Engineering Section

The Engineering Section

 Beyond the obvious technologies removed from normal Traveller for the Dark Stars setting, a few assumptions are made about the rate of progress with other technologies.  Among the most obvious of those is the delayed tech levels at which fusion power plants and drives become available.  In the Dark Stars setting, pulse fusion drives do not become a reality until TL11, fusion power plants follow a tech level later at TL12, and finally at TL13 the fusion torch drive becomes practical.

The Dark Stars setting also departs from standard Traveller in paying attention to waste heat management.  Power producing drives and power plants require radiator areas on the hull.  These come from the mount points calculated in the hull design sequence and are assumed to be armored with IR transparent variations of the hull armor.  The mass and cost of these radiators is included in the mass and cost of the drives and power plants.  Only the reduction in available mount points needs to be a consideration.

FTL

Quantum Skip Drive (QSD)

Quantum Skip Drives are available at TL10+.  While the operational characteristics of the QSD are quite different than traditional Traveller Jump drives, the representation is nearly identical to a Traveller Jump-2 drive.  The primary difference being the QSD requires no fuel (directly at least) and does not create a jump bubble of hydrogen nor require a jump grid of lanthanum on the hull.  It does require some surface space however for field emitters.  A QSD requires 5% of a spacecraft's wet mass at a cost of MCr 0.25 per ton of drive.  It also requires 5% of the spacecraft's mount points (round fractions up) for the emitters.  The drive requires 0.1 Mj per ton of spacecraft (current tonnage at jump time).  This energy must be provided over a period of not more than four hours, although if sufficient power is available, the drive is capable of being charged in a minimum time of 30 minutes.  Thus the power required is anywhere from 0.025 Mw per ton of spacecraft to 0.2 Mw per ton of spacecraft. 

Maneuver

Magneto Plasma Dynamic (MPD)

Available at TL8+, the mature version of the MPD engine has a variable Isp and in 'low gear' barely qualifies as 1m/s^2 capable requiring 10% of the spacecraft's mass (not necessarily its total wet mass) for the drive alone for each 1m/s^2 of acceleration.  In addition, a MPD engine requires 0.25 Mw per ton of engine to be supplied by the craft's power plant (regardless of mode).  The minimum engine mass is 5 tons, it requires 1 mount point per 100 tons of engine for nozzles (round up), and costs MCr 0.1 per ton.

Were it not for two features, the MPD drive would be extremely seldom seen, however because of them it sees widespread use for deep space and bulk freight applications.  The first feature is that it can use hydrogen, usually in the form of liquid hydrogen slush (LHS), as fuel as well as many other alternatives.  The second is that it has variable specific impulse, and while performance is abysmal at the highest thrust levels, over the long haul it is second to none.  In 'low gear' max thrust, the engine has an Isp of only 1800.  However, in high gear, while the thrust drops to only 5% of low gear, Isp skyrockets to 36000.

Low gear produces 1 ton of thrust and consumes 2 tons of fuel per hour per ton of drive.
High gear produces 0.05 ton of thrust and consumes 0.005 tons of fuel per hour per ton of drive.

LHS fuel costs Cr50 per ton.

 Metastable Metallic Hydrogen Augmented Solid Rocket (MMHASR)

Available at TL9+, the MMHASR is a solid fuel rocket technology that augments the chemical propellant with metastable hydrogen.  While originally employed as a secondary thrust agency (booster) for STO spacecraft, it has become the propellant of choice for modern missiles.  MMHASR has an Isp of 1200; divide the propellant mass by 3 to determine the thrust in ton/hours, maximum thrust in tons is 5000.  MMHASR propellant costs Cr 2500 per ton.  The minimum mass of a MMHASR engine is 0.5 tons.

  Trimodal Augmented Nuclear Thermal Rocket (TANTR)

The TANTR engines are the workhorses of the Dark Star universe.  While earlier primitive variants exist, the combinations of technology required for safe, reliable, and ecologically friendly operation combined with near theoretical maximum performance does not occur until TL9+.  The TANTR has three modes of operation, reactor mode giving no thrust but supplying power, cruise mode with an Isp of 1800 using Liquid Hydrogen Slush (LHS) fuel; and full thrust mode with an Isp of 1200, augmenting the LHS fuel with either Liquid Oxygen (LOX) fuel or compressed air (scramjet mode if available).  The nuclear fuel supply is included in the mass and cost of the drive, it is sufficient for one year's operation.  Refueling the nuclear fuel costs 10% of the total drive cost.

Each 1m/s^2 of cruise mode acceleration requires 2% of the spacecraft's mass (not necessarily its total wet mass, more commonly its combat mass or cruise mass).  In other words, each ton of TANTR produces 5 tons of thrust and consumes 10 tons of LHS fuel per hour.  In full thrust mode, each ton of TANTR produces 12 tons of thrust and consumes an additional 26 tons of LOX fuel per hour.  The engine produces a secondary electrical power output of 20 kw per ton in thrust modes and 100 kw per ton in reactor mode.  Each engine requires 1 mount point per 50 tons of drive (round fractions up) for the nozzle.  Radiator area required is 1 mount point per 2 tons of engine (round fractions up).  Minimum engine size is 10 tons.  Cost is MCr 0.1 per ton of drive.

Scramjet Mode:
TANTR engines may be equipped with scoops and compressors for scramjet mode operation, replacing half the LOX fuel requirement with compressed air while in a planetary atmosphere.  This modification adds 10% to the engine's mass, requires 4 mount points per ton of engine, and costs MCr 0.25 per ton.  This modification, while in operation, consumes all of the secondary electrical power that would normally be produced by the TANTR engine.  This modification may only be installed on spacecraft with streamlined or airframe hull configurations.

LHS fuel costs Cr50 per ton.
LOX fuel costs Cr500 per ton.

Anti-proton Initiated Pulse Fusion (AIPF)

A practical, reliable, commercially feasible fusion drive was a goal that frustrated countless researchers until TL11.  Even at TL11 it is considered by many to be a marginal technology as it relies heavily on infrastructure for both fuel and maintenance.  On the other hand, this drive type obtains an Isp of 36000 using specially manufactured metastable metallic hydrogen (MMH) pellets and mere nanograms of anti-protons.  Note that engine exhaust is highly radioactive.

Each 1m/s^2 of acceleration requires 5% of the spacecraft's mass (not necessarily its total wet mass).  Thus each ton of AIPF produces 2 tons of thrust and consumes 0.2 tons of fuel pellets per hour.  The engine produces a secondary electrical power output of 20 kw per ton.  One mount point for each 100 tons of engine is required for nozzle.  Radiator area required is 1 mount points per ton of engine.  Minimum engine size is 10 tons.  Cost is MCr 0.25 per ton of drive.  Sufficient anti-proton mass is included in the drive mass and cost for one year of operation.  Replacement of the anti-proton initiator fuel adds MCr 0.05 per ton of drive to the cost of annual maintenance.

MMH fuel pellets cost Cr 2500 per ton.

Magnetic Bottle Fusion Drive aka Fusion Torch

Finally arriving at TL13+, fusion torch drives rapidly become the engine of choice for those who have access to the technology required.  With an Isp of 36000 from a deuterium/helium3 (DH3) fuel mix, the fusion torch drive not only offers superior performance but adds the prospect of limited wilderness refueling operations.  Like the AIPF however, the engine exhaust is highly radioactive.

Each 1m/s^2 of acceleration requires 10% of the spacecraft's mass (not necessarily its total wet mass).  Thus each ton of drive produces 1 tons of thrust and consumes 0.1 tons of fuel per hour.  The engine produces a secondary electrical power output of 20 kw per ton.  One mount point for each 100 tons of engine is required for nozzle.  Radiator area required is 5 mount points per ton of engine.  Minimum engine size is 5 tons.  Cost is MCr 0.5 per ton of drive.

DH3 fuel costs Cr 5000 per ton.

Power

Nuclear Fission 

While earlier version are available at half the output, three times the mass, and five times the cost; at TL8+ nuclear fission power plants become the most commonly used power source in space until the arrival of nuclear fusion at TL12.  Fission power plants produce 0.125 Mw and cost MCr 0.02 per ton.  One mount point is required per 25 tons of power plant for radiators (round up).  Minimum power plant mass is 25 tons.  Large scale fission power plants, of at least 250 tons mass, have twice the power output per ton.  Fission power plants include sufficient fuel for one years operation, replacement costs 10% of the original power plant cost.

Nuclear Fusion

Finally at TL12+ nuclear fusion power plants become a reality.  Based on the deuterium/tritium cycle they produce 0.5 Mw and cost MCr 0.05 per ton.  One mount point is required per 5 tons of power plant for radiators (round up).  Minimum power plant mass is 5 tons.  Fusion power plants include sufficient fuel for one years operation, replacement cost is included in the cost of annual maintenance.  Fusion power plant efficiency varies with mass according to the following table.

Mass	Output modifier
25+	x1.5
50+	x2.0
100+	x3.0

Support

Fuel Tankage

Fuel tankage requires no additional mass beyond the fuel they contain but the tonnage must be specified at design time and costs MCr 0.001 per ton.

Fuel Refinery

Onboard fuel refineries can be installed to refine LHS, LOX, and DH3 fuel from liquids, gases, or liquified solids.  Each ton of fuel refinery can refine 0.1 tons of fuel per hour.   Minimum refinery mass is 10 tons.  Cost is MCr 0.01 per ton.  If fuel scoops are desired, add one mount point per 10 tons of refinery and double the refinery's cost.   Engines with a scramjet modification are assumed to already include fuel scoops.  Note that DH3 fuel is refined at 0.01x the normal rate.

Workshops

At a mass of 4 tons and cost of 0.25MCr per engineer, onboard workshops allow +1 to all repair attempts and allow a chance of ad-hoc replacement of  irreparably damaged components.

Frontier Upgrade

Drives (both FTL and Maneuver) and Power Plants may be installed which are modified for high reliability long duration service.  These components mass 50% more than normal and cost three times as much.  This upgrade gives +1 to all reliability check, +1 to all repair attempts, and extends  the service lifetime to three years.  If sufficient workshops are also installed, annual maintenance may be delayed without penalty to three years between overhauls.

Radiator Wings

Spacecraft which need additional radiator mount points may install up to two radiator wings.  Each radiator wing can provide an additional number of mount points of radiators up to a maximum of 50% of the spacecraft's normal mount points.  They mass 1 ton and cost MCr 0.1 per mount point of radiator added.  There are two options that may be used with radiator wings.

1) Retractable radiator wings.  If the spacecraft's configuration is not 0 (unstreamlined) it must use this option.  This adds 20% to the mass and cost of the wings.

2) Armored radiator wings.  The wings may be armored the same as the normal hull mounted radiators with IR transparent material. Calculating the added tonnage and cost of the armor is a bit involved.  Using the same armor rating as the hull, the armor factor for the wings is Ar * 4.  The structure rating for the wings is equal to Gt * Ga * 0.1, minimum of 1.  The wing material rating is then equal to Sr + Af.  The mass of the added armor is then equal to the radiator mass * Pc * Mr (see hull page).  The cost per ton of the added armor is twice the figure given in the armor table of the hull page.

Heat dumps

When the total deployed radiator mount points is less than the required radiator mount points, the difference represents points of heat that must be dumped (else the craft turns into a can of stewed crew).  There are two types of heat dumps, water ice dumps, and reactor coolant dumps.  Each ton of water ice vaporized and ejected removes one heat point.  Water ice heat dumps mass as much as the ice they contain and the water is essentially free.  Reactor coolant heat dumps are twice as efficient removing two heat points per ton vaporized and ejected removes two heat points.  However reactor coolant costs Cr250 per ton and may be difficult to replace in a wilderness setting.  Regardless of type, heat dumps cost MCr 0.001 per ton installed.

Notes

The above should be sufficient, at least to start.  The numbers, of course, may need to be tweaked.  Later on I'll probably add more to the power section: fuel cells, solar panels, and batteries are likely additions.  The big test will come in a few days (or weeks) when I try to design the Frontier Survey Cruiser I have in mind to help me flesh out the Dark Stars setting via solo play.

Update: The drives are currently being reworked, relatively minor changes but still needs cleaned up.