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08-11-2021, 12:31 PM   #31
Fred Brackin

Join Date: Aug 2007
Re: Spaceship Tech in your Setting

Quote:
 Originally Posted by cvannrederode I The superscience available: Artificial Gravity, Rotary Reactionless Drives, and Hyperdrives. A.
You don't mention contragravity lift. Do you include that in "Artificial Gravity" or are real starships orbital only with some sort of HEDM shuttle or aomething like that?
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Fred Brackin

 08-11-2021, 12:51 PM #32 Anthony   Join Date: Feb 2005 Location: Berkeley, CA Re: Spaceship Tech in your Setting Oh, another thing I like for spaceship drives: warp drives function even at low altitudes, but they have a speed that is inversely dependent on the local gravitational field. A drive that can reach 100 m/s near Earth (G=10m/s^2) can reach 170 km/s in stellar orbit at 1 AU (G=5.9e-3 m/s) and more than 30c in deep space (G=1e-10m/s). This guarantees that most travel time is spent in relatively interesting locations (it works out that time to escape is linear in gravitational potential and can be computed as (speed at current distance) * (distance to center of object)). __________________ My GURPS site and Blog.
08-11-2021, 01:14 PM   #33
Varyon

Join Date: Jun 2013
Re: Spaceship Tech in your Setting

Quote:
 Originally Posted by Anthony Oh, another thing I like for spaceship drives: warp drives function even at low altitudes, but they have a speed that is inversely dependent on the local gravitational field. A drive that can reach 100 m/s near Earth (G=10m/s^2) can reach 170 km/s in stellar orbit at 1 AU (G=5.9e-3 m/s) and more than 30c in deep space (G=1e-10m/s). This guarantees that most travel time is spent in relatively interesting locations (it works out that time to escape is linear in gravitational potential and can be computed as (speed at current distance) * (distance to center of object)).
The reactionless drives in my Harpyias setting function somewhat-similarly, although there it's simply dependent on distance from the system's star rather than any gravitational interactions. Each of the setting's Aetheric Stars (those that hyperspace travel can travel between, and thus the only ones the PC's would ever be visiting) have 12 orbits of note - one each at one each at 0.25 AU, 0.41 AU, 0.67 AU, 1.11 AU, 1.84 AU, 3 AU, 5 AU, 8.25 AU, 13.6 AU, 22.45 AU, 37 AU, and finally 61.15 AU. The first 11 typically have something in them - a planet or asteroid field - while the last is where ships are able to transition into and out of hyperspace. The further you get from the central star, the faster the ship goes, such that a typical vessel takes around 1 day to travel between two orbits (regardless of if this is the "short" 0.16 AU jaunt between the first two orbits or the 24.15 AU expanse between the last two).
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08-11-2021, 08:24 PM   #34
Fred Brackin

Join Date: Aug 2007
Re: Spaceship Tech in your Setting

Quote:
 Originally Posted by Anthony Oand more than 30c in deep space (G=1e-10m/s). T
30c isn't very fast. That works out to 1 ly every 12 days or a bit more than 50 days to Alpha Centauri.

I've seen calculations that put the average distance to stars with Earth-like planets at 200 ly. That's 6.5 years with your drive.
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Fred Brackin

08-11-2021, 09:10 PM   #35
The Benj

Join Date: Aug 2004
Location: Platform Zero, Sydney, Australia
Re: Spaceship Tech in your Setting

Quote:
 Originally Posted by Anthony Oh, another thing I like for spaceship drives: warp drives function even at low altitudes, but they have a speed that is inversely dependent on the local gravitational field. A drive that can reach 100 m/s near Earth (G=10m/s^2) can reach 170 km/s in stellar orbit at 1 AU (G=5.9e-3 m/s) and more than 30c in deep space (G=1e-10m/s). This guarantees that most travel time is spent in relatively interesting locations (it works out that time to escape is linear in gravitational potential and can be computed as (speed at current distance) * (distance to center of object)).
Great concept, but, like Fred said, that scale still gives a very long travel time.

08-11-2021, 09:30 PM   #36
Anthony

Join Date: Feb 2005
Location: Berkeley, CA
Re: Spaceship Tech in your Setting

Quote:
 Originally Posted by Fred Brackin 30c isn't very fast. That works out to 1 ly every 12 days or a bit more than 50 days to Alpha Centauri.
That's a deliberately slow example. It also takes 18 hours to escape Earth and more than a week for solar escape.
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08-11-2021, 10:18 PM   #37
Fred Brackin

Join Date: Aug 2007
Re: Spaceship Tech in your Setting

Quote:
 Originally Posted by Anthony That's a deliberately slow example. It also takes 18 hours to escape Earth and more than a week for solar escape.
In terms of interstelar travel Alpha Centauri is as quick as it gets. There might even be a reason to go there. Alpha Centauri a+b are both the right sort of stars to produce an Earth-like planet.

There is very little reason to go just to the heliopause.
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Fred Brackin

08-12-2021, 09:13 AM   #40
Rupert

Join Date: Aug 2004
Location: Wellington, NZ
Re: Spaceship Tech in your Setting

Quote:
 Originally Posted by Fred Brackin You don't mention contragravity lift. Do you include that in "Artificial Gravity" or are real starships orbital only with some sort of HEDM shuttle or aomething like that?
Rotary reactionless drives are probably sufficient to make HEDM, etc. uneconomic and unnecessary.
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Rupert Boleyn

"A pessimist is an optimist with a sense of history."

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