Jump Drive C impossible in a 100-ton ship?

[BFalcon]

Got bored this afternoon and decided to design a few ships just for fun...

Decided that, for the heck of it, I'd design a 6-parsec, 100-ton scout-type ship, in case such a need ever came up. It was supposed to have excellent sensors, a decent-to-advanced computer which would also be jump-specialised and ECM-hardened, figuring that such a ship would be military. I was planning to use drop-tanks to provide the initial jump and then the internal tanks for the return trip to make the fast-cycle possible.

I was also planning, if possible, to add the Stealth, Stealth Jump and Fast-Cycle Jump Drive, figuring that the ship might be sent to spy on enemy fleets for intelligence-gathering missions and might need to get out of there in a hurry (the ship would already cost a lot, given the small size, so would make sense to keep it alive if possible).

The trouble is... the class C J-drive takes up 20 tons. The class C P-plant takes up 10... the bridge takes up 10. The ship needs at LEAST 66 tons of fuel to jump, doesn't it? So a basic J-Drive C ship is already over-tonnage with just the essentials, even without other necessities like crew quarters, electronics, etc.

Anything I've overlooked? Have I overlooked something in High Guard or another book? I can't have 2 drop-tanks, so I'm guessing that the ship would need to use drop tanks just to jump the full 6 parsecs so could only carry fuel for lesser jumps (4 would seem the maximum).

The ship was just done "because it was supposed to be possible", but it's seeming like it can't be done right now.

Edit: just managed it - the ship's now an unmanned, unthrusted courier ship (presumably the navigator boards the ship with the course plotted on a data crystal or plots it on-board, before leaving the ship to board the tender and, when the tender is at a safe distance, triggering the jump. Presumably also, another tender retrieves the ship at the other end... there's no cargo space, so I'd assume that it would be used for very urgent mail and the mail storage device would be stored in the corridor behind the bridge or in the airlock...

The only other thing I can think of doing is blagging it and replacing the bridge with a 2-seat cockpit and having a single double occupancy stateroom right behind it along with a little storage space and basically having it like one of the WWII or modern bombers where you can squeeze out of the cockpit and go into the back - presumably it would be the case that the crew would take turns on watch.

 

[BP]

Use TL upgrades from HG (~pg 52/53, IIRC)...

Who says you can't use 2 drop-tanks?

Further - no reason some PP fuel can't be carried in releasable tanks as well - dropping them before jump (better have fuel waiting thou for life support - and enough for ~week of jump!)

Also, you don't necessarily need an M-Drive - let another ship haul her around - that should give quite a bit of wiggle room.

Esp. as you are dropping her in for spying - expecting to jump her back out rather than count on maneuver.

Just some thoughts...

 

[BFalcon]

Thanks BP - I've not really built that many ships yet (I've done the near-compulsory 100-ton trader, but only a couple more than that).

I though the drop-tank description said only one set? Now I've got to go find those rules too

(Sorry for the edit - I wasn't expecting a reply quite so soon).

 

[BP]

...
I though the drop-tank description said only one set? Now I've got to go find those rules too

Could have - I've never used them in MgT.

I've actually only designed maybe half a dozen MgT ships myself... but I tend to analyze 'rules' as I'm reading them (i.e. see flaws ) and that has a tendency to make things stick, if I might use (abuse) them.

 

[BFalcon]

OK, just checked on a couple of things...

Drop tanks, not sure if you can have multiple, but I'm guessing yes. The tonnage of the ship, however, goes up if you keep them attached, so I'd suggest that they'd have 4 drop tanks - 2 of 30 tons each to power the initial jump and 2 of 30 tons, which would be retained for the return trip, but would boost the mass of the ship on the initial jump to 200 tons, dropping the performance to 3 parsecs.

(I would guess that the ship would be dropped into a system by a jump-tender (possibly into a dead space area of space) where it would also be retrieved after the mission.

As for the high-tech discounts on tonnage, you'd need a TL-18 jump drive to be able to save 25% on a 6-parsec jump drive - the basic 6-parsec is TL-15

The only thing I could save on would be the Power Plant - I'd suggest that the 2.5 tons saved would still not be enough to allow a crew though.

The ditching of the M-drive and shedding excess fuel to the drop-tanks is a good idea though - as would be using solar panels for the sustained on-station use and the possible use of a solar sail (presumably in stealth material like the main hull). The drop tanks would then provide emergency thrust fuel in case of discovery and could be ejected in the event that it needed to scramble back to the fleet without stopping for more fuel (I'm assuming here that they'd not wish to leave TL-15 drop tanks lying around without good reason).

 

[billclo]

I also see you could use a Compact Bridge, saving 25% off the weight of a bridge, albiet with a -1DM to checks due to cramped design.

Therefore:
Class C jump Drive, TL 15 20 tons
Powerplant - 6, TL 15 (*.75) 7.5 tons
Compact Bridge 7.5 tons
Fuel: Jump-6, 60 tons
Power plant fuel (2 weeks) (7.5 tons * .66) 4.95 tons

Total 99.95 tons.


Being as there isn't enough room for a stateroom, you might have to Handwavium it and say that the crew lives on the bridge or in their spacesuits. I'd consider posting to such a ship duty to be a hardship/punishment, for sure.

Personally, I'd consider a larger hull and refigure it with a stateroom, and better sensors, etc.

 

[Jeraa]

Use a TL 15 power plant (High Guard, page 53). Doubles the cost of the power plant, but reduces its size to 75%. (So the Power Plant C would cost MCr 48, and take up 7.5 tons. You save 2.5 tons in space.)

Also, use a compact bridge (high guard page 44). Cost is the same, but it saves 25% of the bridge space. (so frees up another 2.5 tons). I was going to suggest just making it a drone, but the drone controls can only be put into a small craft, and small craft can't have jump drives. That would of removed the need for crew entirely.

 

[BFalcon]

OK, brain fart there - I still had the 60 tons of internal fuel...

I think I'd be tempted to boost the fuel tanks for the return trip to 50 tons each (I'm thinking pairs are easier to balance than just singles and 1x100 tons would look daft on a 100 ton ship).

I've retained 30 tons of internal fuel with an eye to still making the rendezvous if need be after emergency manuevering or with a full tank of fuel if a routine jump, allowing it to double-jump back to the fleet with the tanks still attached.

For more routine tasks, it would be capable of 2 parsecs per jump, allowing it to keep up with the main fleet with both tanks attached.

 

[AndrewW]

Also, use a compact bridge (high guard page 44). Cost is the same, but it saves 25% of the bridge space. (so frees up another 2.5 tons).

A compact bridge costs 10% more (See High Guard Errata or LBB2).

 

[billclo]

Also, use a compact bridge (high guard page 44). Cost is the same, but it saves 25% of the bridge space. (so frees up another 2.5 tons).

A compact bridge costs 10% more (See High Guard Errata or LBB2).

Thanks, I missed that.

 

[BP]

...
As for the high-tech discounts on tonnage, you'd need a TL-18 jump drive to be able to save 25% on a 6-parsec jump drive - the basic 6-parsec is TL-15

And that's a problem because...? (Well, I didn't see a tech limit listed )

Of course, it is sort of the point that the smaller vessels are inhibited from longer range, higher capability due to volume restrictions. I'd actually rather have exceptional tech levels for handling higher performance/capability be above the normal TL of the setting. Also, don't overlook an additional aspect of the design/capability characteristics addressed by other mechanics - i.e. factoring in the carbon based units.

Just make it a J-4 ship and crew it with Captain Snotty and Lt. LaForger who boost the P.P. output and the J-Drive two ratings when they need the long jumps!

 

[BFalcon]

Actually I was looking at cheating and using the cabin from the small craft design rules, saving 4 tons there right away... 5 if I was to use a cockpit instead... of course, after a month of not being able to walk, they'd be pretty much crippled, but hey...

Yeah, I'm probably going to do a Jump-4 ship instead or keep it Jump-6, but make it only have enough fuel for a Jump-4, relying instead on the fuel scoop and refining or on external drop-tanks. Reliance on drop tanks does make sense in a way, since it's a military ship and they tend not to worry *quite* so much about wasting money and/or resources if it means they get intelligence on the "enemy" instead.

Been thinking about a 200 or 300-ton jump-3 or jump-6 fuel tender to go with the ship too, tbh - figuring that, once it's jumped back to the rendezvous sector, they could then jump back the full distance to the fleet (abandoning the drop pods at that point). This would also allow a small squadron of recon ships (thinking 3, if possible) to meet up in one empty region of space, refuel and then jump back to the fleet - the odds of being disturbed drop greatly with that tactic and the jump-3 wouldn't matter. Getting OUT there would be a pain since they'd need to jump twice to get there, but I guess that's the problem with such long-range missions...

Practically-speaking, I think that TL-15 might be a little impractical given that most 'ports are TL-13 at most, it seems, so perhaps I should aim for a Jump-4 drive, which would be TL-13, so stands a chance of being able to find a tech to repair it if need be...

And yeah, I actually did the reverse of the normal procedure I use for designing things - decide on the role, work out what I need it to do to fill that role (and things I'd like it to do if possible) and then design it. This time I decided to try to make a Jump-6, 100 ton ship and found that it wasn't possible using the basic rulebook, which kind of raised the question "why is it on the jump chart for a 100-ton ship then?". I just wanted to be sure I hadn't missed anything.

 

[BP]

... of course, after a month of not being able to walk, they'd be pretty much crippled, but hey...

Handicapped only starship! :8

I'm reminded of a WWII double amputee pilot (and I seem to recall others). So, I wouldn't discount the design totally!

...decided to try to make a Jump-6, 100 ton ship and found that it wasn't possible using the basic rulebook, which kind of raised the question "why is it on the jump chart for a 100-ton ship then?". I just wanted to be sure I hadn't missed anything.

I made a spreadsheet before designing any ships - and a simple table of Drives+PP+Fuel+Bridge for each jump range... 100 ton ships ended up negative tons remaining, IIRC. Not to mention, the 100 ton jump drives only have J2, J4 and J6, I believe - which is rather silly and inconsistent with the rest of the table.

Really, all craft should use the same technique as for capital ships - simple formulas (different performance curves being ok). The tables are a complete waste - don't even think they match CT, so that is no excuse (and wouldn't be anyway, given the minor mismatches in other areas).

 

[BFalcon]

... of course, after a month of not being able to walk, they'd be pretty much crippled, but hey...

Handicapped only starship! :8

I'm reminded of a WWII double amputee pilot (and I seem to recall others). So, I wouldn't discount the design totally!

Douglas Bader is the one I know who had the "tin legs"...

No, but would you want to be sat in the same seat for a month?

...decided to try to make a Jump-6, 100 ton ship and found that it wasn't possible using the basic rulebook, which kind of raised the question "why is it on the jump chart for a 100-ton ship then?". I just wanted to be sure I hadn't missed anything.

I made a spreadsheet before designing any ships - and a simple table of Drives+PP+Fuel+Bridge for each jump range... 100 ton ships ended up negative tons remaining, IIRC. Not to mention, the 100 ton jump drives only have J2, J4 and J6, I believe - which is rather silly and inconsistent with the rest of the table.

Really, all craft should use the same technique as for capital ships - simple formulas (different performance curves being ok). The tables are a complete waste - don't even think they match CT, so that is no excuse (and wouldn't be anyway, given the minor mismatches in other areas).

Agreed - someone failed to pick up on that in the proofreading and playtesting...

 

[BP]

...No, but would you want to be sat in the same seat for a month?

Uh, actually... don't sound much different from my day/night job!

...Agreed - someone failed to pick up on that in the proofreading and playtesting...

Yeah - 'That Guy' sure was busy! :?

 

[DFW]

Practically-speaking, I think that TL-15 might be a little impractical given that most 'ports are TL-13 at most, it seems, so perhaps I should aim for a Jump-4 drive, which would be TL-13, so stands a chance of being able to find a tech to repair it if need be...

Not a problem. Repairs and spare parts are available for all TL's in use. No restrictions in rules except for building a ship from the ground up.

 

[Beastttt]

go with a robot crew
no need for state rooms
go with 60 ton drop tanks(leave with fleet when jumping)
pilot normal robot
engineer liquid metal type(can get around the ship easier)
ECM/ECCM normal robot

you might go with a fission power plant to increase on station time behind enemy lines

with stealth could be used as for kamakazi opening attack on a station or such

 

[DFW]

Another weird aspect. A Type "C" J-Drive isn't a J6 drive per se. It is variable. A rule oddity.

 

[BP]

Not following you on this one - in general, the jump range of a drive rating varies with the tonnage. So an A could be a J2 or J1, etc.

There is an inconsistency at the low end of the table in that J1, J3, J5 lack at least one specific rating for 100 ton ships, IIRC.

 

[DFW]

Not following you on this one - in general, the jump range of a drive rating varies with the tonnage. So an A could be a J2 or J1, etc.

There is an inconsistency at the low end of the table in that J1, J3, J5 lack at least one specific rating for 100 ton ships, IIRC.

Sorry, I was clear as mud. Earlier in thread figuring TL price reductions. On a larger ship that same exact drive would have been say, a J4 and a "lower" TL for price reduction.