage standardization), it can be found anywhere.
In 1116, many Imperial and colonial auxiliaries were of this class. While too slow to accompany combat units, the class was adequate for transport of regular supplies and parts to established bases and garrisons.
Yes, this is similar to WWII's Liberty boat, a mass produced bulk transport.

 

[Major B]

I can find/disclose the CT and MGT 1 versions.

Aramis, please post at least the CT information. I will be posting some preliminary drive requirements (volume and price) later today and I think your analysis in CT will help me make some decisions.

A J1 or 2 would be far more appropriate to a Liberty ship while a J3+ being more of the Victory ship design.

Enoki, I am thinking along the same lines. A J2 ship uses mature and readily available technology (even for the period of the 3FW) while J3 is more expensive and limits cargo capacity. But please see below to get some more food for thought.

If you have to worry about the economics of operating a ship, then you are not in the Liberty Ship category.

Timerover, thanks for the spot on comment. To be plausible the Liberty Ship design has to meet a specific need for the Imperium at the time it was introduced. However, Clay's notes indicate that it is still in use after the 5FW meaning that the design, or a modified version of the design, still fills a commercial need. So what I am trying to get help with is to come up with both a plausible original and an understanding of why it is still in use so long after the original was created.

For the economic, T5 is into ACS ships, (max 2,500) and use free trading cargo/passengers tables suited for the small ships characters gets at mustering out. So, T5= no 10K dT; no bothering about the micro economic of liners or the economy of global tramping: if the macro economic provide an adequate load factor for large cargo, somehow, the lowest cost carried will get a share. You just presume that the operators meet by your PC are efficient enough to be in business because there is a market segment for them.

Point taken Selandia. I am using ACS for something it was not intended to do but I think it is capable because I have in mind a cluster hull made up of a number of smaller subhulls, each of which can be designed using ACS.

The drives for the ship are not hard to extrapolate from ACS either. I am going to try to get some of that preliminary information posted later today.

One of the key consideration is planetary landing. The J-3 (strategic mobility overide cost concert) that would have been built as auxiliary "assault" logistic may be required to be a lander for the state of high port in the target area is dubious. Then, you may decide to rely on lighters anyway and accept innexpensive & versatile dispersed structure as an "auxiliary assault tender". A 2,500 dt involved in "high volume" trade may trust the presence of high port of lighter at destination. BTW a 2,500 dT main hull may be the base for a 10,000 dT fully loaded tender.

Were you looking at my notes? If not, thanks for validating my thinking. Though it is too early to decide, I envision two methods for cargo transfer. The first is using cargo lighters to transfer loads and the other is to detach subhulls in orbit so the ship does not have to wait for offloading. Either way, I never intend for this thing to be a surface lander.

Thanks to all of you for all the feedback!

 

[Enoki]

for reasons explained by timeover51 never truer words were spoken.

For the economic, T5 is into ACS ships, (max 2,500) and use free trading cargo/passengers tables suited for the small ships characters gets at mustering out. So, T5= no 10K dT; no bothering about the micro economic of liners or the economy of global tramping: if the macro economic provide an adequate load factor for large cargo, somehow, the lowest cost carried will get a share. You just presume that the operators meet by your PC are efficient enough to be in business because there is a market segment for them.

Liners tend to be more efficient than Tramps because they are made for a specific J-1, J2, J3, route. Because they must cover a wide range of options, tramps will gain from being J2, although on the J-1 Main, J-1 will beat the crap out of the J-2 if the extra space could be filled.

Therefore, I would allow for J-2 engineering but make the J fuel in permanent tankage limited to PP & J-1, fit Transfert Pumps in the main hull, with connection to "Fuel pods" for the additionnal fuel storage to acheive J-2. Fuel tanks of Cargo pods being fitted accordint to circumstance.

One of the key consideration is planetary landing. The J-3 (strategic mobility overide cost concert) that would have been built as auxiliary "assault" logistic may be required to be a lander for the state of high port in the target area is dubious. Then, you may decide to rely on lighters anyway and accept innexpensive & versatile dispersed structure as an "auxiliary assault tender". A 2,500 dt involved in "high volume" trade may trust the presence of high port of lighter at destination. BTW a 2,500 dT main hull may be the base for a 10,000 dT fully loaded tender.

have fun

Selandia

I see the merchant shipping system differently. Although it may not be some canon system, its the one that makes sense, and it really doesn't matter which version of Traveller you're playing.

The way I see it, "big" merchant ships, freighters, and passenger liners don't go to every system. In most subsectors they go to just one or two, maybe three at most. These would be the most technologically advanced, most populous, and have the "best" and largest starports.
There would likely be a need most of the time for two types of large merchant:
A very economical freighter to carry almost entirely goods. There might be several kinds that cater to specific types of freight too like one that carries bulk cargo, another for containers, and a third for liquids, like a tanker. There would likely be other types too.
The second would be one that also has some capacity for passengers as well as cargo. This would be the economy means of travelling as a passenger as the ship primarily gets its profit from moving masses of cargo.
A more uncommon type would be the passenger liner. You have to have a route that has sufficient people wanting to use it all the time, and those people have the cash to pay for a ticket. These ships likely would carry some cargo as well.

Through all of this, the large merchants have fixed routes, regular schedules, and are really, in terms of Traveller, boring. A big liner or merchant always gives you the option for something like Murder on the Orient Express for a scenario. But, beyond that they would be scenery in a game for me.

The rest of the subsector gets serviced by small ships akin to coastal freighters on Earth today:

That is the equivalent of a free or far trader type ship. Something a bit larger would be a subsidized merchant. These operate on a more flexible schedule, and there's room for the owner / captain to take on "side work" when it presents itself. So, this is where most of Traveller with a ship would play out.

There's plenty of room for small merchant ships that mostly operate locally. The long haul and most important routes are served by large merchants. Whether you include the later in the game beyond just scenery in the background is really up to you. For me, scenery is important too.

 

[aramis]

Aramis, please post at least the CT information. I will be posting some preliminary drive requirements (volume and price) later today and I think your analysis in CT will help me make some decisions.

The CT Bk5, Bk2 2E, and 1E data is all in the reference library.
http://www.travellerrpg.com/CotI/Discuss/showthread.php?t=33584

 

[AnotherDilbert]

The Spinward Marches has the following Imperial A ports, if we assume the same ports and populations, but one TL less (a few border worlds such as Jewell removed):

TL ~1110	TL11	TL12	TL13	TL14
TL ~3FW	TL10	TL11	TL12	TL13
Jump	J-1	J-2	J-3	J-4
# A ports	14	7	4	2
Capacity	21744	21668	17000	3060

As we can see the production capacity for J-1 and J-2 ships were probably much higher than J-3 ships.

It would suggest that "Liberty-ships" would be J-1 and J-2, with higher tech port capacity reserved for the Navy.

 

[mike wightman]

Hmm...

Oberlindes Lines (Interface Line): Established in 487, Oberlindes Lines was a family run
free trader operation until it acquired naval surplus transports and used them
to provide extensive cargo service in the Regina subsector. At the same time,
Oberlindes expanded into trade with the Vargr just beyond the lmperial border, and
has become a major importer of Vargr products and goods.

Oberlindes Lines maintains a transport fleet ranging in tonnage
from 100-ton couriers to 5000-ton transports. Typical of its fleet is the 1000-ton cargo carrier.

I would argue for the 1000t jump 3 cargo carrier to be the ex-IN transport and a candidate for liberty ship:

Cargo Carrier (type CT): Using the 1000-ton hull, the
cargo carrier is a freight transport vessel. It mounts jump
drive-Q, maneuver drive-E, and power plant-Q, giving a performance
of jump-3 and 1 G acceleration. Fuel tankage for
330 tons supports the power plant and one jump-3. Adjacent
to the bridge is a computer Model13. There are 20
staterooms and 10 low berths. The ship has ten hardpoints
and ten tons allocated to fire control. Installed on the hardpoints
are 3 triple beam laser turrets. There is one ship's
vehicle: an airlraft. Cargo capacity is 409 tons. The hull is
streamlined.
The cargo carrier requires a crew of 11: captain/pilot,
navigator, 5 engineers, medic, and 3 gunners. The navigator
typically operates the air/raft. The ship can carry 12
passengers and 10 low passengers. The ship costs
MCr410.4 (including 1 % architect's fee, and 10% volume
discount), and takes 30 months to build.
The cargo carrier is a standard design commissioned by
Oberlindes, and is reflective of its total fleet. Originally,
Oberlindes outfitted his fleet using naval surplus vessels;
when the cargo carrier was designed, it reflected the
Oberlindes fleet's predisposition to extensive armament.
Oberlindes ships show no consistent system of naming.

If the Oberlindes cargo carrier is based on the old ex-IN ships...

 

[agorski]

On another aspect of the design, I've noted the difference between peacetime construction warships vs wartime construction warships in the 20th century. Ships built in the 20s-30s seemed to be more designed to show the flag and impress people. Big dining rooms with fancy china, for example. Wartime construction ships had stark, cramped accommodations and carried more weaponry per ton of hull.

So my take would be that a liberty ship should be similarly austere. I'd strip off anything fancy. I wouldn't even include carried craft or vehicles, relying on local lighters.

 

[AnotherDilbert]

Cargo Carrier (type CT):

That is a TL13 design (Q-drives).

Since production capacity for TL13 ship was probably severely constrained during 3FW, it seems unlikely to be a 3FW-era "Liberty-ship".

 

[Selandia]

,I envision two methods for cargo transfer. The first is using cargo lighters to transfer loads and the other is to detach subhulls in orbit so the ship does not have to wait for offloading. Either way, I never intend for this thing to be a surface lander.

The subhulls would be more like a LASH system and practical for liners: you have two jumpers and three or four sets of subhull, with a pair of sets that are filled/emptied, while the other sets are moved. The lot is working on a rotation basis. You could (I do) use "Jumpers" (jump tugs) with subhull brought to and from the planet by "manoeuver tug" (that also bring fuel, store and replacement crew). Essentially an optimized liner system unsuitable for tramping.

Liberties as tramp, would need to wait to pick-back-up their cargo carrying subhull, therefore no time gain. Containerized cargo could be unloaded very quickly in 0G and the dT range you mention. Of course, you may just go for the trades where the shipper provide its own cargo pods /pre-loaded lighter. They would pick-up the seasonnal trade that overwhelm regular liner service or get involved in "special project" (like moving space habitat/industrial module from a TL 12 building shipyard to an asteroid belt/highport ...)

have fun

Selandia

 

[mike wightman]

That is a TL13 design (Q-drives).

Since production capacity for TL13 ship was probably severely constrained during 3FW, it seems unlikely to be a 3FW-era "Liberty-ship".

3FW the Imperium was solidly TL14, I don't see the problem. Q drives could be shipped to assembly yards if necessary.