Wednesday, November 3, 2010


I just had a lecture on human G-limits and some training. I'm not an aviator but I have flown in some high performance aircraft and pulled significant Gs. It isn't easy, and equipment/training helps.

Here's some rules of thumb for sustained Gs:

1-3 Gs: Generally no problem for people in average health
4-6 Gs: Gray out occurs. Untrained personnel or unprepared people can black out or suffer G-LOC.
7-9 Gs: Without G-training and equipment, blackout or G-LOC is likely. Even trained people will find this challenging.
10+ Gs: Generally leads to G-LOC

Partial G Suit: +1.5G
Full G Suit: Add +2.5G
Anti-G Straining: Add +3G
Adjusting seat tilt from 30 degrees to 65 degrees: +2G

Negative G is much harder to deal with; humans can handle about 1/2 that G-Load.

What this means for a Game?

As previously discussed, acceleration is the key thing for a space game that should determine scales, not velocity. Let's assume a system where 3 Gs = 1 square of movement, 6 is 2 squares, and so on. If you are accelerating at less than 3 Gs (say, a gentle 1G push) then you have a 2/6 chance of accelerating one square. A super-gentle 1/2 G push would be but a 1/6 chance.

If you assume a one minute turn, then 3G acceleration gets your velocity increased by about 1800 meters. Round it off to two clicks to make the math easy, or down to 1 click and use ~30 second turns instead of one minute turns.

With this sort of system, you'd be able to make a light burn to add 1 hex to your velocity, a moderate burn to add 2 hexes, and a strong burn to add 3. We could postulate some sort of enhancements to human physiology/g-suit technology that might make burns of10-12 G's possible that would allow adding 4 hexes to your velocity.

Alternatively, you can use an alternate G-scale (perhaps going in units of four or six instead of three). This would allow much higher velocities to be rapidly attained, and basically assume that a combination of properly reclined seats, improved G-suits, and perhaps sci-fi tech is in play to allow those greater accelerations. This would basically require hexes of 3 or 4 KM in size rather than 2 KM.

Modeling G-LOC

You could say that 1-3 Gs is no problem. Once you hit 4Gs, then you need to start making some sort of check or take damage. Bonuses to the check could be obtained from a hardy constitution/good health and high-G training (G-straining maneuvers). Moreover, appropriate equipment could give bonuses to the G's you can handle without trouble. For example, maybe having a G-Suit gives you another +3Gs of tolerance and having an acceleration couch designed for high G gives you another +3G. That would let a pilot of an optimized high-G spacecraft to pull up to 9Gs (3 hexes) without making a single check.

The G-LOC "damage" track might have three hits, or combined with some sort of "stunning" damage:
  • First Strike: Greyout. Minor impairment.
  • Second Strike: Blackout. Vision severely impaired. Other functions severely impaired.
  • Third Strike: G-LOC. You're out.
You could require folks to make one save for each category of acceleration they're exceeding their safe threshold by. So, say you are just an average Joe in a Space Civic. You have no G-protection devices. Your safe max G is 3. You initiate a maneuver that pumps you up to 9 Gs. You're going to go from just fine to "blackout" if you fail your tolerance checks. So, an experienced high-G pilot who knows how to G-strain and is in good shape might be able to take it, but the average Joe is going to be mighty close to passing out. Heck, even that simulation is pretty generous I think because most folks would actually pass out if rapidly accelerated to 9G with no protection.

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