Hull design

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Bastian-Bux
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Hull design

#1 Post by Bastian-Bux » Thu Nov 18, 2004 12:04 pm

Well, someone brought this topic up, and I gonna present a very nice solution I found in my large RPG collection:

the following explanations are taken from Fire, Fusion & Steel, Traveller New Era Technical Architecture, a GDW product.

It might be to complicated for the main stream user, but its very usefull for us designers trying to come up with "believable" numbers. Its so awefull to see those 100m length needle starships that houses more equipment then a 100m diameter sphere starship.

To design a hull you need to know severall variables:

1.) the size in displacement tons. Each displacement ton is equivalent to 14m³ of internal volume.

2.) the hull form. 9 standard forms are known: open frame, needle, wedge, cylinder, box, sphere, dome/disc, close structure and slab. The base form is the sphere, having the best surface/internal volume ratio. All other forms will have more surface (thus needing more amor).

3.) the hull configuration. An hull can have one of three configurations: unstreamlined, streamlined and airframe. Lets skip streamlined (only necessary, and concentrade on unstreamlined and airframe. Unstreamlined ships can't land on planets with an atmosphere, but cost less.

4.) the material and thickness of the hull. The material has 3 important values: weight, armor points and price

With this 3 variables we can come up with all kinds of hulls, and get good numbers on the following variables:

a) Material Volume (MV), the volume in m³ of material required to enclose the hull in a shell 1 cm thick.

b) Length, the longest length of the hull. For spheres and domes/discs this is the diameter, for all ships this is the maximum length of spinal mounts.

c) Surface area. its MV*100

d) Price. Well, just that, how much a hull costs in Credits. Can be easily transfered to Mineral Point and Production point cost.

Basic for the design are some tables, which can be easily brought back to the mathematical functions behind them.

Let me give two examples:

I gonna design a TL 8 wedge shaped viper hull (actually its a modern fighter), and a TL 17 sphere shaped doom star hull.

-------------------------------------------------------------------------------------

The doom star:

Its a small doom star. Only 1,000,000,000,000 displacement tons. Hull form is spherical of course. Hull configuration unstreamlined (you dont want to land a 30km diameter doom star on a planet, dont you). ;) Oh, the armor is the best of the best: Coherent Bonded Superdense. Whatever that is. :twisted:

Now the numbers: a doom star of such size has 14,000 km³ internal volume. Yep, lotsa space for stupid white helmed a...
It has an MV of 0.0274 km³. So a 1 cm shell for this monster its up 27.4 million m³ of our wonderfull CBSD. Well, lets not be greedy, 100 cm CBS aint anything, isn't it?
Just by chance a sphere of that magnitude has a diameter of 30 km.

Lets now come to the interessting parts:

A sphere is the base of calculation, so it doesnt need more armor due to form. Unstreamlined configuration is cheap, costing only 80% of streamlined.

Our ship will have a surface of 2,740 km², the 100 cm CBSD bring its totall hull to 2.74 km³. As each cm of CBSD has 40 armor points we got an impressive 4,000 armor points. But the price is impressive as well. 1 m³ of CBSD costs 35,000 Credits, add in the unstreamlined modifier, so our wonderfull hull comes at a rate of 76,7 TCr. Thats TeraCredits, so 10^12 Credits ;).

-------------------------------------------------------------------------------------

The viper:

Its a small ship. Only 10 displacement tons. Hull form is wedge. Hull configuration airframe (its an airplane). ;) Oh, the armor is the best of TL 8 : Composite Laminate. You know, the stuff that use for fighters today. Does the tupper guarantee go for them as well? :twisted:

Now the numbers: our tiny fighter has 140 m³ internal volume. Not much, the same as a 60 m² appartment.
It has a MV of 1.9 m³. As we wanna churn out many of them we stay with a 1 cm hull. But it isn't a sphere. Its a wedge. Wedges have a MV multiplier of 1.5. Airframe adds another 1.3. So alltogether we have an MV of 3.7 m³.
If our viper was a sphere it would have a diameter of 7m. A wedge has its length multiplied by 2.5, so our viper is 17.5 m long.



Our ship will have a surface of 370m². The 1 cm composite laminate has an armor value of 6. And as each m³ of Composite Laminate costs 8,000 Credits, and our airframe wedge configuration has a price modifier of 1.5, the hull costs us only 44.000 Credits.

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Re: Hull design

#2 Post by utilae » Thu Nov 18, 2004 9:06 pm

Bastian-Bux wrote: 1.) the size in displacement tons. Each displacement ton is equivalent to 14m³ of internal volume.
I think that displacement tons and m³ may be too complex to use in the game, unless we have a window that shows super detailed information like this. In designing the ship I would like to see a simple term like space being used, of course mass would be fine too.
Bastian-Bux wrote: 2.) the hull form. 9 standard forms are known: open frame, needle, wedge, cylinder, box, sphere, dome/disc, close structure and slab. The base form is the sphere, having the best surface/internal volume ratio. All other forms will have more surface (thus needing more amor).
I like this idea. Different shaped ships reflecting different internal storage and different surface storage (armor). Though I would have thought that a box would have a higher surface/internal volume ratio, because with a sphere you have curves. If the items you put into the sphere are not curved and match into space perfectly then you waste space. Think of trying to fit box shaped desks around a circular room. A Box allows box shaped items (which could be more common) to fit perfectly, wasting no space.
Bastian-Bux wrote: 3.) the hull configuration. An hull can have one of three configurations: unstreamlined, streamlined and airframe. Lets skip streamlined (only necessary, and concentrade on unstreamlined and airframe. Unstreamlined ships can't land on planets with an atmosphere, but cost less.
I like the idea that it is cheaper to make a ship unatractive, unstreamlined, then to make it a work of art and streamlined. I would like to know what airframe is by the way.
Bastian-Bux wrote: 4.) the material and thickness of the hull. The material has 3 important values: weight, armor points and price

With this 3 variables we can come up with all kinds of hulls, and get good numbers on the following variables:

a) Material Volume (MV), the volume in m³ of material required to enclose the hull in a shell 1 cm thick.

b) Length, the longest length of the hull. For spheres and domes/discs this is the diameter, for all ships this is the maximum length of spinal mounts.

c) Surface area. its MV*100

d) Price. Well, just that, how much a hull costs in Credits. Can be easily transfered to Mineral Point and Production point cost.
I think these values may have to be simplified for the game as well. I don't see the usefulness of length and I could imagine spinal mounts being longer than the ship legnth. I also think that armor needs to be tied in with heavy armor(eg 3cm), light armor (eg 1cm) to make it less complex to the user. I still like the idea of getting more armor per surface volume.
Bastian-Bux wrote: The doom star:

Its a small doom star. Only 1,000,000,000,000 displacement tons. Hull form is spherical of course. Hull configuration unstreamlined (you dont want to land a 30km diameter doom star on a planet, dont you). ;) Oh, the armor is the best of the best: Coherent Bonded Superdense. Whatever that is. :twisted:

Now the numbers: a doom star of such size has 14,000 km³ internal volume. Yep, lotsa space for stupid white helmed a...
It has an MV of 0.0274 km³. So a 1 cm shell for this monster its up 27.4 million m³ of our wonderfull CBSD. Well, lets not be greedy, 100 cm CBS aint anything, isn't it?
Just by chance a sphere of that magnitude has a diameter of 30 km.

Lets now come to the interessting parts:

A sphere is the base of calculation, so it doesnt need more armor due to form. Unstreamlined configuration is cheap, costing only 80% of streamlined.

Our ship will have a surface of 2,740 km², the 100 cm CBSD bring its totall hull to 2.74 km³. As each cm of CBSD has 40 armor points we got an impressive 4,000 armor points. But the price is impressive as well. 1 m³ of CBSD costs 35,000 Credits, add in the unstreamlined modifier, so our wonderfull hull comes at a rate of 76,7 TCr. Thats TeraCredits, so 10^12 Credits ;).
My only problem with these ideas is that they are gonna choose the shape that stores the most and jsut choose unstreamlined all the time. Maybe shapes like wedge and streamlined lend more speed to the ship.

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Ships

#3 Post by guiguibaah » Fri Nov 19, 2004 1:46 am

... Where would the Spathi Eluder fit in all this? :)

Or the Zot-Fot-Pik stinger?

come to think about it, what kind of air do we want to give this game? Are we going to the stern and serious Moo2, or do we want to be a bit goofy and do something like Starcontrol 2?
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Re: Ships

#4 Post by utilae » Fri Nov 19, 2004 2:40 am

guiguibaah wrote:... Where would the Spathi Eluder fit in all this? :)

Or the Zot-Fot-Pik stinger?

come to think about it, what kind of air do we want to give this game? Are we going to the stern and serious Moo2, or do we want to be a bit goofy and do something like Starcontrol 2?
Serious

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#5 Post by Impaler » Fri Nov 19, 2004 6:44 am

This is some nice material Bux, I think theirs room for a bit of simplification while still keeping the core strengths.

Firstly I would drop the consept of Airframe/Streamlined. Landing on planets and flying through atmospheres is a desirable game element but I would make it a dependent on a component of the ships like "Landing gear" "Retro Rockets" "Scram Engines" "Retractable Air-foil". This eliminates the variable from hull considerations and presents us with the possibily of upgrading ships to aquire these abilites when they are needed.

Second, use the terms Space or Volume rather them cubic meters, its realy not important to define how much physical volume this represents so long as all the devices have well balanced values. MV as you call it could be called Armoring Area (AA) as this more directly implies the purpose of acting as a multiplier for Armor cost. Again its not nessary to specify 1cm, rather one "layer" is a beter term. Protection is proportional to the Armor Quality multiplied by # Layers. Cost equals AA muliplied by the per unit cost of the Armor and # Layers.

Third, I get the sense that their would/could be an explicity defined Equation for each shape that will describe its volume, Armoring Area and Cost. The single length/Size factor plugs into each of these. A sphere for example has 3/4 Pie (Length/2) Squared as its Surface area.

Lastly if might be usefull to include "Structure" points as one the the equations, The player can select one of their Armor materials to use a the ships structureal frame and select how light/heavy the frame is. Unlike Armor the Frame will consume internal Volume in the ship.
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#6 Post by Bastian-Bux » Fri Nov 19, 2004 7:16 am

utilae wrote:
I think that displacement tons and m³ may be too complex to use in the game, unless we have a window that shows super detailed information like this. In designing the ship I would like to see a simple term like space being used, of course mass would be fine too.
Yes, dt and m³ is to complex. As I said, I just presented you the original information. I'd strongely suggest to name 1m³ a "space", and skip the displacement ton all together. This way we sound serious without beeing to close to terran terms.


utilae wrote:
I like this idea. Different shaped ships reflecting different internal storage and different surface storage (armor). Though I would have thought that a box would have a higher surface/internal volume ratio, because with a sphere you have curves. If the items you put into the sphere are not curved and match into space perfectly then you waste space. Think of trying to fit box shaped desks around a circular room. A Box allows box shaped items (which could be more common) to fit perfectly, wasting no space.
Actually thats true as long as you look for a) a box obsessed race like ours, and b) for smaller crafts. Yes, we would have problems to build spherical fighters, cause most of our designs are box shaped. But if you make the sphere big enough, then it gets much easier, as the slopes are very leisurely.

An example with mathematical formulaes.

Lets take a cube (=the most efficent box) and a sphere, both with a diameter (cube = length) of 1m.

The cube is very easy: 1*1*1= 1 m³ volume, and 6*1*1 = 6 m² surface.

So 6:1

The sphere is also not to difficult: pi*1*1*1 /6 = pi/6 ~ 0.52 m³ and pi*1*1 = pi ~ 3.14 m² for the surface.

So also 6:1 ;).

A cube and a sphere are both the most efficent in surface/volume ratio. But as soon as you use non-cubic boxes, it gets worse.

As an example a box with one length = 2m, and two lengths = 1 m.

Volume: 2*1*1 = 2m³
Surface: 4*2*1+2*1*1 = 10 m³

Its already 5:1, so you need 20% more surface for the same volume, as a cube or a sphere.

utilae wrote:
I like the idea that it is cheaper to make a ship unatractive, unstreamlined, then to make it a work of art and streamlined. I would like to know what airframe is by the way.
In FF&S you have 3 streamlining statues: unstreamlined is, well build as it comes. Streamlined allows a spaceship to skim the upper atmospheres of gas giants for hydrogen. It would also allow a car or ship to drive fast. Airframe is needed if you want something to fly in the air, be it for an airplane, or for a spaceship thats intended to enter atmosphere.

For FO the streamlined category is IMHO of no importance, so I would skip it. Either its intended to enter atmosphere, or its not.

utilae wrote:
I think these values may have to be simplified for the game as well. I don't see the usefulness of length and I could imagine spinal mounts being longer than the ship legnth. I also think that armor needs to be tied in with heavy armor(eg 3cm), light armor (eg 1cm) to make it less complex to the user. I still like the idea of getting more armor per surface volume.
Yes, simplification is needed. I just didn't want to simplify first, and then present, but give all information (well, most) for discussion.
About spinal mounts: can you make the barrel of a weapon longer then the length of the whole weapon? Nope. So the spinal mount can't be longer then the main axis (spine) of a ship = length. Thats also the reason why not all ships will have sphere or cube form: a needle shaped ship can house a 3 times longer = more devastating spinal mount then a cube or sphere of the same magnitude, as it is 3 times "longer".


utilae wrote:
My only problem with these ideas is that they are gonna choose the shape that stores the most and jsut choose unstreamlined all the time. Maybe shapes like wedge and streamlined lend more speed to the ship.
I suppose I forgot to mention that only needle, wedge, cylinder, dome/disc and slab forms can be airframe :). So while most spaceships of a non-aestethic race (like borg) will have open frame, cube or sphere form, those can't enter atmosphere. But sometimes you'll troop transports. And if you plan to build flying cannons (one big cannon surrounded by a small ship), then you'll go for wedge, cylinder or a similar shape.
Or imagine a carrier. It will need quite a bit of surface area for those fighter bays.

guiguibaah wrote:
... Where would the Spathi Eluder fit in all this? Smile

Or the Zot-Fot-Pik stinger?
Hmm, the Spathi Eluder is wedge shaped like a viper, just more ugly, right? And the Zot-Fot-Pik stinger resembles a part of the human male body not to be named more directly here, so cylinder?

I see where you wanna go with that questions, but they aint a true problem. Nearly all spaceships will come down to a simple geometrical form with appendages.

Look at the Enterprise: A disc, 2 cylinder, and a connecting cylinder. And thats a fairly complicated arrangement.

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#7 Post by PowerCrazy » Fri Nov 19, 2004 8:01 am

I do kind of like the idea of defining an airframe for the ships.

Sphere:
maximum surface area/volume Lots of guns/missiles etc.
minimum manueverability/speed
Typically very large (battleships, dreadnoughts, doom stars).

Wedge/cone:
Spinal Mount Cannons.
Manueverability and speed.
typically for manueverable ships (fighters,cruisers).

Ellipsoid:
Maximum Surface area
Good Speed poor manueverability
For carriers typically.

Oh and the Surface area of a Sphere is 4*Pi*R^2 Impaler.
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#8 Post by Bastian-Bux » Fri Nov 19, 2004 8:22 am

Powercrazy wrote:
Oh and the Surface area of a Sphere is 4*Pi*R^2 Impaler.

And as R = D/2 -> 4*pi*R² = 4*pi*(D/2)² = 4*pi*D²/2² = 4*pi*D²/4

= pi * D²

Much easier :).

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#9 Post by Geoff the Medio » Fri Nov 19, 2004 9:01 am

Bastian-Bux wrote:An example with mathematical formulaes.

Lets take a cube (=the most efficent box) and a sphere, both with a diameter (cube = length) of 1m.

The cube is very easy: 1*1*1= 1 m³ volume, and 6*1*1 = 6 m² surface.

So 6:1

The sphere is also not to difficult: pi*1*1*1 /6 = pi/6 ~ 0.52 m³ and pi*1*1 = pi ~ 3.14 m² for the surface.

So also 6:1 ;).
Saying the surface area to volume ratio of a sphere and cube are the same because the ratio is the same if the cube side length equals the sphere diameter is kind of misleading. The volume of the sphere is question is somewhat less than the cube you've compared it to. You have just picked the particular value for those two parameters (sphere radius and cube side length) at which the ratios work out to be the same. It looks good, because both parameters seem like natural / obvious ones, but this just hides the fact that the objects have different volumes. It would be just as valid, though less good-looking, to claim that the box of side lengths 2d, d and d, with volume 2*d^3 and surface area 10*d has the same SA:V ratio as a sphere because if d = 5/3 m, it has a SA:V ratio of 6 as well.

If the sphere and cube have the same volume (so presumably the same "cost"), things are different. For a 1 m^3 volume, the sphere diameter is 1.24 m and sphere surface area 4.84 m^2. The SA:V ratio for the sphere is 4.84 (should have units 1/m), compared to 6 for the cube, as before.

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#10 Post by Bastian-Bux » Fri Nov 19, 2004 9:38 am

You are right geoff, my fault :). I did know that the sphere IS the est surface/volume ratio body, but was misslead by my calculation ;).

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#11 Post by iamrobk » Fri Nov 19, 2004 12:07 pm

The fact is, this is getting really confusing and complicated, and I know I for one don't want to have to deal with all this. Why not just have it so that hull X has Y space, so I can fit Z amount of A, and B amount of C, and whatever.

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#12 Post by Bastian-Bux » Fri Nov 19, 2004 1:26 pm

Thats what the player will see at the end. but someone has to come up with those numbers :).

So either we "invent" those numbers freely, and end up with totally weird things. Or we use some mathematics to get to that numbers. Or we include a routine into the game that allows this mathematics to be made during the game, increasing the number of possible hulls.

Anyway, if we dont wanna invent the numbers we HAVE to get through the math.

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#13 Post by utilae » Fri Nov 19, 2004 10:10 pm

What if we had hull shapes, eg:
Cube, Sphere, Wedge, etc

and also shapes for components that go in them, eg:
Cube, Sphere, Wedge, etc

A component of shape X fits better into a hull of shape Y then it fits into a hull of shape Z. Also the race that you have determines what shape your components will be. So if you are race A, then your components are a circular shape, which fit better into hull shape Y then hull shape Z. Maybe based on what race you are you get 3 hull shapes to use in designing ships.

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#14 Post by guiguibaah » Fri Nov 19, 2004 11:50 pm

Hmm, the Spathi Eluder is wedge shaped like a viper, just more ugly, right? And the Zot-Fot-Pik stinger resembles a part of the human male body not to be named more directly here, so cylinder?

I see where you wanna go with that questions, but they aint a true problem. Nearly all spaceships will come down to a simple geometrical form with appendages.

- - -

Sounds like someone needs to review their SC2 lore! :)

The Spathi Eluder
http://www.classicgaming.com/starcontro ... athi.shtml

The Zot-Fot-Pik Stinger
http://www.classicgaming.com/starcontro ... -pik.shtml


I think perhaps you were thinking of the Supox and the Syreen?

(BTW: I really like that wire-mesh of the Zoq-Fot-Pik stinger).

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#15 Post by That Guy » Sat Nov 20, 2004 12:37 am

As for finding the internal space, if a model is built right, 3DS can find that out for us. I would be willing to scale abunch of ships if necessary so that all the ships have a internal volume close to all others of their class size.
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