[kreios]

Originally Posted by ericthered

They start at rest with regards to the object? Ok, that took guts to go for. It also means that if your STL light drives fails, you face certain death after a FTL jump.

It's actually not that different from any other method: If your main drive fails, you'll either crash into something or will be on a month-long journey for which your supplies probably won't hold. (Excepting things like a free return trajectory).

5 kps is a huge delta-V cost, particularly if you make it apply both ways. with 10 kps I can get into orbit from earth's surface. And I can't just use an efficient Ion drive, because I'll slam into the earth first. So it looks like I'm going to have to spend large parts of my ship either storing fuel or massing three rocket engines to get the acceleration I need. Its not as bad as planetary take-off, fortunately, because falling is an option, and because you don't need to accelerate quite as fast, but it still places restricting demands on the drives.

Agreed, and this is something we'll see in the next post.

if you don't use engines after appearing around earth, you have a little less than 8 hours before you impact. using 1.11 * (R^3/(GM))^.5 gives the time to the center of the body. I figured the actual numbers, but those equations are nasty, and this gives pretty good results.

Resting time to impact simplifies down to about 35 * (GM)^.25 if you use .1 newtons instead of .01G

Engines need to be .015 G's or greater in order to make orbital velocity before the powered crash time is up. This is constant regardless of the body you are orbiting. the actual minimum is something else, but it lower, depends on the mass and radius of the orbiting body, and this is probably a good rule of thumb. It's also interesting, because a lot of rocket engines play just above or just below this values.

Quite interesting, and I didn't actually compute that myself - I had just assumed that a sufficiently strong engine (which I've already defined) would be available. I'll definitely have to spend another post later on on a few more options and math.

On minimally viable objects, all the planets have a recharge zone, the Galileans and Titan have recharge zones, but Pluto and Ceres do not, reinforcing the categorization of them as dwarf planets. Earth's moon does have a recharge zone, and in fact bodes like it take less fuel to use as stopping places. The cheapest place to stop in the solar system is Europa, but the next is earth's moon, both being about of third of what you'd spend to land on earth. There are probably some kuiper belt objects that can be used as rechargers, but we haven't found any in the solar system, which means they may very well be secrets well guarded by militaries, guilds, and smugglers. Or valuable waypoints through gaps in a network.

Also very interesting. My assumption is that the range is sufficiently high that there's almost always going to be a few stars in range, and that brown dwarfs would be too inefficient to stop at for a commercial route.