[Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

Greetings, all!

Both Space and Spaceships have some generic ideas regarding FTL drives and their use. Currently I'm wondering about the playability and gameworld-shaping properties of these FTL methods. For one, 'lighter' space games (such as space opera) should probably avoid scenarios where a one-hit kill will destroy a civilizations. Thus, fast sublight drives should be out of the question. Also, it should be impossible to just drop a planetbuster out of hyperspace/warp/etc. right onto the planet or enemy starbase. So, my opinions of the options presented in Spaceships:

• Jump drives, while theoretically neat, actually lead to too-easy blockading. Smugglers become broke, and warefare is dominated by being able to build the largest 'minefield' and have the most platforms at the choke points.
• Jump gates are even worse in terms of blockades, as they can be powered down if needed . . . or sabotaged by jumping a bomb from the other side, if their mechanism prevents shutdown somehow.
• Warp is a case where human pilots become useless, and speed is stealth (because sensors become all but useless against a warping target). Well, at least in deep space they do.
• Hyperdrives are complex, but probably can be turned into a balanced form of FTL. I'll look at it in more detail.

I think Hyperdrives can be very different:

• Whether the course has to be plotted ahead of time makes a big difference for retreating.
• Whether it is okay to diverge from a course while in hyperspace could change how tactics work - especially when hypercommunications become available (like in Master of Orion).
• Whether ships interact in HS or not changes some encounters. Notably, whether it is possible for two war parties to meet when Party A is hypering to B's Base and Party B is hypering to A's Base. If they don't interact, both bases will end up destroyed - another MAD scenario, under some setups.
• Assuming that ships mostly move at normal speed in HS, but HS distances are shorter than their realspace counterparts seems to ease many headaches. It does, however, create another one: will ships entering HS too close from each other end up colliding (or worse)?
• If it is possible to 'drop' out of HS, it is somewhat less scary to get lost, but still scary if HS is 'unmapped' and/or not even remotely aligned to points in realspace.
• Accessible points of entry and exit change a lot of things. For instance, entry/exit points too near to gravity wells result in more MAD scenarios. Setting them too far without providing a fast sublight drive makes raids too slow. Also, allowing HS entry/exit in places arbitrarily far from stars allows 'safewarps' of scary proportions - a pirate space station thus can be placed anywhere with no way of figuring out where it is other than by following someone (I'm not sure if it is good or bad, but it seems a bit unbalanced to me). I'm considering two ideas, both of which prevent normally entering/exiting HS both too close and too far from planetary systems:
  1. Lagrange points. I wonder if it's too close to the planets and/or too easily blockaded.
  2. A spot where the gravity gradient is exactly some number, i.e. the surface of a sphere around the star (or black hole!) of some radius (depending on mass/size). Allows attackers to come from any direction, gives some time to prepare, doesn't allow creation of arbitrary safewarp spots without some stellar object that can be noticed (either directly or from HS).

I'm sure there are more considerations. I'd like to ask you for your comments, observations, considerations etc. regarding FTL movement in space games, as well as to share any experience you had.
Thanks in advance to all who answer!

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

I infer that by jump drive you mean drives that jump between points of some kind of astrophysical significance, providing something like a jump gate network, except that the point is naturally occurring and the hardware goes on the ship rather than a space station.

'Jump drive' is also used to describe drives where you jump through hyperspace or non-space, with start and end points constrained similarly to hyperdrives (which is to say, depends heavily on setting). If they're distinct from hyperdrives, it usually is by an instant or range-independent jump time. Sometimes jump times from the ship's perspective differ radically from jump times from outside.
Typically a two-ended jumpgate will be guarded from both sides by people who claim control of it, to make it hard for someone to fly a freighterload of antimatter in. If the jumpgates are completely connected, chances are one organization owns all of them.

In at least one setting, jumpgates can also farcast: instantly transport your ship to the destination without a receiver gate, but with sizable error margins that can require a lengthy sub-light trip to the destination. Farcasting can be smuggler-friendly, so long as they can find a farcaster not watched by customs.

Another setting has jumpgates that can't be sabotaged because they're self-defending (and probably invulnerable) Ancient supertechnology. They also make matters...interesting by enforcing a no-attack radius around themselves. That probably isn't enough to make smuggling work.
I infer that you're allowing FTL travel but not FTL sensors? A long-ranged FTL warp detector (which might or might not work against non-warping objects) would negate those problems. Very large warp-denial fields also might work.
One option is to make the points of entry/exit governable by something other than astrophysics.

-Schlock Mercenary has a drive (more jump than hyper, really) that permits huge areas to be covered with 'denial fields'. Trying to jump into or out of a denial field without the permission of the operator is fatal.
-As with warp, hyperscan can make a big difference. If everyone knows where you're going to come out well before you get there, your planet-buster is going to get a hot reception.
-You could require offboard assistance at one or both ends of a jump. B5 small craft seem to need jumpgates to enter and possibly exit hyperspace. You could have either or both of hyperspace boosters and hyperspace catchers/beacons. (If you need a catcher, and can't detect them or track your position while in hyper, you're at risk of going flying dutchman if the catcher goes down while you're in hyper.) Natural boosters/catchers could also make interesting spatial anomalies.

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

I liked the Stardrive (from setting of same name for Alternity). It worked somewhat similar to the jump drive of Traveller with a few changes. Below are a few of the details of the drive.

1) Fuel, ships in stardrive don't have to worry about refueling and their FTL drive doesn't suck up fuel. But after emerging a ship had to spend 1d4 days waiting for the system to recharge.

2) the amount of time a ship spent in drive space as slightly different but not much (about a week) and like traveller while in ftl you couldn't change course or communicate.

3) If the system you were heading too had a drive space relay (FTL com system) they would detect you approach 11 hours after you engaged your drive. Giving them time to prepare (if at war and send a distress call). FTL communications took 11 hours to travel to any drive space relay in range (max range was about 50 ly) so long distance coms took a long time.

4) The max distance a ship could travel in ftl was based on the size of it's powerplant vs the size of the ship. Largerships needed more power to to travel the same distance but the size of the power plant needed for this was overall a smaller % of the ship the larger the vessel. (Largeships often gave smaller vessels a pigyback ride).

5) where were no limits on where a ship could enter or exit drivespace in system (just not on planets/in atmosphere).

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

In a SF setting I'm thinking of, hyperspace can be entered most anywhere, but can only be exited within a certain gravity gradient. You can impart enough stabilization in subspace to enter hyperspace, but once in, it takes a fairly strong gravity well to stabilize it to the point that it maps reliably to reality. Turn off the drives in deep space and your atoms are going to be scattered over a few cubic light-seconds.

Basically, it allows you to the inner system of typical stars, generally well within the inner limit of the life zone. You can also jump to brown dwarfs and even large gas giants, but the narrower margins require careful navigation.

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

Summary before waffle:
I've chosen hyperspace for the reasons you give and added Shock to deter close attacks. No in-flight course change or comm. No special fuel.

Star Drives are huge sponge-brain NAIs with Warp (Hyperspace, etc) and various related talents.
Travel between stars is very fast, taking mere hours to cover a few parsecs. Hyperspace insertion is safest in deep space (relative stellar mass x6 AU) but can be done in a La Grange @ -(1d-2) to skill. Not recommended in a gravity well.
Emergence point and velocity, relative to your target planet, depend on your navigation check margin of success/failure and modify a basic RSMx6AU; closer to planet = slower. Mods to skill for known/blind warp, and time taken.
Despite having subwarp/ pseudovelocity drive 300mps, realspace journey times are still dire - 5AU takes 18 days? But microjumps are possible; 30 seconds prep time gets you a -10 on 5 lgt secs and the star drive has Reliable+10.
A bad nav check could leave you in deep space going the wrong way very fast and subwarp cannot be used if already moving faster than your rated drive. So microjumps also correct nav errors by allowing deceleration.

Disadvantages:
Hyperspace is exhausting. Each warp causes shock and fatigue. Extreme distances deplete HPs and can kill. Light Coma (B361;#28) is not unknown. You emerge from hyperspace exhausted, dehydrated, hungry and disorientated for vital seconds. It isn't always good for the ship either. Vulnerability/ Resistance to hyper-shock is a definite factor in starship crew suitability.

Hyperspace entry and exit also cause a gravity hiccup and optical flare +10 to detection. Don't warp near friends.

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

a) Fast sublight drives can use Pseudo-Velocity (p.33). I myself want fast sublight drives for interplanetary travel.

b) Look at the Probability Drive option on p.41. I prefer a jump drive that can jump anywhere sufficiently far away from the next big mass, is instantaneous, has limited range, and needs time between jumps.

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

My only fear of PV drives is that a sudden stop can be abused as an extremely high sAccel for the purposes of a dodge.

I also found that Reactionless drives seem too cheap/efficient/fast-accelerating on average when compared to Reaction drives of the same TL.

I'm not sure I 'get' what is so special about the Probability Drive.

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

I'm designing a space setting for my next campaign, so these are questions that have been on my mind lately. :-)

The problem with this is that it tends to make the solar system too huge. Without high acceleration and high delta-v ships, trips to other planets take months or years. You're left with a scenario where either there's only one "interesting" planet per system, or else using the FTL drive for pretty much all travel, with drives confined to maneuvering. Neither is a result I like, personally.
The suggestion to use pseudo-velocity can help, of course, but pseudo-velocity has its own issues for me - I don't like the image of space combat it creates, with ships stopping instantly when they hit a pebble, or colliding with each other without effect.
In my setting, I'm using reactionless thrusters, but I'm also allowing force screens. I'm just assuming that anything too big to dodge a relativistic rock will have extensive force screens in an anti-kinetic "Whipple" configuration, capable of stopping most impactors.

On the other hand, jump gates do have some advantages for a space setting. They essentially provide space with more "terrain" - jump gates are the Thermopyleas and Straits of Malacca of space. They provide dramatic potential for players to guard, to sneak past, to get stopped at for customs, etc. etc. Of course, it's true that if they're too easy to interdict, things get boring. In my setting, I'm making some asssumptions about jumpgates:

• Jumpgates are expensive - it takes the resources of a major industrial nation to build one. So there are major disincentives to just destroying one to prevent an attack.
• They're not easy to open, once you shut one down. It takes a lot of exotic matter to restart a shut-down gate, taking about 5 years to collect. Again, a disincentive to shut down a gate to avoid an attack.
• Gates are "one way". If you have an active gate, you can go to the destination, regardless of whether there's an active gate at the other end (an active gate at the other end just lets you get back). So, destroying a gate in your system doesn't prevent an invaison anyway - you have to destroy the gate on their side.
• It's not necessary to go through the physical gate to make use of the wormhole. A gate "weakens" space in an volume within 100,000 miles of the physical terminus. Reactionless drives, which operate on a similar principle to the jumpgates, can be manipulated to punch through into the wormhole(called "gatecrashing"). You have to make a skill roll, unlike just going through the physical gate, but it lets smugglers, invading fleets, pirates, and various and sundry others go through without having to crunch down to such a narrrow area.

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

Personally, I prefer the Lagrange Point version of the hyperdrive you outlined above mixed with a go-anywhere limited-range in-system jump drive for small craft. Allowing only small ships to use in-system FTL (aside from lagrange-point to lagrange-point jumps) makes fighters much more useful than they are in the normal system - plus it makes the game a lot like Freespace 2, which was awesome.

So long as there is a sufficiently high minimum mass for the lagrange point (say, the mass of the Ceres or something like that), there shouldn't be too many lagrange points in any given star system. That would make it so you can't use the Earth/Moon L-points or most any other Planet/Moon system except Titan/Saturn and Ganymede/Jupiter.

Re: [Spaceships] Designing Hyperspace / FTL for space opera (and implications)
 

I had a lot of fun in one game by making using a conventional hyperspace drive similar to the Traveller jump drive, but making the time in hyperspace be zero from the perceptions of the ship and its crew. I used about 1-2 days of travel each end to get far enough from a planet to use the drive. The zero time in jump prevented a lot of "down time" and gave a nice sense of spacers aging at a different rate than planet folks. Also reduced wear and tear on the ship.