08-22-2021, 04:30 AM | #31 | |
Join Date: Mar 2008
|
Re: [Spaceships] getting into orbit without superscience?
Quote:
|
|
08-23-2021, 07:40 AM | #32 | |
Join Date: Jun 2013
|
Re: [Spaceships] getting into orbit without superscience?
Quote:
For the math on these, you need one molecule of methane for every two molecules of oxygen, and O2 has twice the molecular mass of methane. So, that's one unit mass of methane and four units mass of oxygen - carrying just methane divides methane's heat of combustion by 1, carrying just oxygen divides by 4, and carrying both divides by 5. For hydrogen, it's instead two molecules of hydrogen for every molecule of oxygen, but oxygen has 16x the molecular mass of hydrogen, for divisors of 1, 8 (only need half a mol of oxygen per mol of hydrogen), and 9, respectively.
__________________
GURPS Overhaul |
|
08-23-2021, 10:17 AM | #33 |
Join Date: Feb 2005
Location: Berkeley, CA
|
Re: [Spaceships] getting into orbit without superscience?
At low velocity and altitude it can be useful to scoop atmosphere even if it doesn't provide any energy, because it acts as reaction mass, but this loses effectiveness fast and requires you to carry a lot of additional hardware. On Titan, you can get from surface to orbit with a conventional rocket and a 40% fuel fraction so I doubt anyone will bother.
|
08-23-2021, 08:16 PM | #34 | |
Join Date: Aug 2004
Location: Denver, Colorado
|
Re: [Spaceships] getting into orbit without superscience?
Quote:
On Mars, with only 38 percent of Earth's gravity, you could probably build the elevator cable out of Kevlar or current technology carbon fiber, or something. Every other place would only need steel cables.
__________________
-- MXLP:9 [JD=1, DK=1, DM-M=1, M(FAW)=1, SS=2, Nym=1 (nose coffee), sj=1 (nose cocoa), Maz=1] "Some days, I just don't know what to think." -Daryl Dixon. |
|
08-24-2021, 04:52 AM | #35 | |
Join Date: May 2021
Location: Eastern Kentucky
|
Re: [Spaceships] getting into orbit without superscience?
Quote:
|
|
08-24-2021, 01:06 PM | #36 |
Join Date: Mar 2005
Location: The deep dark haunted woods
|
Re: [Spaceships] getting into orbit without superscience?
There are lots of proposals for cheap reusable ground-to-orbit systems. The catch is that virtually all of them require enormous infrastructure. Many of them could be with modern tech, they're just enormously expensive. Others are borderline superscience.
For all practical purposes, a ground-to-space flight will probably not be possible with just what a realistic ship carries. Some sort of facility on or near a planet will be necessary. Ther's a reference here.
__________________
"When you talk about damage radius, even atomic weapons pale before that of an unfettered idiot in a position of power." - Sam Starfall from the webcomic Freefall Last edited by Mysterious Dark Lord v3.2; 08-24-2021 at 03:15 PM. |
08-25-2021, 07:24 AM | #37 |
☣
Join Date: Sep 2004
Location: Southeast NC
|
Re: [Spaceships] getting into orbit without superscience?
It could be noted that superscience ranges from "It's magic, don't question it" to "The math works out but we don't pretend to know how it works" to "Completely realistic except for the part where it doesn't instantly melt itself at this sort of energy density."
__________________
RyanW - Actually one normal sized guy in three tiny trenchcoats. |
08-25-2021, 08:26 AM | #38 |
Join Date: Aug 2007
Location: Boston, Hub of the Universe!
|
Re: [Spaceships] getting into orbit without superscience?
I know I already responded, but let me put it in a different way:
Without super science or magic, getting to orbit from an Earth-sized planet is incredibly expensive and requires a truly staggering amount of infrastructure. If you want a future society to have regular space travel, your options are
Each of these has follow-on implications for the setting you’re working up.
__________________
Demi Benson |
08-27-2021, 03:58 PM | #39 | |
Join Date: Mar 2005
Location: The deep dark haunted woods
|
Re: [Spaceships] getting into orbit without superscience?
Quote:
CON: Lack of reality, unforseen consequences.
CON: Requires either a wealthier and more peaceful world, or a world running the razor's edge of World War Last.
PRO: More advanced world, realistic, and has the possibility of private spacecraft. CON: Realistic space-plane tech would be Rich Folk's Toys, which would mean the mandatory presence of wealthy PCs or powerful Patrons.
__________________
"When you talk about damage radius, even atomic weapons pale before that of an unfettered idiot in a position of power." - Sam Starfall from the webcomic Freefall |
|
08-28-2021, 07:55 PM | #40 |
Join Date: May 2011
|
Re: [Spaceships] getting into orbit without superscience?
In a context in which metallic hydrogen is the main fuel source, might there still be applications for which chemical engines are preferred for safety reasons?
The downside to metallic hydrogen is that it is metastable, which means that while it would work in the sense of allowing for easier rocket design, it seems like it would be much higher risk in the event of damage to your craft. Mechanically it has similar dangers to antimatter, even if to a much lesser scale. |
Tags |
spaceships |
Thread Tools | |
Display Modes | |
|
|