Astrogation clarification

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leprekawn
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Astrogation clarification

Postby leprekawn » Mon Mar 11, 2013 5:06 pm

Hello and thanks for reading.

I've recently bought the pdf for Traveller and I'm a little confused. In reading the book the skill for Astrogation it says:

Plotting a course to a target world using a gas giant for a gravity
slingshot
: Education, 10–60 minutes, Difficult (–2)

The section for jumping, under Starship Operation is missing any reference to the idea.

Was there errata or am I missing something?
F33D
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Re: Astrogation clarification

Postby F33D » Mon Mar 11, 2013 5:21 pm

leprekawn wrote:Hello and thanks for reading.

I've recently bought the pdf for Traveller and I'm a little confused. In reading the book the skill for Astrogation it says:

Plotting a course to a target world using a gas giant for a gravity
slingshot
: Education, 10–60 minutes, Difficult (–2)

The section for jumping, under Starship Operation is missing any reference to the idea.

Was there errata or am I missing something?
Two separate things. The example above is for in-system travel in normal space. Not through jump space...
leprekawn
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Re: Astrogation clarification

Postby leprekawn » Mon Mar 11, 2013 5:21 pm

Yeah, i just saw that. Wow.. My bad.

Thanks for the response!

Edit:

Okay.. so now I'm extra confused. There's nothing in the book about altering your travel times so I'm again wondering the background on that description? Reduced travel time?
F33D
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Re: Astrogation clarification

Postby F33D » Mon Mar 11, 2013 6:37 pm

leprekawn wrote:Okay.. so now I'm extra confused. There's nothing in the book about altering your travel times so I'm again wondering the background on that description? Reduced travel time?
Jump space travel times or, real space?
locarno24
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Re: Astrogation clarification

Postby locarno24 » Tue Mar 12, 2013 8:20 am

Okay.. so now I'm extra confused. There's nothing in the book about altering your travel times so I'm again wondering the background on that description? Reduced travel time?
There's nothing in the 'hard' rules about slingshots per se. It's more for flavour or those 'I've got a cunning plan' moments in an emergency/combat.

It's a big deal in contemporary spaceflight because a few hours of 'free' 1-2 G acceleration is a big deal as it's not costing you fuel. With 4G traveller M-drives that can run indefinitely it's less important.

If you want an in-game effect, it's easy enough to model. The point of a slingshot is to use a planet's gravity as well as your engines to accelerate you. Hence, if you're doing in-system travel with a slingshot thrown in, you'd work out the travel time with your thrust counted as higher than just the rating of your drives.

It's the same for the skill check to 'overcharge engines'. This did have a rules effect in the playtest (which included power management rules) but is now just a flavour thing for GM-set challenges.
Understand that I'm not advocating violence.
I'm just saying that it's highly effective and I strongly recommend using it.
sjmiller
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Re: Astrogation clarification

Postby sjmiller » Tue Mar 12, 2013 1:14 pm

leprekawn wrote:Hello and thanks for reading.

I've recently bought the pdf for Traveller and I'm a little confused. In reading the book the skill for Astrogation it says:

Plotting a course to a target world using a gas giant for a gravity
slingshot
: Education, 10–60 minutes, Difficult (–2)

The section for jumping, under Starship Operation is missing any reference to the idea.

Was there errata or am I missing something?
OK, first thing to realize is that the task described above does not involve your Jump Drive, but your Maneuver Drive. The description of the skill states:
Core Rulebook, p52 wrote:This skill is for plotting the courses of starships and calculating accurate jumps. See Spacecraft Operations, page 137.
What you quote above is the "plotting the course" part of that description.

Secondly, the time shown is how long it takes to plot the course, not actually taking the course you just plotted. The amount of time it takes can be altered, which will change the DM for using the skill. See, "Timing" and "Going Faster or Slower" on page 50.
Stephen J. Miller
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Traveller junkie since 1979
leprekawn
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Re: Astrogation clarification

Postby leprekawn » Tue Mar 12, 2013 6:00 pm

Okay.. perhaps a side question is in order.

Is inter-planet navigation and system generation talked about anywhere?

I understand the plot course portion takes the 10-60 minutes and if I want to modify the DM I can take less or more time. It would seem to be self-explanatory except the travel times section doesn't speak in intervals for travelling to/from Orbit through a solar system.

If I'm reading this in relation to Earth and if I'm doing my math proper..

It takes a M-1 Free Trader-A ~33 minutes to break orbit, another 37 hours to reach Mars.
On the far end of this, in the example traveling from Jupiter to Saturn would take 30.6 hours. But what if i use the described maneuver plotting? Half?

The rules also describe an Engineering feat like overcharging the thruster plates. Neat.. but to what effect? Some things in this book are hinted at but aren't well fleshed out as though there's a future book that will go into full detail.
F33D
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Re: Astrogation clarification

Postby F33D » Tue Mar 12, 2013 6:35 pm

leprekawn wrote: I understand the plot course portion takes the 10-60 minutes and if I want to modify the DM I can take less or more time.
That's for jump space. Interplanetary is trivial. I wouldn't even time it.
leprekawn wrote: It would seem to be self-explanatory except the travel times section doesn't speak in intervals for travelling to/from Orbit through a solar system.
Here is a link to a calculator. Just plug in the M-Drive G rating and the distance. http://www.transhuman.talktalk.net/iw/TravTime.htm
leprekawn wrote:If I'm reading this in relation to Earth and if I'm doing my math proper..

It takes a M-1 Free Trader-A ~33 minutes to break orbit, another 37 hours to reach Mars.
On the far end of this, in the example traveling from Jupiter to Saturn would take 30.6 hours. But what if i use the described maneuver plotting? Half?
No. It is simply a function of distance & acceleration. Assume (unless the pilot or navigator is insane) the shortest distance is plotted, always.
leprekawn wrote:The rules also describe an Engineering feat like overcharging the thruster plates. Neat.. but to what effect? Some things in this book are hinted at but aren't well fleshed out as though there's a future book that will go into full detail.
Ignore that. It was mistakenly cut & pasted from an earlier version of the game that used a different maneuver drive system than Mongoose Traveller uses for its ships..

As to complete star system generation, I don't believe that MgT has come out with that. Prior versions of Trav had it. There is a GURPS Trav advanced system generator .xls named GURPSssgeneratorbeta.xls . If you Google that you can download it...
leprekawn
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Re: Astrogation clarification

Postby leprekawn » Tue Mar 12, 2013 8:47 pm

F33D wrote:
leprekawn wrote: I understand the plot course portion takes the 10-60 minutes and if I want to modify the DM I can take less or more time.
That's for jump space. Interplanetary is trivial. I wouldn't even time it.
leprekawn wrote: It would seem to be self-explanatory except the travel times section doesn't speak in intervals for travelling to/from Orbit through a solar system.
Here is a link to a calculator. Just plug in the M-Drive G rating and the distance. http://www.transhuman.talktalk.net/iw/TravTime.htm
leprekawn wrote:If I'm reading this in relation to Earth and if I'm doing my math proper..

It takes a M-1 Free Trader-A ~33 minutes to break orbit, another 37 hours to reach Mars.
On the far end of this, in the example traveling from Jupiter to Saturn would take 30.6 hours. But what if i use the described maneuver plotting? Half?
No. It is simply a function of distance & acceleration. Assume (unless the pilot or navigator is insane) the shortest distance is plotted, always.
leprekawn wrote:The rules also describe an Engineering feat like overcharging the thruster plates. Neat.. but to what effect? Some things in this book are hinted at but aren't well fleshed out as though there's a future book that will go into full detail.
Ignore that. It was mistakenly cut & pasted from an earlier version of the game that used a different maneuver drive system than Mongoose Traveller uses for its ships..

As to complete star system generation, I don't believe that MgT has come out with that. Prior versions of Trav had it. There is a GURPS Trav advanced system generator .xls named GURPSssgeneratorbeta.xls . If you Google that you can download it...
Fully understandable. After all, a story is about the Journey and the events during said journey not about the numbers for travelling and speed. I was mostly just curious what the Skill suggestion meant as I know a player is going to look at that and go "Can I do this, what will it do?" and I'll have to have an answer as a GM. And I rarely do time-sensitive missions (too much math tasking for my amusement) so I'm not even sure i'll have an answer that will mean anything.

Thanks for your time and explanation and suggestion. I'm looking it up now and I might just get the book to support SJ Games for having a resource I can use. I'm loving the look of Traveller more and more and the only problems and ideas I'm toying with are the description of Jump Drives and how they operate (i'm thinking more slingshot and less 'bubble-universe'). But I know my players are more about whatever comes up and less about a linear story so I'll want to be prepared for the occasional "We go check out planet 2, it sounds exciting."
leprekawn
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Re: Astrogation clarification

Postby leprekawn » Tue Mar 12, 2013 11:00 pm

And in regards to my previous question, Scout has a system for System generation. I tested the numbers to Earth/Sol/Terra and it maths out fairly well.

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