So, I was wondering if anyone might help me? I want to create a ship component, but I'm not sure exactly how, mechanically, it should work, and it certainly isn't something most people would need, so I doubt it would be a mass-produced component, but...

Okay, what I want is a component that can, with risk, mind, shave off some distance from things you can be, and still exit the Warp. I know that the Orks have a stunt in Frozen Reaches where they exit right near Damaris, and it ends badly, but it can be done. I don't need a gizmo that can allow a ship to translocate to or from orbit with a planet, necessarily, but I was wondering how I might work a part that would allow a ship to "show up out of nowhere", like a surprise a raider might pull. I have a scene in a story where the fit has hit the shan, and no backup is coming, but then the other ship of the heroes' side DOES pop in, as if by a miracle, and saves the day. Depending on where in a system you are, it could take days of nail-biting tedium before you reach the friends you were endeavoring to save, all the while maybe being detected on sensors, and so I sort of want a hyper-calculator, that might let you exit the warp closer to the point you want, for dramatic effect. Thing is, I don't know if it is possible. Does anyone know how I might make this part work? It SHOULD have some risk, and I'm okay with that. Also, it doesn't need to let one "appear" above a world, as if by magic, or exit said doom, if one was getting hammered, but something cool, please? Thanks much.

How does this sound:
Xenotech Component 1 Space 4 Power 3SP

Gravity Tolerance Manipulator
Supposedly based on alien designs unearthed on a lost world within the Koronus Expanse, the function of this arcane device is poorly understood by the Adeptus Mechanicus. What is known, is that it somehow projects a gravitic field that calms the vortices that generally appear in the Warp near high-gravity objects such as planets or stars. This effect allows a vessel to translate to or from the Warp much closer to large objects.

A vessel equipped with a Gravity Tolerance Manipulator can perform Warp Jumps even when within the gravity well of a system's star, although it must still remain 20 VU from a planetary-sized object to prevent catastrophy.

However, the inherent risks of such a jump can only ever be mitigated. As such, roll a 1d10 before the vessel enters the Warp. On a 4-10, the translation happens as normal (with some violent shaking and bucking of the vessel).
On a 1-3 however, a wild gravity vortex buffets and tears at the ship upon translation. The GM chooses 1d3 Components that are now counted as damaged. In addition, the ship is thrown off course. The Navigator counts as having failed his Divining the Auguries regardless of his former roll.

I think I could work with something like that; thank you.

Everyone lives in fear that the Tyranids will develop such a device. Personally, I'd never create such a device for my campaign, and I never have Orks or Chaos (they do the same thing in a couple fluff stories) pulling it off, BUT if you're bent on adding that to your campaign you could do worse than SCKoNi's suggestion. I'd add something more to the disadvantage. Maybe a failure means the Navigator gains 1d10 Insanity. That would limit its overall use in the campaign. Of course, SCKoNi's device doesn't account for an entire squadron pulling it off in unison.

Of course, SCKoNi's device doesn't account for an entire squadron pulling it off in unison.

Dear god... well that's what GMs are for, and also what sort of campaign would you need to be running to have resources to have a squadron of ultra-rare Xenotech-equipped ships? o_O

I was thinking of a story where a squadron/fleet of Chaos vessels kept warping into and out of range of an opposing Imperial fleet/squadron. The whole thing took part in near orbit of a planet. The play balance issues should be apparent to all. I don't even allow emergency warp in my campaigns. Committing yourself to battle is just that...committment. If you want out, try silent running, otherwise polish up those fate points.

Reminds me of when I read the rules for BFG, and, as I understood them, Chaos Daemon Ships could "phase" for periods, becoming invulnerable, but unable to do anything, either. Like I said, I wasn't shooting for the thing that would let Abaddon the Despoiler "appear" above Holy Terra, to deliver the Emperor his long-overdue pizza (thin crust nurgle-rot, of course). Mostly, just shooting for a method by which an ally could "magically" appear on the brink of disaster, even if out, in the middle of nowhere, to save the day. When I try to think of stuff for my fluff, it helps to poke the minds of the other people who know the source material (40k), and if it COULD help other people in a mechanical way, that's great, too. I'm not even sure how the Artemis Resplendent would know which plot of realspace to jump to, to save the Exalted Wyrm from the Tau, so I still have some gaps there, but, especially in a story, having some "awesome", visually-cool, and quite possibly otherwise impossible stunts can be important, especially when, in a way, 40k is one of the few "sci-fi" universes that, at least some of the time, remembers how long some things can take. Using a warp drive in Star Trek might not be particularly more advisable than a warp drive in 40k, when you are still in a planetary system, but the Enterprise doesn't spend weeks cruising from Pluto, back to Earth. Star Wars is worse, since they actually take mass shadows into account, of how the tech works, but they don't spend a month in realspace, after the hyperspace jump, either. In 40k, if your backup isn't there, already, they'll probably never arrive, while you are still alive, or you "heard" them coming hours ago. Sort of like the Millennium Falcon zipping in, out of nowhere, to save Luke from Vader, I want the Artemis Resplendent to poof onto the scene, so that the Tau have no time to reconnoiter, and lance the hell out of the remaining Tau Protector's vulnerable flank, while her Captain is saving captured crew members, previously lost in a raid, since it should already be busy with the Exalted Wyrm , possibly the Wyvern , and the Aegis . Perhaps I asked for the wrong thing, I'm not sure, but it just seems too easy to say "and I say it appears smack dab where it is supposed to, just because." I know ships don't work like deep-striking Terminators, landing on a teleport homer, but for the scene, it's sort of what I need it to do.

silent running? "Hey, we got the call weeks ago, but didn't want to alert the Tau to our position."

Well if you want them to just appear out of nowhere, then a Warp Jump is not really necessary. The technology of 40k actually works in your favor in this situation, especially since Augurs and Vox systems are spotty at the best of times.

If you want a situation where they appear as if by a miracle, then have them simply... appear. On the edge of the map, hell make it even a big, "Heard you needed help there!" moment. As reasoning you can quote a lot of different things, that the Augurs were focused on the enemy ship, that a solar flare masked their approach, etc.

Sometimes a simpler solution works just as well

silent running? "Hey, we got the call weeks ago, but didn't want to alert the Tau to our position."

Yeah, I know Silent Running could work there, and the ship in question is even stealth-focused, for the most part, but I don't know how decent I'd have the Tau sensors/augurs be (they might not be as "junk" the Imperium's tech, but they also haven't had as much cause and time to improve them), and the critical point, for my little moment, is the WEEKS part. If the Tau caught part of the attacking force, and the Artemis Resplendent had time to run away, get to an Imperial port, for repairs, and then another ship had time to figure out where they were now, get there, and engage them, while the Artemis gets weakly patched, leaves, and then catches up, for the surprise save, that's potentially several months of time the people have been held prisoner, and I'm not sure that the Tau would keep them alive so long, even if they thought that their indoctrinating was partly working. I suppose mostly I might just be asking for something that can't work well; I'm a bit spoiled by Star Trek, and Star Wars, where the things are a bit easier, and the vehicle of a show/movie makes otherwise improbable drama a more frequent occurrence, so it stays good, but doesn't take forever. Sensors are almost fool-proof, the Force doesn't rip your brain out when you use it wrong, and neither is grimdark, even at the worst of times. Oh well. She is a stealthy ship, so maybe "swooping in", clearing a nearby asteroid, that otherwise blocked visual view, would work just as well. Even with much of space being "empty", there's no reason this spot of it must be.

their Astropath saw a vision and the RT heeds the astropath's advice?

I'm not sure a ship Component/Upgrade is necessary, or at least necessarily the right way to go. If we assume the danger of jumping insystem is due to the presence of a gravity well (or at least partly- the usual inaccuracy and possibility of hitting something when leaving the Empyrean is part, and so is the possibility of Immaterium-based pollution, which of course you don't want anywhere near inhabited planets) creating a shear gradient, plus potential tides; then in theory it should be safe (for the ship in question, anyway) to translate in or out at Lagrange points.

Warp pollution is then something of the major factor, particularly when jumping out.

Jumping in, it becomes a test of the Navigator's skill, and how accurate/up-to-date the charts are (and how well synched the charts aboard ship are with the actual positions of planets, moons etc. in the system. The longer a ship has been in Warp, the less accurately they'll be able to plot the Lagrange points, thanks to warp-dilation).

Assuming accurate charts, it's just a case of hitting a much smaller exit locus than usual. Difficult, certainly (I'd up the test's difficulty quite significantly), but a relatively simple problem that doesn't require extra gear.

I would say that it's not something that could be done the first time a ship enters a system, particularly not after a long passage. BUT- if you were to come out short (a couple light-weeks out would do, but I would say anything within 1LY or so), and spent a day or so looking at the system ahead and plotting the positions of major bodies, such a trick would be possible (and pretty much undetectable unless someone was keeping a psychic watch on your original exit locus (and it is possible to "ease" a ship back into realspace virtually undetected at such range, according to Execution Hour)). Then all it takes is a very short micro-jump (probably put a lot of stress onto the warp engines hauling a ship in and virtually straight back out, but it will minimise warp-dilation, and time at risk of daemon-gribblies).

I'd probably recommend a Warp Sextant, mind you.

^all off the top of my head. I'll probably have a more detailed think and look later, but I hope it is helpful.

a short jump with Markov drives?

I'm about to just make some **** up, but with one of the personages involved being an OX inquisitor of the Oblationist bent, and the JR Tau as her area of expertise, could their excuse for a warp drive do something similar? I know what they say about how the Tau "warp-skip" drives work, but I don't always understand what that all means. If a ship had a "typical" warp drive, they could go like normal, but only from system edge to another system edge, but then the Tau don't actually enter the warp, and thus travel much shorter distances, but more safely. If the Inquisitor in question was of a mind, and seeing her personal methods of fighting Tau would possibly clue in that she is (ah, the Oblationists), she could have some salvaged piece of Tau tech, loosely based off of Imperial tech, possibly, anyway, be implemented into the Artemis Resplendent , room/power permitting, sort of how the Star Wars ships have a secondary/back-up hyperdrive; you wouldn't want it to be how you get from point A to point B, but if you were stranded in space, and point B was half a sector away, you'd like to possibly get there in your LIFETIME. Since the Tau bit is more short-range, and also "less dangerous?", might it allow more "intrasystem puddle-jumping", where an Imperial drive wouldn't, but that is what allows for "real" warp travel? Other than "this is pointlessly ridiculous, unnecessary BS", and possibly space/power demands on an already set-up ship, I don't know if there are any problems with it. Like I said, at this point, simple stealth might even be the way I go, rather than "snowflake --> snowball rolling down hill" ridiculous, and even though the 40k galaxy's representatives can't be as window-free as say the Geth, from the Mass Effect series, in the heat of battle, few to no Tau might be looking out their vista ports for a ship their sensors haven't even seen, but being put to the task of stopping a small invasion, almost solely, demands some extras, and having alliances with a somewhat crazy, Radical Inquisitor, putting her to that task, can have their perks; some crazy, and unorthodox. When the situation is over, Von Cossrath would simply reclaim the drive, and, being an Oblationist, she MIGHT kill Artymus's crew, since only Oblationists can be "safely exposed" to such technology (and they might even plan to ensure their own death, at the end, to cover their own "corruption, I don't remember), blah, blah, blah, but I don't know if that's how Tau drives work, right now, in the fluff.

If it's just going off into stupidsville, I think that the stealth the ship is already focused on could work. Despite liking the idea of seeing the enemy ships, the massive explosions, and such, of the big battles, from the throne of your bridge, I tend to assume that, sort of like warp travel, prior to space-combat, the ship buttons up its shutters, so the vista ports aren't obvious structural weakness, like the Geth would claim them to be, as well as explosions blinding your naked eyes, and you rely on augers to fight your enemy. Be that the case, the Tau wouldn't see the Artemis Resplendent until it opened fire with lances, and then the moment is there.

a short jump with Markov drives?

Quite possibly.

I'd probably rule the stresses of micro-jumping knock a couple-hundred hours off the service life/time til next major refit, mind you.

As for fitting a secondary drive system- major dockyard job, I'd say. As in, have to rework the power conduits to at least 1/3 to 1/2 the ship to get it to fit, reshape the hull over at least that much, overstressing the plasma reactors (somewhat, at least. Potentially catastrophically at that, but I'd likely GM-Fiat that away as "power plant goes into meltdown: burn Fate to survive, stranded in deep space with half a ship and no drive" is no fun and likely a crap story. Or at least not the planned story).

If it's replacing the warp drive- it's still a major dockyard job, but not to quite the same degree (or at least in quite the same way), but you still have the same problems with targeting safe emergence zones. I might give a bit of extra leeway, but I suspect I'd actually rule in the other direction, with them being more sensitive to non-flat Lorentzian metrics. I'd have to look more into how Tau drives work. It'd fit with the descriptions of the Tau "merchant" fleets (pre-Damocles Crusade, at least) being significantly more vulnerable, and not just because of their unwieldy and modular designs.

The biggest issue (religious/xeno-corruptive aside) in fitting a Tau-style drive to an Imperial ship is probably going to be software-based, but I'd say a (more-or-less heavily) modified version of the Navigator-free jump calculations would do it.

I still think it's doable without modifying the ship (although stealth systems aboard will help once in-system), particularly when remembering that the Tau are limited to speed-of-light detection, provided the ship in question has a reason to be headed that way (which Errant has provided, if you need one). It's just a really impressive display of bravura Navigation.