Artificial gravity and acceleration

Discuss the Traveller RPG and its many settings
Dagorlad
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Artificial gravity and acceleration

Postby Dagorlad » Mon Sep 18, 2017 10:03 am

Hi everyone, this is my first post here. Hopefully it's not too contentious.

I bought the original boxed-set of Traveller way back in the late 1970s but never played it (sad face). I've just recently rediscovered the game and have bought the new hardback edition and am loving the faithful adherence to the spirit of the original game.

One question I've had ever since the first edition and it's not been really explained anywhere that I've seen... does the artificial gravity on board a spacecraft overcome the inertia that would be felt due to external forces, such as impacts or the constant acceleration of the manoeuvre drives?

So often in TV shows and movies, we see a spacecraft lurching under the assault of enemy 'photon torpedoes' or being struck by asteroids. How many times in Star Trek or Lost in Space did we see the crew being thrown around as a ship is hit. So, at least in these stories, external forces acting on a ship are felt by the people inside, despite the artificial gravity.

In the Traveller game, we have drives that produce a constant acceleration, measured in gees - 1g, 2g etc. Do the crews feel that acceleration? Can the crew of a ship travelling at 6g walk and talk as normal or are they pressed in their acceleration couches slowly having their internal organs crushed?

And if so (as I would expect), why are the spaceships designed like aircraft or ocean vessels, with their decks running length-ways to the direction of thrust?

Any thoughts on this?

Am I over thinking it? (probably :) )
PsiTraveller
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Re: Artificial gravity and acceleration

Postby PsiTraveller » Mon Sep 18, 2017 10:47 am

The artificial gravity overcomes the acceleration, top acceleration is 9 g now so of it got through the crew would be flattened. They do not feel anything. No lurching about during manoeuvers.

Actually the term acceleration might not be the correct term anymore since it is apparently possible for two ships to be approaching each other from opposite directions and then dock together.

Less hard crunchy science part and more space opera focus on the plot and ignore the hand wavium.
Jeraa
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Re: Artificial gravity and acceleration

Postby Jeraa » Mon Sep 18, 2017 11:00 am

PsiTraveller wrote:
Mon Sep 18, 2017 10:47 am
The artificial gravity overcomes the acceleration, top acceleration is 9 g now so of it got through the crew would be flattened. They do not feel anything. No lurching about during manoeuvers.

Actually the term acceleration might not be the correct term anymore since it is apparently possible for two ships to be approaching each other from opposite directions and then dock together.

Less hard crunchy science part and more space opera focus on the plot and ignore the hand wavium.
Reaction drives go up to 16g, and you can combine both a maneuver drive and a reaction drive and get 25g acceleration.

Edit: Also, maneuver drives aren't limited to 9 g, but 11g. While 10g and 11g maneuver drives are normally beyond the TL of the Imperium, you can use the prototype rules to get versions that are TL15, though with drawbacks.
Reynard
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Re: Artificial gravity and acceleration

Postby Reynard » Mon Sep 18, 2017 1:29 pm

Ships in movies lurch and buck to exaggerate action and make thing exciting just like they love sounds in a vacuum. Players in Traveller get their excitement when their ship takes a hit and the ref describes a rumble from the shock or a hull sensor alarm announcing a breech. If some sort of damage or fault could cause a temporary power drop that could affect the artificial gravity and/or inertial compensator systems, you could have an exciting moment of weightlessness or tossing about before either the system or an engineer corrects the fault.

At the same time you can also have your control panels go off like sparklers and roman candles to represent power overloads which...never seem to have a lasting effect during or after the event. The intercom automatically plays an exciting bit of background music during these moments of danger. No one know why.
Dagorlad
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Re: Artificial gravity and acceleration

Postby Dagorlad » Mon Sep 18, 2017 1:47 pm

Interesting replies, thanks everyone.

I agree that the actual mechanics of space ship movement don't make for especially interesting game play - it's all about story-telling after all. So I'll declare to my players that the artificial gravity generators also include inertial compensators, thereby enabling the crew to sip their lattes while burning hard to dodge the pulse lasers of the pirate fleet in hot pursuit.

Does make me think though... if a ship is accelerating at 9+ g and takes a hit disabling the gravity generators, I wouldn't want to be the guy who goes inside to clean up the mess afterwards.
Reynard
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Re: Artificial gravity and acceleration

Postby Reynard » Mon Sep 18, 2017 2:20 pm

Anti-grav and Inertial compensation should technically be part of the Life Support system. Closest I can see for a AG failure is a Crew critical on the Critical Hit Effects Severity 2 through 4 but at least you have warning of imminent failure and could take action to reduce or prevent acceleration damage such as stop acceleration immediately and no vector changes.
paltrysum
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Re: Artificial gravity and acceleration

Postby paltrysum » Mon Sep 18, 2017 9:17 pm

Dagorlad wrote:
Mon Sep 18, 2017 1:47 pm
Does make me think though... if a ship is accelerating at 9+ g and takes a hit disabling the gravity generators, I wouldn't want to be the guy who goes inside to clean up the mess afterwards.
There should be a failsafe that cuts the thrust if the gravitics goes down. That should prevent your travellers from becoming a fine paste. :)
"Spacers lead a sedentary life. They live at home, and their home is always with them—their starship, and so is their country—the depths of space."
Condottiere
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Re: Artificial gravity and acceleration

Postby Condottiere » Mon Sep 18, 2017 10:20 pm

It's a general assumption that most of our spaceships are inertially compensated to the maximum performance of their manoeuvre drive, though it doesn't seem to be explicitly stated in the current set of rules.
Sigtrygg
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Re: Artificial gravity and acceleration

Postby Sigtrygg » Tue Sep 19, 2017 4:41 pm

In the very first CT adventure The Kinunir we learn this:
Gravity: The ship decks have grav plates built-in to provide a constant 1G floor
field. These plates may be turned off only through computer instructions. In
addition, the ship itself is under the influence of acceleration dampers which negate
the effects of acceleration while maneuvering.
by the time CT supplement 7 was written it had expanded to:
Gravity: Most ships have grav plates built into the deck flooring. These plates
provide a constant artificial gravity field of 1G. Acceleration compensators are also
usually installed, to negate the effects of high acceleration and lateral G forces
while maneuvering. A ship's passengers would be unable to tell whether they were
moving through space or grounded on a planet without looking out a viewscreen.
Dagorlad
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Re: Artificial gravity and acceleration

Postby Dagorlad » Wed Sep 20, 2017 11:44 am

The jury is still out on this for me.

According to the rule book, the transit time for 1 AU (the distance from the sun to the earth - approximately 150 million km) is 27.6 hours at 6g. Using high school physics (a = (v2 - v1) / t), I did the sums. Assuming a standing start, after 27.5 hours at 6g, a vehicle would be travelling at 21,384,000 km/h (13.3 million miles per hour), which is 2% of the speed of light. Travelling on to Jupiter, and the speed kicks up to almost 50 million km/h.

Not sure I feel comfortable as a GM dismissing that kind of thing with a hand wave.
Jeraa
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Re: Artificial gravity and acceleration

Postby Jeraa » Wed Sep 20, 2017 11:51 am

Dagorlad wrote:
Wed Sep 20, 2017 11:44 am
The jury is still out on this for me.

According to the rule book, the transit time for 1 AU (the distance from the sun to the earth - approximately 150 million km) is 27.6 hours at 6g. Using high school physics (a = (v2 - v1) / t), I did the sums. Assuming a standing start, after 27.5 hours at 6g, a vehicle would be travelling at 21,384,000 km/h (13.3 million miles per hour), which is 2% of the speed of light. Travelling on to Jupiter, and the speed kicks up to almost 50 million km/h.

Not sure I feel comfortable as a GM dismissing that kind of thing with a hand wave.
That doesn't really have anything to do with it. It isn't your total velocity that matters, but your acceleration. In your case, it is still 6g acceleration all along, and that is what the people on the ship feel and that is all the internal compensators have to deal with.
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Re: Artificial gravity and acceleration

Postby SSWarlock » Thu Sep 21, 2017 9:37 pm

paltrysum wrote:
Mon Sep 18, 2017 9:17 pm
There should be a failsafe that cuts the thrust if the gravitics goes down. That should prevent your travellers from becoming a fine paste. :)
"Make it so, Number One."

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Epicenter
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Re: Artificial gravity and acceleration

Postby Epicenter » Thu Sep 21, 2017 9:44 pm

Dagorlad wrote:
Mon Sep 18, 2017 10:03 am

Any thoughts on this?
In earlier editions of Traveller (like TNE or MegaTraveller), Inertial Compensation was listed as a thing while in other editions, no mention is made of it.

I've always interpreted that inertial compensation is always something included in a starship's subsystems, it's just in some editions of Traveller they feel it necessary to specify that it is there while in others it is assumed that it is there, included as part of the mass and cost of some other subsystem (likely artificial gravity or life support).
Condottiere
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Re: Artificial gravity and acceleration

Postby Condottiere » Sat Sep 23, 2017 6:22 am

Second Edition threw that in disarray by permitting a potential twenty five gee acceleration.
steve98052
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Re: Artificial gravity and acceleration

Postby steve98052 » Sun Sep 24, 2017 5:33 pm

In the types of ships one might encounter in most Traveller adventures, not much besides missiles have more acceleration than 2 G. Thats not going to squish occupants, but a quick switch between compensators on and off might cause some blunt trauma injuries.

Adventures with significant space combat are another story, but they're messy business because -- although just about every rule version includes the same general collections of ship weapon technology, the balance between them is different in every version. (I favor GURPS Traveller rules for ship design, even though I find most of GURPS too crunchy for my tastes.)

The way I am inclined to run Traveller, most of the good stuff happens planetside, and space combat normally doesn't get any hotter than enough to get players to want to spend some of their characters' hard-earned Credits on space combat gear, with an occasional incident to make them feel like it was money well spent.
Sigtrygg
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Re: Artificial gravity and acceleration

Postby Sigtrygg » Sun Sep 24, 2017 7:20 pm

You are standing outside the door to the bridge of the standard type s scout. You are threatening to do nasty stuff.

The pilot switches off the internal gravity and compensators.

You fall 15m at 2g...
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Re: Artificial gravity and acceleration

Postby Condottiere » Mon Sep 25, 2017 12:24 pm

Image

If your personality isn't magnetic, your sole may be.


More seriously, I doubt that most commercial ships will install more than a three gee manoeuvre drive, which should be enough to visit most human habitable worlds.

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