General Gravity effects on spaceship acceleration

[Otto Harkaman]

If you don't have any super science (antigravity) to change the "G" acceleration of a spaceship what would these effects be like? How many "Gs" could the crew handle and for how long? What would the stress be like in a combat situation?

 

[Otto Harkaman]

Normal humans can withstand no more than 9 g's, and even that for only a few seconds. When undergoing an acceleration of 9 g's, your body feels nine times heavier than usual, blood rushes to the feet, and the heart can't pump hard enough to bring this heavier blood to the brain

https://www.scientificamerican.com/article/star-wars-science-light-speed/

Astronauts normally experience a maximum g-force of around 3gs during a rocket launch. This is equivalent to three times the force of gravity humans are normally exposed to when on Earth but is survivable for the passengers. Astronauts are trained in high g-force, wear g-suits and must be correctly prepared.

https://www.spaceanswers.com/space-exploration/what-g-force-do-astronauts-experience-during-a-rocket-launch/

 

[Otto Harkaman]

G-Force is a Nightmare for Fighter Jet Pilots
https://www.youtube.com/watch?v=J1O0Q3Y0Yrw

 

[Xerxeskingofking]

its very hard, and its not the same in all directions. a human can take more positive gs than negative (ie, a force "Down" towards your feet, not "Up" towards your head). something to do with the more delicate blood vessals in the brain being less able to stand the strain of overpressure form the extra blood forced into the head by negative G.

A quick google says about 4-5 positive G is the upper limit for a "normal" person, with trained pilots in G-suits able to take 9g for a few seconds, but negative g is more like 2-3 G.

if your lying on your back facing the direction of travel, this apparently improves G tolerance significantly, with test subjects able to take 5-6G for over 10 minutes with minimal long term effects.

however, I don't think much research was done on long term exposure to high g, simply because these tests didn't need to for their research (which was for rocket powered space travel, and ejection seat/fighter aircraft design).

I think the current "hard sci-fi" solution (which is my only real reference for this) is that the crew would be strapped into place before the start of combat, wearing some form of G-suit (and often full vac suits) and remain strapped into place during any manoeuvres they may make. everything we do know about shifting apparent gravity on someone (ie turning a room upside down or similar) shows that it can be very disorienting and its extremely hard for a person to stay upright as it happens so movment around the cabin would be right out.

I don't think very high G could be maintained for more than a few minutes without the crew starting to pass out (and its worth mentioning that test subjects began to see signs of mental incapacitation before actual loss of consciousness). Crew fatigue would become a real issue in a prolonged fight.

 

[Otto Harkaman]

Very interesting video, Top G-Force Things Ever
https://www.youtube.com/watch?v=-oF2q4CXwM0

 

[Otto Harkaman]

its very hard, and its not the same in all directions. a human can take more positive gs than negative (ie, a force "Down" towards your feet, not "Up" towards your head). something to do with the more delicate blood vessals in the brain being less able to stand the strain of overpressure form the extra blood forced into the head by negative G.

A quick google says about 4-5 positive G is the upper limit for a "normal" person, with trained pilots in G-suits able to take 9g for a few seconds, but negative g is more like 2-3 G.

if your lying on your back facing the direction of travel, this apparently improves G tolerance significantly, with test subjects able to take 5-6G for over 10 minutes with minimal long term effects.

however, I don't think much research was done on long term exposure to high g, simply because these tests didn't need to for their research (which was for rocket powered space travel, and ejection seat/fighter aircraft design).

I think the current "hard sci-fi" solution (which is my only real reference for this) is that the crew would be strapped into place before the start of combat, wearing some form of G-suit (and often full vac suits) and remain strapped into place during any manoeuvres they may make. everything we do know about shifting apparent gravity on someone (ie turning a room upside down or similar) shows that it can be very disorienting and its extremely hard for a person to stay upright as it happens so movment around the cabin would be right out.

I don't think very high G could be maintained for more than a few minutes without the crew starting to pass out (and its worth mentioning that test subjects began to see signs of mental incapacitation before actual loss of consciousness). Crew fatigue would become a real issue in a prolonged fight.

Thanks for your input! I just starting thinking about all this when toying around with some space games and watching "The Expanse"

 

[Condottiere]

1. Depends on length of time per turn, whether twenty minutes, six minutes, or dogfighting.

2. I'd chain it to physical endurance factor, plus training.

3. Normal mitigation is by acceleration furniture, anti gee suit, and acceleration tank.

4. Constant acceleration of one hundred forty percent Terran shouldn't cause any long term damage.

5. In theory, you could convert a grav belt to one that can negate one or two gees that the wearer will experience.

 

[whartung]

G-Force is a Nightmare for Fighter Jet Pilots

It's also a problem for Indycar drivers.

They pull 3+Gs in the corners, and with their speeds, the straights don't give them much time to recover, resulting net G load to the right hand side of the body.

This in turn can create a deficit on the left hand side of the brain and blood pools to the right, and can cause impairment with, well, all sorts of things when half of your brain is drained of blood.

I think they've basically made efforts to slow the cars down. Simply, the sport has become too fast for man to participate safely.

 

[Otto Harkaman]

1. Depends on length of time per turn, whether twenty minutes, six minutes, or dogfighting.

2. I'd chain it to physical endurance factor, plus training.

3. Normal mitigation is by acceleration furniture, anti gee suit, and acceleration tank.

4. Constant acceleration of one hundred forty percent Terran shouldn't cause any long term damage.

5. In theory, you could convert a grav belt to one that can negate one or two gees that the wearer will experience.

I was looking at some basic space combat games; Triplanetary has day long turns, Mayday uses 100 minute turns, Starfire has no mentioned scale.

I was trying to imagine dealing with gravity with no super science. I suppose I might look at some jet fighter games to see how they deal with Gs on the pilot. Well I guess it could get really tedious coming up with a stamina factor and factoring what actions would deplete it and the effects of what the depletion might mean. How fast a better trained crew could recover and what level the different grades of crew might start out at.

But it got me curious thinking about what space combat might really be like.

 

[mike wightman]

It wouldn't involve manned craft.

Most of the combat would be between autonomous drones capable of withstanding 10s of g or even 100s of g acceleration.

Once the drones decide whose side has won you either run away, surrender or die if on the losing side.

 

[Nathan Brazil]

Well what would be gaming effect then in our favorite game then?

CT. Mongoose, and Cepheus all space combat turns of 1000 seconds. While CT never mentions reaction drives, MgT and Cepheus do.

 

[Condottiere]

Pilot whales.

 

[mike wightman]

CT 77 maneuver drives are reaction drives. It mentions burning fuel for maneuvering in LBB2 and HG79 states the m-drive is a fusion rocket.

First thing I would do is adjust the scale for combat.

If you watch the Donnager battle in the Expanse you get the idea, the only thing missing is launching drones to fight each other. You need minute long turns for the missile, torpedo and drone combat cloud.

First get detection ranges and weapon ranges right. Detection range is way longer than combat range so can be a separate game in itself.

Space based lasers do not have light second ranges if they want to burn through armoured hulls, PAWS are probably you long range weapon of choice but they and lasers will be good out to a few thousand km. As you go up through the frequencies for lasers they get longer ranged - an x ray laser will have a longer range than a UV laser which is longer than a visible light frequency laser.

Railguns would be lucky to get projectiles up to 10km/s so your range to hit with railguns is going to be a few tens of km

Railguns firing plasma projectiles can get up to 100km/s, so they have ranges of a couple of hundred km, fusion guns will be similar if you can crack the problem of keeping the plasma/fusing plasma together.

Your unmanned stuff will have accelerations ratings of tens to hundreds of gs so they will move quickly across your game board, manned ships are going to be limited to a few g at best, more if travelling in a straight line but as soon as they start to turn then the g load goes up so pull too tight a maneuver and your entire crew is at risk of blackout or worse - note the ship itself can probably withstand accelerations that will kill the crew so a 6g drive ship may well save itself at eh expense of the meat inside (hope you took a wafer backup)

 

[mike wightman]

So you have different phases for your battle where different time scales may be useful.

Minute long turns for the ordnance, turns of only a few seconds for the ship mounted weapons, with their ranges being limited to a certain performance envelope

 

[Otto Harkaman]

I just quickly looked at SPI's Air War, they just have aircraft performance charts, I would have to look deeper if they have G effects on pilots.

Yes I agree looks like actual space combat would be between drones just like modern air combat is predicted to be in the near future.

 

[mike wightman]

A g stress chart would be a good way to go, and for even more realism some sort of heat stress chart too

 

[whartung]

I was looking at some basic space combat games; Triplanetary has day long turns, Mayday uses 100 minute turns, Starfire has no mentioned scale.

Starfire tactical scale is 30s turns.

A map hex is 1/4 light second in size, 75,000 km.

Speed "1" is, I guess, 1/4 speed of light. No, that's not right. Man, my math is not working here (or my pooh brain is suffering a honey deficiency).

Speed 1 is 75,000km in 30s. That means 75,000km/30s, is 2,500km/s. SoL is 300,000km/s, so Speed 1 is 2,500/300,000 = 0.008 the SoL.

I think.

Anyway.

But they do not use reaction drives in Starfire, and they don't have momentum.

 

[Nathan Brazil]

I was not asking about rewriting the entire space combat system. I was thinking something something more simple like a remain undamaged roll when you make use of Auto/Evade like:

"Using Auto/Evade carries risk due to rapid changes in vector and acceleration while in use. Crew members need to make an Average (+0) Endurance roll to avoid damage. DMs:
-Auto/Evade level
-4 if crewmember not strapped in (performing repairs, moving to a smallcraft or other such activities)

Failing causes damage equal to ((Gs acceleration)/2+Auto/Evade) D6. Exceptional Failure causes unconsciousness regardless of damage taken."

 

[Fovean]

I’ve been house-ruling something I picked up from GURPS Space; varying turn length based on range.

I had to rework the ranges slightly, and give sensors ranges like weapons (MgT 2e) but it’s working well and neatly ties into personal combat rounds.

As far as G forces go, we’ve found evasive maneuvers don’t really seem to kick in until the shorter, 1 minute or 30 sec rounds so we use a 1 minute baseline for the effects of G stress. There’s several things you can do to mitigate it (acceleration couch, vacc suit, g-drugs). We’re playing MgT 2e so we just do END checks every minute, with DMs appropriate to the situation (basically DM-1 for every uncompensated 0.5G).

 

[BRover]

StarFleet Battles use, IIRC, 30 (or 60?) second turns, where speed of 1 = lightspeed, and game speeds go up to 31 (32+ for non-ships), which means making some pretty involved choices in 2 seconds (or less). Unless there are special rules about time dilation under warp drive . . .