Non OTU: Ahab's Traveller Stuff

[Captain_Ahab]

A thread to toss stuff stuff I'm tinkering with
unless otherwise noted, everything I post will be cc-0



Just to start, I'm building a ship, with interior, loosely based off the Gazelle
I need to figure stuff out some old homebrew crap to get some of the details right
I recall I did g-limits, hardpoints, computers and maybe some other stuff differently than MT

similar to something I did ages ago using a cc-0 asset set by greyoxide
the turrets are mine though


Bridge WIP for making deck plans
(yes, the interior fits completely inside the pictured hull)

 

[Spinward Flow]

Can you provide links to the tools you're using for these 3D presentations? Finding good 3D composition tools can be a real chore.

 

[Captain_Ahab]

blender.org - Home of the Blender project - Free and Open 3D Creation Software

The Freedom to Create

www.blender.org

as you can see in the lower right corner of the bridge WIP screenshot, I'm using 3.1
nothing else for these

 

[Captain_Ahab]

In order to continue work on this ship, I have to 'design' it to get certain details about it
unfortunately, blender tells me the volume would be a bit over 500dt, so now I need to settle on a scheme to handle hardpoints before moving on to computers, which I'll need to know to get crew sizes for staterooms and life support.
Hardpoints will be based on the square/cube law to approximate surface area.
I used to estimate this by using math tricks to stretch a sphere inside a bounding box to get general dimensions and area, but I've gotten lazy in my old age.

In the meantime....

 

[Spinward Flow]

Interesting choice for interior layout ... the "railway Pullman car" of putting the staterooms/cabins all on one side with an access hallway on the other side in order to keep the hull slender enough.

From an analysis of alternatives perspective, using a double sided single hallway access is a more efficient use of space than a single sided double hallway arrangement (on two different decks).

Not saying you should scrap and start over ... just noting that it's an interesting choice of design aesthetic.

 

[coliver988]

it may be more efficient unless you need to move wide things through the hallway. not that there is access at either end needing that though. and having additional space, though not directly in most rules, would help with the submarine feeling. can't recall the T5 thing, but basically improves morale or comfort. though admittedly the ships I draw all have single width corridors.

 

[Captain_Ahab]

Well, blender says this ship is about 500dt (3D-Print plug-in can give the volume of a closed mesh), so not exactly similar to the OTU Gazelle
Too bad, as it looks spot-on as far as proportional to humans and all
So be it

So now to worry about niggling issues i have with vehicle construction
First will be hardpoints

I have always felt hardpoints should be related to surface area even though by volume is easier
Hardpoints per volume makes larger ships over powered compared to small ships
Based on the cube/square law, and using a 100dt sphere hull as a reference point, I take the 2/3 power to estimate the number of hardpoints on a ship, and for a sphere this gives 1 hardpoint for an area of ~600m^2

MT gives hardpoints as standard for Traveller AND total volume must be no more than 40% of total vehicle's volume but with an energy budget. This seems an artifact of the writer's poorly mixing HighGuard and Striker, but as there is no actual difference between a spaceship and a vehicle beyond range, really, this doesn't help me.

Number of hardpoints could easily stand in as a unit of measure for surface area and as such could be used to place things on the ship besides weapons. I'll go with some of the larger bits; weapons, sensors, radiators, landing gear (if used) and large hatches/airlocks, and thruster things (no reactionless thrusters IMTU)

I'll treat a 100dt ship as having 6 'hardpoints', one on each side (forward, aft, dosal, ventral, port, starboard) and each object takes up one hardpoint at the sizes used on a std 100dt scout. That gives 1 mounting point per ~100m^2

larger versions of each object may take up more than 1 hardpoint. Thrusters on a heavy cruiser will take up more hardpoints than thrusters on a Type S, for example.
I'll have to work details out later.

To find # of hardpoints for an arbitrary ship, divide the ship's displacement in dtons by 100 and raise the result to the 2/3 power to approximate the surface area relative to the 100dt hull, and multiply by 6.

thus my 500dt ship will have (500/100)^(2/3) * 6 'hardpoints' to mount various spaceshippy hardware on
or 17 spots to fill with thrusters, cargo hatches, weaponry, sensors and radiators. No landing gear though.

 

[kilemall]

Not to counter your choices, but my rationale for hardpoint limits is less surface area but more internal power wiring, large area between exterior and interior for racks or exciter tubes and capacitors.

The more weapons mounted the more this crawl space gets, duplicate fuel/power/control lines get deleted, supports get removed or cut through and the more fragile the ship is.

Your universe, your preference, just pointing out hardpoints may not be modeling surface area.

 

[Captain_Ahab]

hardpoints are limited by volume in CT, MT, MongT and are more abstract
in TNE and T4, they are limited by hull surface area and are less abstract

I prefer the latter to the former, despite the extra effort
I'm just using the cube/square law to estimate area rather than a full calculation requiring notes or a spreadsheet

Compare a 100dt sphere vs a 100,000dt sphere
100dt has 1 hardpoint for a turret @ 1 per ~600m^2
100,000dt has 1000 hardpoints for turrets @ ~10 per 600m^2

this inconsistency bother me
my method gives 1000^(2/3) = 100 for 1 per ~600m^2 (assuming similar usage for thrusters/sensors/radiators, etc.)

 

[mike wightman]

I prefer to model hardpoints based on surface are too, I have posted on this a few times. The GURPS Traveller Interstellar Wars ship design sequence is probably the best version I have seen that includes surface area as a factor on hardpoint number.

 

[Captain_Ahab]

I did some quick figuring on what can fit on a hardpoint based on a type 'S' and T4 FF&S tables

assuming a 1000 tonne mass, and 20,000kN thrust, it looks like a hardpoint would carry ~10m^2 of thrusters
This fits with ~10m^2 for a 3dton turret socket, ~10m^2 EMS+PEMS sensor arrays and ~10m^2 radiators for the power plant as per T4
I'll just assume landing gear takes up 1 hp on a type 'S' and scale up/down if needed (big ships probably won't be able to land anyways)
and ~10m^2 seems a decent size for a cargo hatch
So I'll go with 1hp per 10m^2 for the equipment being considered

Given that my ship is about 500dt, it will need 5 times the thrust to have 2g performance, which will take up 5 of the available 17 hp, leaving 12 for turrets, sensors, a cargo airlock and radiators

it seems obvious that large ships will not have high accelerations with HEPlaR unless mass (armor) is cut to an absolute minimum, and they may also be power starved for lack of radiators... mass will increase far faster than available surface area

I can ignore heat with thrusters as hot mass is dumped overboard anyways
powerplants would only come online as needed with a warmstart for weapons' powerplants and power to charge jump capacitors which would only be run when needed
running 'silent/cold' would be using power caps/batteries to power things so all powerplants could be shut down or idled and only life support, computers/controls, passive sensors and comms would be drawing power

I'll eventually do other ships and see if this holds up for other cases

for small ships, I think i'll have to keep 1 decimal place for hardpoints

---------

I'm sticking to MT and T4 plus houserules
those are the only rulesets I still own concerning Traveller

 

[Spinward Flow]

If you're using a surface area rather than volume model for hardpoint eligibility ... then Sphere configurations will have the lowest surface area to volume ratio (making a Tigress style class a less viable battleship proposition), while Dispersed Structure configurations will have a MUCH higher surface area to volume ratio (think about it).

CAN it be done? Yes, of course ... with enough time, tools and tech manuals, you can do almost anything.
Is it WORTH THE ADDED COMPLEXITY to try and model this? Often times no ... but sometimes yes, if you're willing to throw enough time, tools and tech manuals at the problem to "solve" it.

I'm thinking that "added layer of complexity" is the reason why CT went with a volumetric displacement rather than any kind of surface area "limit" on hardpoint allocations. The volumetric approach is just so much SIMPLER (to explain, to calculate) than the surface area approach in a design sequence as abstracted as LBB2 and LBB5 (et al.) used. It's only once you start getting into MT and later where you're defining actual dimensions and ship mass and so on in an extended Striker-esque design sequence that you can even begin to get close to being able to calculate surface areas ... and of course 3D modeling software such as Blender which can be used today for deck plans will make it much easier to approximate such derived characteristics.

 

[Captain_Ahab]

I've done the 'calculate surface area' before by doing math stuff on a sphere inside a bounding box and then stretching that bounding box in different ways (fineness ratios, etc.) that also gave cross sectional area for aerodynamics stuff concerning life and drag (you probably don't want to do mach cones and stagnation points as that would mess up most ship designs in an atmosphere)
if there is an interest, I'll post it even though I don't really use it anymore

easy to do in a spreadsheet

but using the cube/square law is very simple and good enough considering that editions of trav that don't use area all base their hulls on spheres with modifiers for other configurations, which i can also use
thus this method is more complex only by raising the dtons/100 to the 2/3 power
the rest is as easy as looking up stuff on tables once the relationships are worked out, which I am doing for my own enjoyment

but I feel this models my Traveller universe better for only the cost of a few extra keystrokes on a student calculator

 

[Captain_Ahab]

I've forgotten so much and I have no errata for some things making this a bit of a slog
(MT EMS tables, some weird decimal points???)

anyways, doing a MT scout, and tinkering, I figure a hardpoint can be worth 12.5m^2

based on T4 numbers, that will allow HEPlaR thrust of 25,000kN and 12.5m^2 isn't too much larger than the nozzle of a Rocketdyne F1 engine's nozzle. I'll use ammonia as source of hydrogen and reaction mass.

a fusion PP operating at 90% can allow 1000Mw to radiate 100Mw waste heat at ~8MW/m^2 for a blackbody temp of ~3500K, which is doable

J-drive just vents waste heat by dumping thermal mass overboard.... the fuel, but I'm going to handwave it as enough

turret
landing gear
AEMS
PEMS
round out the remaining Hardpoints for a 100dt Scout

now to make a cheap spreadsheet for this
a relaxing way to spend my retirement, eh?

 

[Captain_Ahab]

another minor bit for hulls is that max acceleration possible is 10g's*(armor toughness/7.97)*(dton/100)^(-1/3)
assuming a refence ship being a 100dton tech-10/crystaliron ship being stressed for 10g's max
(7.97 toughness for crystaliron needs to be mulitpied by ~1.45 to get T4 toughness values)

along with limited area available for thrusters, giant ships likely won't be able to accelerate very fast

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

Thinking about computers in MT
Instead of buying a computer with a certain CP multiplier, divide each computer stat by the CP multiplier to get a number of "cpu's" for each control panel
The computer number used for tasks in combat, etc. then becomes sqrt(cpus/control_panel)-2,
then make a table that differentiates cpu's for each tech level instead of there being only minor differences for each tech level
It could integrate the CPU and storage parts of a robot brain
Something to work on, but it won't be an easy fit and might be a bit weird given how robots figure Int and CP multipliers, but could be fun to worry about software use

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

I set up a blender material to make grids on floors for deckplans and added some color, but I still need to model some bits and organise my assets better
Once I'm happy with it, I'll release deckplans and the .blend file, too

For this tech-10 ship. I'm guessing a crew of 18

 

[Spinward Flow]

For this tech-10 ship. I'm guessing a crew of 18

18 is a LARGE crew for a 400-600 dTon starship.

The legacy Type-T Patrol Cruiser has a crew of 10 (pilot, navigator, 3x engineers, medic, 4x gunners) plus 8 troops for boarding parties.

 

[Grav_Moped]

18 is a LARGE crew for a 400-600 dTon starship.

The legacy Type-T Patrol Cruiser has a crew of 10 (pilot, navigator, 3x engineers, medic, 4x gunners) plus 8 troops for boarding parties.

Two of those troops double as the pilot and gunner for the carried Ship's Boat, but even if they were separate crew positions that'd only bring you up to 12 on that 400-tonner. Which further supports your point, as the boarding team is basically an armed group of passengers with a small craft.

 

[Captain_Ahab]

An estimate based on my own experience
12 on/12 off plus port/starboard duty sections standing watch
CO and XO, a couple of nco's, then ratings, so maybe 16 instead
most of the time, 'work' means maintenance/cleaning/paperwork/training

Naturally, I'm working on computers as a way of determining crew sizes, as per MT, but MT is not so good, imho
In MT, crew size is related to control panels and control panels are determined by ship's price and tech level
because prices are also related to tech level and increase with tech in a non-linear fashion, higher tech means more crew although tech mitigates this some through cp multipliers, but it looks like prices increase much faster than the multipliers, so even then, high tech computers may increase crew sizes

Even for control panels, tech-9 computer linked are superior to tech-13 holographic linked for a given volume

I'll have to look to see how T4 does it
a quick glance seems more reasonable as it appears to not be based on price
MT would require an overhaul to suit me

 

[infojunky]

First will be hardpoints

I have always felt hardpoints should be related to surface area even though by volume is easier
Hardpoints per volume makes larger ships over powered compared to small ships
Based on the cube/square law, and using a 100dt sphere hull as a reference point, I take the 2/3 power to estimate the number of hardpoints on a ship, and for a sphere this gives 1 hardpoint for an area of ~600m^2

Hum, one of my favorite Rabbit holes.

MT gives hardpoints as standard for Traveller AND total volume must be no more than 40% of total vehicle's volume but with an energy budget. This seems an artifact of the writer's poorly mixing HighGuard and Striker, but as there is no actual difference between a spaceship and a vehicle beyond range, really, this doesn't help me.

MT in technical terms is irreversible broken due to its reliance on Striker... i.e. the "Traveller" portions of Striker are pretty much ad-hoc. A 250mw laser basically will burn through all armor ratings of High Guard ships per those rules.

To find # of hardpoints for an arbitrary ship, divide the ship's displacement in dtons by 100 and raise the result to the 2/3 power to approximate the surface area relative to the 100dt hull, and multiply by 6.

Gee, I have used that set of calculations with variation. Though I tend to go with 3 three instead of a 6, but I tend to track just the weapon load out.

With that one ends with fewer Hardpoints per capita, but then consider larger weapons would use just a hardpoint. Fewer weapons but larger weapons.

thus my 500dt ship will have (500/100)^(2/3) * 6 'hardpoints' to mount various spaceshippy hardware on
or 17 spots to fill with thrusters, cargo hatches, weaponry, sensors and radiators. No landing gear though.

 

[Captain_Ahab]

Hum, one of my favorite Rabbit holes.

Now that I am retired, I have an abundance of time to fill until I drop dead

MT in technical terms is irreversible broken due to its reliance on Striker... i.e. the "Traveller" portions of Striker are pretty much ad-hoc. A 250mw laser basically will burn through all armor ratings of High Guard ships per those rules.

Not really
Based on pen/dmg given in MT (at best, 80/5), a 250Mw laser can normally only get a low pen result against spaceships and many grav-tanks, and a high-pen only against the bare minimum armor allowed for spaceships.
And zero pen against battleships and many cruisers

the 'high guard' style combat is rough to work with the large-scale combat rules in the Ref companion anyways