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Thread: Regarding acceleration and travel times

  1. #11
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    Re: Regarding acceleration and travel times

    There's an estimate of what's involved in an Epstein drive over on the Atomic Rockets website. That gives 6.9g with a .09kg/s flow rate, for a rocket with a wet mass of 15 tonnes and a dry mass of 3.75 tonnes. This breaks down to about 36 hours of burn at 6.9g, or around 250 hours at 1g (which is probably what you'd use to get around).

    From this, you can expect to get wherever you need to go out to about Saturn within 10 days, without running out of fuel. If you're going to something farther away, you'll probably stop to refuel, breaking it up into two trips. Essentially, use the 1G travel times table unless the hours are more than 250, in which case a normal ship needs to refuel or go slowly. If you need to do it without stopping, at .3g, you can get between any two systems, but you're looking at travel times of a month to get to Pluto. You'd be a bit faster at 1g, since you can accelerate for 5 days, maybe cruise for 15 more, then decelerate for 5 days at the end (I'm just guessing on the cruise time).
    Last edited by ubik2; 03-14-2019 at 06:59 PM.

  2. #12
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    Re: Regarding acceleration and travel times

    Yeah I was looking at the AR site as well, but they were also doing their estimate for the Roci which is a war ship and doesnít really carry much other then a small crew, reaction mass and weapons. I also think their swag for the efficiency seemed pretty high and not well supported , higher then seemed to be justified by the examples of travel in the book for instance

    I was thinking about tuning down their efficiency assumptions to about half. That would explain why places like Saturn and farther are hard to get to and why the belt matters so much , and would still be a damn efficient torch drive

    For more common civilian ships that are devoting a fair amount of space to cargo I think reaction mass reserves are considerably smaller. I think you probably need another stat for the ship to capture actual % of ship devoted to reaction mass

    It also leads to more intersting ship vs ship interactions, if itís not just raw acceleration but also staying power that factor in races and chases

  3. #13
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    Re: Regarding acceleration and travel times

    This thread has been bugging me.. scared as many other things regarding a series that I love that even the smallest wrong detail can ruin my relationship with the rpg.

    I'm not finished with the manual yet, nor with the books, and mainly I don't have time to search for data to confirm this, but I think the problem with the traveling time issue is human survivability to Hi G, not the fuel.
    Think of when the Roci pursues Eros, it's not the motor the limit in the pursue, it's the crew capacity to sustain Hi Gs even under Juice..
    The manual says that common drugs lasts for 2d6 minutes, doesn't stats how much the Juice last actually. But in the end it's clear to me that it's not very dangerous for the crew to speed up to 1G but if you sail a manned vessel to pluto at 7 or 12G it will arrive quickly, full of dead bodies.

  4. #14
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    Re: Regarding acceleration and travel times

    Apa, donít worry, there are many factors in calculating flight times, not just fuel/mass etc, but the relative position of the target location (planet) within the suns orbit,

    You would think say Mars would be closer to say Jupiter than Earth right? (Due to being taught the order of planets at school)

    But, during Mars roughly two yearish orbit itís about 2 AU further away from Jupiter than Earth,

    So there is a lot of waltzing around of planets, and thatís not counting slingshoting if you get the chance to use it,

    In the tv show it took over 6 months for U.N ships to get near the ring (near Uranus)

    At the end of the day this isnít hard hard science, it just leans towards what is accepted as harder science,
    Donít sweat the small stuff, embrace the Poetic License,

    I mean Epstein Drive?, hello, thatís a nice idea but,

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