Bunch 'o Thoughts and the 6G Limit

[Supplement Four]

In Traveller (at least in Classic), the fastest M-Drives produce 6 Gs of thrust. When I was young with the game, I always wondered, "Why the 6G limit?"

Is that the limit of technology? We just don't know how to build a 7G M-Drive yet?

That's seems unlikely to me, especially given what Traveller has done with like technology--entire cities floating in the clouds on some planets.

Maybe Marc & Co. liked the 1-6 connection with a 1D6?

Dunno. Maybe.

Maybe the 7G drives can be built, but they're non-practical in some way? They're way too big? (I don't buy that because a large fast spaceship would have great uses for in-system travel.) They're fuel ineffecient? (I don't buy that either, given how relatively efficient the 1-6 G drives are.) Some other reason along these lines?

Not buyin' it.

OK, then, why?

What's the reason?

The J-6 limit is a lot easier to swallow (since we're dealing with Jump Space) than the M-6 limit.

So...why?





Well, let me give you a reason that may not exactly be canon (and it may also be some forgotten canon), but it sure is fun and colors a game with some detail that makes the universe that much more real.

I wish I could take credit for this idea, but it's not mine. I mined it from an old White Dwarf Traveller article.

The idea is this. Very simple: The M rating on a vessel describes the acceleration capability of that drive to push that vessel to the indicated acceleration, and it also describes the drives rating to compensate for the thrust.

For example, a vessel with a M-3 drive can accelerate up to 3Gs. If the ship does this, then the crew experiences 3G acceleration (gravity inside the ship is 3Gs). That's 3Gs acceleration and 0G compensation.

If the captain wants to keep the crew and passengers comfy in a standard 1G field, then the maximum he can accelerate the craft is 2Gs. The M-3 drive is used to accelerate at 2Gs while using the remaing 1G to compensate. 2 - 1 = 1. The crew will be in a 1G field.

So, for a M-3 vessel, the ship could...

1: Accelerate at 3Gs, while maintaining 0G compensation. Crew exposed to 3Gs throughout the acceleration.

3 - 0 = 3

2: Accelerate at 2Gs, while maintaining 1G compensation. Crew exposed to 1Gs throughout the acceleration.

2 - 1 = 1

3: Accelerate at 1Gs, while maintaining 2G compensation. Crew exposed to 3Gs throughout the acceleration.

1 - 2 = 1 (absolute value)

4: No acceleration. Max interior compensation is 3Gs.

0 - 3 = 3 (absolute value)



That last option is interesting, because it tells you the maximum G rating that the drive can produce in the interior of the craft. If pirates swarm aboard, the max G field you can crush them with is 3Gs....which is heavy, but not deadly (probably a enough to give the crew a big edge, though).



Another interesting factoid is that the maximum G rating that a human can withstand for a long period of time, without aides like pressure suits, is about 5Gs. In Traveller, it is mostly military craft that have 6G M-Drives. So, if the captain calls for high G maneuvers, the crew must know to don their vacc suits and strap into their acceleration couches.



So, what does this mean?

On planets, ships should be able to combine the surface gravity of a vessel with the G rating to make for a stronger force. If on a standard 1G, Size 8 world, then a ship with a M-3 drive can create an interior force of 4Gs.

For a game...what if a ship with a 1G drive is repelling borders? One tactic may be to get to a nearby gas giant to use that world's G field to increase the interior G rating.

No longer can certain sections of the ship be thrust into zero G while other sections maintain standard 1 G gravity. The G rating is set for the entire ship...if the cargo hold is in 0G, then so is the entire craft. The G field is a true field that encompasses the entire ship. It's not an on/off light switch. In a game, this makes skills like Zero-G Enviroment more important again.

Large capital ships multiple M-Drives could have different fields around different sections of the ship. The boundary between fields will not be clear, but fuzzy. And, maybe the entire design of the ship may circle around the boundary of the G fields.



In a game...Captains will have choices to make. No longer is "max G" the only choice to be made when travelling in-system, starport to gas giant. If it's 1 day and 8 hours to the nearest GG at 3G acceleration, then a vessel with a M-3 drive will expose the crew to the uncomfortable 3Gs for over a day.

Think of the passengers...can this be done?

If running from pirates, then, you bet.

If making a normal milk run, then the crew would probably be more comfortable in a 1G field. Heck, High Passages may require the ship to remain in a 1G field by law.

What I like is how this brings "detail" to a game...those touches that make the universe seem real to the players. They've got the ins-and-outs of the ship's drive to consider, not unlike an ocean going vessel's captain saying, "All ahead one third!"

 

[Supplement Four]

Bunch 'o More Thoughts on the 6G Limit

And, let's talk about the vessels with the M-1 drives. These vessels are the bare bones minimum equipped vessels in space. When the ship accelerates, it is using the acceleration (and not compensation) as the internal gravity for the ship. The 1G acceleration exerts a 1G field on the interior of the vessel.

When the ship is at rest, the 1G is used for compensation, still leaving the crew in a 1G field.

Acceleration always produces Gs that "press down" on the crew, like normal gravity.

Compensation can be used in two ways. It can be used as "artificial acceleration" to "press down" on the crew. Or, it can be used alleviate G force produced by acceleration.

In other words, Acceleration always produces "gravity" for the crew while compensation can be used to increase or decrease that force.

A vessel with a 1G drive will have an intricate marriage between the ship's acceleration and its compensator.

As a 1G vessel accelerates, it moves through fractional accleration until it makes the full 1G of thrust. The compensator is used during this time to keep the crew in a 1G field.

Accel   Comp   Internal
====   ====   ======
 0.1      0.9       1G
 0.2      0.8       1G
 0.3      0.7       1G
 0.4      0.6       1G
 0.5      0.5       1G
 0.6      0.4       1G
 0.7      0.3       1G
 0.8      0.2       1G
 0.9      0.1       1G

In the game...the compenstor is used to create artificial acceleration Gs on the crew. When the ship is moving at 0.1 Gs, the compenstor is compensating for the other 0.9 Gs.

Once the vessel makes it to a full 1G acceleration, there is no compensation happening. The acceleration is creating the 1G interior field.

In a game...there may be a "bump" signalling when the compensator turns off. Or, maybe this just happens with old, un-serviced drives. This is just a thought for the GM to make his universe cool and realistic. Maybe a particular type of drive does this.



Why get a M-2 drive?

For the simple fact that the ship can be pushed to 2Gs acceleration. During this time, though, the ship will be under 2Gs of stress in the interior. Normal operations for a M-2 equipped vessel will be to travel around at 1G acceleration: 1G of thrust and 0G compensation.

A vessel equipped with a M-2 drive can go to 0Gs internally while accelerating at 1G, if it needs or wants to. That's 1G of thrust, and 1G of compensation to alleviate that thrust.

When the ship speeds at 2G acceleration, though, the crew is exposed to 2Gs of gravity, and that's not pleasant for a long period of time. 2G acceleration should be considered for emergency maneuvers (Combat).

In Traveller, it's usually very easy to figure what another ship has under the hood in terms of it's M-Drive. The reason is that most Traveller vessels are always travelling at their full thrust (Full thrust to mid-point and Full deceleration to destination). It only takes a starship computer a micro second to report the G rating of the target ship's M-Drive.

In a game using these rules, though...that paragraph I just wrote will no longer be true. If you're about to attack a vessel that you see travelling at 1G acceleration, you have no idea if that vessel has a M-1 drive or has a M-2 drive but is travelling at 1G to keep the crew in a 1G field. This is another little detail that adds to the game, imo.



On the other end of the spectrum are vessels with high G ratings. Most times, these are military vessels. You'll find these types of ships equipped with acceleration couches and the crew issued pressure (or Vacc) suits to deal with High G maneuvers.

A ship with a M-5 drive might be travelling at 3Gs, using 2Gs of compensaton to keep the crew and passengers in a comfortable 1G field. But, if trouble breaks out, the ship is fully capable of ramping up to 5Gs of acceleration. And, during that time, the crew will be exposed to the full 5Gs.

As I stated above, 5Gs is about the limit that an unprotected human can withstand for a long length of time. But, it's not pleasant. The pressure suits and confinement to the acceleration couches will help.

In game terms, I'd say that each items compensates for 1G of pressure. So, if in a 5G field, the pressure suit will reduce that to 4Gs, and the acceleration couch will reduce it further to 3Gs. That's still not very comfortable, though.

High G maneuvers (any maneuvers that put greater than a standard 1G of pressure on the crew) will typically not be used unless in emergency situations.

High Passengers, in your game (if you like), must always be provided a 1G field (and since we're talking about the entire ship, it means the entire ship must stay in a 1G field while the High Passengers are aboard).

So, when you make port, you'll unload your High Passengers first, THEN turn the ship into zero G to unload the cargo hold. This may not be the most efficient use of time, but the High Passengers are paying Cr10,000 a head and should retain the 1G right by law.



That's a lot of random thoughts on the issue.

How about you? What do you think of this?

 

[Supplement Four]

Oh, and why the 6G limit?

My guess is that it's mandated by Imperial law because of the threshold of that amount of force exerted on a sentient being, for a long period of time, without the use of protection like pressure suits and acceleration couches.

Game idea...So, this means that there ARE some 7G, 8G....10G....30G drives out there, custom built, for specific purposes. But, they must also have some heavy protection for the beings that operate the craft.

Let's say a high-tech acceleration couch is built that will alleviate 2Gs of thrust, and a pressure suit is created that will alleviate another 2Gs. This means the max drive is still only 5Gs...to keep the crew in a comfortable 1G field.

Anything over 1G will be very hard on a being if that being is not used to it.

Game idea...the players, from a Size A world, are sought out because they are used to higher G forces...for whatever reason....

 

[aramis]

The compensation limit being the drive limit is borne out by TNE's FF&S, and born of the HG limitations (which carried through to MT).

It's the explanation I've always used. And I've never read the WD article in question, since I've only read one WD Traveller article (Hit Locations).

Given that even 6G ships under CT were fully compensated to provide 90° compensation to full rating, PLUS 1G local, it is sensible.

Note that the TNE Compensation limit, IIRC, is TL-9.

 

[Supplement Four]

The compensation limit being the drive limit is borne out by TNE's FF&S, and born of the HG limitations (which carried through to MT).

So I don't have to dig it out, what did it say, in a nutshell? I've stuck mostly to CT, as you know, and am not that familiar with non-CT rules and explanations.

And I've never read the WD article in question, since I've only read one WD Traveller article (Hit Locations).

It's a quite intriguing idea with lots of ideas for gameplay (as I note in my posts above).

It may be non-canon, but I think it really adds a lot to the game.

I've been using the above idea plus the old CT Escape Velocity idea (where a 1G ship cannot make escape velocity from a Size 9+ world), and the two ideas together sure add a lot of neat "detail" to the Traveller universe. It makes for a lot of differences between different vessels with different equipment. They're not all the same "but faster".

 

[aramis]

As you know, HG limits G's by TL.

MT does likewise, but requires adding inertial compensators as a system; the implication of certain rules wasn't followed through. They are not available until TL 10 (MT RM p81) Antigravity Maneuver Drives and Standard Grav Modules are TL9 in MT (p65-66), while full reactionless thrusters are TL11, and gravitics for in-gravity well improve at TL's 10 and 12. (ibid.) Limits on MD thrust (but not gravitic systems) match HG.

Somewhere there is a note that AG thrusters don't work past 100diam. I can't find it at the moment.

I don't have my FF&S to hand (it's in a crate I can't dig down to because I can't remove the crate above due to my knee), however, IC was a separate installable system. It cancelled TL-9 G's. A second, double cost, installation increased compensation by, IIRC, 1/2 the rating.

TL  9   A   B   C   D   E   F   G 
GCs 0   1   2   3   4   5   6   7
GCd 0   1.5 3   4.5 6   7.5 9  10.5

Further, G-suits added 1-2G's, and Immersion tanks 2-3G's...

Typically, TNE Excess detail, not actively supported with rules.

 

[Supplement Four]

Further, G-suits added 1-2G's, and Immersion tanks 2-3G's...

Cool. I was just eyeballin' those in my description above. Looks like I hit the nail on the head.

 

[DaveChase]

Gravity Compensators I believe are based on efficiency of TL. The Higher the TL the more they are able to compensate for so the higher the maneuvers possible.

Also the higher the TL the higher G's you can pull.

At least that is how I have always played it.

Thanks for the information locators. I did not know about the WD issue. We will have to see if someone here has the information to share with us.

Dave Chase

 

[far-trader]

In Traveller (at least in Classic), the fastest M-Drives produce 6 Gs of thrust. When I was young with the game, I always wondered, "Why the 6G limit?"

Because that's as fast as gravitons can be pulled/pushed on

It's kind of like the speed of light. Light can only go so fast in a given medium, same thing for gravitons.

It's also part of what makes jump space work, the speed of gravitons in jump space is much faster, but again with limits depending on the level of jump space accessed. So in J1 space the speed of gravitons is enough that you can travel 1 parsec in 1 week. And so on.

Of course my long held suspicion for it being 1-6 too is, as you guessed too, because the game is a D6 mechanic core.

 

[Supplement Four]

Regardless if the WD idea is canon or not (obviously not), the idea is pretty cool: Using your M drive to limit both acceleration and compensation.

I like the aspect it puts on the game.

 

[BillDowns]

IMTU, I never paid attention to the 6G limit. I figured that extra-ordinarily high cost of staterooms provided compensators, and you can put in as much thrust as you want. Or are willing to pay for

 

[Supplement Four]

Star Trek Tricks

I like the "Star Trek Tricks" this type of Traveller gaming provides.

You're the captain of a vessel with a M-1 drive. Your passengers turn out to be pirates, attempting to take over the ship from within. One of the crewmembers comes up with the idea of throwing the ship into zero-G or high G to hinder the attackers while the crew operates from accleration couches.

But, moving at 1G acceleration makes that impossible. The only way to throw the ship into zero G is to stop acceleration. The captain wants to speed towards the starport (and help). There's no way to effect high G....

Or, is there.

Diving deep into the nearby gas giant compound the G force to 2Gs...one for the acceleration and one for the natural gravity of the GG.

It's a Star Trek Trick! The crew solves the problem by hindering the boarders with 2G gravity while the crew operates in accleration couches on the bridge.

Crafty players can come up with other uses.

I just dig this aspect of the game--what is brought to the game using the WD idea.

 

[BlackBat242]

The only problem with having acceleration provide ship's gravity is that 95+% of Traveller deck plans have the decks 90 degrees off from the axis of acceleration... under accel, everything will slide to the stern wall of the compartment, not be pressed to its floor.

 

[Supplement Four]

The only problem with having acceleration provide ship's gravity is that 95+% of Traveller deck plans have the decks 90 degrees off from the axis of acceleration... under accel, everything will slide to the stern wall of the compartment, not be pressed to its floor.

Had to go and ruin a cool idea, didn't cha?

You're right, of course.

 

[dean]

Had to go and ruin a cool idea, didn't cha?

You're right, of course.

Merchies.

The AHL had it's decks set up so that they were perpendicular to the axis of thrust.

 

[Supplement Four]

Aha...but the idea will still work. Compensation is artificial acceleration or fighting the effects of real accleration, and this can be any direction the compensator is directed to "push".

So...the idea stands.

And, it makes for some interesting choices for 1G ships, given that they cannot choose which direction during acceleration.

 

[atpollard]

If pirates swarm aboard, the max G field you can crush them with is 3Gs....which is heavy, but not deadly (probably a enough to give the crew a big edge, though).

Actually, many people will find that their heart is unable to pump blood to their brain at 2G. IIRC all people will find 3G to be fatal.

 

[atpollard]

I always assumed that the 6 gee maximum represented a limit on inertia compensation. Who wants to spend 8 hours plastered to the aft bulkhead because the ship travels at 8G but only compensates for 6G? (See note above about potential 2G lethality).

 

[aramis]

Actually, many people will find that their heart is unable to pump blood to their brain at 2G. IIRC all people will find 3G to be fatal.

Go reread the NASA data. 3G's is safe, and sustainable, for most people. It's not FUNCTIONAL, however. Most people will be couch-bound at 2G's, or even 1.5. However, most people don't realize that a typical roller coaster is 2.5G's.

The 3G safety limit is why roller coasters are limited to 3G's positive. Most small airplane hard turns are 2G-3G.

 

[Supplement Four]

Actually, many people will find that their heart is unable to pump blood to their brain at 2G. IIRC all people will find 3G to be fatal.

According to a wiki (which we know ain't Gospel), the limit for prolonged exposure is around 5 Gs. But, I'm sure that's for a man in relatively good shape.