Round Trip?

[DangerousThing]

Originally Posted by timerover51

I deal with it in two ways in MTU.

I deal with it a bit differently IMTU. I have an advantage because I never had the OTU as a background.

I have the Jump Drive as stated as the fastest human-built FTL drive. One problem is that the J-Drive cannot use fission power sources (I assume because the jump needs a massive amount of power in a short time period and a fission reactor can't support that).

So I have Hyperdrive (H-Drive) and the Hypersail Drive (S-Drive). These both use less power than the J-Drive and can be powered by fission drives happily (or for that matter a clockwork power source - at one time I was working on the numbers for such a power source). I've also used batteries and energy cells, but they aren't efficient enough at the TLs I'm running at for my current campaign.

I've also never believed in normal star ships that can skim gas giants efficiently.

I'm doing this because the current campaign is set inside an area where J-1 routes for small, and for the most part a trader needs at least J3.

Also I figure (purely my speculation) that the jump drive needs a lot of computation, and there are no microelectronics in my campaign (something happened to make them non-functional). So it's possible to use a J-drive from a system that has computing to a system that has computing (it is possible to make *large* computers that can do jump calculations).

But mainly it's the fuel problem. Since the Shattering caused a new Long Night, the TLs have gotten low enough there either are either are no star ports or the ports don't have fuel purifiers. So there are two reasons why a jump ship might have a one-way trip.

And keeping the H- and S-Drives slower than the J-Drive keeps a reason for having the J-Drive around.

[CosmicGamer]

Originally Posted by timerover51

The biggest headache the one-way rules cause is for exploration and space combat.

I'm not aware of any "one -way" rules.

Originally Posted by Rigel Stardin

I could never understand why Traveller ship design didn't allow for ships to travel from point A to point B and back again without a fuel scoop?

In the version of Traveller I use, no such issue exists.

I would think in any Traveller version a jump 2 ship can easily be adapted to be a round trip jump 1 ship, no?

What's the jump capability of these supposedly one way combat ships? Anything over Jump 1 and they should be capable of a round trip mission without refueling.

Unless I'm misunderstanding something, round trip exploration and space combat is very possible. Do some versions of Traveller say that a Jump drive can't make multiple shorter jumps? If so, then just take a current ship design and rip out the larger jump drive and put in a smaller one.

It seams obvious to me that if logistics require a round trip your maximum distance would be aprox half that of your maximum one way distance without refueling.

Am I missing something?

[rancke]

Originally Posted by Rigel Stardin

I could never understand why Traveller ship design didn't allow for ships to travel from point A to point B and back again without a fuel scoop?

Because carrying any more fuel than you absolutely have to reduces your payload.

If you're not interested in hauling cargo, you can get around 80% of a ship to carry fuel. That's enough to get 3 parsecs away, dump a bit of fuel to build up a cache, and get back again. It may be more efficient to jump out two parsecs and dump a lot more fuel, or only one parsec and dump even more fuel; I have'nt sat down and worked out the various options. But getting out and back again is not a problem, at least not once the jump-to-deep-space technique has been invented. It's just a matter of how much time you put into it.


Hans

[BlackBat242]

Originally Posted by DangerousThing

I deal with it a bit differently IMTU. I have an advantage because I never had the OTU as a background.

I have the Jump Drive as stated as the fastest human-built FTL drive. One problem is that the J-Drive cannot use fission power sources (I assume because the jump needs a massive amount of power in a short time period and a fission reactor can't support that).

So I have Hyperdrive (H-Drive) and the Hypersail Drive (S-Drive). These both use less power than the J-Drive and can be powered by fission drives happily (or for that matter a clockwork power source - at one time I was working on the numbers for such a power source). I've also used batteries and energy cells, but they aren't efficient enough at the TLs I'm running at for my current campaign.

I've also never believed in normal star ships that can skim gas giants efficiently.
.....

And keeping the H- and S-Drives slower than the J-Drive keeps a reason for having the J-Drive around.

I have done the same. I have the "normal" first FTL drive a civilization develops be a classic "hyperdrive", based mainly off that in Andre Norton's books.


First, these drives are larger than a comparable J-drive... twice the tonnage at TL9, 1.66x at TL 10, and 1.5x at TL 11.


Second, it uses a lot less fuel than a J-drive, you only use some 5 tons of fuel per parsec at all TLs. You can make a single trip covering however many parsecs you have fuel for... and you can also, while in H-drive, reverse course to your start-point, as long as you have enough remaining fuel.

When you run out of fuel, the safeties on the drive safely drop you back into normal-space wherever you are... even if that is in empty space halfway between stellar systems! This normally only happens with a malfunction, as the course-generation program prevents you from initiating a trip that requires more fuel than you have on-board... unless you over-ride it, of course.


Third, it takes a LOT longer to get anywhere. Specifically, early (TL9) H-drives take 15 days per parsec, TL10 12.5 days, and TL11 10 days. These are the only speeds possible.



Compare a H-drive ship with fuel for 2 parsecs to a J-1 ship which makes a "refuel-only stop" at the halfway point. The economics are better with the J-1 ship, as you take basically the same time to cover 2 parsecs, and need the same volume of fuel, but the J-drive is smaller, leaving more room for cargo.
It is better with a J2 drive. Yes you need more ship's tonnage for fuel, but you can make 2 parsecs per 10 days, where even a TL11 H-drive would take 20 days to cover the same distance.

So you can see that, as soon as you can make J-drives, that they become, in large part, more popular than "slow-ships" for all but low-priority bulk freight... like grain, ore, etc. Anything with passengers or live cargo uses J-drive, due to the tonnage needed for life-support systems.

[whartung]

Originally Posted by Rigel Stardin

All I’m trying to point out here is early star travel is hinder by the rule set provide by the game. Traveller assumes at the point a races is ready to start expansion key elements are in place for round trips to take place. When in fact, most of the time those elements are missing in real world scenarios. The moon landing would have been delayed by years had we taken the outlook present to us by Traveller. The discovery that the moon had water would spur exploration. Columbus’s voyage would have been seen as a failure without the means of returning to Spain. The belief that the world was flat would have continued for centuries without the sail.

No it doesn't. This is like commenting on how all of the modern appliances assume you have electricity in your house. Of course they do! The infrastructure is there to support them.

For those where the infrastructure doesn't exist, you can bring your own generation systems to power such devices. Or you can punt entirely (gas powered refrigeration anyone?).

Just because the modern ships are not designed for a round trip doesn't mean you can't make ships that ARE so capable. They just add another requirement to the design and it's costs, capabilities, and tradeoffs that modern ships don't need.

And, of course, in the OTU there are no "early star" travelers, they're all quite mature.

With some clever extrapolation of the mechanics you could make a large ship that can go 8-10 parsecs without refueling. Water ice carries about 30% more hydrogen than LHyd does per liter, so, build a ship with a 66% sized ice "tank", a 10% sized LHyd tank, a big-o-heater and a fuel purification plant, and you get get 9 parsecs of fuel at J-1, and still have ~24% of ship space for cabins and power and whatever. Kick off the large ice tank and you can probably coax another 2 out of the ship.

This is possible. In the OTU, it's not necessary.

[aramis]

Originally Posted by rancke

Because carrying any more fuel than you absolutely have to reduces your payload.

If you're not interested in hauling cargo, you can get around 70% of a ship to carry fuel. That's enough to get 3 parsecs away, dump a bit of fuel to build up a cache, and get back again. It may be more efficient to jump out two parsecs and dump a lot more fuel, or only one parsec and dump even more fuel; I have'nt sat down and worked out the various options. But getting out and back again is not a problem, at least not once the jump-to-deep-space technique has been invented. It's just a matter of how much time you put into it.


Hans

a 1000 TD can exceed 75% under bk 5

020 bridge
003 model 3
040 j3
010 m1
060 pp3 at tl 12
030 pp fuel, 4 wk
016 4 double occupancy staterooms PNMEEEE

179 Td... enough for 80%... and more staterooms.

Under bk2 1e,
020 bridge
003 model 3
080 jd q =3
009 MD E=1
016 PP E=1
010 PP Fuel
020 Crew PNMEEE
158 total

Under bk2 2e,
020 bridge
003 model 3
080 jd q =3
009 MD E=1
046 PP Q=3
030 PP Fuel
028 Crew PNMEEEE
216 total

Under MgT.
020 bridge
000 model 3
080 jd q =3
009 MD E=1
046 PP Q=3
045 PP Fuel 3 weeks
028 Crew PNMEEEE
228 total, but the navigator, medic, and half the engineering guys can be omitted... for 212 Td total.


note that bk2 basic crewing applies until 1001 Td in any of the three.

[HiverLord]

Originally Posted by timerover51

One is reduce the fuel for Jump by half, and then I have enough for round trips using the standard tankage.

I tried designing this into a new campaign (MgT rules), and I broke the ship rules. (Not literally, of course! ) It became TOO easy to design ships, even small ones, capable of fulfilling most mission requirements (or those most players would be called to perform). (This setting will be a small ship universe, btw.)

So instead I developed the following formula for jump fuel use:

Ships require a minimum 10% volume of fuel for jump-1. Each level of jump above this adds the square of that jump level in volume. So:
Jump-1 = 10%
Jump-2 = 14%
Jump-3 = 20%
Jump-4 = 28%
Jump-5 = 38%
Jump-6 = 50%

Enough of a space savings to make a big difference at the mid-range jumps, and absolutely no difference at jump-1, of course. I've found so far that it seems to work out ok, gets me where I want the campaign to be.
We'll see if it works long term.

[DangerousThing]

Originally Posted by HiverLord

I tried designing this into a new campaign (MgT rules), and I broke the ship rules. (Not literally, of course! ) It became TOO easy to design ships, even small ones, capable of fulfilling most mission requirements (or those most players would be called to perform). (This setting will be a small ship universe, btw.)

So instead I developed the following formula for jump fuel use:

Ships require a minimum 10% volume of fuel for jump-1. Each level of jump above this adds the square of that jump level in volume. So:
Jump-1 = 10%
Jump-2 = 14%
Jump-3 = 20%
Jump-4 = 28%
Jump-5 = 38%
Jump-6 = 50%

Enough of a space savings to make a big difference at the mid-range jumps, and absolutely no difference at jump-1, of course. I've found so far that it seems to work out ok, gets me where I want the campaign to be.
We'll see if it works long term.

I think I like the concept, but I don't get the numbers.

J-2 = 10% + (2 * 2)%

I get that one. Would you mind explaining how you get your numbers above 2?

Thanks in advance.

[CosmicGamer]

Originally Posted by DangerousThing

I think I like the concept, but I don't get the numbers.

J-2 = 10% + (2 * 2)%

I get that one. Would you mind explaining how you get your numbers above 2?

Thanks in advance.

It's not the square. My math makes it:
Jump 2 = Jump 1 (10) + 2+2 = 14.
Jump 3 = Jump 2 (14) + 3+3 = 20.
Jump 4 = Jump 3 (20) + 4+4 = 28.
Jump 5 = Jump 4 (28) + 5+5 = 38
...

Square would be
Jump 2 = Jump 1 (10) + 2*2 (4) = 14
Jump 3 = Jump 2 (14) + 3*3 (9) = 23
Jump 4 = Jump 3 (20) + 4*4 (16) = 36
Jump 5 = Jump 4 (36) + 5*5 (25) = 61
...

[Fritz_Brown]

Originally Posted by Rigel Stardin

The belief that the world was flat would have continued for centuries without the sail.

First thing I have to correct is this notion. That is patently untrue. Anyone who can see a horizon (yes, at sea is clearer, we get that) can work out that the world is round. It didn't take sailors to know this, much less by sailing "around the world."

Originally Posted by Rigel Stardin

Traveller assumes at the point a races is ready to start expansion key elements are in place for round trips to take place. When in fact, most of the time those elements are missing in real world scenarios.

How is this true? What key elements are missing? Hydrogen is the most abundant element in the known universe. The vast majority of star systems in Traveller have gas giants or planets with *some* sort of surface water. And, of course, there are always ice asteroids if you're desperate. Are you saying that people jump to a star before they have done the distant probing of said star system? Who said the original explorers didn't double up their fuel? It is very easy to do, and those original explorers didn't have to carry cargo with them.

Originally Posted by Rigel Stardin

In exploration scenarios Traveller makes races wait until fuel scoops technology is available before a race can start expansion.

Not even remotely.

Originally Posted by Rigel Stardin

In reality, mankind would make ships that carried extra fuel for the return trip

Ummmm, they do. There are some broken designs in Traveller, sure, but that doesn't necessarily make the whole paradigm broken.

Originally Posted by Rigel Stardin

Tankers would be more important than battleships because without them there would be no way your force could return to friendly territory without them.

In RL, tankers are incredibly important - whether using ships or aircraft as your point of departure.

Originally Posted by Rigel Stardin

Even under a trade scenario with hostile neighbors, all the trade federation has to do is cut off your ability to refuel and that would end your crews’ chance of returning to friendly space.

Any idea how hard it is to cut off your ability to refuel? Go find a bunch of the threads around here about tactics and strategy of defending a star system from bad guys, and how you can't guard everything very easily. Again, hydrogen is the most abundant element in the universe.

Originally Posted by CosmicGamer

Am I missing something?

Nope, you have it right.

Originally Posted by DangerousThing

I think I like the concept, but I don't get the numbers.

He didn't square, he doubled.