Beyond 6g...

[The Hinterworlds Rambler]

Anyone out there ever do any math on going beyond the 6g "limit" set down in the books? The ship percentage required seems to work on an additive three setup on the Drive Potential Table in high guard.

What in your opinions would be the pros and cons of going beyond 6g accerleration in a given setting? Do you think it is possible and SHOULD it be possible to have a faster than 6g engine on a ship?

Consider:

1. A 6g engine can be produced at TL 9+.
2. The Drive Cost seems fixed at 0.5 per ton
at 3g and up.

 

[bryan gibson]

well, it occurs:

take into account you have inertial compensation of gravity, that being said it stands to reason that you should be able to manage compenstaion of higher Gs acceleration as you go - say, the higher the TL the better the capability?

So, at that point there really isn't any reason to imagine that higher Gs are impossible, quite the opposite - they would be likely. This would really apply to military craft where hot performance is a real plus - civilain ships could do so, but might be less likely simply due to costs, but if you were running a speed service like FEDEX then the costs may be outweighed by its usefulness.

so, assuming so you have a few issues to contend with:

How many Gs can be managed? I would imagine, following the logical progressions of the system ( I assume youre talking high guard, is youre talking CT/FF@S or TNE then naturally differnt factors/numbers apply) all you need to do is follow the trends set by the system, probably logarithmically rather than a linear progression

take into account the DMs will change for agility, to hit and evade in combat, and so on

Plus, tying in the gravitic compesation to the acceleration makes sense, I think - after all, a vessel doing 10 G will have greater hull stresses imposed on it than a 6G hull, by definition.

 

[The Hinterworlds Rambler]

There were (are?) real world precedents for this, like the HiMat program. Granted, it was a drone aircraft, but able to pull 12g plus turns, in really radical arcs. I had the same thought exactly. Gravitic Compensation would be key as you say.

PLus the concept of gas giant skimming would require (realistically I think) that ships be able to pull much more than just 6g to make it even possible. Gas Giants have a lot of gravity to consider.

Also considering that the early astronauts trained for maneuvers far beyond what they would encounter in a typical launch/mission scenario, makes it even more plausible that a high g craft would be possible even at lower tech levels (say, 9-10)

So do you think the Drive Potential table should just follow its pattern for higher g engines?

(IE, a 7g engine would require 20% of ship tonnage at TL 9, at a cost of 0.5 MCr per ton)

Drive
Number Tonnage %
8g 23%
9g 26%
10g 29%
11g 32%
12g 35%

etc.

 

[Sifu Blackirish]

I remember a book called Nightrider by David Mace, that had special acceleration couches for the crew.

Form fitting with about 1cm of water all around, occupant could withstand 10g. Also had keypads built into hand areas and built in flat screens at eye level. No inertial compensation.

IIRC aren't grav plates and thruster technology somewhat related? Does the large percentage requirements for powerplants of lower TL include inertial compensation?

If the percentages are for thruster plate drives, one might want to impose TL limitations as well...

 

[parmasson]

"If the percentages are for thruster plate drives, one might want to impose TL limitations as well..."

Perhaps it is part of the thruster "effect". The engine must cancel out the forces to within a few Gs due to the wacky way they work.

Just a thought.

 

[atpollard]

Back in the last ship design contest, I created some rules for ships without G compensation. I used the NASA medical data on allowable G forces to determine how long a 'normal' person could tolerate G forces.

If G compensation continues at the HG listed progression then the data from the Baron would work fine.

If it tops out at 6G, then the NASA data from 'minicraft' will establish the limits for short durations beyond 6G.

Being suspendeed in a liquid will drasticly increase G tolerance if you wanted to design a very strange High Performance ship.

 

[Plankowner]

IMTU, I used the following Maximum G progression:

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">TL Max G
9 6
10 8
11 10
12 11
13 12
14 13
15 15
16 20
</pre>[/QUOTE]Percentages were per HG up to TL 13, then they were halved due to improved Gravitics making the drives more efficient.

As Bryan said, it only really came up in military ships, civilians rarely needed or wanted more than 2G.

 

[Icosahedron]

Originally posted by Baron Saarthuran von Gushiddan:

PLus the concept of gas giant skimming would require (realistically I think) that ships be able to pull much more than just 6g to make it even possible. Gas Giants have a lot of gravity to consider.

So do you think the Drive Potential table should just follow its pattern for higher g engines?

(IE, a 7g engine would require 20% of ship tonnage at TL 9, at a cost of 0.5 MCr per ton)

Drive
Number Tonnage %
8g 23%
9g 26%
10g 29%
11g 32%
12g 35%

etc.

Gravity at the 'surface' (cloud tops) of gas giants is only a couple of Gs generally - you are a long way from the centre of gravity up there.

Yes, I'd play it with an additional 3% per G.

TL progression is not so cut-and-dried in the tables, however, you could alter this as you see fit, and this would be your limiting factor to prevent uber-G drives.

Civilian ships may be prohibited from using high Gs. Or pilots limited by skill level (G = 2 x skill?) - no point buying a 9G ship if you only have a 6G licence.

Looking at the repulsor development in the Bay Weapons table, there do not appear to be any discontinuities up to TL 15 - development of this gravity-related device is linear. We could deduce, therefore, that M-Drive development should also be linear.

 

[atpollard]

To simplify a little, the High Guard Maneuver Drive table progression could be expressed as a simple equation:

P = (3 x A) - 1

where "P" = Percent requited for the drives and "A" = Acceleration in Gees.

For example:
2 G acceleration, P = (3x2)-1 = 5 (percent)
7 G acceleration, P = (3x7)-1 = 20 (percent)
12 G acceleration, P = (3x12)-1 = 35 (percent)
20 G acceleration, P = (3x20)-1 = 59 (percent)

 

[Jeff M. Hopper]

A quick-and-dirty rule that I use for high-G situations. For every G in excess of the G-compensation, the difficulty of skill checks increases by a level ( an Easy Task at 1G becomes a Formidable Task at 4G uncompensated).

You really have to be concerned about the human factor at high-G, simple movements like turning your head to the right could cause a blood vessel in the brain to rupture giving stoke-like effects. The same thing can happen if the ship is undergoing evasive maneuvering, just imagine the effects on the human circulatory system when a forward 6-G acceleration suddenly becomes random 4-G lateral accelerations.

In Walter John Williams' Dread Empire's Fall trilogy, he suggests using drugs to both thin out the blood being pumped and strengthening the veins/arteries/capillaries so that they are less susceptable to bursting under high-G maneuvers. Not a bad idea that fits well in with Traveller's canon drugs.

High-G may also collapse a person's lungs, modern G-suits use a positive pressure air flow to force air into the lungs but under long-term acceleration the lungs themselves may be damaged. I'm wondering if some kind of "liquid breathing" oxygenated flourocarbon system would be better for long term high acceleration - I've got to research it further though ( here's a Wikipedia article on the subject ).

 

[The Hinterworlds Rambler]

What's normally the G-Limit for humans before they black out?

 

[The Hinterworlds Rambler]

X-26 High G Operation Experimental Performance Platform

USP:
XHGP-110AA21-000000-00000-0

TL= 15

Hull: 100 tons (MCr 10)
Wedge Configuration (MCr 2)
Armor: 0

Jump Drive: 0
Maneuver Drive: 10g (29 tons, MCr 14.5)
Power Plant: 10 (10 tons, MCr 30, 10 EP)
Agility: 10

Power Plant Fuel (10 Tons)
Fuel Scoops

Bridge (20 Tons, MCr .5)
Computer, Model 2 (2 tons, MCr 9)

Weapons : None

Screens : None

Facilities: None

Crew: 1 Pilot, 1 Engineer

Quarters: 2 Single Staterooms (8 tons, MCr 1)

Cargo: 21 Tons (usual option to add 8 weeks of additional power plant fuel)

Totals: MCr 73.81 (67.1 MCr plus 6.71 MCr in architect fees for total of 73.81)

 

[Jeff M. Hopper]

Originally posted by Baron Saarthuran von Gushiddan:
What's normally the G-Limit for humans before they black out?

IIRC humans can withstand up to 15Gs for a few seconds before blacking out as a maximum. The problem is, the longer time spent at high G below that limit would be the norm for a Traveller space combat.

 

[atpollard]

Originally posted by Baron Saarthuran von Gushiddan:
What's normally the G-Limit for humans before they black out?

HERE is the wikipedia answer.

From some personal research into NASA astronaut criteria, I came up with these figures for accelerating forward: The average person can tolerate 2G for 100 minutes, 3G for 30 minutes and 4G for 10 minutes.

Less than 10 minutes has little game benefit.

 

[Plankowner]

In the airline industry, there is something called the 9-G rule and the newer 16-G rule.

Originally, airline interiors (seats and stuff) were built to withstand a 9-G crash load. In other words, the seats would not come out of the floor, the galleys and lavs would not come apart and fly through the cabin at 9-Gs. HOWEVER, after decades of crash investigations, the NTSB found that people were surviving the crash and dying from the debris that flew through the plane. After some experimentation (including crashing an L-1011 into the desert!) the FAA changed the design rules and now requires all new airplanes to be designed to survive a 16-G crash.

So, from a survivability point of view, people can survive a 10+G force for a short period of time. They may have broken bones etc, but they will be alive.

Make of that what you will.

 

[Andrew Boulton]

A car crash can be well over 16g.

 

[atpollard]

From the earlier wikipedia link:

Strongest g-forces survived by humans.

Voluntarily: Colonel John Stapp in 1954 sustained 46.2 g in a rocket sled, while conducting research on the effects of human deceleration.

Involuntarily: Formula One racing car driver David Purley survived an estimated 178 g in 1977 when he decelerated from 173 km·h−1 (108 mph) to 0 in a distance of 66 cm (26 inches) after his throttle got stuck wide open and he hit a wall.

Do not try this at home.

 

[Sifu Blackirish]

Being suspendeed in a liquid will drasticly increase G tolerance if you wanted to design a very strange High Performance ship.

Joe Haldeman's Forever War extensively discusses acceleration tanks. Oxygenated flurocarbon solution under pressure was pumped into a five-person (IIRC) chamber. Occupants needed a special cell-strenthening drug and had a surgically implanted fitting so the solution would enter their bodies. Navy crew at essential posts had a portable system that weighed 5+ tons, and they had to be immobile during evasive maneuvers.

It was mentioned that the ships using this system could perform close to their maximum performance of 25 gees!

One interesting effect is that no time semed to pass for the occupants. Also, no mention is made of the 'bends' but that could be due to no nitrogen in the system.

One week, no problem. Two weeks, took about 15 minutes recovers time. Theoretical maximum was 4 weeks before something broke and...

 

[Space Cadet]

At 100-gs, I've calculated that it would take 43.3 subjective days to reach Alpha Centauri which is a distance of 4.4 light years assuming an acceleration for half the distance, a turnaround at mid point and a deceleration the rest of the way. It would be interesting to run a Merchant campaign where there is no FTL drive with regular runs between Earth and Alpha Centauri. Average Gamma would be 10:1 for the time of the campaign world compared to shipboard time. Assume the energy source is a decaying blackhole and that the interior of the ship is inertially compensated, then you could have a convenient Free Trader type ship that makes the Alpha Centauri run in 43.3 days ship time and 4.4 years Earth time, the ship would then dip into a local gas giant and feed it black hole some hydrogen or whatever matter is convenient so that it can make the trip back. Failure to feed the black hole would cause the blackhole to explode once it radiated away enough energy, so refueling after each trip is important. I think minature black holes make ideal energy sources for realistic starships as they take up little space and with inertia compensators, you don't really have to worry about pushing around these black holes as you accelerate at 100-gs. What do you think about centering a Traveller campaign based on this technology?

 

[Plankowner]

Originally posted by Andrew Boulton:
A car crash can be well over 16g.

Quite true. I believe that car seats are tested to 23Gs. YES, your car seat is safer than your airplane seat.

BUT, remember, there are a lot fewer plane crashes than there are car crashes, so it is still safer to fly on a plane than to drive to the airport. (Airline guy, I HAD to say that... )