maneuver drives no fuel?

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maneuver drives no fuel?

Postby briansommers » Tue Jun 30, 2020 3:57 pm

why or how can maneuver drives don't use fuel?

This doesn't make any sense to me. Where is it getting power from to maneuver?
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Re: maneuver drives no fuel?

Postby Galadrion » Tue Jun 30, 2020 4:47 pm

Simplest answer: FROM THE POWER PLANT! One of the standing tropes in Traveller from the very beginning is that maneuver drives directly convert power (the output from the power plant) to acceleration, as a reactionless thruster.
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Re: maneuver drives no fuel?

Postby Sigtrygg » Tue Jun 30, 2020 5:08 pm

Umm, no, not from the beginning.

The idea of a reactionless maneuver drive that converts energy from the power plant to acceleration began to rear its ugly head when a certain group of fandom interpreted High Guard 80 in a certain way.

LBB2 77 edition hinted at a reaction drive - fuel was needed for 'burns' and the burn rate for ships and smallcraft was given.
In HG79 it was flat out stated that the maneuver drive is a fusion rocket of some sort.

HG80 removed the references to the fusion rocket but doesn't explicitly state the maneuver drive is reactionless.

MegaTraveller was the rule set that came up with the first explicit description of the maneuver drive as a reactionless drive.

TNE went back to a reaction drive model and the game authors have stated that this was the intention all along.

GT, T4, T20, HT, GT:ISW, MgT and T5 have all gone with some sort of gravitic handwavium to explain the maneuver drive being reactionless, but it does require energy usually from a fusion power plant.
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Re: maneuver drives no fuel?

Postby briansommers » Tue Jun 30, 2020 5:11 pm

ahhh... now that makes sense.
Thanks.
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Re: maneuver drives no fuel?

Postby Condottiere » Tue Jun 30, 2020 7:16 pm

Current edition draws a clear line between power output, from apparently any source, to the subsystem that needs it, whether batteries or solar panelling.

Solar panelling, however, has some caveats.

Connecting the dots indicates that manoeuvre drives are based on manipulation of gravitational fields, so you only need to stick in the plug. Fuel consumption is indirect.

Reactionary rockets don't need power, but do suck fuel directly from the tanks.
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Re: maneuver drives no fuel?

Postby Linwood » Tue Jun 30, 2020 10:46 pm

Requiring reaction mass for maneuver would drastically change the game. Imagine how much reaction mass it would take to accelerate a Tigress at 1G for any significant amount of time. And then you have to slow down again....
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Re: maneuver drives no fuel?

Postby Ursus Maior » Wed Jul 01, 2020 8:28 am

This contra-grav or anti-grav technology is why I sometimes struggle with large ships in Traveller. It feels strange to imagine a dreadnought being as fast as the Sindalian Harrier from Pirates of Drinax. On the other hand, I can live with that, since it's supported throughout both the system and the fluff.

What I find strange is that r-drives and high-burn thrusters from the current Highguard increase in size linearly and not exponentially. For me, that breaks the spirit of Traveller. It also makes for weird ships, if you install a thrust 11 m-drive, add a thrust 16 r-drive and put high-burn thrusters with a rating of 16 ontop.
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Re: maneuver drives no fuel?

Postby Reynard » Wed Jul 01, 2020 11:05 am

I have designed ships with reaction drives and they barely get off the ground let alone get to a far gas giant. Next to useless. This goes for just about any edition featuring reaction. In real life, our space craft spend the vast majority of their flights drifting for very long periods with just about all fuel burned on liftoff. Even the Expanse universe had to cheat with the major handwavium Epstein Drive.

For the last 40 years, I favored maneuver drive as a powerful and efficient means to actually get around without spending months or years and getting on with the science fiction adventure. We got rid of room sized computers, let the super powerful, outlandishly fuel sipping reaction drives of the 70s go too.
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Re: maneuver drives no fuel?

Postby Condottiere » Wed Jul 01, 2020 8:40 pm

1. High thrust is now subsumed by COmbined Manoeuvre And Rocket compound drives.

2. In the previous edition, reactionary rockets were half the size and half the cost of gravitic motors; actual High Thrusters even more so, though cost of fuel seemed astronomical.
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Re: maneuver drives no fuel?

Postby AnotherDilbert » Thu Jul 02, 2020 7:17 am

Ursus Maior wrote: What I find strange is that r-drives and high-burn thrusters from the current Highguard increase in size linearly and not exponentially.
Why? There is nothing non-linear about Newton's second: F = ma.

Apply twice the thrust, you get twice the acceleration. Simple enough?
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Re: maneuver drives no fuel?

Postby Ursus Maior » Thu Jul 02, 2020 7:48 am

Yes, it is. I'm just not used to space and atmospheres change a lot of things. I get stupid too, sometimes.
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Re: maneuver drives no fuel?

Postby Sigtrygg » Thu Jul 02, 2020 7:48 am

I wouldn't try and use real physics to try and describe/explain the magic reaction drives of MgT anymore than real physics to describe/explain the magic reactionless gravitic maneuver drive.

For a start mass is not an issue with Traveller ships (except in TNE)

In MgT momentum and Newtonian movement appears to be absent in their dogfighting rules
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Re: maneuver drives no fuel?

Postby AnotherDilbert » Thu Jul 02, 2020 11:27 am

Ursus Maior wrote: I'm just not used to space and atmospheres change a lot of things.
Agreed, aerodynamics and hydrodynamics are much more complicated. Spacecraft are simple in comparison...
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Re: maneuver drives no fuel?

Postby AnotherDilbert » Thu Jul 02, 2020 11:38 am

Sigtrygg wrote: I wouldn't try and use real physics to try and describe/explain the magic reaction drives of MgT anymore than real physics to describe/explain the magic reactionless gravitic maneuver drive.
How the thrust is produced is "unclear" (i.e. magical), but how it is applied is simple Newton, e.g. see the travel time formulæ.

The independence of mass is, I believe, just a simplification, not an in-game physical principle. I have made the MT system totally dependent on mass instead of displacement, and the differences are small for normal ships. The needed calculations are much more cumbersome. It's just not worth it, as FF&S demonstrated.
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Re: maneuver drives no fuel?

Postby Linwood » Thu Jul 02, 2020 12:02 pm

AnotherDilbert wrote:
Thu Jul 02, 2020 7:17 am
Ursus Maior wrote: What I find strange is that r-drives and high-burn thrusters from the current Highguard increase in size linearly and not exponentially.
Why? There is nothing non-linear about Newton's second: F = ma.

Apply twice the thrust, you get twice the acceleration. Simple enough?
In the real world, things like thrust don’t always have a linear relationship with mass/size of the system producing them. Adding more engines, for example, doesn’t increase speed in a linear fashion. But for game purposes I think it’s probably close enough. It’s too easy to let the rules get in the way of the fun if you try too hard to exactly model the real world.

This can be true in system modeling too. Sometimes the simpler models actually do a better job of modeling a process or system than the more complex ones.
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Re: maneuver drives no fuel?

Postby Reynard » Thu Jul 02, 2020 7:58 pm

The other issue with reaction only is high acceleration. Maneuver inherently includes inertial compensation as part of its gravitic technology. Long term high Gs and tight maneuvering would be a serious concern.
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Re: maneuver drives no fuel?

Postby Condottiere » Thu Jul 02, 2020 8:15 pm

While it's mentioned in Tee Five, I don't recall any Mongoose publication taking a stance as to where inertial compensation originates from.

Also, if you add an extra sixteen gravities from the High Burn thrusters add on, the crew is still mush.
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Re: maneuver drives no fuel?

Postby AnotherDilbert » Thu Jul 02, 2020 8:41 pm

Linwood wrote: In the real world, things like thrust don’t always have a linear relationship with mass/size of the system producing them. Adding more engines, for example, doesn’t increase speed in a linear fashion.
In-atmosphere top speed is limited by friction, there are no such limits in space, at least not at the speeds Traveller ships generally achieve.

Air resistance is certainly non-linear. Newton's second, ruling spacecraft, isn't.

Linwood wrote: This can be true in system modeling too. Sometimes the simpler models actually do a better job of modeling a process or system than the more complex ones.
Agreed, certainly, especially in RPGs.
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Re: maneuver drives no fuel?

Postby AnotherDilbert » Thu Jul 02, 2020 8:47 pm

Reynard wrote: Maneuver inherently includes inertial compensation as part of its gravitic technology.
CT to T4 explicitly made Inertial Compensators a separate system, using artificial gravity. See e.g. T4:
T4 FFS, p80 wrote: Artificial Gravity & G Compensation
Artificial gravity inertial compensators create an artificial gravity field directed between the deck plates of a ship to provide a constant gravity field. The generators are also tied into the ship's computer, which varies the field strength to counteract the effects of a ship's acceleration, up to a maximum level.
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Re: maneuver drives no fuel?

Postby Condottiere » Fri Jul 03, 2020 7:57 pm

With the current edition, it still isn't clear if inertial compensation is localized, or a general field effect generated from the manoeuvre drives.

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