General expected number of misjumps in a system?

[Grav_Moped]

Jump drives are not "rockets" that action/reaction thrust you across interstellar distances.

At best, they are small children handed a present to rip open ... which tears the fabric of space/time and the starship "falls through the hole" into a higher dimensional "space" (jumpspace) that they emerge from about a week later at a distance from where they fell in.

If it helps, think of them as "reality drain" drives that suck your ship from place to place, rather than as "rockets" that shove your ship from place to place ... because once you jump, it's all "downhill" from there until you "hit bottom" and get tossed back out into normal space/time.

Different issue. It's not the jump drive exhaust propelling the ship into or through Jumpspace, it's using the jump drive exhaust (there's a lot of it, but it isn't necessarily moving very fast) as reaction mass to aim the ship so it's pointing the correct direction when the rabbit hole opens.

Most ships just use the maneuver drive for this.

 

[aramis]

Jump flash is detectable (per T5). One can presume that systems with access to high-enough technology and the interest to do so can establish some kind of Very Large Array satellite network with adequate range and sensitivity.

It's not stated whether a misjump "looks" different from outside. If it's one of the CT "off-the-map" types, there's a strong case that it would. The later editions' "right hex but you're in the Oort Cloud" misjumps might not.

It's been detectable well before that... MT SSOM made it pretty clear it was readily visible.

 

[Condottiere]

As far as I know, jump drives don't have or need nozzles, and with a jump bubble, you might want to keep them centralized, unless they are a tow ship.

They might be directional, but it seems to me, most starships prefer to fall forward into the rabbit hole, not backwards.

 

[whartung]

ISTR jump lines in T5, that is, a jump is always a straight line to the destination.

From T5

A planned jumpline may be blocked (at any point along the course, at the moment jump begins) by an intervening gravity source (larger than the ship in jump). The ship exits from jump at 100 diameters from the gravity source. The effect mimics quantum mechanics wave function collapse.

I assume that when the ship exits, it exits a week later, like normal, just not necessarily where they planned to be. It thats not the case, then ships would be plotting to, literally, hit, or arrive "past" the destination planet and just magically pop out at 100D.

Given that, whatever blocked the jumpline at the start of jump may well no longer be there when the ship exits. It's a week later, and it could have moved on.

 

[willtron3030]

I feel like I should explain what led me to ask this question. I have been planning to introduce IMTU a polity that was very late to jump technology for their tech level. They exploited another technology that permitted FTL travel for sub-parsec distances between fixed points. Setting up this transit route is complicated and time consuming, but the marginal cost per transit is nearly zero. [It's a limited version of the QSE (quantum spatial entanglements) from Peter Hamilton's "Salvation" series.] In isolation from other starfaring polities for some time after achieving QSE tech, they were making significant achievements exploiting resources in the system.

I wanted to rule that these paths could be shut down by energy from a jump or misjump occurring within a certain distance of either end of the path.

Arbitrarily, I wrote that risk occurred within 600 light seconds, 1000 light seconds for misjumps. [1AU is about 500 light seconds. 100D for an earthlike (size 8) world would be about 4.3 light seconds. 100D for our sun is about 465 light seconds.] One or more QSE shutdowns could seriously impact the economy and safety of the system. Inbound and outbound jump traffic should occur near the larger, outer GG, or way outside the ecliptic. System defense takes a dim view of varying from that.

As a result, the system has some draconian rules about where ships may activate jump drives... and a sabotaged jump engine could work as a WMD.

I was wrapping my head around the risk factors. I appreciate everyone's contribution.

 

[willtron3030]

As far as I know, jump drives don't have or need nozzles, and with a jump bubble, you might want to keep them centralized, unless they are a tow ship.

They might be directional, but it seems to me, most starships prefer to fall forward into the rabbit hole, not backwards.

I marvel at ship drawings that have HUGE "nozzles" that correspond to the location of the jump drive on the desk plans.

 

[whulorigan]

I marvel at ship drawings that have HUGE "nozzles" that correspond to the location of the jump drive on the desk plans.

If the jump-drives are processing massive amounts of hydrogen fuel thru the power plant preparatory to jump, they will be venting a proportional amount of Helium and Hydrogen (or other) isotopes as exhaust, even if it is not thrust-exhuast. Unless you are storing it, it has to go somewhere.

 

[Spinward Flow]

Unless you are storing it, it has to go somewhere.

To quote the commercial ... "Vaporize Him!"

 

[Grav_Moped]

I marvel at ship drawings that have HUGE "nozzles" that correspond to the location of the jump drive on the desk plans.

That's the flip side of a misapprehension I'd had for years, and that nearly all of the art since '77 has.

Jump Drives need big exhausts, since they're processing a lot of fuel (10%MPn) in 16-40 minutes (LBB2 '81 or LBB5 '80). For many years, I didn't realize that they went through all that fuel at once. It's not stated in LBB2, and only made explicit by the drop tank rules in LBB5 -- though they don't say it in so many words.

The thing that I didn't get (and, as noted, almost nobody else did either) is that after LBB5 '80, maneuver drives are gravitic in nature rather than reaction drives. They don't need an exhaust! (Power plants do, though, but not as big as you'd see on a jump drive.) But everyone draws starships with big rocket or afterburner nozzles for the maneuver drives because that's what people expect...

 

[Spinward Flow]

The thing that I didn't get (and, as noted, almost nobody else did either) is that after LBB5 '80, maneuver drives are gravitic in nature rather than reaction drives. They don't need an exhaust! (Power plants do, though, but not as big as you'd see on a jump drive.) But everyone draws starships with big rocket or afterburner nozzles for the maneuver drives because that's what people expect...

To be excessively fair and lenient in interpretation ... those huge nozzles like we're accustomed to seeing on the back of a Type-S Scout/Courier are probably multi-function.

When energized by the fusion power plant, those nozzles can act as HEPlaR engines for maneuvering power beyond most gravity wells.
When not energized by the fusion power plant, those same nozzles are used to jettison/dump drive byproducts (helium waste from the fusion reactor, excess fuel flushed during jump cycle prep as coolant, waste heat, etc.). They probably use a MHD constrictor field energized by the power plant to create a "rocket throat" in the exhaust channel when needing to use the active HEPlaR mode, giving them a "variable rocket geometry" to optimize for action/reaction thrust.

Thruster Plates would be integrated into other parts of the hull (in this case, the ventral and dorsal bulkheads of the outer hull) so as to facilitate and enable VTOL performance in a flat attitude on ventral landing struts, rather than needing the ship to be a tailsitter that lands with an upright orientation resting on the aft hull section and the HEPlaR system pointing into the ground.

So the drives room at the aft of the ship contains the (combination) Jump plus (HEPlaR backup) Maneuver plus (fusion) Power Plant drives as an "all in one" integrated arrangement, with the "main" gravitic Thruster Plates of the Maneuver Drive integrated into the hull at strategic engineering points around the outside of the hull for agility control and reactionless maneuvering.



That's my take on the notion.
So the deck plans aren't "wrong" per se ... but they aren't showing you quite what you might think at first glance. So if there's an error, it's an error of interpretation, rather than an error of deck layout planning.

 

[Grav_Moped]

HEPlaR was a later revision, and would definitely need some sort of rocket exhaust bell or nozzle since they were explicitly reaction drives.

CT '77 had reaction maneuver drives, at least implicitly. HG '77 explicitly weaponized them! HG '80 turned them into grav drives (in part so they couldn't be weaponized...)

 

[whartung]

Unless you are storing it, it has to go somewhere.

Everyone knows this is directed in to the heat sinks...

 

[Condottiere]

1. For a jump bubble, I'd expel the hydrogen in front of the starship, so you'd need to aim the nozzles forward.

2. For the lanthanum grid, who knows?

3. Come to think of it, is there any description of jump driving in the Agent novel?

 

[mike wightman]

1 - there is no hydrogen filled bubble
2 - there is no lanthanum hull grid - lanthanum is used in the drive coils while the hull grid is unspecified as to material
3 - have to check and get back to you on that one, don't think so.

 

[Grav_Moped]

1. For a jump bubble, I'd expel the hydrogen in front of the starship, so you'd need to aim the nozzles forward.

2. For the lanthanum grid, who knows?

3. Come to think of it, is there any description of jump driving in the Agent novel?

Jump Space, yes. Jump exit, too. Jump entry? I don't remember seeing that.

A bubble (if it needs gas to fill it out) is still a bubble, not a cloud. There'd be something maintaining a boundary, so it wouldn't need to be inflated directionally.