This essay discusses some alternate rules for spacecraft in Fading Suns, and commentary on techniques and tactics which result from Fading Suns space travel rules.

(My apologies ahead of time to those of you for whom this may seem pedantic, but you’d be surprised how many people don’t know some of the basic physics involved, or who "know" it, but don’t think about it ).

Why are alternate rules for space travel and spacecraft profiles needed?

Spacecraft as currently defined by Fading Suns are fine if all your characters ever do is simply "book passage" and travel between worlds. But if your players want more detail in order to play a Charioteer character, or a Barbarian Raider, or if you want to add some detail and "realism" to your descriptions of space travel, then the rules as they currently read are somewhat lacking.

First, the characteristics for spacecraft do not make sense mathematically or scientifically. Spacecraft are not just big cars that drive through space. However, Forbidden Lore: Technology (hereafter referred to as FL:T) defines their capabilities little differently than they do a landcraft or beast cart – by listing a speed and a range of travel.

The descriptions of spacecraft do add a secondary comment on speed that notes the number of days to a jumpgate. These numbers are incorrect according to any configuration of acceleration, speed and distance to jumpgates that I tried. Frankly, I suspect the game developers simply made them up and wrote down something that "sounded right." If I’m wrong, I’ll be happy to take that back.

More significantly, the listed stats for spacecraft provide little of direct use to a character or gamemaster who is trying to put detail into space travel. Spacecraft should be rated not according to speed, but rather the maximum acceleration of which they are capable.

Range shouldn’t be listed as a function of distance, but rather one of time – how long the spacecraft can maintain that acceleration. Listing a distance might seem intuitively correct to some, but it isn’t useful except as a general guide. A spacecraft, unlike a landcraft, can coast once it achieves a certain velocity. It isn’t necessary to continue to "push on the gas pedal" to keep going.

If you know the maximum acceleration of a spacecraft, and how long it can maintain that amount of acceleration before it has to refuel, you can figure anything else out that you need to.

If you have only what Holistic lists for the spacecraft in Fading Suns, you are lacking crucial details if you want to do anything creative with a spaceship, or if you are looking for a more "realistic" approach to running space travel adventures.


Recommended Alternate Stats for Fading Suns Spacecraft.

The following changes will provide a realistic level of detail to space travel, without altering the feel of Fading Suns or requiring a lot of heavy calculation. The changes I propose keep a degree of simplicity and "playability" while adding some detail to the rules for spacecraft.

First, add one additional characteristic to all FS spacecraft: acceleration. I have based the recommended ratings on an analysis of various "facts" given in the FS rules, and I will explain how I arrived at these values later in this text, for those who are interested. Those who don’t care about the math can simply use these values without worrying about the details. These stats change very little in the spacecraft listings – you just have to add them on. The only real change is in the time it takes spacecraft to reach the average jumpgate – and those changes are necessary because the times listed in FL:T simply aren’t possible (more on that later).

I have listed below what the acceleration rating for each ship should be based on the speed listed for that ship. Acceleration is given in hours per % lightspeed - i.e. it takes the ship so many hours to increase its velocity by 1% of lightspeed (1% of lightspeed is 3,000 km/second). A ship with an acceleration of 1 hour/ % lightspeed, for example, starting from a "stationary" position in space, would be traveling at 3,000 km/second after 1 hour of acceleration. (This is really fast, by the way, and much faster than even the fastest spacecraft in the Known Worlds.)

A ship with a listed "speed" of 10% lightspeed should have an acceleration of 27.8 hours/ %lightspeed, and would take a total of 278 hours to reach 10% lightspeed (or, about 12 days). Which, incidentally, is the length of time it actually would take that ship to reach a jumpgate (not 8 days as listed in the book – see below for why that is). Other ratings follow:

15% lightspeed – 12.3 hours/ %lightspeed

20% lightspeed – 6.9 hours/ %lightspeed

25% lightspeed – 4.4 hours/ %lightspeed

30% lightspeed – 3.1 hours/ %lightspeed

For range, especially for jump-capable ships where range is listed in terms of the number of jumps that can be made, no change is absolutely necessary. If you want to add some detail, however, the range can be replaced with a characteristic that lists the length of time the ship can accelerate at maximum acceleration. This can be easily calculated by multiplying the number of days it takes a ship to reach jumpgate by the number of jumps it can make, times 2.

This number will give the number of days of full accleration. Multiplying by 24 to get the number of hours of full accleration might be even more useful. That way, a pilot character will know how many hours she can afford to use up on side-jaunts, maneuvering, and can even save some fuel by coasting at a slower speed than the "maximum" listed (if she has the time to spare, that is).

Actual travel times to jumpgate for ships with various maximum "speeds" are shown below:

5% - 23 days

10% - 12 days

15% - 8 days

20% - 6 days

25% - 5 days

30% - 4 days

These times assume constant acceleration and are mandated by physics, based upon the stated distances from planets to jumpgates (see below for a full explanation). The times stated in the books simply are not consistent with the stated distances to jumpgates and the maximum speeds listed for various ships.


How the new values are derived.

Several assumptions had to be made to determine usable values for space travel. Foremost among these is the assumption that physics works the same way in the Fading Suns universe as it does in ours – not a big stretch, but little things like what the speed of light actually is rely on such an assumption. There are a couple of others that aren’t quite as obvious:

  1. Spacecraft "speed" is assumed to indicate the maximum speed that a ship with a constant rate of positive acceleration could reach in the time the ship travels to a jumpgate. A statement to this effect is made on page 201 of the Fading Suns rules, although it is technically incorrect: "…ships accelerate away from the planet and toward the gate at a constant speed…." A ship cannot both accelerate and have a constant speed. The two are mutually exclusive (unless you’re driving in a circle, but that is a minor exception).
  2. The distance to a jumpgate used is the one listed on page 59 of FL:T – 15 billion kilometers (around 100 AU). Variations on this distance would produce variations in travel time to the jumpgate, but such differences are essentially minor, and for the sake of playability, can be ignored.
  3. Fading Suns spacecraft are subject to the laws of inertia – they must accelerate to reach a certain velocity, and can’t just decide to suddenly be going 10% of lightspeed. This is a critical assumption, because if you ignore inertia, things will become so weird that I doubt many gamers could really handle it.

With these assumptions in mind, the maximum acceleration a ship is capable of maintaining can be calculated. The distance is known, and the final velocity is known. Since constant acceleration is assumed, the average velocity is also known (it will be half of the maximum speed for that ship – a ship with a "maximum" speed of 10% lightspeed would average 5% lightspeed over the entire journey). Because the average velocity is known, the travel time is also known, and when that is figured into the values for final speed and distance, acceleration results. So, with constant acceleration assumed, the acceleration ratings for the various ships can be easily calculated, and the resulting values added to spacecraft profiles.

The average speed derived from the listed "maximum" speed also mandates the minimum travel times to a jumpgate. If a ship can travel no faster than 10% of lightspeed, for example, it cannot start (stationary) at a planet and arrive at a location 15 billion kilometers away any sooner than 12 days later. It just isn’t possible unless the laws of inertia are somehow ignored (see assumption 3 above). The other revised times to jumpgate are based on this kind of simple calculation (take half the speed listed, multiply by 300,000 km/sec, and do the math based on minutes, hours, and the 15 billion km/100 AU distance).

As a side note, 1 Astronomical Unit (AU) is equal to roughly 500 light-seconds. Put another way, it takes light about 8 minutes to reach the earth from the sun. A ship traveling at 10% of lightspeed would take 83 minutes to travel the same distance. A ship which started at the sun and accelerated constantly toward the earth at a rate which would cause it to hit 20% of lightspeed just as it reached the earth would also take 83 minutes to make that trip (it’s average speed over that distance would be 10% of lightspeed).


Some probable common practices in space travel.

In my alternate rules, I discussed the assumption that ship ratings listed in FL:T were derived by assuming constant acceleration toward the jumpgate, resulting in spacecraft crossing through the jumpgate at the speed listed in their profile. There are several reasons why this would not be the case, however.

The most significant reason for not "jumping" while going at the "maximum" speed listed is quite obvious if you think about it. Ask yourself the following question: How do you get from Byzantium Secundus to Stigmata as fast as possible?

The answer is, you jump from Byzantium Secundus to Criticorum, then to Shaprut, and then to Stigmata. What you don’t do is jump into the Criticorum and Shaprut systems going full-speed! Why? Because you have to turn around and jump back through the gate as soon as you can. If you jump into the system going full-speed, it will take you many days to slow down, turn around, and travel back to the jumpgate. If you accelerate from Byzantium Secundus until the halfway point, then turn around and decelerate until you reach the jumpgate, you go through the gate at a slower speed (much less than even 1% lightspeed), and you will be able to quickly turn around, make the next jump into Shaprut, and then make the next jump into the Stigmata system. Then you accelerate again, but only halfway to Stigmata – you have to start decelerating again so that you won’t run into the planet going 20% of lightspeed.

Thus, a ship on such a trip never will reach the "maximum" speed listed in the book. At most, it would only reach half that speed, before it had to turn around and begin decelerating again.

By comparison, a ship traveling from Byzantium Secundus to Criticorum (only one jump) would be able to accelerate all the way out to the jumpgate, jump through at its listed "maximum" speed, and then decelerate all the way in to Criticorum.

There is one problem with that scenario. If you are the pilot of that second ship traveling to Criticorum, you are assuming that you will be able to jump through the gate exactly as you reach it going 10%, 15%, or 20% of lightspeed. Given the fact of jumpgate reset delays and fairly high amounts of traffic between those two systems, that is a very risky assumption.

A conservative captain will therefore set a course that will allow him to decelerate towards the jumpgate and if necessary stop before passing by/through the gate, allowing for delays in reset times. The rules mention slowing down before a jumpgate at the top of page 62 in FL:T.

There are only two situations that would allow a ship to more safely pursue a course of constant acceleration towards the jumpgate. One, the ship has a reset jumpkey that will allow them to ensure that they can jump when they reach the jumpgate. Or, two, the ship has a certain amount of control over and knowledge of the situation at the jumpgate. For example, the ruling Duke of a world has a naval patrol at the gate which keeps his ship informed as to the situation at the jumpgate, and can control traffic through the gate, ensuring the Duke’s ship can pass through as it gets there. Even there, a bad result on the jump-reset delay could ruin the plan.

So most ships wouldn’t reach their listed speed on a typical jumpgate trip. They would normally accelerate to half the listed speed, turn the ship around, and fire the thrusters in reverse to decelerate towards the destination. (Once again, this assumes that the maximum rate of acceleration the ship is capable of is defined as stated in part one of this message).


What is the value of an atmospheric grade spacecraft?

As I see it, there are two advantages of an atmospheric grade spacecraft over a void grade craft.

  1. For warships, it enables the spacecraft to exercise close support / air superiority missions from orbit. This is especially true for small ships that might be based on orbiting defense stations. There is no need for the ship to land on a planet, and the design can even take advantage of this.
  2. For all craft, it enables the ship to breach the "re-entry barrier" itself, before deploying shuttles, fighters, dropships, droptroops, or other carried craft such as flitters or hoppers. Thus, an atmospheric grade yacht could enter the atmosphere, descend to a level at which the noble’s flitter could operate from, launch the flitter, and rise again to orbit. This has two benefits: one, the noble doesn’t need a full-out shuttle, and two, the noble doesn’t need to bother landing the yacht, paying for a lander grade design, or pay the fuel costs associated with actually landing and having to burn out of the gravity well from a dead stop. This advantage would be especially valuable for a cargo craft like the Swellingpug, which could utilize a Wagon of Paulus to ferry cargo or passengers down to a planet which lacks an orbiting station, but wouldn’t have to waste a lot of fuel on the gravity well. Note: this brings up a conceptual problem with the Benifice costs for the Wagon of Paulus vs. the Runt Shuttle – a full-up spacecraft is cheaper than a hopper (although the firebird cost is identical). Somehow, that ain’t right J

Granted, Lander-grade craft also have these advantages, but there are plenty of reasons to design a ship so that it can’t land. The first, best reason is cost – its just cheaper to build a ship that way. Second is a function of design. Especially for larger warships, landing a ship of that size would require additional bracing design for sitting in a gravity well, enormous landing gear (and associated operating cost increases for tires or whatever), etc.

Another reason for warships to be designed so that they can’t land is weaponry. The larger the ship, the more problem it will have with "blind spots" – places where it can’t "see" or shoot. Spacing sensors and weaponry around the ship in all directions solve this problem, or at least partially solve it. Of course, this means that designing such a ship to land has added costs and design problems associated with it.

And of course, some ships are just TOO big to land, period.

Now, anti-gravity technology such as that found on flitters can help solve this, but large ships, or ships that need to dedicate more of their power to things like weapons and shields, won’t be as likely to use such features, even if the technology is available to the builder.

Which is why I think that the two frigate examples in FL:T should really be considered atmospheric grade, rather than lander grade. True, this is a preference thing, but those ships really are large enough that they should have a lot of trouble landing. Both have significant amounts of weaponry and large shields – enough to make anti-grav landing improbable, as it would drain too much power. The range of weaponry and size of the ships mean that it should really have turrets spaced around the hull to cover various sectors. And, although artwork isn’t the best argument, the illustrations of these craft indicate a non-landing ship (and maybe even a non-atmospheric one, but…).

A related problem is the rating of the Runt Shuttle and Republic Dropship speeds. Both are listed as having speeds in the "mach" category. Now, this is appropriate in one sense for a craft that is intended to operate in an atmosphere. However… the ships really should have a lightspeed rating as well, since both are listed as being able to go to a jumpgate – and mach 8 or 10 won’t cut it in that respect.

Just to give a frame of reference on this, a spacecraft travelling at only 5% lightspeed is travelling at the equivalent of an aircraft flying at Mach 45! And such a craft would still take a minimum of 23 days to reach a jumpgate. Something travelling at a mere Mach 10 probably wouldn’t have enough life support to reach a jumpgate.

Added to that, the term "mach" is an aeronautical term – it really has no place outside of an atmosphere, since it is meaningless there. So based on the relative "days to jumpgate" ratings of the Runt and Republic craft, I propose the following speed and acceleration values:

Runt Shuttle – Speed of 7% lightspeed (17 days to jumpgate), Acceleration of 56.7 hours / % lightspeed.

Republic Dropship – Speed of 8% lightspeed (14 days to jumpgate), Acceleration of 43.4 hours / % lightspeed.

This keeps the time frame essentially the same, while still making them slower than the typical freighter.

On a related note, other craft which are atmospheric or lander grade should also be given atmospheric speed ratings, to determine how fast they can operate inside an atmosphere. Mach 8 – 10 is really pretty fast, even for a really high-tech spacecraft. Mach 4-5 is much more likely, especially for Tech 5 spacecraft like the Runt.

The Republic Dropship is unlikely to be rated at Mach 10 as well, since it has numerous turrets, is heavily armored, and is described as having an "awkward, bulky frame." Mach 2 or 3 seems more like it – and that assumes that somehow Tech 7 craft can overcome some of the limitations of aerodynamics which prevent current aircraft from reaching those speeds unless they are very streamlined.