Range Limits of Jumpships

[Hellraiser]

I'm not familiar with the rules for making a KF Jump, but, I'm wondering how hard that 30LY limit is?

For example, if I'm wanting to go from Wyatt to Denebola, that is 30.2 LY per Sarna.

So is that a Flat out, NO, you can't do that?

You MUST jump to a half way point?

OR

Is there some sort of penalty to the navigator calculations roll?

Is it possible to make that jump at all & if it is, how much harder is it?

[AlphaMirage]

Impossible, full stop....

Why? KF Physics.

Caveat the Word of Blake did it, once, and burned out the jump cores in the process.

It is entirely possible there is a viable star between those two points you can jump to or you can just float in space and recharge with your reactor. Neither of which are particularly difficult and likely banal to experienced spacers.

Just tell COMSTAR beforehand if you suffer a jump drive malfunction and don't report in a few weeks.

[Hellraiser]

It is entirely possible there is a viable star between those two points you can jump to or you can just float in space and recharge with your reactor. Neither of which are particularly difficult and likely banal to experienced spacers.

I was just trying to figure out a better path on a map.

If my total distance is say 57 LY that is in theory 2 jumps.

But my "Route" to populated planets leaves me w/ jump points at the 25 & 31ish points it means I'm having to make a small 3rd jump or jump to deep space instead of a standard world.   Annoying is all :(

I was hoping it was something like 30 is the baseline, but you can risk burn out/miss jump for an extra +1 on the dice roll per extra 1 LY.
Similar to fast charging a KF drive.

[Frabby]

It’s not a hard limit, but not a baseline either.

There are jumps in canon that go slightly over the 30 ly limit (up to 32 iirc).
Think of the 30 ly limit as a game rule, like the 3 hexes (90 meter) range of machine guns. The bullets don’t drop to the ground after 91 meters but under game rules they don’t reach beyond 3 hexes, period.

I discussed jump ranges in this post a while back.

[Hellraiser]

Interesting stuff.

I do like the notes about some authors having JS move just over 30LY for certain jumps.

The Luthien/Wolcott one is obviously way off, but the GDL ones are close enough to be doable IMHO w/ some sort of penalty.

[Cannonshop]

Interesting stuff.

I do like the notes about some authors having JS move just over 30LY for certain jumps.

The Luthien/Wolcott one is obviously way off, but the GDL ones are close enough to be doable IMHO w/ some sort of penalty.

To be fair, the "maps" with "Scale" are, in terms of the game's history, relatively newish, often have imperfections and flaws that get corrected in subsequent printings, and aren't necessarily in the hands of a contracted author when he's writing...or, they get forgotten because the Plot has to go a certain way and too much delay corncobs the flow of the book or story.  (The tension collapses if the villain, protagonist, or villain protagonist is going to be arriving far too late to challenge their nemesis, because he's done his business and got gone while they had to fart around in empty systems for three chapters while said nemesis is doing their business...)

Speed of Plot is very much a factor in this here genre, and some authors just don't like doing that much math and/or geometry.

[RifleMech]

Impossible, full stop....

Why? KF Physics.

Caveat the Word of Blake did it, once, and burned out the jump cores in the process.

It is entirely possible there is a viable star between those two points you can jump to or you can just float in space and recharge with your reactor. Neither of which are particularly difficult and likely banal to experienced spacers.

Just tell COMSTAR beforehand if you suffer a jump drive malfunction and don't report in a few weeks.

There was one group that had a jumpdrive that could jump further than standard, but not as far as WoB, without burning itself out. I don't remember who had it or what sourcebook the rules are in though.

Also primitive jumpships made shorter jumps. The distance increased over time uo to 30 LY. It'd just be time, and speed of plot, before jumps start increasing again.

[AlphaMirage]

Interconnectedness Unlimited Super-Jump Drive on the Lucretia is not quite canon rumor but either way they are one offs that add flavor to the world not the norm.

Maybe it worked, maybe it didn't,

but they caused a lot of damage to the New Syrtis Yards along the way.

[Hellraiser]

The interesting thing that I've been seeing as I researched this is that most texts point out that the "theoretical limit" of a KF Jump with current technology is "around 30LY".

Words like theoretical & around make me think its not some hard line max where an inch more won't work.

There a flat out exceptions as noted.
Primitive KF Tech was variable in the rules from 1-29 LY with cannon examples being 15 & 20 IIRC.
The Manassas Drive was 40LY
The IU Drive was 50LY.
The WoB super drive was unlimited in theory but it blew out the drive so doing a jump beyond standard was a 1-way trip.

You also have misjumps that can port you through time or cause issues of 100+ LY jumps at a single time.

Point being, I'm thinking there should be some wiggle room in the rules for doing something like the 30.2LY jump I mentioned in the OP.

Like Frabby mentioned, MG bullets don't just stop at 90M hex range, we have the "Extreme" bracket of gunnery ranges that have a higher ToHit modifier.

[AlphaMirage]

I still like the inaccurate map explanation most. Nevertheless it is likely a dropped point of interest in the universe.

[Hellraiser]

So you are saying the Map is wrong & the author made no errors & something like Denebola to Wyatt is actually "under" 30.  (Or whatever the book example was?)


Or your saying the maps are right & the author just made an error that should be ignored?


I'm not in favor of ignoring the novels unless they are horridly mistaken like the Luthien/Wolcott jump which could have been retconned as the author leaving out several weeks of travel.

[AlphaMirage]

The 30.2 is actually 30 makes things much easier without retconning or further explaining a core concept of the BT universe. I'm fact it's more interesting if someone didn't keep their COMSTAR ASTRONAV subscription up to date.

[Hellraiser]

Rounding works for my example true, and I like that, but, one of the novel ones was more like 32.5 from that other thread.
Glengarry to Skye I think it was?

That is almost 10% more, which is why I think some sort of option like the shaving hours off of a recharge rule could be used to explain some of these minor limit issues.

It also just fixes some of the odd "routes" that your forced to do use.

I know Talon is one where your forced to go in the opposite direction to leave there for the rest of the FS/IS, but I've seen others where you end up having to do some crazy "half-loops to get somewhere because a world has nothing to one side of it on the map that is w/in the 30LY border.

[Daryk]

The only person you have to convince is your GM... if that's you, so much the easier. :)

[Cannonshop]

There are currently multiple ways to look at this problem, and a lot of it boils down to Randall's aphorism: "if it works for your  campaign, do it..."

[DevianID]

We know that the star charts are a bit wonky regardless, as they assume a flat plane, instead of a 3d one with z elevation.  So while the game rule is 30 LY hard stop, that is only because we have the benefit of digital maps now with precise measurements like 30.2.  The early writers clearly didnt have that, and whatever method they used likely had a degree of imprecision, such as trying to read a ruler.  But its ok for a writer to mess something like that up, and not ok for players to jump farther then 30 LY when using something like MekHQ--the program wont ever allow it, other then to just use GM mode to magically teleport you anywhere you want at the speed of plot.

As for actual ranges, I could speculate that the explorers in the early star league/terran alliance days stuck to systems not far off the vertical access as a safety protocol, like how they stuck to 30 light years.  If you only use systems on a fixed vertical slice, then you create traffic through that system as you expand outward.  This increases the chance that a marooned or struggling ship could get rescued.  If you start jumping more then 30 light years or to systems greatly off axis, your risk of misjump goes up and also you dont stop along the way to created traffic in the -inbetween- system.  It also would explain why dead-space recharges just arnt a thing... otherwise you could dead-space recharge and show up anywhere in the sphere without bothering with border systems... The clans, for example, could have just appeared on terra in the clan invasion without bothering to stop at a single planet along the way.

The taboo of 'further then 30 LY' or 'dead space' jumps, as well as the desire to be in a real system after each jump incase you need rescue, is apparently mighty powerful in battletech space operations.

[AlphaMirage]

There are canon examples where jumpships do dead space recharge or route through 'uninhabited' systems. As long as someone knows where you are going and can send for you if you go off schedule it's fine. The rules do not penalize this behavior.

Additionally there are plenty of dead worlds or outposts post war that might have a small caretaker population on an orbital or moon that isn't worthy of being recorded by COMSTAR any longer.

[Daryk]

You know... the "caretaker" population angle has some interesting possibilities... ;)

[RifleMech]

Interconnectedness Unlimited Super-Jump Drive on the Lucretia is not quite canon rumor but either way they are one offs that add flavor to the world not the norm.

Maybe it worked, maybe it didn't,

but they caused a lot of damage to the New Syrtis Yards along the way.

That's the group! Thanks :)

Wasn't that WoB that did the damage?  Either way, there are rules for longer range jumps.

The interesting thing that I've been seeing as I researched this is that most texts point out that the "theoretical limit" of a KF Jump with current technology is "around 30LY".

Words like theoretical & around make me think its not some hard line max where an inch more won't work.

There a flat out exceptions as noted.
Primitive KF Tech was variable in the rules from 1-29 LY with cannon examples being 15 & 20 IIRC.
The Manassas Drive was 40LY
The IU Drive was 50LY.
The WoB super drive was unlimited in theory but it blew out the drive so doing a jump beyond standard was a 1-way trip.

You also have misjumps that can port you through time or cause issues of 100+ LY jumps at a single time.

Point being, I'm thinking there should be some wiggle room in the rules for doing something like the 30.2LY jump I mentioned in the OP.

Like Frabby mentioned, MG bullets don't just stop at 90M hex range, we have the "Extreme" bracket of gunnery ranges that have a higher ToHit modifier.

Good list. :) 

[PuppyLikesLaserPointers]

Personally I view it as the safety line, rather than ruled by the god and the creator of the world as if it's an axiom. It's generally considered as safe distance, but I don't think that the precise maximum distance to not get an accident would be exactly 30 light year distance without even some hundreds of kilometers of difference. The exact safe distance would be also modified by the stars near of the jumpship and target(and maybe also the stars near of the course?).

Anyway, if you had an another system on 30.2 light year distance, then... well, they better think about to jump twice. Although it's only plus 0.2, but it's 0.2 LIGHT YEAR. I don't think that such unit would be easy to be ignored. It's not like moves 101km/h on the road with maximum speed of 100km/h. The distance over than 30 LY is around 12600 times of the distance between sun and earth. I don't say that every single jumpship cannot jump that much distance without an accident, but I bet that you don't want to commit suicide while spend ridiculous amount of money and life either. At least there would be some chance to do.

Still, if you are in emergency, it would be worth considering. It's not TOO far than the safety line, after all, so if your situation makes you to seriously consider such an option, then it can't be helped.

[Daryk]

If I jumped in a fifth of a LY short, I'd burn a little fuel on station keeping thrust to start moving toward the target while calling for HELP!

[DevianID]

I think this is a great point.  If a 30.2 light year jump incurs even a fraction of a bit more risk for a misjump due to range, when the 'advantage' of taking that risk is to skip waiting 1 week or less to recharge at a midway point... like 1 week is nothing.  A misjump is months or years worth of damage.

Jumps in battletech are crazy fast, in a light year per day rating, so the name of the game is safety not speed or distance.  Jumping 120 lightyears in a month with risky push the limits 30+ LY jumps, versus taking 90 light years with 4 shorter safer jumps, the 90 wins every time.  The amount of stuff within 90 light years is already stupendous, and if speed was really a factor you would use a command circuit or something.  Command circuits or space recharge stations are terrifyingly fast in a stellar sense.

[Hellraiser]

I don't disagree with you, and yet, we have rules for fast-charging a KF Drive, and that the same concept.
Sometimes time really IS of the essence.

This isn't about shipping lanes that I'm asking btw.
Its about moving troops for an assault/raid/relief mission.

Using my theoretical 57 LY in 2 jumps v/s 3 jumps scenario.
That is a full week delay on launching a raid or getting a relief force to the planet, etc etc.
Or heck, just escaping from the invasion force bearing down on you in the case of fast charge.

Now if that extra 1/5 of a LY is a 90% failure rate then clearly you don't do it.
But again, this is why I was asking what sort of rules there were.
In the same way you can shave off a few hours of charging, can you plot that jump a bit further.

Even the descriptions as I mentioned above are not HARD limits, they tend to say things like theoretical when talking about the limit.
Is there really a difference between a 29.99LY jump calculation v/s a 30.01LY calculation?  That is what I was wondering.
For that matter 15 v/s 29 LY.  Is the distance a matter of difficulty at all? 
What is the true "limiting factor" that gave us 15LY proto-drives v/s 30LY current drives v/s the 40-50LY experimental drives?
Mass of Germanium?  That seems to be the case w/ Proto drive improvements, but then Compact Cores blow that out of the water.  And its hard to imaging a Standard core getting much bigger but the IU drive was on a standard JS so something had to be different.
For that matter the Aegis doesn't have a HUGE amount of Cargo like most SLDF ships to increase its core in size.

If Distance is a factor at all in calculations then how much of a factor, like does it affect a to-hit roll for a successful jump?
If 30LY is the dead set limit then does exceeding it at all cause a fail?  What if the Nadir is 30LY but you try to jump to the far side of the system outside the orbit of "Pluto" or something.  Fail for a distance of a couple AU?

I feel like I'm going to chalk this one up to "works for your campaign" or "close enough on the map" w/o getting too detailed on the actual distances listed on Sarna.

[Daryk]

That's the chalk I'd use... :)

[PuppyLikesLaserPointers]

There is nothing on SO, at least, that says what happens if you try to do so. It have no mention about calculate the range, only for the jump points the ship initiate jump and the supposed destination. Although various fluff writes on SO does says that thirty LY is a hard limit since 23th century. It won't be a exact 30LY, though, but nothing says its exact length either.

I did searched A Time of War but no avail. The rules even don't concern about this.

Perhaps such vacancy means that the settings team thought that it is not possible to try to do this intentionally by modern K-F drive, unless you did some weird touches such as 'super jump'. But nothing says what exactly occurs when you did, or I didn't find that.

[Cannonshop]

There is nothing on SO, at least, that says what happens if you try to do so. It have no mention about calculate the range, only for the jump points the ship initiate jump and the supposed destination. Although various fluff writes on SO does says that thirty LY is a hard limit since 23th century. It won't be a exact 30LY, though, but nothing says its exact length either.

I did searched A Time of War but no avail. The rules even don't concern about this.

Perhaps such vacancy means that the settings team thought that it is not possible to try to do this intentionally by modern K-F drive, unless you did some weird touches such as 'super jump'. But nothing says what exactly occurs when you did, or I didn't find that.

alternatively, sometimes they leave stuff out so they have some flex for later, for instances, if the Plot demands something that would otherwise be impossible, having that gap lets them fill it to make it possible for the sake of a given plot point or development later.

[RifleMech]

Primitive Jumpships and Warships do have maneuvering drives so maybe jumping .2 LY short isn't as big a deal for them as it is standard Jumpships? And maybe the little bit past 30 LY is the furthest point in a planet's rotation, like during the summer months? Or the jump limit is about 30 LY, so a little over doesn't hurt while a lot does.

[Daryk]

0.2 LY is more than a little too much to overcome with conventional thrust.

[ANS Kamas P81]

No, that little bit past 30 light years - that 0.2 LY we're talking about - is over 12,600 times the distance from the Earth to the Sun.  The week-long transit from the jump point to Earth is about 8-9 AU, so there's no way someone's simply relying on maneuvering drives to make up that distance.  That's something like 1500 weeks of transit time, or near thirty years.

Space is big.

[Daryk]

Exactly!