GURPS Spaceships, in use!

[David L Pulver]

Originally Posted by ectropy

So, I've got a directed question for any of you:

Without superscience, how do you get a colony ship to Alpha Centauri (requires about 4000 mps delta-V)?

At TL9, it seems impossible - even using a magsail for braking (to save half the delta-V requirement), multi-staging like crazy, an Adv Fusion Pulse Drive, and the Delta-V Increase table on page 27, that still gives only 32 mps per stage... which comes to 63 stages.

At TL10, it comes just into possibility - using the same parameters, you get 160 mps per stage, or 13 stages. If the colony ship (final stage with magsail) is SM+10, the whole vessel would be SM+23 when it leaves the solar system. And let's not even mention the cost...

At TL11, it becomes possible to do - same parameters again, leaves us with only four extra stages necessary. When it leaves the solar system, the colony ship (SM+11) with all its boosters is going to be SM+15 or larger.

Antimatter has higher delta-V, but generally the fuel costs so much more than the efficiency increase, that it isn't worth it. The exception might be Antimatter Pion (3400 mps per fuel tank), which means that the colony ship could get there in a single stage, 2 at the highest. Fuel cost is still astronomical.

So... am I missing anything?

A lot of colony ships are in book 5. Quick and dirty to carry a minimum of 500 colonists, try a SM+13 ship set up like this:

Front Hull
[1] Diamondoid armor
[2] Habitat (500 luxury cabins, 100 minifacs, 100 establishments, 100 labs, 2,500 tons cargo.)
[3] Hangar (10,000 tons of landing craft, roll on/off cargo, probes, etc.)
[4] Magsail
[5] Open Space (farms)
[6] Fuel
[core] Control Room

Central Hull
[1] Diamondoid Armor
[2-6] Fuel
[core] Reactor

Rear Hull
[1] Diamondoid Armor
[2-5] Fuel
[6] Adv. Fusion Pulse

It therefore has 10 fuel tanks. At TL11, an advanced fusion pulse drive gets 350 mps per tank. We multiply that by 1.4 for having 10 tanks, which gives us a 490 mps per tank. 490 x 10 = 4,900 mps, and we're off with room to spare!







Suppose you assume that 12 systems of the colony ship will be fuel tanks.

[David L Pulver]

Originally Posted by ectropy

So, I've got a directed question for any of you:

Without superscience, how do you get a colony ship to Alpha Centauri (requires about 4000 mps delta-V)?

At TL9, it seems impossible - even using a magsail for braking (to save half the delta-V requirement), multi-staging like crazy, an Adv Fusion Pulse Drive, and the Delta-V Increase table on page 27, that still gives only 32 mps per stage... which comes to 63 stages.

So... am I missing anything?

Yah. I think you missed that the delta-V is per tank. E.g., if you've got advanced fusion pulse at 20 mps/tank and then use 13 tanks for a x1.6 on the delta-V increase table, the delta-V is calculated as follows:

20 mps x 13 tanks x 1.6 = 416 mps. So it's only 10 stages at that TL. Still kind of dubious, though you do better with magsail and the final stage being mostly tank. But in fact, you can do slow interstellar as a practical multi-stage at TL10 and as a single stage at TL11 (TL10 if you go antimatter plasma). And you can reach 10-12% of light as a multi-stage (Daedelus, etc.) at TL11 without too much problem.

[dirtysnowball]

Contragrav? Stardrives? Beam weapons?
Ha!
All you need in enough plutonium.

RICKENBACKER-CLASS "INTERCEPTOR" (TL7)
The standard US Aerospace Force light space combatant of the early 1970s, designed for operations in the Earth-Moon system but capable of making it to Mars (especially after the arrival of more efficient TL8 pulse units in the 80s).

TL: 7
dST/HP: 100
HT: 12
Hnd/SR: -1/5
Move: 2G/8mps
SM: +9
LWt: 3000t
dDR: 10/10/50
Occ: 30ASV
Load: 148t
COST: $163.5 million, plus $150 million fuel (pulse units), plus $66.67 million ammo (even more with nuclear-tipped shells and missiles, which typically made up much of the warload).
Crew is 22
Notes: Designed to fight facing backwards with the massive armour of the pusher plate facing hostile fire.

Front Hull
[1] Light Alloy Armour (dDR 10)
[2] Tactical Array
[3] Defensive ECM
[4] Fuel (150t pulse units)
[5] Fuel (150t pulse units)
[6] Fuel (150t pulse units]
[Core] Habitat (5 cabins, 5 bunkrooms, briefing room, sickbay, rec-room/gym, 45t steerage)

Centre Hull
[1] Light Alloy Armour (dDR 10)
[2] Major Battery (20cm gun)
[3] Major Battery (20cm gun)
[4] Tertiary Battery (10 x 3cm VRF guns), 100t cargo
[5] Major Battery (30 x 40cm missiles)
[6] Fuel (150t pulse units]
[core] Control Room

Rear Hull
[1] Orion Drive (2G acceleration)
[2] Light Alloy Armour (dDR 10)
[3] Light Alloy Armour (dDR 10)
[4] Light Alloy Armour (dDR 10)
[5] Light Alloy Armour (dDR 10)
[6] Light Alloy Armour (dDR 10)

[David L Pulver]

[QUOTE=dirtysnowball]Contragrav? Stardrives? Beam weapons?
Ha!
All you need in enough plutonium.

RICKENBACKER-CLASS "INTERCEPTOR" (TL7)
The standard US Aerospace Force light space combatant of the early 1970s, designed for operations in the Earth-Moon system but capable of making it to Mars (especially after the arrival of more efficient TL8 pulse units in the 80s).

Nice design! Lots of real guns, none of those wimpy lasers. Now, if we only new what Casaba Howitzer was...

These are good fun A few years ago, I proposed two settings for SJ Games. One was an alternative-history book in which US and Russia happily built all this sort of stuff in the 1960s and 70s and colonized the system; the other was Transhuman Space. I'd still like to do it, actually.

[Not another shrubbery]

Originally Posted by David L Pulver

Now, if we only new what Casaba Howitzer was...

That's my melon cannon, baby!

I said it, and I'm glad!

heh

[dirtysnowball]

Originally Posted by David L Pulver

Nice design! Lots of real guns, none of those wimpy lasers. Now, if we only new what Casaba Howitzer was...

These are good fun A few years ago, I proposed two settings for SJ Games. One was an alternative-history book in which US and Russia happily built all this sort of stuff in the 1960s and 70s and colonized the system; the other was Transhuman Space. I'd still like to do it, actually.

Well, I'll buy it in a flash... Maybe an Infinite Worlds ebook?

Assuming that Casaba Howitzer is some sort of weaponised Orion pulse unit, a one-shot plasma beam, I suppose it would be used like a short-ranged X-ray detonation laser. It could be a missile warhead, or fired safely clear of the ship on a small rocket then aimed and fired by remote control.
Unless you just detonate the thing aboard your ship like one of Doc Smith's primary beams...

Full marks for GURPS Spaceships, for me it's the nicest balance of realism, detail (these aren't the same thing), flexibility and playability I've seen in a set of ship design rules. And it lets me build the atomicpunk space battleships that have been orbiting in the back of my brain for years now...
I would like to see the ability to make smaller craft, though. And a Transhuman Space Ship Book (Volume 1), and a pony, and...

[DemiBenson]

Originally Posted by David L Pulver

Yah. I think you missed that the delta-V is per tank. E.g., if you've got advanced fusion pulse at 20 mps/tank and then use 13 tanks for a x1.6 on the delta-V increase table, the delta-V is calculated as follows:

20 mps x 13 tanks x 1.6 = 416 mps. So it's only 10 stages at that TL. Still kind of dubious, though you do better with magsail and the final stage being mostly tank. But in fact, you can do slow interstellar as a practical multi-stage at TL10 and as a single stage at TL11 (TL10 if you go antimatter plasma). And you can reach 10-12% of light as a multi-stage (Daedelus, etc.) at TL11 without too much problem.

It's not that I missed (since several others of my designs dutifully added up dV from multiple tanks), but I .... er.... missed adding up the dV per tank for these calculations.

Yeah, that makes a lot more sense now.

Off to finish my Jump Gate carrier vessel...

(Note to self: no more Spaceships while at work)

[ham2anv]

B'rel-class Bird-of-Prey

The B'rel-class bird-of-prey is the workhorse of the Klingon fleet. Small, sturdy, and well-armed for a ship its size, the B'rel is designed to be a fast attack ship, often deployed in packs of 3-5.

The B'rel's major problem is that it is woefully underpowered. This isn't noticed while traveling under cloak, but in battle a B'rel's engineering crew will often be found struggling to shuffle energy to critical systems. The most common choice is between two of weapons, secondary impulse engines, and increased deflector performance.

Crew typically consists of a captain, a first officer, a chief engineer, a pilot, a communications and sensor officer, a tactical officer, a surgeon, two gunners, and 36 enlisted technicians.

TL: 12^
dST/HP: 200

HT: 13
Hnd/SR: -2/5
Move: 4G/c
SM: +11
LWt.: 30,000
dDR: 550/550/450
Occ: 52ASV
Load: 5,250
Cost: B$7.33

Design Features: artificial gravity, gravitic compensators

Design Switches: Force Screens are dDRx10 and Hardened 1 against missiles; Force Screens do not regenerate ablated dDR every combat round, but may be jury-rigged to restore half of lost dDR.

Front Hull

[1-2] Exotic Laminate Armor (dDR 200)
[3!] Medium Weapon Battery (2 fixed 3GJ heat beams, 1 fixed 48cm warp missile launcher)
[4] Tactical Comm/Sensor Array (Level 10)
[5!]Secondary Weapon Battery (6 fixed 1GJ heat beams, 3 fixed 40cm warp missile launchers, 1 turreted 1GJ tractor beam)
[6] Control Room (Complexity 9 computer network; 8 control stations)

Central Hull

[1-2] Exotic Laminate Armor (dDR 200)
[3] Habitat (1 luxury cabin, 6 cabins, 12 bunkrooms, 19 replicator minifacs, teleport projector, five-bed sickbay, 40-man mess hall, gym, 745 tons of steerage cargo)
[4-6] Cargo Holds (4,500 tons)
[core!] Cloaking Device

Rear Hull

[1] Exotic Laminate Armor (dDR 100)
[2-3!] Stardrive Engine (FTL-2)
[4!] Heavy Force Screen (dDR 350)
[5-6!] Hot Reactionless Engine (provides 4G acceleration)
[core] Antimatter Reactor (provides four Power Points)

[DemiBenson]

A TL10 (with one TL^ feature) for sending a startup colony to Alpha Centauri without needing a generation ship.


Steppingstone Carrier Booster (TL10)
SM+12 100,000 tons Length 600 feet dST/HP 300 HT13
dDR 0/15/0 Occ 200 Load 65,000 tons Fuel + 30,000 tons Upper Stage Cost $2.39B + $19.5B Fuel
Move 0.005G/2080 mps Hnd/SR -6/5

Front
[1-6] Upper Stage, Steppingstone Carrier (below)

Center
[1-6c] Fuel Tank, holds 35,000 tons ($210M) + Fuel Pellets ($10.5B)

Rear
[1-6] Fuel Tank, holds 30,000 tons ($180M) + Fuel Pellets ($9B)
[c] Advanced Fusion Pulse Drive, 0.005G accel, 100 mps per tank, 10 workspaces ($2B)

Notes: 13 Fuel Tanks gives delta-V x1.6, for a total of 2080 mps.

For a one-way voyage to Alpha Centauri
Time to Accelerate: 18928 hrs (2.16 yrs)
Distance Traveled during Boost: 752 AU
Cruise Time: None. Booster is dropped and Carrier uses Ramscoop to continue

***

Steppingstone Station Carrier (TL10)
SM+11 30,000 tons Length 450 feet dST/HP 200 HT13
dDR 0/15/0 Occ 200 Load 19,300 tons Cost $3,342M + $18M (Fuel)
Move 0.01G/216 mps Hnd/SR -4/5

Spin Gravity, 0.3G max, only center section spins ($1M)

Front
[1-6] Cargo Hold, 10,000 tons, contains Steppingstone Station (below)
[c.] Ramscoop, 3 workspaces ($3B)

Center
[1] Steel Armor, dDR 15 ($6M)
[2P] Fission Reactor, 1 PP, lasts 75 years, 3 workspaces ($100M)
[3] Control Room, computer C9, sensor 10, 15 stations, 3 workspaces ($60M)
[4] Habitat, 200 cabins base, 3 workspaces ($30M)
20 establishments, 200 hibernation chambers, 5 labs including Physics ($14M),
10 MiniRobofacs $1k/hr skill-13 ($10M), 10 offices, 10 bed clinic, 10 automeds ($1M),
300 tons cargo
[5-6] Habitat, Total Life Support, 200 cabins base, 6 workspaces ($60M)

Rear
[1-6] Fuel Tank, holds 9,000 tons ($60M) + Hydrogen Fuel ($18M)
[c] High Thrust Fusion Engine, 0.01G accel, 30 mps each tank, 3 workspaces ($300M)

Notes: The main Cargo Hold is designed as a break-away container for a single vessel - when the Carrier arrives at its destination, the hold's panels are ejected and the Steppingstone Station is released to mag-brake itself into position.
6 Fuel Tanks provide delta-V x1.2, for a total of 216 mps. The Fuel Tanks are used for terminal maneuvering and any braking that cannot be accomplished via the Ramscoop.

For a one-way voyage to Alpha Centauri
Ramscoop Performance:
Remaining Distance to Alpha Centauri: 276848 AU
Travel Time: 357791 hrs (40.8 yrs)
Max Vc: 0.431c (80180 mps)

Total Travel Time: ~43 years, 40 yrs of which is at significant fractions of lightspeed.

***

Steppingstone Jump Gate Station (TL10^)
SM+10 10,000 tons Length 300 feet dST/HP 150 HT 14
dDR 50 Occ 120 Load 1,112 tons Cost $3.0412 B
Move 0.001G/375 mps Hnd/SR -5/5

6 Airlocks (each 4 person)
Spin Gravity, 0.2G max, only rear section spins ($300k)

Front
[1] Nanocomposite Armor, dDR 50 ($50M)
[2] Science Array, sensor 11, 1 workspace ($20M)
[3.] Magnetic Sail, 1 workspace ($100M)
[4-6!!!] Jump Gate, 1000 tons, 3 workspaces ($1500M)

Center
[1] Nanocomposite Armor, dDR 50 ($50M)
[2] Hangar Bay, 300 tons capacity, 100 tons per minute, 1 workspaces ($1M)
[3] Cargo Hold, 500 tons
[4!] Fabricator Factory, $100k/hr, 1 workspace ($1B)
[5!] Mining Processor, 50 tons/hr, 1 workspace ($10M)
[6PP] Fusion Power Plant, 2 PP, lasts 200 years, 1 workspaces ($100M)
[cPP] Fusion Power Plant, 2 PP, lasts 200 years, 1 workspaces ($100M)

Rear
[1] Nanocomposite Armor, dDR 50 ($50M)
[2-3] Habitat, 120 cabins base, 2 workspace ($20M)
[4] Open Space, 5 areas, devoted to farmland, 1 workspace ($100k)
[5] Open Space, 5 areas, 1 workspace ($100k)
[6] Control Room, computer C9, sensor 9, 10 stations, 1 workspace ($20M)
[c] Hangar Bay, 300 tons capacity, 100 tons per minute, 1 workspace ($1M)

Crew: 16 techs, 10 bridge => 26 crew on each of 3 shifts => 78 regular crew

Notes: This station is designed to be the minimum necessary to establish an industrialized colony. Primarily, this will be immediately setting up the Jump Gate back to Earth so specialized vessels can arrive.
However, the designers considered the possibility that no support vessel would arrive from Earth. Therefore, the Steppingstone Station has just enough refining and factory capacity to create its own support ships, although at a shockingly slow pace. In this scenario, the Carrier vessel would certainly be cannibalized for parts to speed up the process.

[Moonsword]

How is it supposed to slow down? When the ship has to reverse thrust, the ramscoop is going to be pointed aft and therefore not much use for pulling in reaction mass, if I understand the physics correctly.

Also, a 43 year flight time is getting up to the point where you probably want to consider transhuman solutions for crew - robots, AIs, mind emulations, or simply humans genemodded for an extended lifespan.

I like the design, though, aside from those caveats above (one of which is more of a setting concern than a design caveat anyway).