The Eight Worlds -- Ship Operations
     Startup, Atmospheric, Normal Space, and Hyperdrive

Overview

Starship operations in the Eight Worlds can be divided into several phases. These are described in the followng sections:

A Note About Explosions
Casual readers may note that the word explosion occurs fairly often in the following sections. Explosions occur in several categories, none of them desirable.

Category Description
Embarassing explosion Up to 1 ton TNT. Kills the operator
Tragic explosion Between 0.001 and 0.1 kilotons. Kills everyone aboard
Catastrophic explosion Greater than 0.1 kilotons. Kills everyone nearby

The final category, 'catastrophic explosions', could in principle be divided into subcategories (e.g. 'catastrophic', 'very catastrophic', 'extremely catastrophic', 'destroys the entire planet', etc.), but from the standpoint of the crew of the ship involved (the 'explodees'), these distinctions may not be of much importance.

Startup and Shutdown

A starship is a complex system, like a diesel locomotive or a relationship. Like a diesel locomotive, a succession of operations must be performed to start it. And like a relationship, failure to follow these procedures correctly can lead to a catastrophic explosion.

Power and Readiness Levels
Ships can be kept at a nuymber of different readiness levels. The lower readiness levels are less capable, but also harder to detect due to their lower thermal, charged particle, and radiation signatures. Higher readiness levels are more capable, but they consume more fuel, are easier to detect, and involve more wear and tear on the engineering plant.

Down: All systems are shut down, and may have been so for some time. Nothing is running or ready to run. A vessel is in this state after it's been delivered from the yard, after an overhaul, or if it's been found abandoned on some unknown world with no record of its origin other than a cryptic recording. Which you can't play. Because the power is off.

Cold: Diagnostic and control systems have been started up and are running on battery power. There is no reason to keep a ship at this level except as part of the startup process since it cannot be maintained without external power. In theory, one could run the lifters on battery power and fly the ship in an atmosphere at this readiness status, but it would involve some risk.

Reserve: Engineering plant is running at 0.1% power, batteries are charging, and enough spare power is available to run equipment such as sensors and the fuel refiner. Ship can be brought to Standby status in an hour or so (5 space combat rounds) by a skilled crew. It can be brought up even faster by a skilled crew who are willing to accept the risk of a catastrophic explosion. Grounded vessels and vessels in hyperspace are usually kept at Reserve readiness status. This can also be used for stealthy planetary approaches, but if one's ship is detected by a hostile vessel less than an hour's flight away, the consequences can be unfortunate.

Low Standby: Engineering plant is running at 1% power. Reaction drives cannot be used and weapons cannot be fired, but the vessel can be brought up to Standby status in 12 minutes or less (1 space combat round). This is a typical energy level for planetary approaches. Vessels spend most of their time in normal space at some level of Standby.

Standby: Engineering plant is running at 10% power, ready for immediate use. In theory one could run the vessel's reaction drives at 10% thrust at this readiness status, but there is no reason to do so.

Full Power: Obvious.

Summary of Readiness Status Levels
Status Level Fuel consumption Warmup time
Reserve 0.1% 1.73 kg/PU-day Cold -> Reserve 8 hrs
Low Standby 1% 17.3 kg/PU-day Reserve -> Low Standby 1 hr
Standby 10% 173 kg/PU-day Low Standby -> Standby 12 min
Full 100% 1.73 tonnes/PU-day Standby -> Full 1 min

The following table lists approximate ranges at which a ship can be detected by passive sensors. Active sensors have a range of around 300,000 km, but make the scanning ship visible to passive sensors at ranges up to 1.5 million km -- i.e. you can see anyone hiding nearby if you don't mind revealing yourself to everyine in the system.

Detection Ranges (x1000 km)
Number of
Power Level
Sensor Boxes Cold Reserve Low Standby Standby Full Huge
1 10 20 50 150 500 1500
3 20 40 100 300 500 3000
6 30 60 150 450 500 4500
10 40 80 200 600 500 6000

The 'Bringing The Ship Up' Table
This table table lists some of the operations and skill rolls needed to bring a ship up. It can be ommited for purposes of simplicity since it serves little purpose other than to provide a list of startup times, color, and an opportunity for amusing or catastrophic skill rolls. But it has served these functions well.

Action Crew Bridge Engineering Gunnery
Down -> Cold LS Filters & Maint, ick(1)
(3 d, Mech)		 Circuit tests
(1 wk, Comp, Elec)		 Circuit tests, check batts
(1 wk, Eng, Elec)		 Circuit tests
 
Battery Power to All Systems
(8 hrs)
  General Maint
(Mech)		 [Basic Avionics]
(3 d, Comp, Elec, Nav)		 Alignment tests
(1 wk, Eng)
Pumpdown Fusors
(2d + 1d, Eng)
Start Cooling & Injector
(1 d, Eng)		 Control Tests
(1 d, Gun, Elec)
Load Munitions, if any
(1 hr/unit)
 
Control Tests
(1d, Pilot, Elec, Eng)
Cold -> Reserve LS Flush & Load, yuk(2)
(1 d, Mech)		 [Reboot Main CPU]
(√Nboxes/2 hr, Comp)
[Test Avionics]
(√boxes*systems hr, Comp, Elec)		 [Eng Checklist]
(1hr, Eng)
Warm & Flash Fusor(3)
(8hr, Eng)
Engage Convertor(4)
(15 m, Eng)		 [Gunnery Checklist]
(1 hr, Gun)


Cooling & Reserve
(1 min)
Reserve -> Standby [Final LS check]
(1 hr, Mech)		 [File Flight Plan]
(varies)		 [Final Eng Checks]
(1hr, Eng)
Warm Drive
(15 m, Eng, Mech)
Drive to Standby
(30 m, Eng)		 [Full Power Tests!](5)
(12 min, Gun)
[Test Missile Avs](12 min)
Standby -> Full [Final Preflight Hull Systems]
(15 m, any)		 Comp, Nav, Pilot
(requires 2+ people)		 Read adult mags
Watch dials		 Read adult mags
Watch dials
(1) This job is every bit as loathsome as it sounds
(2) This job is also every bit as loathsome as it sounds
(3) Or die in a tragic explosion
(4) And watch with relief as the battery meters swing over to 'Charge'.
(5) If you're on a desolate world where no one will object. Spaceport administators just don't seem to understand these things...

Atmospheric Flight

In general, a vessel's fusion drives cannot be used in an atmosphere. Some military drives have been rated for atmospheric operations by designers who read too many Larry Niven stories from the classic era before the dawn of space travel, but attempts to use these drives in any atmosphere significantly denser than that of Mars has often lead to tears.

Atmospheric operations are conducted using Lifters: a syetm of thermal turbo-scramjets powered by the fusors. In general, these provide 1 g more acceleration than the ship's reaction drives and can propel the vessel at speeds ranging from Mach 3-15, depending of atmospheric density, temperture, composition, the quality of the vessel's steralining, and the extent to which the crew might object to having their hull melt. Power consumption for lifters is minimal. Even on battery power a ship could, in theory, fly for days, and endurance under fusion power is limited only by the endurance of the machinery.

During an ordinary launch, a ship takes off using the lifters, accelerates first to and then to hypersonic speeds, climbs to an altitude at which it is safe to start the fusion drives, and then uses these to continue to orbit and beyond. Rentry and landing are the revese of this procedure. The ship can also cruise in the atmosphere under lifters for an indefinite length of time. On airless worlds, procedure is slightly different and the ship must vent reaction mass through the lifters. It is in principle possible to take off from an airless world using fusion drives, but many things can go wrong with such a plan.

Ordinary 'streamlined' hulls are tail-landers, restricted to landing zones or prepared fields of reasonable quality. 'Belly-landers' -- which may still land on their tails in some cases -- have additional lifters and more robust landing jacks that allow them to land in more 'rustic' locations. The additional thrust-vectoring capability make them more maneuverable in air combat.


Normal Space Operations

These rules are incredibly important. I haven't transcribed them yet, but a quick summary is given here. Since hyperspace jumps conserve momentum and preserve intrinsic velocity, ships must accekrrate in normal space to match velocities with their destination. This means that to travel from world to world, a ship must lift from its planet of origin, travel sufficiently far away to use the hyperdrive, change velocity with its destination -- this can be done in stages before and/or after the hyperspace jump -- approach its destination world, re-enter, and land. An amibitious referee would keep track of the orbital ephemera and stellar motions of every world to calculate the delta-v requirements associated with each and every jump. This would allow him or her to track seasonal variations in the fuel requirments to travel from world to world in a way that would have exciting implications for the campaign. In practice, anyone who tries this is likely to go nuts, so it's easier to assume that the delta-v requirement will always be around 72 km/s.

The following list gives a brief summary of departure operations

  1. The ship takes off using lifters as described above.
  2. The ship burns fuel to accelerate at approximately 1 g for 1 hours to reach a speed of approximately 36 km/s. For a 100 tonne ship, this will require 0.75 tonnes of fuel. Fuel requirements for more massive ships scale accordingly.
  3. The ship coasts in free fall for approximately 12 hours to reach the 'Jump Limit', which is around 1.5 million km from a world of Earth-like mass.

Approach is the reverse of the above procedure.

Fuel
Fuel costs 1 F/tonne. Unless there's a war on, in which case the port might stick you for everything they can get. It's generally available at 1 tonne/day plus whatever is in the port's ready reserve, for which they might levy a surcharge. One can also refine fuel from hydrogen at 1 tonne/day using the ship's Refiner, but since Refiner elements (basically a neutron source) are expensive, and begin to degrade after 10 uses or so, one generally reserves the Refiner for use on undeveloped worlds. And yes, it might be possible to make a marginal living by flying to world's threatened by war, selling fuel from your Refiner, then flying home to buy a new one after the war was over, but this would rank low on the list of enjoyable careers.

Hydrogen for the ship's Refiner can be obtained in a variety of ways. The easiest is to run a pipe to a nearby body of water, pump the stuff aboard, and apply the Miracle of Electrolysis. This does require a certain number of Mech and Wilderness Survival skill rolls to deploy the pipe, drag it to an appropriate source, and protect it from local environmental hazards -- particularly large obstreperous ones with teeth. It also requires that the planet have water. If no free-standing water is available, one can resort to other options, which are listed below in ascending order of ickiness.

  1. Shoveling snow from a cold world.
  2. Chipping ice from an airless moon or extremely cold world.
  3. Chipping methane or ammonium ice from an airless moon or extremely cold world that's covered with frozen methane or ammonium instead of water ice.
  4. Diving into the atmosphere of a Neptune- or smaller-sized gas giant on a ship equipped with a Scooper in a desparate attempt to gather a few tonnes of hydrogen without burning up in the atmosphere.
  5. Diving into the atmosphere of a Saturn- or larger-sized gas giant on a ship equipped with a Scooper in a near-certain-to-be-fatal attempt to gather a few tonnes of hydrogen without burning up in the atmosphere.
  6. Landing on a cryoworld with a surface temperature near Absolute Zero and dying due to life support failure before you can even begin to chip away at whatever covers its umimaginably hostile surface.

Hyperspace

These rules are even more important. I haven't transcribed them either. Here's a very quick summary of a standard jump at Jump 2.

  • Charge time -- 2.5 hours
  • Fuel consumption -- 2.25 tonnes for a 100 tonne ship. Don't ask why hyperdrives use fuel.
  • Transit time -- 7 days
  • Transit distance -- 30 parsecs
  • Breakout time -- 2.5 hours

Shorter jumps are possible. In fact, 'microjumps', with charge times of less than a minute and transit distances of a billion kilometers are less are standard practice for in-system transit or to foil attempts to track a ship's interstellar jump.

The Jump Limit
Attempts to jump too close to a planet can result in a catastrophic explosion (see A Note About Explosions above). This jump limit is determined by the curvature of space and scales with tidal forces -- i.e. as M1/3 where M is the mass of the target body. For a planet of earth-like mass, this distance is around 1.5 million kilometers, and for a star of one Solar Mass, it is around 60 million kilometers. In general, the 'stellar jump limit' will be well inside the orbit of any habitable world, but for type M dwarves or fainter stars, whose habitable zone lies close to the primary, habitable worlds may lie inside the stellar jump limit, making them more time-consuming and expensive to reach, but harder to attack and easier to defend.


Repairs, Maintenance, and Annual Overhauls

Ships are complex systems, whose components can wear out and fail. These failures become more likely as a vessel grows older. When they occur, they must be repaired, which involved an exercise of skill and some cost in spare parts. The probability of systems failure for a single flight, which includes planeraty departure, hyperspace transit, and planetary approach, varies with the grade of the vessel, and is determined by rolling 2d6 using the table below

Grade Fusor Drives Jumper Some Other Stuff1
1 never never 12+ never
2 12+ 12+ 11+ 12+
3 11+ 11+ 10+ 11+
4 10+ 10+ 9+ 10+
(1) Life support, weapons, or whatever, depending on the GM's mood

An engineer can apply their skill to detect a potential failure before it happens. On a modified 9 (Eng skill + 2d6), they detect the failure before the ship lifts. On a modified 7, they detect if before the system is engaged. Lower rolls mean that an unpleasant occurs in flight, and a natural 2 (snake eyes) means they broke something that would have been fine if they hadn't been messing around.

"Houston, we've got a problem."
Once a system breaks, one must survive the failure. The probability of survival is up to the referee's discretion. I use the Demon Die variation scheme that we delevoped at Caltech many years ago to decide just how badly the system is broken, roll a die to determine which subsystem is involved and then ask the engineer to roll a modifed 3 or higher to avoid a tragic explosion -- snake eyes always fail. Under this scheme, a Grade Three ship remains an acceptable risk, but a Grade Four vessel is suicidally dangerous.

Repairs
After the crew survives the malfunction, they must repair it. Repairs require a valuable commodity known as Spare Parts. Spare Parts cost 100 F/tonne and are assumed to be generic, because it's too much trouble to keep track of different types. It requires 0.1*N tonnes of Spare Parts to repair a device that generates or handles N units of power. In theory, repairing the Apollo 13 Service Module, which generated 91.2 kN of thrust (0.0456 Thrust Units) would have required 4.56 kg of Spare Parts and cost 456 B (the equivalent of $2,300 USD in the currency of 2010).

Overhauls and Surveys

A brand spanking new ship, fresh out of the yard, is Grade One. It would be possible to do shoddy work and produce cheaper vessels of lower quality, but for reasons described below, this is not economical. Every year, or after any damage that threatened the ship's integrity -- this generally only happens as a result of near-destruction in combat -- a ship must undergo an Overhaul and Survey. If it fails the Survey, it drops one grade. If they wish, the crew may then attempt a Major Overhaul and have the vessel resurveyed, but for older vessels, it can make more sense to spend some of the money drowning one's sorrows in a bar (this involves use of the Carousing skill) and use the rest on a down-payment for another ship. Costs of overhauls are listed below.

Grade Overhaul Fail Survey Major Overhaul
1 2% new cost 11+ 6% new cost
2 4% new cost 11+ 12% new cost
3 8% new cost 11+ 24% new cost
4 16% new cost 11+ 48% new cost

A bit of calculation and probability will show that in spite of their higher purchase price, Grade One vessels have significantly lower operating costs after one accounts for maintenance and overhauls. They are followed by Grade Two vessels. Like many things in the Eight Worlds, this was deliberate. A lot of thought went into these rules.

Troublemakers may ask, "Why must overhauls occur on an annual basis? What's so special about Earth's year? Or must ships built on worlds with a different orbital period be overhauled with different frequencies?" We don't like people like you. Cynics may ask what happens if one misses an annual overhaul, either because one was outside the Pale with no access to a spaceport, or was tryiong to sneak something past the GM. The Survey roll happens anyway, with a +1 penalty because life is cruel.


Last modified: 20 January 2010