I've been reading some "hard" science-fiction novels lately (Antares War, Night's Dawn) and thought about how combats played out in those books. The way rogue trader handles ship-to-ship combat, it assumes that both ships are starting from basically zero speed and both parties *want* to engage in a dogfight.

But what happens, if both combattants have been accelerating for some time towards each other? Their engagement will be over in minutes or even seconds, with no quick way to turn and re-engage, turning the normal, gentlemanly tactical combat into edge-of-the-seat, split-second decisions.

Head-on Engagement
A head-on engagement, or intercept, needs no tactical map and will take less than 5 minutes to play through. As play aids, you might want to use a couple of different tokens for each party: break through, hold fast and engage for phase one, evade and attack for phase two. Use coloured dice, or write the orders on scraps of paper. If you really want to crank up speed and tension of the fight, use a stopwatch, giving the players only ten or twenty seconds to make their decisions. If they break the time limit, in phase one they default to “Hold Fast!” in phase two, they simply do nothing – indecision has literally paralysed their crew.
During an intercept, neither party can take extended or manoeuver actions - both crews are strapped into their acceleration couches and there is simply no time for anything but firing and praying to the god-emperor.

Phase 1 – Determine Speed: while both ships power towards each other, their captains must decide: “Break Through!” (red), “Hold Fast!” (yellow) or “Engage!” (green). Each party covertly selects the token corresponding to their decision. Let your players discuss for a short time without listening in. When they are ready, count to three. On three, you and the party's captain reveal their choice. Proceed to:

Phase 2 – Determine Duration: Depending on your choices, both ships will have the option of firing for a number of rounds. Consult this table for the exact number and fire arcs:
“Break Through!” “Hold Fast!” “Engage!”
“Break Through!” 1 Fore 1 Fore + 1 Side 2 Fore + 1 Side
“Hold Fast!” 1 Fore + 1 Side 2 Fore + 1 Side 3 Fore + 1 Side
“Engage!” 2 Fore + 1 Side 3 Fore + 1 Side 4 Fore + 2 Side
Note: For the purpose of range dependent modifier, the first half (round up) of Fore arc shooting action are considered to happen at 10 VU, the second half at 5 VU and the Side arc shooting happens at 2 VU.

Phase 3 - “Fire!”/”Evasive Manoeuvers!”: With speeds determined, both parties decide if they want to open fire or evade the incoming ordnance. Again, let the party discuss without listening in and make your own choice. Count to three and reveal your decisions.

“Fire!” means the ships fires all weapons in the relevant arc. Due to the extremely high relative speed, add +2 to every weapon’s damage code, as at hypervelocity, even microshrapnel hit with the force of a railgun slug. If both selected “Break Through!”, the hypervelocity bonus increases to +4 weapon damage.

“Evasive Manoeuvers!” also works as advertised – the ship’s pilot takes the Extended Action of the same name.

Note: There is no initiative order during an intercept, all ships act and fire simultaneously (Evasive Action happens first, though – duh.). Yes, that does open up the possibility of mutual destruction. And yes, that is intentional.

In the rare case that both parties chose “Engage!”, don’t apply the hypervelocity damage bonus, instead both ships can take one extended action during either of the side arc firing rounds. Apply common sense at what actions can be taken, for example, there is no time for hit and run or boarding actions, although a callous captain might choose to sacrifice his assault craft for one more chance to damage his enemy, leaving them either dead or marooned, with neither sufficient fuel nor air to return to the mothership.

Repeat Phase 3 until the ships have passed each other or until one (or both) parties are destroyed.

Bombers: You normally can NOT attack with bombers during an intercept, as they lack the necessary delta-V for a return journey. If you choose to use them, they will make their attack run and then they’ll be considered lost with all hands. The captain might need to make a Hard or harder interaction test to convince the crews, as they know it will be a one-way trip.
Torpedoes: There is no way to reload Torpedo Tubes during an intercept – all crew are strapped in, so once all tubes are empty, that’s it. Also, no re-engage action for the torpedo, it doesn’t have sufficient delta-V either.

Blockade Run
A blockade run works almost identical to an intercept, except that the defender can choose to set up his ship(s) either head on or with their broadsides towards the runner.
During Phase 1, the blockade automatically chooses “Engage”
During Phase 3, the blockade gets an additional round of shooting after (if) the runner has broken through. This parting shot can only be taken, if the blockade has weapons able to fire in that arc. That means a ship that meets the runner head on needs a keel weapon to take a parting shot. The blockade can choose “Evasive Manoeuvers”, but takes the Pilot Test at one difficulty step harder – their ships are moving at negligible speeds (if at all) and make for easy targets.

It's a coherent system, and one that sounds like it would work out very well, although I find that secret decisions are always hard as the storyteller.
That being said, I don't think this system fits in with the fluff at all. Besides just the descriptions of space combat we see in the books, or the bases out of the BFG game, it also doesn't work under its own internal world.

In your vision, the ships essentially pass by each other in a few minutes. The strength rating of the weapons is based on around half and hour of continuous fire. By the fluff, it shouldn’t even be possible for the ships to even brake threw each other’s void shields over the course of the entire five minute engagement.

The Micro-shrapnel doesn’t make particular sense either, as one of the points of a Void Shield is to deflect micrometeorites and other small, fast moving items that are a danger to navigation. It also only makes sense as an add-on to fire if your actually using physical rounds, which only two of the weapons presented so far do.

Thanks for the reply.

Quicksilver said:

thanks, but why is it hard? in this case, you play the captain of the opposing ship. compare the players' ship to your own and make a tactical decision: stand and fight or run.

Quicksilver said:

I know, i love those battle descriptions. I don't want to completely replace the standard system, but offer an alternative. In almost all of the stories, you have fleets of warships, that more or less agree on the whole "let's have ourselves a nice shooting war" thing. In RT, you play rogue traders in a single vessel, most of the time. maybe you do not want to duke it out with the enemy.

Quicksilver said:

again, my system is supposed to simulate an intercept at cruising speed, not a dogfight. take for example the Sword. It has a max sustainable acceleration of 4.4g, that's rounded (very roughly) 44m/s². Since Velocity = Acceleration x Time, after one turn (30 minutes) of full acceleration, its speed is about 79.2 km/s - that is 285120km/h or 14 void units per round. This is well within the Saber's speed cap. But in space, there is no maximum speed, since continuous thrust = continuous acceleration. Imagine at what speed the Sword would be travelling after a day of continuous acceleration. So, yeah. They'll pass each other real quick.

Quicksilver said:

Citation Needed .^^ I really can't find anything to back that up. In the book it's always "one devastating volley" and so on.

Quicksilver said:

With micro-shrapnel, i mostly meant the airburst (spaceburst?) from standard macrocannons (which should be the most widespread armament), yeah, but also parts sliced off, slagged or kaboom'd from beam weapon hits. Those happen within the shield. Imagine a ray from a sunsear laser, hitting - whatever - a geller field emitter. The emitter bursts into pieces flying off in all directions . If rest of the ship is still moving at a measurable fraction of lightspeed, those are bound to leave a dent.

I really hope, i got that high school physics right and didn't make a fool out of myself.

1) I was noting the difficulty of both monitoring the players actions & desisions against making an uninformed desision for the opposing captain. The GM, by the nature of being involved with the players, becomes biased in some way.

2) That's true, except for scouting missions, or Convoy attacks or planetary landings, none of which want to engage in actual combat. Now I tend to read of of the IA books and BFG publications, not much of the black library, so my view of 'what's published' may be a bit different.

3) This assumes that these Sci-Fi arcana engines actualy use Neutonian physics to propel themselves, given both the way the turn and the way they run from half and full speed, this is quite an assumption. There is also demishing returns, even in a vacuum, the speed/weight ratio of the ejected particules puts a hard limit on how fast the object they are propelling can go. This is why a conventional chemical rocket, no matter how long it burns, will never reach a sugnificant fraction of c.

4) "Strategic and Naritive time - In Space!" Turns are half an hour long and you can fire each gun once. Even if you assume that this is because the guns fire instantainously then reload for half an hour, the most you could be looking at is one volley. Because of the way the starship system is designed, its essentialy impossable to even cripple a ship, much less stop/destroy it in one round round of fireing.

5) Any splintering from weapons strikes would be traveling at the same aproximate speed to the vessel they exploded off from. Unless the ships are passing close enough to be hit by eachothers shrapnel, there's nothing to cause severe damage. Also, I note again the issue with the armor & shields. If these ships can travel at a reasonable %c, then they must be able to survive micromtiorite hits at that speed. Otherwise they'd never make it out of the system.

maybe i should clarify my intent again: i like space combat in RT, i'm simply offering an alternative to either spice things up, or to keep the non-wargamers from falling asleep. my party fought one big space battle (it took about 90 minutes to resolve), and of the six of us, i was the only active wargamer and one other was interested in those. The two of us really had a blast maneouvering the ships, trading shots, using asteroids as cover. the other four nearly dozed off. to make my system able to coexist with the original, i added the fluff description of a high speed encounter.

1) maybe. that's down to style, i guess.

2) i never really got into bfg, but the IA stuff is pretty much in line with standard BL stuff. Still, some writers like abnett use "real" physics from time to time. I remember in one of the ghosts novels, one of the ships fighting an incursion misjudged the distance, decelerated too late and took itself out of the combat by overshooting.

3) Well, the book gives us numbers for mass, max sustainable accel and all that. the combat mechanics are not a good "proof" for the uncoventional physics argument, i think. after all, there is no z-axis either, and nobody is arguing that the 40k universe is a slab of space infinitely long and wide, but only 10k kilometers high. not everyone is into realism as much as i am, and calculating accel or decel rates, vectors, delta-V and stuff would kinda take the fun out of combat. also, plasma drive: en.wikipedia.org/wiki/Electrically_powered_spacecraft_propulsion#Ion.2Fplasma_drives i am pretty sure, that the ffg guys at least googled what they were putting in their books.^^

4) I read that part. So, maybe the crew only fires once every half an hour to reduce wear, to conserve ammo or for whatever other reason. Maybe the Void Gunners' union forced them to sign a form that forbids them from firing their guns before the ship has completed its move. Said move takes 29 Minutes. It doesn't say anywhere what the rate of fire of every single component is. That isn't important either. Glossing over such details is what abstraction is for. I know it's hard to knock out a ship in one turn (linked broadside from a heavy cruiser with 3 ryza plasma cannons: 12d10+48, not counting shields), that's why most times, each ship will fire two or more volleys.

5) Thanks for clearing that up. Relative speeds and stuff are not my forte. In general the extra damage is supposed to crank up the danger, even when exchanging only very few shots. I go with the layman's explanation of "faster things hurt more when they hit you" and to keep confusion and bookkeeping to a minimum, the modifier applies to all weapons. also again, the shrapnel i was refferring to mostly is from macrocannon shells exploding inside the shield barrier. pieces normally too small to penetrate a ship's armour get more dangerous, the higher the relative speed between shooter and target gets, right?

I think it may be more nessisary for me to clear up my modivations. I'm really playing devil's advicate here, trying to point out the things that are eather what I feal are flaws or that I think have the potential to break emersion for some players. I don't meen to come down hard as 'your shouldn't do this'. I can understand the problem of people not being interested in the space combat, but I think there are other ways to approch this issue, such as moving to abstract (markerless) combat and making sure everyone had something to do aleast every few turns, even if it's just yelling at the crew. However, if you think this is the best way to get on with the plot, I fully support it.

2) Haven't read that so I can't comment, but it is possable to disingage by 'leaving the battlefied' (going off the board). Not that hard if you do All Ahead Full at the wrong spot.

3) While they may have googled it, they've been called Plasma Drives from before FFG had anything to do with it. Perhaps more importantly, we can pritty much rule out that kind of plasma drive as a viable option, they don't have anywhere near the acceleration nessisary to produce what's listed in the book, much less whats described. Its being considered for deap space probes because of its ability to store lots of fuel, and its higher top speed compared to conventional rockets (both because of wight of fuel and relitive high speeds of the exit particles), not because of acceleration. While your right that game-rules can't be used to prove non-real physics, FFG making up numbers can't be used to prove real physics eather. Why doesn't a ship have to turn around to stop? Or perhaps more importantly, why does it only take 2-4 weeks to get anywere in a system, be it Earth to Mars or Earth to Pluto?

4) I was just pointing out how you were streaching the internal logic. Even if it is going really really fast, why should a ship do the same damage in 5 minutes that it does in 1-2 hours during a pitched battle?

5) I understand the need to increase base damages, I was just pointing out the fluff issue.

Quicksilver said:

i tried abstract combat, but the problem i encountered was that my players had problems visualizing events and in a battle, where facing and distance are an issue, i find it hard to portray it well. as to breaking immersion - the huge amount of time that passes during a space combat is, at least for my group, a flowbreaker. personal combat is nonstop action, but during space combat, a character could theoretically take a shower and grab a bite to eat. i get it that one test represents half an hour of activity, but still...

Quicksilver said:

you can spend hours discussing made-up technology, i know.^^ personally, i choose to believe, that 40k ships move under newtonian laws maybe a plasma drive is a fusion rocket, or maybe it's simply made up. we really can't tell, can we?

Quicksilver said:

i'd like to fall back on my abstraction/rool of cool joker card.^^ but to argue internal logic: maybe all the guys normally doing other stuff are now firing and loading. or the first salvoes are being fired long before coming into combat range, creating a submunition screen in front of the ship. the higher the ships' speed, the less projectiles hit - whyever. in the end, i just want a system that offers a certain amount of tactical choice, but not so much, that it's boring for non-wargamers.

While it is a very cool idea, it some what conflicts with the style of the warhammer 40,000 universe. I would love to see a hard Sci-Fi system that did space combat well, but in truth, vessals in rogue trader arn't really space ships so much as Gallions in space.

Combat happens at the speeds it does in rogue trader, because that is how the writers envision it. It doesn't match up with reality, but it is damned cool. I would be temped to say that the right decision is to ignore the laws of physics on this occation.

If you need reasons why people don't fight battles at the speeds your thinking of, i would guess that they are limited by issues related mathimatics. Without cognitors processing the firing solutions for gunnery, the mathimatics has to be done by human and servitor systems, which are comparatively limited. This means that cruising speed engagements are just to complicated for the gunnery systems of imperial vessals. It might be an interesting tactic used by tau however.