Affects of Acceleration on D20 Future Characters?

[Chaldfont]

So I'm working on a loose conversion of Star Frontiers to D20 Future. The starships in SF make use of an FTL plot device that allows objects to slip into "the void" when they reach 1% of light speed. When in the void, ships can travel vast distances in small amounts of time.

But the ships still need to accelerate to 0.01c to enter the void and, after leaving it, need to decelerate to their destination. Usually, ships accelerate at 1g. But in emergencies you might want ships to accelerate at much higher rates. How does this affect the characters?

Cursory googling indicates that humans can handle up to 3g acceleration over time. They might be able to handle up to 10g in sci-fi liquid tanks and even higher if they breathe oxygenated fluids.

How would this work mechanically? I'm thinking of keeping it simple, and just doing it with Con damage. Say 1 point of Con damage per g of accleration per day over 1g. Maybe special equipment could reduce this damage.

For combat during flight, one can use the "high gravity rules" in D20 Future for up to 3g. Characters are immobilized while accelerating faster than 3g.

What do you think?

 

[C. Baize]

Inertial dampeners. Purchase DC 25.

 

[Chaldfont]

Inertial dampeners. Purchase DC 25.

The SF setting lacks such technology. It's one of the more interesting bits. No inertial dampers. No anti-gravity.

 

[Byrons_Ghost]

I'm no scientist, and someone else is going to have to come along and actually explain how it works (or correct me), but I'm pretty sure that acceleration G's only apply while in a planet's gravity well. IOW, it's the sort of thing that's going to be a problem while blasting off from the planet.

Once in space, there's no force pushing against the ship to keep it down on the planet. The ship could keep increasing speed without anyone really noticing. At any rate, I imagine that the amount of time and distance involved in getting a ship to .01c would take it out of a planet's gravity.

 

[aurance]

I'm no scientist, and someone else is going to have to come along and actually explain how it works (or correct me), but I'm pretty sure that acceleration G's only apply while in a planet's gravity well. IOW, it's the sort of thing that's going to be a problem while blasting off from the planet.

Once in space, there's no force pushing against the ship to keep it down on the planet. The ship could keep increasing speed without anyone really noticing. At any rate, I imagine that the amount of time and distance involved in getting a ship to .01c would take it out of a planet's gravity.

You feel the affects of acceleration anywhere.

In space the ship could keep moving at constant velocity without any energy - but acceleration will require energy.

 

[Bagpuss]

Hence accelerating at 1g is a good idea as it creates an artifical gravity similar to Earths. Down being towards the rear of the ship. In the opposite direction to the one you are travelling in. Of course when you decelerate (again at 1g) down is towards the front of the ship, or in the same direction as you are travelling.

The most likely solution is to just turn the ship around mid journey. Which would cheap down in the same relative direction within the ship, and allow you to use your main engines to accelerate and deccelerate.

10g does sound like the maximum you could manage in sealed liquid medium, with liquid breathing medium. You probably wouldn't want to sustain that for too long however. The other option to consider is cyrogenics, a frozen crew would probably could take higher g ratings and wouldn't be so bored on the journey.

How long does it take to get to 0.01c at 1g acceleration? I've just done some quick calculations...

Its going to take about a month (34.7 days) to get to 0.01c at 1g, which would be like a long vacation on a cruise liner.

You could do it at 3g without much techical equippment other than a acceleration couch, but who would want to spend 11.5 days stuck to a couch?

The acceleration tank is going to still be tricky since you need to figure out a way to feed someone who will be in it for 3.4 days.

I think more likely is that they would do some short high g burns, every now and again an the rest of the time maintain, something only mindly uncomfortable like 1.5g.

No matter what system you use they aren't getting anywhere in a hurry.

 

[Dagger75]

Back in my ol Star Frontier Days we had some home rules for ships.

ION engines whould take a week or so of accelerating to get to "Jump Speed", then another week of decelrating.

The Atomic engines cut the time in half + were able to land on planets with those engines.

I don't know if this is real world physics or what not but this how we dealt with acceleration.

Intial boost of acceltration was to 1g so the ship seem to have normal gravity. Then the steady accelaration over time, not noticable. Some strange thinking with realativity or what have you from our leet 6th grade science class physics

During combat we had "Crash Couches". Liquid filled seats like Lay-Z-Boys. If you werent in those you would be thrown around the ship durning manuevers. We had flight suits like fighter pilots to help as well. Don't ask about a Vrusk Lay-Z-Boy, we just said they had one but never really though much about it. Was a square on the deckplans. As long as the Vrusk new how to use it.

PS: Do they have the ice shield thingy in D20 future.

 

[Chaldfont]

How long does it take to get to 0.01c at 1g acceleration? I've just done some quick calculations...

Its going to take about a month (34.7 days) to get to 0.01c at 1g, which would be like a long vacation on a cruise liner.

My math might be off. I came in at an order of magnitude lower. Check my math:

t = v/a = (0.01 * 299,792,458 m/s) / 9.81 m/s^2 = 305,600s = 85h = 3.5d.

That's a week's travel. Not unreasonable. In emergencies, you might lower it to 2-4 days by accelerating at 2-3g. Or less than a day if you could make 10g.

I'm mostly interested in those exciting moments in a campaign where The Fleet must make it to a system just in time to protect The Innocent from the Alien Onslaught. It would be fun if the PCs were impaired somewhat by the exhausting acceleration and, once won, their victory all the more memorable.

If anyone's interested--it's pretty easy to convert SF to D20 Future. With the racial stats already done for you, all you really need to do is make an equipment list (mostly PL6 stuff but some higher tech items) and deal with the differences in the starship combat system (I will just use D20 Future for simplicity).

Oh yeah, one more thing I remember about SF. Sathar are cool.

 

[Bagpuss]

Your maths is right. I know where I went wrong I calculate with accelerate at 1 m/s2 not 1 g which is nearer 10 m/s2. Hence the order of magnitude. Doh!

2300AD had a similair "travel for a few days before bringing the FTL drive online" affair, although there reason was you had to get a certain distance from the gravity well of the systems star before the FTL would work effectively.

 

[Mustrum_Ridcully]

Your maths is right. I know where I went wrong I calculate with accelerate at 1 m/s2 not 1 g which is nearer 10 m/s2. Hence the order of magnitude. Doh!

2300AD had a similair "travel for a few days before bringing the FTL drive online" affair, although there reason was you had to get a certain distance from the gravity well of the systems star before the FTL would work effectively.

The starships in SF make use of an FTL plot device that allows objects to slip into "the void" when they reach 1% of light speed. When in the void, ships can travel vast distances in small amounts of time.

Okay, since it is the fictional part of your science fiction setting, it might not be important, but not that that, thanks to relativity, it should not be important wether you are at 0, 1 or 10 % of light speed. Because, from your own point of view, you are still stationary, it is just the rest of the world that is moving. But you can ignore it, if you´d say the rules for relativity don´t apply for the void - the void actually is something you can have an absolute position and speed too. (something like the "ether" that was theorized before Einstein as the medium the light travels through and allowing absolute references...)

But back to the real topic:
The acceleration basically has the same effect like a high-g world would have. The D20 Future system isn´t very precise - there are basically only three or four "settings" of gravity - no, light, normal or heavy, but you might work along that lines.
The SRD and probably also the MSRD do contain rules about enviromental effects from weather/heat or cold, and you might work along that lines - maybe some fortitude saves to avoid fatigue/exhaustion/unconciousness, depending on the actual "g" and the time the characters are exposed to the effect.