Canon Jump Core Diameters?

[Daryk]

Has anyone seen a canon diameter for jump cores?  I'm laying out deck plans for a Scout JumpShip, and don't want to have to re-draw them if I've missed something.  If no one has seen anything, I'll probably go with a suspiciously round figure like 5 or 10 meters, then roughly double it for the helium tankage and support systems.

[Frabby]

We don't have much canonical data on jump cores at all, except that they're supposedly enforcing the oblong needle shape of JumpShips. This is apparently not so much the case for WarShips, regardless of how many docking hardpoints they feature.

Also, the rules say between 47.5 and 95% of a given vessel's mass is taken up by the jump drive, but since that includes helium tanks, controls, sundries and kitchen sinks it doesn't really say much about the actual core either. In another thread here we tried to determine how much germanium goes into a drive core, with no conclusive result.

In Warrior: Coupé we learn that Monoliths can have either a big single or multiple smaller helium tanks around their core.

A sidenote in the TRO:3057 entry for the Tramp indicates that a device called a mesh spinner is involved in producing jump cores; a faulty mesh spinner created faulty jump cores that apparently were still functional at least to some degree.

Finally, the fluff for the (non-functional) Monitor vessels in XTRO:Boondoggles indicates that the "drive core" encompasses a substantial part of a given vessel's skeleton/internal structure.

[The_Caveman]

DropShips & JumpShips might have the right kind of cutaway. Or maybe one of the roleplaying adventure books.

[Daryk]

Great, thanks Frabby!  Using 5.5 tons/m³ for the density of germanium gives about a 5m radius for a 200m long core of 85,500 tons (acknowledging it isn't a solid chunk of germanium, but the helium tankage and support structure will be a mix of denser stuff and voids).  Due to the large door on the side of the Scout, I'm going to offset the jump core so it's more like a vertebrate's spine.  I think KF-antenna technology obviates any difficulty with not putting it in the exact center of the ship.

Caveman: page 11 of the "Operations Manual" section of DS&JS has a cut away of an Invader which I'll bounce off of Bren's vector diagrams to validate my estimate above.  Thanks!  I had totally forgotten that diagram was in there.

[Daryk]

Bren used a different template than DS&JS, but judging by eye I think a 10 meter diameter will work for the core and supporting equipment.

[Frabby]

Oh, and there's of course the deck plans of the SLS Manassas in the Living Legends adventure. These might be helpful in determining the size of that ship's jump core... unfortunately, that specific jump core was modified and a bit larger than usual and also a compact core, so may not be very helpful to determine the diameter of a regular jump core.

[Daryk]

If I do a bigger JumpShip, I'll keep that one in mind.  Thanks again!

[Intermittent_Coherence]

Speaking of cutaways, you might also want to consider the cutaway of the Aegis.

[Daryk]

Which book is that one in?

[Intermittent_Coherence]

http://www.sarna.net/wiki/images/4/48/Color-warship.png

[Daryk]

Interesting, thanks!  That definitely validates my thinking that the core doesn't need to be as long as the ship.

[Giovanni Blasini]

Interesting, thanks!  That definitely validates my thinking that the core doesn't need to be as long as the ship.

That may only hold true for compact cores. Compare the Invader:

http://www.sarna.net/wiki/images/2/2b/Color-jumpship2.png

[Daryk]

The cut away in DS&JS is similar, but they both fall slightly short of the entire length of the ship (which is how I'm setting up the Scout), so I think I'm OK.

[Zweihart]

That may only hold true for compact cores. Compare the Invader:

http://www.sarna.net/wiki/images/2/2b/Color-jumpship2.png

That could be due merely to a cost-saving mindset though. "Civilian" Jumpships like the Invader are often described as being little more than a jump-slave put into orbit, and not much else. It would make sense that they're only making it big enough to fit the Core.

[Giovanni Blasini]

That could be due merely to a cost-saving mindset though. "Civilian" Jumpships like the Invader are often described as being little more than a jump-slave put into orbit, and not much else. It would make sense that they're only making it big enough to fit the Core.

That, and there's an appreciable technology difference between standard and compact cores.  The Aquilla shows us that early jump cores were essentially the same as the standard JumpShip core in later vessels, just with the latter optimized for longer distances.

[Daryk]

I'm only putting in two decks aft and three decks forward of the core (one of which isn't actually in front of the core since it's off center).  The issue with the Scout is its small size compared to a lot of DropShips.

[Giovanni Blasini]

That seems logical.

[gomiville]

Is there anything canon that says compact cores are fundamentally different from standard cores?  Especially considering they're exactly half the mass (per overall ship mass), I've always figured they're basically the same thing, just with an extra thingamabob that allows the core to jump twice the usual ship mass.  That would also be consistent with the extra volume warships have around their cores, and the needle shape of jumpships.

A core of N size is X long and Y wide.  A jumpship using that core would be slightly longer than X and only marginally wider than Y.  A warship might be about the same length (X-ish) but significantly wider than Y.

I like the earlier estimate of 5mx200m, based on the density of germanium.  That would be pretty rough, considering it's not pure germanium, but an alloy, and includes extra gear, like the helium tanks.  Maybe say the core itself is about 5m, but the surrounding support structure extends that by 2-5m, depending.  Maybe the He tanks are towards aft, ballooning the core to 10m total diameter, but towards the stern, it's only 7m diameter.  If the overall jumpship is 12-15m in diameter, that would mean the back half is almost all engineering, without much room between the core and inner hull.  But towards the nose, and presumably the bridge, there's more room for bunks, shuttle bays, etc.  By the way, since many canon jumpships seem to have a slightly bulbous nose, that's probably where the shuttle bays are, actually.  More volume.

(Anyone else noticed the similarity between jumpships and the XD-1 in 2001?)

Using that rough idea, and canon artwork, many warships might be something like 50-100m in diameter, giving them a lot more internal volume around the core.  Especially if the core is offset, that would give them plenty of room for cargo bays, fighter/shuttle bays, weapons, etc.

[Frabby]

(Anyone else noticed the similarity between jumpships and the XD-1 in 2001?)

You mean like the Huntress? ;D

[Daryk]

Using Bren's adaptation of the canon art, the Scout is 56 meters in diameter at its narrowest.  My back of the envelope math above yielded a 5m radius, thus 10m diameter for the core and support systems.  On the Scout, I've offset the core to fit the drop collar, which I'm interpreting as an airlock system that can accommodate different sized and shaped DropShips (essentially, a large retractable tube that can mate to one of four positions on the JumpShip side, and has enough flexibility to reach almost anywhere on a DropShip's hull from there).

I'm also trying to honor the Scout's original fluff about being able to gravity maneuver with a DropShip docked (yes, this flies in the face of Strat Ops).  It's tricky, but I think doable.  I'm shooting to be done by the end of March.  There are 55 human-sized decks on a Scout, though just under half of them will be identical service areas around the core.  Nine of them will be engineering spaces that house the fuel tankage and jump sail, while the small craft bay will soak up another eight or nine of them in the nose section.  The remaining 14 decks in the nose will house the crew, auxiliary systems, and avionics.

EDIT: Ninja'd by Frabby while typing this!