Creating a Breakaway Hull

[snrdg121408]

Hello again PsiTraveller,

4 Docking Clamps for 4 MCr and 20 tons. This means the core unit loses 20 tons of cargo. 20 tons is 5% of your total 400 ton design. The Breakaway hull connectors only take up 8 tons, for 16 Million credits. So there is a cost saving. But you lose 12 tons of cargo in exchange.

Based on my conclusion that the author started with a 400 ton hull I agree with the numbers and the loss of cargo capacity when using docking clamps.

My understanding is that a combined 400 ton breakaway hull requires 8 tons of extra bulkheads and connectors for MCr16. The core hull at 200 tons requires 4 tons for the extra bulkheads and connectors with a cost of MCr8. The four other hulls each need 1 ton of extra bulkheads and connectors at a cost of MCr2. If this is more on track then the core hull loses 4 tons of cargo capacity while the pods each lose 1 ton of cargo capability.

Carrying 4 ships is possible, even 4 ships like the sub units. But the Docking Clamp carried ships would not be hooked up to allow their fuel, power and M-Drives to contribute to the ship like Breakaway units would. Your fuel module ship would have to transfer fuel from itself to the ship in a separate action, not automatically through the breakaway connections.

Based on the conclusion that Fessor was designed as a 400 ton hull and then broken down into four 49-ton hulls their maneuver drives do not contribute to the combined hull. In order to achieve 2-G with the four pods attached the core hull's MD must be 3-G to compensate for the 1-G drives of the pods.

I like the idea of a Core unit Jump section with Docking Clamps to carry a 99 ton cargo module. I think this can offer a ship a lot of flexibility and profitability. The part that sucks is that the 99 ton limit means you cannot jump a 100 ton small ship from system to system as a service, you have to the 10 ton clamp to move 100-300 tons at a time. Jump Nets can be used to shift ships though, so that's an option.

IIRC CT has a jump drive section that can be mounted on a SDB using the SDB's fuel tankage.

You seem to be looking at Breakaway Hulls or Docking Clamps to give flexibility to a ship design. What sort of job is the ship needing to do? Is there a time when you think Docking Clamps would be better than a Breakaway ship?

In my opinion that both breakaway hulls and docking clamps add flexibility to the ship's design. In the Star Carrier series by Ian Douglas Earth had an Earth probe and an alien vessel that did break up into a number of smaller units which in my opinion are MgT's breakaway hulls. The probe was sent to a colony we had lost on a reconnaissance mission and was attacked and a very large alien ship with serious damage. In order to get the data back to earth the probe broke up into several sections each capable of making an interstellar trip. None of the probe's sections made a direct flight back to Earth. The large alien ship also used breakaway hulls to follow the probe's sections. One of the alien hulls got lucky a tracked one probe section to Earth. In turn the alien ship was attacked and it too broke down into single crew ships in order to get the information back to their base. One hull got away, one hull was damaged so it could not go interstellar, and the rest where destroyed.

A series 1 Clamp can only hold 30 tons of ship. The Fessor units are 49 tons, or 50 if you redo them and include the 1 ton of connector hull the design left out.

I agree that a single Type I docking clamp is capable of attaching a maximum of 30 tons. However, based on the text for HG 2e grapple arms pages 43-44, other Traveller versions, and the real world two Type I docking clamps can handle a total of 60 tons together.

 

[snrdg121408]

Hello again PSiTraveller,

I do not think you can use two smaller clamps to carry a larger ship. My reading of the Docking clamp is that it is one clamp, one ship. So a 50 ton ship would need a Type 2 Docking clamp, not two Type 1's

Am I wrong in this? pg 43 of Highguard

The size of a docking clamp dictates the tonnage of the
ship it may attach as shown in the Docking Clamp table.

I don't see anything that says you can use three 1 ton clamps to hold a 90 ton ship, instead of a single 5 ton clamp to hold a 90 ton ship.

As usual more replies show up as I'm working on another one.

My conclusion about how the docking clamp works is based on the grappling arm options on HG 2e pages 43-44, previous Traveller material , and the real world use. I also vaguely recall asking the question about combining docking clamps sometime in the past here, but my search came up empty as usual.

 

[snrdg121408]

Hello Condottiere,

Unless fifty tonne clamps can carry an infinite number of tonnes, I think this can be scaled.

My approach to the Type V docking clamp is the upper limit is about 14,000 tons for one clamp.

 

[PsiTraveller]

The Fessor Core Unit has 8 tons of M-Drives. This would be 2% at 400 tons, so a Thrust of 2 when all 4 pods are attached. No compensation needed. I do not see where you think you need to upgrade any of the drives to 3G.

The M Drives of the sub units are 0.5 tons each, which would add 2 more tons when all 4 pods are attached, 10 tons of drives total onboard the ship at 400 tons. With the sub units in place the ship could actually tow another 100 tons of tonnage (500 tons total ) at 2G, since the volume of drives is 2% of 500 tons.

The flexibility of a Breakaway system is the ability to combine the drive values, and fuel of the sub units to improve the overall ship. Here is an extreme example

The 400 ton Fessor is Jump 1 capable. It has 15 tons of J1 drives in the core unit. You could make a sub unit with 25 tons of Jump 2 drives in the sub unit and allow the Fessor ship to become Jump 2 capable. Having 1 "Jump unit" and 3 fuel units would allow a Jump range of 4 Jumps or 8 parsecs before refueling.
Or you could add a sub unit with more than 25 tons of Jump drives and add a docking clamp to another sub unit and Jump more than 400 tons.

A ship that is not breakaway enabled cannot combine the abilities of the clamped ships to the capabilities of the Core unit. This is the disadvantage of the Docking Clamp. But you save a lot of money up front.


And I am not convinced about the Docking clamps being used in multiples. If it is allowed I can see some design options to abuse this. Not saying that is a bad thing, just an observation.

 

[snrdg121408]

Hello PsiTraveller

The Fessor Core Unit has 8 tons of M-Drives. This would be 2% at 400 tons, so a Thrust of 2 when all 4 pods are attached. No compensation needed. I do not see where you think you need to upgrade any of the drives to 3G.

The M Drives of the sub units are 0.5 tons each, which would add 2 more tons when all 4 pods are attached, 10 tons of drives total onboard the ship at 400 tons. With the sub units in place the ship could actually tow another 100 tons of tonnage (500 tons total ) at 2G, since the volume of drives is 2% of 500 tons.

The flexibility of a Breakaway system is the ability to combine the drive values, and fuel of the sub units to improve the overall ship. Here is an extreme example

The 400 ton Fessor is Jump 1 capable. It has 15 tons of J1 drives in the core unit. You could make a sub unit with 25 tons of Jump 2 drives in the sub unit and allow the Fessor ship to become Jump 2 capable. Having 1 "Jump unit" and 3 fuel units would allow a Jump range of 4 Jumps or 8 parsecs before refueling.

Or you could add a sub unit with more than 25 tons of Jump drives and add a docking clamp to another sub unit and Jump more than 400 tons.

The Fessor's combined tonnage is per the record sheet is 400-tons with an 8 ton 2-G MD.

The four 49-ton pods each mount a 0.5-ton 1-G MD. Combing the four pods results in a 196-ton hull with a 2-ton MD. Dividing 2-tons by 196-tons returns a result of 0.010204 or rounding down is 1% which cross references to an 1-G giving the combined hull a 2-ton 1-G MD.

Subtracting the 2-tons of the 196-tons of the combined pods from the 8-ton MD of the combined 400-ton hull results in the core 400 - 196 = 204-ton and a 6-ton MD. Dividing 6-ton by 204-tons results in a number of 0.029412 rounding down to 0.02 or 2% which is 2-Gs.

I screwed up by rounding up instead of down.

A ship that is not breakaway enabled cannot combine the abilities of the clamped ships to the capabilities of the Core unit. This is the disadvantage of the Docking Clamp. But you save a lot of money up front.

In this case the pods maneuver drives really do not alter the 204-ton core hull's 2-G thrust rating .

And I am not convinced about the Docking clamps being used in multiples. If it is allowed I can see some design options to abuse this. Not saying that is a bad thing, just an observation.

Grapple arms per HG 2e pages 43-44 can be combined to move heavier objects. Locking combined grapple arms in place while holding on an object is effectively the same as using docking clamps. Any design option can be abused.

 

[PsiTraveller]

The core has 8 tons of drives,so even if the sub units had no drives working the 400 tobn ship would move at thrust 2.

Why would you subtract 2 tons of drives from the core ships 8 tons of drives? The core ship drives never leave. When the ship is all together there are 10 tons of drives onboard.this is enough drive to move 500 tons at thrust 2.

And I do not think thensub units can form a new ship. The connectors allow the smaller units to dock in with the core unit, not each other.

I did start another thread where the breakaway sections are all the same size. In that case you could link ships together, but smaller units connect to the core, not each other.

I am basing this on the picture of the ship, and thew deep night endeavour design.

 

[AnotherDilbert]

And I am not convinced about the Docking clamps being used in multiples. If it is allowed I can see some design options to abuse this. Not saying that is a bad thing, just an observation.

Grapple arms per HG 2e pages 43-44 can be combined to move heavier objects. Locking combined grapple arms in place while holding on an object is effectively the same as using docking clamps. Any design option can be abused.

As far as I can see the text about Docking Clamps are pretty clear: One clamp holds one single ship, and one ship is held in one single clamp.

The size of a docking clamp dictates the tonnage of the ship it may attach...

A ship holding another ship in a docking clamp will...

Otherwise no one would ever use Type II clamps and we could remove them from the table.


Grappling Arms are far larger and more expensive, and not really suited to holding stuff fixed. They are flexible, so will form a flexible bond that would allow a ship to move around slightly. I'm not sure that is ideal for sensitive jump calculations...

 

[PsiTraveller]

This is my thought as well. My only question is the 2000 ton and greater ship size on a Type V clamp. Personally I think there should be an upper limit. Although a type IV clamp can hold a ship 100 times its tonnage, so maybe I should not be worried about a Type V clamp.

 

[AnotherDilbert]

My only question is the 2000 ton and greater ship size on a Type V clamp.

Agreed, I tend to use one Type V clamp per 10000 Dt of carried ship, just because it is even...

 

[Condottiere]

I believe that previous editions had a one in thirtyish ratio for clampor versus clampee.

Type two is an odd duck, since it's less than twenty.

Type four was surprising because it increased the ratio to a hundred, but it might be economies of scale.

Type five is too open ended.

 

[PsiTraveller]

Putting a cap at 10 000 for a 5 to 1 ratio, or 20 000 for a 10 to 1 ratio.

The limiting factor may well be the M Drive tonnage on the Clamping ship. 2000 tons needs 20 tons of M Drive to get a thrust of 1. So a ship with clamps better have a lot of extra M Drive capacity to move things. Plus the power plants to supply the power to move the entire tonnage. 2000 tons is 200 points of extra power to give Thrust 1.

 

[snrdg121408]

Hello again PsiTraveller,

The core has 8 tons of drives,so even if the sub units had no drives working the 400 tobn ship would move at thrust 2.

No, the Fessor's record sheet shows the total tonnage of the power plant, maneuver drive, and jump drive is for the combined 400-ton hull not the core hull of 204-tons.

The breakaway hull example starts with a 1,000-ton that is broken down into a 400-ton hull with a 20-ton 5-G MD and a 600-ton hull with a 66-ton 9-G MD. When both sections are together the MD is 86-tons providing thrust for an 1,000-ton hull. Dividing 86-tons by 1,000-ton equals 0.086 rounding to the second decimal point is 0.08 or 8%. An MD that takes 8% hull's tonnage cross references to a thrust of 8. The combined 1,000-ton hull has an 86-ton 8-G MD.

Why would you subtract 2 tons of drives from the core ships 8 tons of drives? The core ship drives never leave. When the ship is all together there are 10 tons of drives onboard.this is enough drive to move 500 tons at thrust 2.

The Fessor's record sheet Hull block description column's information on line 1 is 400-tons, 160 Hull Points. The information below Line 1 is Breakaway Hull (196 tons). The core hull is 400-tons - 196-tons = 204-tons.

Using the breakaway hull example and using the information available this why 2-tons was subtracted from the core hulls MD.

The only information provided for the Fessor is for the 196-ton breakaway hull composed of four 49-ton small craft identified as pods. The four pods have a combined MD equal to 2-tons in a 196-ton hull. Dividing 2-tons by 196-ton equals 0.010204 rounding to the second decimal place is 0.01 or 1%. An MD that takes 1% hull's tonnage cross references to a thrust of 1-G.

The combined 196-tons of the four pods has a 2-ton 1-G MD that adds to tonnage of the MD on the core 204-ton hull that when all five sections are combined results is a 400 ton hull with an 8-ton 2-G MD. Subtracting the combined 196-ton hull 2-ton 1-G MD from the combined 400-ton hull's 8-ton 2-G drive returns the result of a 6-ton MD for the 204-ton core hull.

And I do not think the nsub units can form a new ship. The connectors allow the smaller units to dock in with the core unit, not each other.

My work, even with my math errors, is using the information provided from the record sheets provided for the Core Hull and the four pods and following the breakaway example HG 2e page 12. The four pods MD tonnage combines with the core hulls tonnage that results in the total MD tonnage mounted on a combined hull equal to 400-tons.

I did start another thread where the breakaway sections are all the same size. In that case you could link ships together, but smaller units connect to the core, not each other.

The Fessor's four 49-ton breakaway hull sections are technically all the same size.

The breakaway hull example split an 1,000 ton hull into two sections one section is 400-tons and the other is 600-tons which one is the core hull?

Which hull is the core section of an 1,000-ton that is divided into four 250-ton hulls?

I am basing this on the picture of the ship, and thew deep night endeavour design.

My first thought when I looked at the illustration of the Fessor was the hull used docking clamps and then I looked at the write-up or record sheets.

 

[PsiTraveller]

Whoops, you are correct. 8 tons total M Drive tonnage. My mistake there. Your math is correct for the percentages and thrust values. I design my breakaway ships with different sheets for different pieces, so I don't have the combined stat block as a front page. My error in thinking the Fessor ship did the same thing.

My point about sub units and Core units stands I think. The Fessor was designed to have 4 sub units able to disconnect and fly off and act as drones. There is an over/under design to the ship with the sub units docking into the central spine. You could argue that any docking unit can clamp onto any other docking unit. It seems odd to me that the drones would lock together. The Deepnight Endeavour and the Fessor both have a larger Core and smaller sub units. Your question about the 600 and 400 pieces, which one is Core would have my answer as either the 600 ton piece since it is larger, or whichever piece has the main bridge.

My infinite breakaway thread was asking the question of what if you designed a breakaway ship of all equal sizes? The Core piece would have the bridge, and the other pieces would be plug and play with whatever you needed for the final ship design.

 

[Condottiere]

I have.

There are pros and cons dealing mainly with performance and costs involved, but by sacrificing two percent of volume, you'll find that the whole is greater than the sum of its parts, as you can combine all engineering and fuel tanks under one roof.

 

[snrdg121408]

Hello PsiTraveller,

Whoops, you are correct. 8 tons total M Drive tonnage. My mistake there. Your math is correct for the percentages and thrust values. I design my breakaway ships with different sheets for different pieces, so I don't have the combined stat block as a front page. My error in thinking the Fessor ship did the same thing.

Whew, I am glad that I was not on the wrong track and that I may be getting the hang of reading the record sheet.

My point about sub units and Core units stands I think. The Fessor was designed to have 4 sub units able to disconnect and fly off and act as drones. There is an over/under design to the ship with the sub units docking into the central spine. You could argue that any docking unit can clamp onto any other docking unit. It seems odd to me that the drones would lock together. The Deepnight Endeavour and the Fessor both have a larger Core and smaller sub units. Your question about the 600 and 400 pieces, which one is Core would have my answer as either the 600 ton piece since it is larger, or whichever piece has the main bridge.

Referring to the Fressor's record sheet the Hull block's second entry is Breakaway Hull (196-tons) the Tons column shows 4 and the cost column is 8,000,000. The 4-tons appear to be the total tonnage of the extra bulkheads and connectors assigned to each pod. Based on the information in HG 2e my guess is that two pods could use the extra bulkheads and connectors to form a 98-ton hull there does not appear to be way to connect all four together.

Both the 400-ton and the 600-ton section per HG 2e page 17 Bridge table mount the same 20 ton bridge. As has been mentioned Star Trek's Enterprise is an example of a breakaway hull. The main bridge is in the saucer which is smaller than the secondary hull. Of course the auxiliary bridge is much more cramped that the main bridge.

The hull designated as the core is left to the designer's definition.

My infinite breakaway thread was asking the question of what if you designed a breakaway ship of all equal sizes? The Core piece would have the bridge, and the other pieces would be plug and play with whatever you needed for the final ship design.

Technically, each section must have an appropriate bridge and power plant to operate it and everything else is optional but should be included. The Fessor used the computer and virtual crew to get around the bridge requirement which can be seen in my opinion as abusing the intent of the breakaway hull option. However, I like the idea so if I design something similar I will surely use the Fessor interpretation.

 

[snrdg121408]

Hello AnotherDIlbert,

First may apologies for taking so long to reply part of the reason for the delay is that I've been distracted by reading the first two books of The Expanse series as suggested by The Expanse Roleplaying Game. The other part was researching material that unfortunately as often happens I can rarely find when I'm looking for myself.

And I am not convinced about the Docking clamps being used in multiples. If it is allowed I can see some design options to abuse this. Not saying that is a bad thing, just an observation.

Grapple arms per HG 2e pages 43-44 can be combined to move heavier objects. Locking combined grapple arms in place while holding on an object is effectively the same as using docking clamps. Any design option can be abused.

As far as I can see the text about Docking Clamps are pretty clear: One clamp holds one single ship, and one ship is held in one single clamp.

The size of a docking clamp dictates the tonnage of the ship it may attach...

A ship holding another ship in a docking clamp will...

Otherwise no one would ever use Type II clamps and we could remove them from the table.


Grappling Arms are far larger and more expensive, and not really suited to holding stuff fixed. They are flexible, so will form a flexible bond that would allow a ship to move around slightly. I'm not sure that is ideal for sensitive jump calculations...

The complete quote of the cited material from HG 2e page 43 is "The size of a docking clamp dictates the tonnage of the ship it may attach as shown in the Docking Clamp Table"

The text indicates that the docking clamp table lists the tonnage of an object, not ship since shipping containers are not usually capable of autonomous movement, a specific clamp can handle, but not that one clamp holds one ship or one ship to one clamp. I do not agree that multiple docking clamps of the same capacity can not be used to handle one object with a tonnage that falls within their total capacity.

In the real world multiple clamping systems are used to attach standardized shipping containers to semi-truck flat bed trailers and to flat bed railway cars. Most of cranes designed for load and unload standard shipping container from ships I've seen on documentaries have at least to clamps that hold the container into place.

A single clamp would, in theory, be capable of holding the container in place however the one clamp is going to be taking all of the varying weights on one point that over time stresses the materiel of the clamp until it fails. The more clamps used the more the weight is distributed, and in theory, spreads the stresses across all the clamps which reduces the chances of the container flying off the trailer or railway flatbed car.


Using two Type I Docking Clamps allows a hull to carry an external load of 60 tons. Taking a 60 ton load that spans both clamps distributes the tonnage into 30 tons for each clamp which is technically one 30 ton load per clamp used. By using two Type I docking clamps the hull losses 2 ton of space at the same cost of the Type II clamps than 5 tons for the same cost of MCr1.

To carry a 90 ton load using three Type I clamps still takes up less tonnage than a single Type II but costs MCr0.5. In this case I would use one Type II since the clamp is cheaper.

An airlock has a flexible docking tube that is some how clamped to either another docking tube or airlock of a ship or other object that is larger, same size, or smaller of the ship trying to dock with.

Finally, as Matthew Sprange comments in a different topic thread the RAW are flexible.

 

[Condottiere]

Docking to multiple clamps will likely take longer than docking to a single one.

 

[snrdg121408]

Hello Condottiere,

Docking to multiple clamps will likely take longer than docking to a single one.

Shipping containers come in varying standard lengths that have to line up with the clamping systems on the trailer flatbed or the railway flatbed. There is as far as I can tell normally no changes in the time taken load containers of different lengths.

If two separate objects are being attached to two clamps at the same time the docking for each, in theory should take the same duration. One object spanning two clamps in theory should take the same amount of time as two objects on two different clamps.

 

[phavoc]

Hello Condottiere,

Docking to multiple clamps will likely take longer than docking to a single one.

Shipping containers come in varying standard lengths that have to line up with the clamping systems on the trailer flatbed or the railway flatbed. There is as far as I can tell normally no changes in the time taken load containers of different lengths.

If two separate objects are being attached to two clamps at the same time the docking for each, in theory should take the same duration. One object spanning two clamps in theory should take the same amount of time as two objects on two different clamps.

Container trailers typically have latches, two per side, at the front and rear of the trailer. It's as much for stability, safety and regulations as anything else. A single clamp would have to be located underneath in the center and would certainly be subjected to a lot more torsional stresses as the container moves during transport. Locking it down the four corners of the trailer makes for a much stronger attachment. They are called twistlocks and are pretty simple and robust. It's why you often see whole stacks of containers falling overboard from ships. Some good images in this Quora thread - https://www.quora.com/How-do-containers-stay-in-place-in-high-seas

As far as a ship having two docking clamps to join to, it should be mostly trivial to line them up, except for when there was incoming fire. Though some of that depends on how the clamp works and it's design. For anything that potentially needed to be docked at speed and under fire, a mechanism that clamped on to the ship and pulled it in would work better than relying upon the pilot to make an exact docking lock.

 

[Condottiere]

Most captains probably want visitors to be docked at designated spots on their hull, and not be like barnacles, which is why they are the clampor.

Having multiple clamps means more care in lining up the two hulls; release should be almost instantaneous.