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Flattened Sphere Starship

They were sorta BORING [imho] ... but 20% cheaper is 20% cheaper ... so mostly we just squint and call everything a "flattened sphere" (like the venerable Type A).
I have been playing with new software (AutoCAD Civil 3D) that I need to use at WORK [boo hiss, it hurrttss our Traveller time] and decided to take a shot at modeling various complex 3D ships as I build familiarity with the software.

Long winded way of saying ... here is a 100 dTon Flattened Sphere:

100 dT Flattened Sphere.jpg
 
Click to expand...
Timerover51 said:
I can see those as Scouts, but not as cargo ships. My cargo ships tend to resemble a cross between a nuclear submarine and the Space Shuttle. Sort of like the March Harrier subsidized merchant.
Click to expand...
Perhaps, but that would not be a “Flattened Sphere” (High Guard configuration 6; streamlined: -20% cost).
That would be a “Needle/Wedge” (High Guard configuration 1; streamlined: +20% cost) … not that I particularly agree with that description of its shape, but MegaTraveller lists the ship as a “Needle/Wedge” (Configuration 1SL).

[… as a cylinder, it cannot be streamlined to land in CT].

In any event, TEUs do not fit well in any round hull shape … cargo ships should be more rectangular.
 
atpollard said:
In any event, TEUs do not fit well in any round hull shape … cargo ships should be more rectangular.
Click to expand...
This is one of the conceptual challenges that I faced trying to come up with configuration: 6 deck plan ideas, because it rather literally involves needing to "square the circle" (so to speak). You can do it by doing rectangle blocks of space inside with "rounded" fuel tanks wrapped around that internal structure ... but no matter how you do it you're going to wind up with a pretty decent amount of "wasted space" (or what looks like it on a 2D grid drawing) given over to fuel tanks around the perimeter of the "flattened sphere" form factor.

For a while I toyed with the idea of trying to "hex the circle" by going with a hexagonal interior deck plan wrapped inside a circle. It quickly became apparent that such an effort would yield little more than novelty, simply because "the shapes no longer fit together sweetly" inside hull on the deck plan (like you get with a square grid, rather than staggered offset hexes like sector maps). It just turned into a complex monstrosity MESS that turned into being more trouble than it's worth.

If you're going to be using (somewhat) standardized symbology for deck plans, such as copy/pasting from Geomorphs resources like I've been doing, there are certain things that only fit specific shapes at specific sizes ... such as vehicles.
  • Air/Rafts cost 4 tons of displacement, but the icon for them can fit into 2x3 deck squares of space. Ostensibly, there ought to be at least 2x4 or 2.75x3 deck squares (4 tons) of space devoted to an Air/Raft berth, even though the vehicle icon only occupies 2x3 deck squares.
  • Grav Tanks have a 3x4 icon or a 3.2x6 icon.
  • GCarriers cost 8 tons of displacement, but the icon for them is 3x6.75 deck squares of space. However, @ 8 tons of displacement they ought to only occupy up to 8*14/3/1.5/1.5=16.6 deck squares of space, which for something 3 squares wide ought to be only 5.5 deck squares long. The problem is that GCarriers aren't 3m tall (single deck height), so they're longer and lower (which "wastes" area on deck plans, meaning that the 3x6.75 icon shape is justified, albeit annoying.
  • ATVs cost 10 tons of displacement, but the icon for them can fit into 3x6 deck squares of space. Ostensibly, there ought to be at least 3x7 or 3.5x6 deck squares (10 tons) of space devoted to an ATV berth, even though the vehicle icon only occupies 3x6 deck squares.
This has ... interesting consequences ... for deck plan considerations.

For example, my 12 ton cargo modules use a 5x5 deck plan shape to them (7.5*7.5*3/14=12.036 tons) ... but the only way that I can fit a 6 squares long ATV (10 tons) into such a space is to angle the ATV at a 45º diagonal within the box (because 6/1.4=4.3) and even then you have to wonder if it can be roll on/roll off driven without scraping the walls of the box to get out the door(s) due to the inconvenient parking angle. An ATV will actually fit inside, but it doesn't look all that comfortable. Move the doors into the corners, though, and the arrangement isn't quite as ridiculous (although it still kind of is, really).

There's all kinds of little fiddly bits like that when moving from the CT naval architect's office spreadsheet tally over into actually trying to keep the accounting straight in the organization and arrangement of deck plans. In a lot of cases, stuff like spreadsheet tonnage allocations turn into "suggestions" for deck area decisions, rather than being hard and fast "strict rules" for how big things ought to be on the deck plans. 😖

Ot4K0fY.gif
 
atpollard said:
Perhaps, but that would not be a “Flattened Sphere” (High Guard configuration 6; streamlined: -20% cost).
That would be a “Needle/Wedge” (High Guard configuration 1; streamlined: +20% cost) … not that I particularly agree with that description of its shape, but MegaTraveller lists the ship as a “Needle/Wedge” (Configuration 1SL).

[… as a cylinder, it cannot be streamlined to land in CT].

In any event, TEUs do not fit well in any round hull shape … cargo ships should be more rectangular.
Click to expand...
Per Supplement 7: Traders and Gunboats, the Type R 400 dTon Subsidized Merchant is streamlined and can land on world surfaces. I have designed a Type R2 600 dTon Subsidized Merchant, basically a stretched Type R for use in my Piper-Norton sector, using a blend of Cepheus and 1977 Traveller Books and some home rules.

Cargo ships here on Earth can be rectangular as they do not have to deal with major changes in atmospheric pressure, unless of course they sink. Then the pressure changes rapidly. However, spaceships and starships have to deal with pressure changes from vacuum to say 1.5 times Earth atmospheric pressure. That sort of range tends to dictate a cylindrical hull as the lightest type to handle the pressure changes. Early aircraft with limited altitudes could have rectangular fuselages, but when you start operating at 25,000 plus feet with a pressurized fuselage, the cylindrical shape takes over.

I understand that the standard cargo module in Traveller, 3 meters by 3 meters by 6 meters, or roughly 10 feet by 10 feet by 20 feet, does not fit a circular hull very well, but that assumes that you are trying to completely fill a cargo hold. I assume a rectangular cargo hold, with loading doors fore and aft, with fuel tanks filling out the space between the rectangular hold and the cylindrical hull. This would be very similar to the US submarines used in World War 2. The Tench-class, with a 7/8th inch high-tensile strength hull of 16 feet diameter were rated at an operational depth of 400 feet, but had a collapse depth of about 900 feet. As the pressure resistance of a cylinder is directly proportional to diameter, a 7/8th inch thick hull of high-tensile strength steel of a diameter of 160 feet would have a probable collapse depth of about 90 feet, or 3 atmosphere pressure. I have not made my Type R2 160 feet in diameter, but I do assume a hull thickness of 1 inch of high-tensile strength steel. Actually, I could cut it to 0.5 inch thickness with a rating of vacuum to 3 atmosphere pressure with a 40 to 80 foot diameter, and have a good safely margin. I should be able to load 3 or 4 standard cargo modules abreast and stack them 2 high, with adequate room for crew and passenger quarters on the upper deck. My preference for easier cargo handling is a cargo module of 1.5 by 1.5 by 3 meters, or 1.5 by 3 by 6 meters.
 
Timerover51 said:
7/8th inch thick hull of high-tensile strength steel
Click to expand...
This is where materials science comes into the picture to make "Deck Plan Life" easier.

According to CT Striker Book 4, p3:
  • TL=5 Soft Steel = x0.8 toughness
  • TL=6 Hard Steel = x1 toughness
  • TL=7-9 Composite Laminates = x2 toughness
  • TL=10-11 Crystaliron = x4 toughness
  • TL=12-13 Superdense = x7 toughness
  • TL=14-15 Bonded Superdense = x14 toughness
According to LBB3.81, p15 ... submersibles are a TL=6 vehicle ... and TL=6 corresponds to circa 1940 to 1969 (so far so good).

What this means for pressure hull engineering is that by the time you get to TL=10 and Crystaliron technology, you only need 25% of the thickness to achieve the same armor rating. So that 7/8th inch thick of Hard Steel only needs 3.5/16th inch thick of Crystaliron to achieve the same structure.

Given that bulkheads aboard starships are going to have a certain "do not go thinner than this" rating for safety margin reasons (because, who ever heard of paper thin bulkheads? that work as bulkheads?), as tech levels advance the "need" for pressure friendly shapes for spaces such as cargo holds diminishes simply due to increased "margins" available due to increasing materials strengths combined with minimum thicknesses for bulkheads.

If it helps, think of "aircraft aluminum" construction as being a (metallic) kind of Composite Laminate, while carbon fiber materials are ALSO a (later, non-metallic) kind of Composite Laminate (just tuned for different engineering demands) ... compared to Hard Steel for the same applications.

The irony, of course, is that Composite Laminates are the least massive/lightest weight by thickness of material ... while Bomded Superdense is the strongest+heaviest material by thickness, but you need less of it to achieve specific armor rating thresholds (so higher density but don't need as much material). So if bulkhead grade walls have a required minimum thickness, in addition to a minimum "armor rating" for pressure containment, that means that beyond a certain inflection point (which I presume as being TL=10+) there's enough structural engineering "margin" available in the materials engineering that pressure vessel optimized shapes become less necessary for structural integrity ... making "boxy" shapes for pressurized hull spaces much more reasonable.

Your mileage may vary, of course. ;)
 
Spinward Flow said:
This is where materials science comes into the picture to make "Deck Plan Life" easier.

According to CT Striker Book 4, p3:
  • TL=5 Soft Steel = x0.8 toughness
  • TL=6 Hard Steel = x1 toughness
  • TL=7-9 Composite Laminates = x2 toughness
  • TL=10-11 Crystaliron = x4 toughness
  • TL=12-13 Superdense = x7 toughness
  • TL=14-15 Bonded Superdense = x14 toughness
According to LBB3.81, p15 ... submersibles are a TL=6 vehicle ... and TL=6 corresponds to circa 1940 to 1969 (so far so good).

What this means for pressure hull engineering is that by the time you get to TL=10 and Crystaliron technology, you only need 25% of the thickness to achieve the same armor rating. So that 7/8th inch thick of Hard Steel only needs 3.5/16th inch thick of Crystaliron to achieve the same structure.

Given that bulkheads aboard starships are going to have a certain "do not go thinner than this" rating for safety margin reasons (because, who ever heard of paper thin bulkheads? that work as bulkheads?), as tech levels advance the "need" for pressure friendly shapes for spaces such as cargo holds diminishes simply due to increased "margins" available due to increasing materials strengths combined with minimum thicknesses for bulkheads.

If it helps, think of "aircraft aluminum" construction as being a (metallic) kind of Composite Laminate, while carbon fiber materials are ALSO a (later, non-metallic) kind of Composite Laminate (just tuned for different engineering demands) ... compared to Hard Steel for the same applications.

The irony, of course, is that Composite Laminates are the least massive/lightest weight by thickness of material ... while Bomded Superdense is the strongest+heaviest material by thickness, but you need less of it to achieve specific armor rating thresholds (so higher density but don't need as much material). So if bulkhead grade walls have a required minimum thickness, in addition to a minimum "armor rating" for pressure containment, that means that beyond a certain inflection point (which I presume as being TL=10+) there's enough structural engineering "margin" available in the materials engineering that pressure vessel optimized shapes become less necessary for structural integrity ... making "boxy" shapes for pressurized hull spaces much more reasonable.

Your mileage may vary, of course. ;)
Click to expand...
As I stated, I designed my ship using a blend of the Cepheus Engine and 1977 edition of Traveller rules along with some home rules. All of the following materials:
  • TL=7-9 Composite Laminates = x2 toughness
  • TL=10-11 Crystaliron = x4 toughness
  • TL=12-13 Superdense = x7 toughness
  • TL=14-15 Bonded Superdense = x14 toughness
Click to expand...
cost significantly more than steel, with Bonded Superdense being 100 times the cost of steel, and Laminates running 5 times the cost of steel. I view Soft Steel as the equivalent of mild steel, with a yield strength of 35,000 pounds, and Hard Steel as higher-tensile strength steel of 50,000 pound tensile strength. I could go with HY-65 or HY-80 steel as well, both being high-tensile strength steel. Those are my base hulls. If you want one of the other materials for your hull, you will pay for it, big time. As a merchant ship has a thin profit margin, paying for one of those higher tech materials is not an option.

I specifically did not mention Striker, because of what I view as the ridiculously low costs for those materials. I understand why they were covered, but view them essentially as irrelevant to any discuss of hull material. They were put in there so as to give higher tech vehicles a massive advantage without being totally priced out of the market.
 
Timerover51 said:
I specifically did not mention Striker, because of what I view as the ridiculously low costs for those materials. I understand why they were covered, but view them essentially as irrelevant to any discuss of hull material. They were put in there so as to give higher tech vehicles a massive advantage without being totally priced out of the market.
Click to expand...
{ * points at LBB5.80, p23 Hull Armor Table in the bottom right corner * }

AWj0PQL.png

Spinward Flow said:
  • TL=7-9 Composite Laminates = x2 toughness
  • TL=10-11 Crystaliron = x4 toughness
  • TL=12-13 Superdense = x7 toughness
  • TL=14-15 Bonded Superdense = x14 toughness
Click to expand...

Huh. 🤔
Probably just a coincidence ... :rolleyes:
 
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