Tuesday, November 17, 2015

Traveller Tuesday: Spinthrift, a Prototype J-7 Ship

Those of us in the Mongoose 2e playtest have access to the "still being written" 2e High Guard, and so I decided to tinker with them a bit to create a prototype Jump-7 starship.

Of course, given that 2e HG uses a completely different ship design process than 1e Mongoose, what I'm doing isn't so much a playtest as it is a Frankenstein approach of chainsawing out the bits I like and stitching them together into an unholy abomination.

But that's par for the course for someone who made a My Little Pony RPG using the Unknown Armies game engine.

My use of Traveller setting and dress falls under
fair use guidelines for both Mongoose and Far Future Enterprises.
Here is the handy table I'm using:


TL Tonnage Cost Modifications
Early Prototype -2 +100% +400% 2 Disadvantages
Prototype -1 - +100% 1 Disadvantage
Budget +0 - -50% 1 Disadvantage
Advanced +1 - +50% 1 Advantage
Very Advanced +2 - +100% 2 Advantages

From context, it should be clear that this is 2e's version of the "Primitive and Advanced Spacecraft" rules found on p.52 of 1e High Guard, and indeed that's the name of the chapter that this table is from. It's pretty straightforward: as tech progresses, you get Advantages like a reduction in tonnage or an increase in performance, but you pay out the nose for them.

What's new is that this chart also goes the other way, and allows folks to create experimental equipment at lower tech levels in exchange for fun drawbacks (in addition to increased price and/or tonnage). 

Since Jump-7 is canonically listed as TL 16, I decided to make a TL 15 Prototype J-7 ship with this chart and 1e's ship creation system. 

(Link leads to Google docs spreadsheet.)
Every ship needs a name. A portmanteu of spindrift and spendthrift seems apropos without courting too much disaster.

I chose a 200 dton hull because the "Performance by Hull Volume" table on p.108 of 1e MongTrav has a handy "1 2 3 4 5 6" progression, which means that J-7 from its hull simply follows next in line. This makes a lot of things easier. 

Power Plant
Since J-7 at 200 dtons is a G code, that means I just need a power plant G, which already exists. Handy, that. 

Prototype Jump Drive
A normal jump drive G would displace 40 dtons and cost 70 MCr. This means that my experimental drive costs 140 MCr, and because increasing tonnage of the drive doesn't seem right (G engines already exist, we're just trying to squeeze more performance from them), I decided to make the J-7 a real fuel guzzler. 

The disadvantage "Energy inefficient" says that it consumes 30% more power than normal, but I'm not using the Power stat, so I want to turn that into fuel consumption. But a 30% increase in fuel raises it from 140 dtons to 182 dtons, and for some reason that still seems low. Because I'm the GM, I decide to tweak this to 50% under the rational that power consumption isn't fuel consumption. This gives me 210 dton for a jump-7, and that feels reasonable to me; I like the notion of an experimental drive requiring as much fuel as the ship displaces. 

Drop Tanks
These are the easiest ways to wring more performance out of a ship. I'd feel guilty if various J-6 ships weren't rotten with drop tanks as well. Being a prototype means it's a test bed that isn't expected to do more except get there (like the Bell X-1), so a single J-7 is fine. 

At this point I begin to imagine the Spinthrift as a Marava-class Far trader, with the top sheared off and replaced with a single 200 dton drop tank. The remaining 10 dtons of jump fuel is carried internally, along with power plant fuel.

Maneuver Drive
M-drives are small and we want this ship to be able to move under its own power in case there's a catastrophic misjump, so M-1 is added as an emergency backup. (Once the first test is successful and the IISS/Navy/whoever is bankrolling this gets tired of hauling the ship out to the 100 diameter line, a ton of cargo space can be lost to upgrade the m-drives to 2G. This would allow Spinthrift to travel under its own power to the jump zone, even with full drop tanks (albeit at 1G)).

Speaking of backups, the Spinthrift is a significant investment for whomever is making it, and given that the risk of misjump** is high, they'd want to protect their investment and give it (and its crew) a fighting chance to make it back. A backup J-1 drive and dedicated power plant (in case the one attached to the J-7 fails) is added, along with fuel processors, enough fuel to make 2 J-1s, and two triple turrets with lasers for self-defense. 

Jump Control/6 requires a rating 30 computer, and lesser jumps decrement by 5, so it's logical for Jump Control/7 to need a rating 35 computer, which is just possible at TL 15 with a 30 million credit Model 7. Even so, plotting a 7 parsec jump might require a larger program, so just to be safe I assume JC/7 is a rating 40 and turn the Model 7 into a jump-specialized bis.

In addition to astrogation, a J-7 test bed is going to need sensors for recording the trip data. Advanced sensors are added. 

We don't want to endanger a bunch of people, so let's take along the bare minimum: A pilot, a navigator/sensor operator, and two mechanics. Space is at a premium, so it's double occupancy for our intrepid jumpnauts. 

The 10 dton cargo hold is filled with food, spare parts, and other supplies to provide 6 months' worth of endurance in case the Spinthrift has to limp back home. 

An emergency low berth is available in case they need to set an SOS and wait for rescue. 

High-rating Evade and Fire Control programs have been added in case combat happens and no one is available to run the guns, and a reflec coating was installed because armor and sand canisters take tonnage.

Total Cost: 307.3 Million Credits
Not bad for advancing technology and a chance at immortality, right? And it's still cheaper than a capital ship.*

* Not counting costs for research, development, tooling of prototypes, personnel costs, and other bits of infrastructure spread out over who-knows-how-long. 

** There are no rules for this in Traveller, but with experimental jump tech I'd raise the roll for a successful jump to 10+. 

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