Spaceships Stats for Future Armada Vessels

[tratclif]

Thanks again for posting all this work. I'm looking forward to the conversion notes, since I have a few d20 spaceship .pdfs lying around.

[SCAR]

Custom Components

I’ve used a couple of custom components in these write-ups, where GURPS Spaceships just doesn’t seem to have a suitable item.

T2 Transport System, Feature used by [FA10: Argos III] and [FA11: Invictus]
Available for SM+9 or larger ships, which have; elevators, turbo-lifts or other internal rapid-transit systems (Spaceships p10 ‘Free Equipment’)
Turbolifts (or whatever) can be ejected from the Spaceship and used as Escape Pods for up to SM-4 people each, with 24-hours of basic life support.
Cost is $10M at SM+9, $30M at SM+10 (following the standard 1,3,10 sequence).
The feature provides 3 Escape Pod/Lifts at SM+9, 10 at SM+10, etc.

For the write-ups, I priced the Feature as per a Fission Reactor, which I estimated was the ‘average’ component for cost purposes.
Alternatively, price could be per Escape Pod, with a maximum number of Lift/Escape Pods for a given SM.


Extended Life Support, System used by [FA10,11,14: Discus Life Boat]
For SM+4 and SM+5 (since standard Habitats are not available at these SM)
Provides 60 people days of Life Support at SM+4 and Costs $30K
Provides 200 people days of Life Support at SM+5, and Costs $100K


Life Support, Specialised Habitat/Cabin used by [FA13: Standard HMT-555 Cargo Pods]
Life Support [1], Provides Unlimited Air & Water for up to 10 people, as well as basic facilities;

The Life Support statistics were estimated based on requirements, rather than calculated from existing components – so they may not be entirely balanced.

[SCAR]

Conversion Notes

Reading the d20 stats, Progress Level (PL) is basically equivalent to GURPS TL. PL6 is roughly equivalent to TL9, and PL7 to TL10 which covers the majority of the FA spaceship designs and technologies.

For calculating SM from Mass (tons) I used: SM=2xlog(tons)+2; and for SM from Length (yards) I used: SM=6xlog(length)-2; converting for the listed Length, and then for half and double that length to give an SM range (since GURPS Spaceships can be between half and double the listed Length for a given SM)
These give an SM which can be used as a starting point, but which might get adjusted up or down by one step if required, within the SM range from length.

The deck plans are drawn on a square grid, each 5 feet. (Notes in the text suggest this could be interpreted as 1.5 or 2 metres if required, so we can assume a little flexibility). For GURPS Spaceships, the only data we have for deck plans are brief notes in the Designer’s Notes, which gives a rough range for the number of 1-yard hexes for systems by SM.
A bit of maths tells us that 1 FA square is approximately 1.6 hexes. Habitats (the main system covered by the deck plans) have around 75% open space, which gives us between 1.2 and 3.5 squares per cabin (for SM+7 upwards at least).
Having run through a lot of deck plans, and juggled lots a figures I found 2 things;

• Habitat systems for FA ships have approximately half the number of cabins (or equivalent) – so an SM+9 FA spaceship would have 10 cabins not the listed 20 from Spaceships.
• An average of 2.33 squares per FA cabin (7 squares = 3 cabins equivalent) gives workable figures when calculating Habitat cabin equivalents from the deck plans.

Control Room Stations on the deck plans can be counted and converted to Control Rooms based on those numbers – several of the larger FA ships have multiple control room equivalents, but I don’t see any problem with having Control rooms split between different map locations as long as it doesn’t bend things too much with regards system location if there were to be damage to specific sub-control rooms.

Cargo systems can be converted directly from the cargo figure from the vehicle stats, although some are a little off with regards ship sizes. Cargo space could also be calculated from deck plan squares using 5 squares of deck for 8 tons of cargo.
A Note of “Tons” - GURPS Spaceship is a mass based system, so Cargo Tonnage is a measure of Mass, whereas FA appears to use Register Tons, which is a measure of internal Volume.
As long as the figures seem reasonable based on the size of ship and its purpose, then we’re OK.

Hangar systems can be converted based on the mass of the smaller ships which are to use them. The FA ships tend to use significantly less Hangar systems than the deck plans might imply, often less than a whole Hangar System. This is again almost certainly due to the use of Register Tons (Volume) as opposed to Tons (Mass).

Armour conversions primarily by TL. Armour systems in d20 account for a fraction of a spaceship’s weight (which we’ll read as Mass which is more sensible anyway) which can be converted directly to a number of armour systems.
Alloy (PL5, 1/8th weight of the spaceship) => 2 or 3 systems of Light Alloy;
Polymeric (PL6, 1/10th weight of the spaceship) => 2 systems of Metallic Laminate;
Vanadium (PL6, military, 1/8th weight of the spaceship) => 2 or 3 systems of Hardened Metallic Laminate;
Neutronite (PL7, 1/4th weight of the spaceship) => 5 systems of Advanced Metallic Laminate;
Cerametal (PL7, 1/8th weight of the spaceship ) => 2 or 3 systems of Nanocomposite;
other Armour systems will be converted as required.

Before we tackle Engines, let us consider Gravity Induction (Contragravity Lifters).
PL7 Gravity Induction would be TL10^ Contragravity, which is consistent with GURPS Ultra Tech. Spaceships gives a Contragravity Lifter TL^ (no specific TL) and a single system can negate up to 10G.
A single Contragravity Lifter system on a spaceship would reduce acceleration and delta-v requirements for landing and take-off considerably, and would allow for much lower power engines.
These conversions will not use Contragravity Lifters as a default for TL10+. It is easier to add a Contragravity Lifter system to one of these conversions, and remove Fuel Tanks and even Engines while retaining sufficient acceleration and delta-v for takeoff; than it would be to remove it and recalculate engine and fuel requirements to replace it.

If you do want to use a Contragravity Lifter in any of these designs, remove a Fuel Tank or Engine system (adjusting fuel or high-trust options if required), and replace it with the following system (using the Smaller Systems rules from SS7.p4)

-1.SM Contragravity Lifter (3G); -1.SM Contragravity Lifter (3G); -1.SM Fusion Power Plant

This single system using -1.SM ‘smaller’ systems is a self-powering Contragravity Lifter system which can negate up to 6G.

Engines are a little trickier since d20 uses generic Thrusters for planetary ascent and descent, largely ignoring fuel requirements; and the Particle Impulse Engine is way more optimistic about the effectively free ram scoop and interstellar dust as fuel!
For simplicity and usability, I will be converting the predominately used Ion Engine and Particle Impulse Engines (with Thrusters) to TL10^ Fusion Torch engines, and then fiddling with the choice of fuel (Hydrogen/Water), High-Thrust option and number of Fuel Tanks to get reasonable Acceleration and delta-V to allow for planetary landing and takeoff. The Fusion Torch also supports the Ram Rocket Feature which would reduce fuel requirements in an atmosphere.
The other main engine used in FA spaceships, the Induction Engines can be converted to Reactionless (Standard or Hot), and require no fuel. Other engine configurations will be converted as required.
Military ships could use the A/M Plasma Torch instead of the Fusion Torch (since the military could afford the cost of antimatter fuel), which would allow for fewer engines and fuel tanks to meet equivalent acceleration and delta-v requirements. The Plasma Torch engine from SS7.p16 would also be a good choice for alternate conversions.

Weapons conversions might depend upon setting specific technology restrictions; simple conversions (primarily by Type and TL) are as follows:
Lasers convert to Lasers!; Mass Cannons to Electromagnetic Guns; Mass Reaction Missiles to X-Ray Laser Warheads; Plasma Cannons to Plasma Beams; and Plasma Missiles to Antimatter Warheads; other Weapon systems will be converted as required.
Battery Size, along with Fixed/Turreted will be defined based on descriptions; PDS can be converted to a Tertiary Battery of suitable Guns or Beams, or a VRF Gun or Beam.

Power Plants will be based on TL of the Ship; Fusion Plant for TL9, and Antimatter for TL10;

For d20, FTL is primarily a function of the various Engines (if FTL is possible in the setting); the specifics of the Jump technology in the FA ‘setting’ assume that any PL7 spaceship larger than a fighter or shuttle has an FTL drive; all PL8 ships will have one; and most PL6 ships will not have one (exceptions are possible).
Following these guidelines, these conversion will have an FTL system where required and where possible.

One interesting note with regards Power Points and Smaller System:

SS7 specifically says that Smaller power plants do not provide sufficient power for normal-size systems.
However, at SM+9 a 1GJ Beam is a Major Battery and requires 1 (SM+9) Power Points; 3 such Major Batteries would require 3 (SM+9) Power Points. Those same 3x 1GJ Beams at SM+10 would be a Medium Battery and would require 1 (SM+10) Power Point. So, we can reasonably consider 3 Power Points at a given SM to be equivalent to 1 Power Point at +1 SM.

For Lifeboats and Escape Pods I’ve hand waved how and where they are carried, most spaceships should have sufficient hanger space carry them. Only the Discuss (11-person) Lifeboat has been converted to an actual GURPS Spaceship, the rest seem best modelled as the Life Pods and Drop Pods from Ultra-Tech p232. See Optional Rules below


Optional Rules

Eric B. Smith, author of the Spaceships Design Spreadsheet as some Optional Rules (pdf) which I would make use of for my own games, specifically:

Mixed Battery – allows the mixing of different sized Mounts in a Weapon Battery – for example: a Medium Battery can hold 2x Medium Mounts, and the third Medium Mount is replaced with 10 Tertiary Mounts, which is useful for converting FA/d20’s PDS systems to multiple smaller weapons on a GURPS Spaceship

Alternate Habitats:
Life Pod – basically a Ultra-Tech Life Pod (which mass 1 ton), as part of a Habitat (the likely location for Escape Pods anyway; 5x Life Pods for 1 Cabin equivalent.