The Eight Worlds -- Ship Construction
     Airframe, Engineering, Lifesystem, Weapons, and Avionics

Overview

Starships in the Eight Worlds were comparatively low-tech, more like hypersonic aircraft with limited space capability than the vessels of Star Trek or Star Wars. Think of something like the Space Shuttle with a fusion reactor and hyperdrive tucked away in the cargo bay. This tech level was chosen because it was easy to relate to. We can instinctively guess how reaction drives or gigawatt x-ray lasers will behave, without having to invent an arbitrary and inconsistent set of rules for magical new technologies. This might not be the case for anti-gravity devices, matter transporters, or simple and reliable computer operating systems. It was also chosen because rocket ships are fun.

An Eight Worlds starship contains the following subsystems:

  • Hull -- The aeroshell, atmospheric drives (thermal turbojets powered from the fusion reactor), landing jacks, and VTOL lifters, if any. Structure -- the rivets, girders, and whatnot that hold the ship together and keep it from folding up under acceration -- is more closely associated with the drives. For this reason, it is included with the Engineering Plant rather than the Hull.
  • Engineering Plant -- The fusion reactor and power convertor, fusion drive, structure, and hyperdrive.
  • Fuel System -- Fuel tanks along with the refiner and scooper, if any.
  • Weapons -- Various forms of lasers, along with a limited number of missile and warhead types.
  • Shields -- Large capital ships, which are easier to hit due to their larger silhouette, may carry shield generators. These are very expensive in terms of power and weight.
  • Lifesystem -- Bridge (usually armored, and large capital ships may have more than one), staterooms, coldsleep berths, autodocs, food converter, air and water recycling, and the ship's supply of chocolate.
  • Avionics -- Includes everything from sensors to computers. This is a huge can of worms, and it will take me some time to transcribe all of the relevant rules.
These systems are desribed in greater detail in the section on technical background below.

Units and Currency
The Eight Worlds uses the metric system. Most weights in the construction tables below are given in metric tonnes (1000 kg, abreviated 1 Tn). Prices are in Eight Worlds currency and should be assumed to be in Ducats (D) unless otherwise noted.

How Can Freelance Starcrew Afford All This?
They can't. But like all vehicles, starships decline in value, price, and reliability with age. Prices below are for new ships, listed as Grade One by an underwriter. Grade Two ships are approximately 1/3 the price of Grade One, abd correspondingly less reliable. Grade Three ships are 1/10 the priice of Grade One -- the equivalent of a used car with 150,000 miles -- which makes them just barely affordable to free-lance starcrew. Grade Four ships exist, and occupy roughly the same rule as a rusted-out pickup truck on cinder blocks in front of the trailer home. They may serve a valuable decorative function, but no one with any sense of self-preservation would consider actually flying one.


Technical Background

Drives
In normal space, ships use fusion-powered reaction drives. These consist of linear fusion reactors, partially open at one end, that burn a deuterium-deuterium or deuterium-tritium plasma. Efficiency is low compared with ship's electrical power plant, but the combination of modest temperatures, high throughput and ready availability of the relevant fuels makes this design particularly well suited to heat a reaction mass. Specific impulses are high -- comparable to ion drives -- but unlike ion drives there are no space charge effects to place an upper limit on thrust. Acclerations typically range between 2 and 4 g's, though higher values can be achieved by sacrificing such luxuries as hyperdrives, life support systems, armor, and sanity.

Drives are generally lumped together with structure, since a ships that produces 800 tonne-g's (8 M-NT) of thrust will require a structure that can withstand this load whetrher it be a 400-tonne packet accelerating at 2 g's or a 200-tonne corvette accelerating at 4 g's. Some barbarian cultures skimp on structure to reduce weight -- accepting the risk that the ship might break up to achieve additional acceleration. They are a source of amusement and concern to their neighbors.

Fusors
Ship power comes from their fusors. These consist of magnetic confinment devices that burn a proton-Boron plasma at high temperature to produce energetic charged particles that can be directed through an MHD generator to yield electrical power. Power levels are much smaller than they are for the reactors used in the drive systems reactors, are the necessary boron isotope (B11) is compartively rare, but efficiency is significantly higher.

Hyperdrives
Hyperdrives are magic. I don't know how they work. If I did, I'd be running a world-wide shipbuilding empire rather than a web site! From a functional standpoint, they consist of a power-conditioning system, the Mass Transfer Stage, into which one feeds energy to charge the Hyperdrive Core. Once the core is charged, you push a button, a 'hyperdrive envelope' forms around the ship, and it is ejected from ordinary space into some other form of reality. At a predetermined time, which may range from seconds to days, the 'envelope' collapses, dumping power back into the Hyperdrive Core, from which it flows through the Mass Transfer Stage to the Hyperdrive Radiators from which it is radiated away as heat. A during a typical 'jump', the drive is charged for 30 minutes to 3 hours and the ship spends 1-10 days in hyperspace, during which the ship may travel between 3-30 parsecs (pc) depending on its level of technology and the skill of the navigator. The time to emerge from hyperspace is comparable to the charging time. During this interval, the ship is blind, unable to manuever, and produces an enormous and easily-detected heat signature. The tactical implications should be obvious.

Time passes in hyperspace at the same rate as in normal space, subject to the considerations of special relativity. This suggests that it would theoretically be possible to use a hyperdrive as a time travel device it one could jump far enough, but the distance required -- on the order of thousands or millions of parsecs -- is far in excess of anything that can be achived with Eight Worlds technology. In practice, two considerations restrict most jumps to 30 pc or less. The first involves the distribution of interstellar matter along the planned route. If this is not accounted for properly, a 'misjump' will occur. The effects of a 'misjump' range from amusing to disastrous. Second is related to the nature of the hyperdrive envelope. In theory, this should collapse prematurely, with catastrophic effects, if the ship radiates any energy or leaks any mass while in transit. In actual practice, the small amounts of leakage that occur during a few days of transit don't seem to cause problems, but transits longer than a week or so consitute an appalling risk.

No one is quite sure what hyperspace looks like. The experience appears to be random and subjective, for different observers on the same jump can report subtly different things. Over the centuries, a vast mythology has developed that relates the patterns seem in hyperspace to the fortunes of a mission. Legend has it that once in a million jumps, the pattern will suggest a Roadrunner cartoon in which the Coyote catches the Roadrunner. This is thought to be an omen of terrible import.

Lifesystems
A ship's lifesystem is good for 3-4 weeks. If the system is not recharged with a fresh supply of oxygen at this point, mold begins to grow on the walls, the air begins to smell, the water becomes stale and slimy, and life becomes increasingly unpleasant. Somewhere beyond this point, life ends. It would in principle be possible to build lifesystems that could last much longer -- indeed, this is common for space stations, asteroid mining operations, and the like. But such capability would be expensive, heavy, and entirely unnecessary for an ordinary starship given that a typical hyperspace transit lasts only a week.

Laser Weapons
Ships are armed with various forms of lasers, because nothing else really works. The technology, wavelength, output time, and duty cycles, and operating principles of laser weapons can vary widely. A standard laser cannon -- coloquaially reffered to as a 'tube' -- has an output of one Gigwatt, and its range is limited by diffraction effects to 50,000 km or less. Ships are sometimes rated by number of 'tubes' in much the same fashion that vessels during the Age of Sail were rated by number of guns. Myth, legend, and the mass of ambiguous records that survive from the Imperial Era suggest that standard Imperial laser cannon was a gas-dynamic infra-red laser with a beam diameters of a meter or so, built using advanced manufacturing technologies that have since been lost. Modern Eight Worlds vessels use free-electron x-ray lasers to achieve comparable performance.

Durring the past 50 years, the standard 1-cm laser cannon has been supplemented by so-called 'long's of significantly higher output, beam diameter, and range. This has made possible the development of large capital ships. At the other end of the spectrum, several worlds have developed light long-wavelength 'laser carronades' suitable for use on small non-hyperspace-capable vessels such as gunboats and fighters. These new technologies -- and the unlooked-for surprises that have accompanied their use -- have done much to destabilize Eight Worlds politics.

Missile Weapons
Like torpedoes in WW-I, these don't work very well... except when they do. I'll write about them later.



Airframe

This page contains tables for mass, cost, and characteristics of components of the Airframe, including Hull, Shields (if any), Engineering Plant, Lifesystem, Weapons, and Miscellaneous. These ship construction tables apply to any type of high-tech aerospace vehicle, and have been used to design everything from large capital ships of 50,000 tones or more to light ships, auxiliaries, missiles, gunboats, fliers, and flying backpacks. Though those flying backpacks were stretching things a bit.

Each table lists the mass in tonnes, cost in D or F, and any supplementary information for different sizes and ratings of a particular class of component. Thus, a conventional (streamlined) hull for a 1200 tonne light cruiser weighs 24 tonnes and costs 60 D (roughly the cost of an F-22 Raptor), while each one of its five tri-mount laser turrets weighs 7 tonnes, costs 6.5 D, and draws 3 Power Units -- 1 tonne and 0.5 D for the turret itself and 2 tonnes, 2 D, and 1 Power Unit for each of its three tubes. The letter 'N' refers to Power Units, Thrust Units, or Energy Levels. Thus, a fusor that generated 3 Power Units (enough to power one tri-mount laser cannon turret) would mass 33 tonnes and cost 12 D.

A Note on 'Streamlining': The hull table below provides infomation for a conventional 'streamlined' hull, consisting of aeroshell, thermal protection system (heat shield), lifters, and landing jacks. 'Belly-landing gear' consisting of additional lifters, better streamlining, and improved landing jacks, adds atmospheric capability and allows use of more 'rustic' landing zones, but cost an additional 50% in mass and price. 'Unstreamlined' hulls are possible, cost nothing, and are good for nothing.

Hull and Aeroshell
Hull Surf1 Sil2 Mass Price
10 0.2 -2 0.2 0.1
200.3-10.40.2
300.4-10.60.3
400.5-10.80.4
500.6-110.5
600.7-11.20.6
80 0.9 -1 1.6 0.8
1001021
2001044
4002088
600301218
800 4 0 16 32
1200512460
1600613260
2000 7 1 40 60
300092--
4000112--
5000 13 2 - -
7000163--
10,000203--
14,000253--
16,000 30 3 - -
NN2/3-N/20N/30
(1) 'Surface Area' -- how many standard
     laser cannon turrents a ship can carry
(2) 'Silhouette' -- Targetting modifier.
      Small ships are harder to hit.

Shield Generators
Effect1 Power Mass Price
1483
230183
360403
4100603
5160963
62201563
73202603
84604203
96325643
10850-3
1111259783
12 1432 - 3
N0.8N3+5060N2+420.01M
(1) Shields work like silhouette but in reverse,
     making a ship harder to hit.
       Engineering Plant
Power Fusor1 Drive2 Structure2 Jumper
  Mass Price Mass Price Mass Price Mass Price
0.1 3.5 1 5 1 1 0.1 5 5
0.2 5.5 2 6 2 2 0.25 10 5
0.5 8 3 7.5 3 3 0.5 15 5
1 13 4 11 4 6 1 20 5
N 10N+3 4N 10N+2 4N 6N N 20N 5N
(1) Mass and cost of Fusor includes mass and cost of the Convertor.
(2) Generally, Drive and Structure go together, and N units of thrust will require
     N units of Structure, but it's possible to skimp on Structure to save mass,
     improve performance, and risk death.

Energy Weapons
Type Tubes1 Turret2
  Output Power Mass Price Hits Surf Mass Price
HLG 0.1 0.1 0.1 0.1 1 0.2 0.2 0.1
LLC 0.3 0.3 0.5 0.5 1 0.5 0.5 0.5
Crnd 1 0.5 1 1 1 1 1 0.5
Pulse 1 0.5 2 1 1 1 1 0.5
LC 1 1 2 2 1 1 1 0.5
[3] 5 5 6 10 3 3 3 1.5
[6] 5 5 6 10 3 3 3 1.5
[10] 10 10 12 20 6 6 6 3
[15] 40 100 40 100 15 15 20 10
[20] 100 300 80 200 20 20 40 20
(1) The characteristics, mass, and cost of an individual gun tube
(2) The characteristics, mass, and cost of a bare tri-mount turret (singles and twins
     cost correspondingly less)

Lifesystem and Miscellaneous
Item Notes Mass Price
Coldsleep1 - 0.2 0.05
Shuttle2 200 hrs4 0.2 0.05
Combat3 200 hrs4 1 0.25
Stateroom 6000 hrs4 2 0.25
Bridge (Armored) (3d6)5 10 0.25
Bridge (Part Arm) (4d6)5 8 0.25
Bridge (No Arm) (5d6)5 6 0.25
Refiner 1tn/day 2 0.5
Scooper - 3 0.5
Tanks Included with Structure
Batteries 0.25 P-hr 1 0.1
Solid Boosters 1 tn-g-hr 1 0.1
Warhead N(d6) 0.04P(N-1) M
(1) Autodocs weigh the same and can function as coldsleep,
     but cost 500 F, and are worth every 0.1 sequin
(2) Lifesystem slot for a shuttle, boat, or lander
(3) Armored acceleration couch for a fighter or gunboat
(4) These appear to be the survival times hamsters. Humans
     would not fare as well
(5) This is how much damage you take if the bridge gets hit and
     your suit can't protect you. Is the saved mass worth the risk?


Avionics

Avionics includes sensors, computers, hardware, and software. These are not strictly comparable to their present-day (Tech Level 8) equivalents since they involve massively parallel distributed systems that have no analogue in present-day techology. In particular, 'hardware' includes a singificant amount of software while 'software' requires a considerable amount of dedicated hardware.

Avionics is divided into 'hardware boxes' and 'software boxes'. (The avionics suite of the Tech Level 12 corvette described below consists of 3 hardware boxes and 2 software boxes that mass 1 tonne). Some of these perform essential functions without which a ship cannot even lift. Others provide desirable functions or optional luxuries. It is common practice to include some redundancy and duplication so that a ship can continue to function if it takes damage.

The Avionics rules are quite complicated in practice, so explanations may take time. After everything was said and done, avionics suites tended to mass between 2-6 tonnes, depending on how capable they were.

Avionics is measured in 'Boxes'
 1 Hardware Box -- 1 MW?
 1 Software Box -- 1 teraflop and/or petabyte?
 
Avionics Mass Price
Hardware 2.5/(TL-3) 0.15
Software 1.5/(TL-5) 0.1

System hdwr/sftwr adtnl cost Comments
Jump 1 1/- 0 Software: HD Nav, HD Control, [Adv Autopilot]
Jump 2 2/- 0 one system is required for each jumper
Jump N ((N+1)/2)2/- 0  
Hyper Nav -/2 100 F Sets up jump (or one can use Jump Tapes)
Hyper Cont -/1 10 F Sets up jump (or one can use Jump Tapes)
Adv Autopilot -/4 500 F As Pilot-1 Nav-2 (Reg Autopilot (-/20 Nav-1)
Orbital Nav -/1 100 F As Pilot-2
Turrent Control 1/- 0 Allows computer to control one turret
Adv Sights 1/- 500 F Allows manual control via Gunner skill
Targeting 1 -/0.5 50 F As Gunner 1
Targeting 2 -/1 100 F As Gunner 2
Targeting 3 -/2 500 F As Gunner 3
Evasion 1 -/0.5 10 F Allows 1/4 Pilot skill
Evasion 2 -/1 30 F Allows 1/2 Pilot skill
Evasion 3 -/2 100 F Allows all Pilot skill
Auto Evade 1 -/1 10 F As Pilot 2
Auto Evade 2 -/3 10 F As Pilot 4 [(-/2: -3), (-/6: -6), (-/8: -7), (-/10, -8), ...]
Sensors 1/- 0  
Ranging Gear 3/- 1 D  
[X Range] 6/- 3 D  
[Adv Range] 12/- 9 D  
X Sensors 6/- 1 D  
Ranging Prog -/3 100 F  
Spotting Prog -/3 200 F  
Missile Control -/3 200 F  
Jammer 3/- 1 D  
Missile Guidance -/1 0  
Hypertrace 1/1 300 F  
Terminal 0.2/- 0  


Examples

Two examples are provided below: a Scout and a Corvette

Singleship Scout (SS)
Equivalent to the classic 100-tonne Traveller 'Scout Ship'. Unarmed, limited to 2 g's and Jump 2, with only the most rudimentary of avionics, a Scout may be the cheapest possible starship. Due to its small size and low thermal signature, a ship of this type is difficult to detect if properly handled. This quality, combined with its low cost and limitless range, makes these vessels perfect for mapping and reconnaisance missions by flight crew who you don't care about very much.

Singleship Scout/Trainer (SS/TS)
Item Info Mass   Item Info Mass
Hull: 100S   2   Main Batt: - -
Power: (1.0) 13     Shields: - -
Drive: (1.0/1.0), 2gs 17 50    Bridge: Armd 10
Jumper: (1.0), J2 20     Lifesystem: 1 2
Refiner: 1   2   Avionics: 3/2 1
Fuel/Cargo: 44hrs   33   Total:   100
  Cost: 16.9D (14.5D)1
Loading Mass Accel
Full 100 2 g's
Empty 67 2.98 g's
(1) With mass production

Corvette (L)
As recently as a generation ago, a 200-tonne corvette would have been considered a significant warship, with a place in fleet combat formations, able to hold its own against many times its tonnage in lower-tech barbarian vessels. This may no longer be the case, but corvettes are still an important class of ship, which serve as maids-of-all-work for escort missions, patrols, courier service, and a wide range of scouting and reconnaisance operations. Used corvettes make great ships for mercenaries (or pirates). Stripped of one laser cannon and equipped with a smaller fusion reactor, they can also carry a profitable amount of cargo. A Grade Three vessel of this type could cost as little as 3 D, putting it just barely in range of a party of freelance adventurers, recently mustered out of service, who know a good loan shark.

Corvette (L)
Item Info Mass   Item Info Mass
Hull: 200S   4   Main Batt: T3 7
Power: (3.0) 33     Shields: - -
Drive: (4.0/4.0), 4gs 62 135    Bridge: Armd 10
Jumper: (2.0), J2 40     Lifesystem: 4/2 8.5
Refiner: 1   2   Avionics: 5/6 2
Fuel/Cargo: 13hrs (158)   31.5   Total:   200
  Cost: 49.2D (39.4D)1
Loading Mass Accel
Full 200 4 g's
Empty 168.5 4.8 g's
(1) With mass production


Last modified: 20 January 2010