Spaceception Posted February 21, 2016 Author Share Posted February 21, 2016 3 hours ago, fredinno said: 35 C colder than Earth is -19 C. Also, https://en.wikipedia.org/wiki/Barnard%27s_Star Barnard's Star has only 30% of the Sun's Mettalicity, so any planets would be small, and would be more concentrated in things like water. I know, that's the temperature of planet c. I also know that, that's why I added only 2 planets, one covered in water, and roughly the size of Earth. Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Bump. Please help Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 With what, exactly? @Spaceception Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 (edited) @Bill Phil The amount of bombs I'll need to get to 8% the Speed of light (And slow down), here are the Spacecraft's specs: The spacecraft is 1.2 km long, The Bomb container is a cylinder 250 meters long, The bombs are about 15 centimeters long, and weigh 140 kg (Like the original design during Project Orion), The sail is 350 meters wide and about 60 meters deep. Edited February 28, 2016 by Spaceception Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 20 minutes ago, Spaceception said: @Bill Phil The amount of bombs I'll need to get to 8% the Speed of light (And slow down), here are the Spacecraft's specs: The spacecraft is 1.2 km long, The Bomb container is a cylinder 250 meters long, The bombs are about 15 centimeters long, and weigh 140 kg (Like the original design during Project Orion), The sail is 350 meters wide and about 60 meters deep. We need the ISP and the total mass, which will give us the total mass of bombs needed and thus the total number of bombs. Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 (edited) 21 minutes ago, Bill Phil said: We need the ISP and the total mass, which will give us the total mass of bombs needed and thus the total number of bombs. One of the better variants of Orion had an ISP of ~13,000 seconds, so looking at the Medusa (Which is more efficient), I'd say between 33,000 seconds Dry mass: 10,000 tonnes, Wet mass (bombs): 20,500 tonnes. Edited February 28, 2016 by Spaceception Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 26 minutes ago, Spaceception said: One of the better variants of Orion had an ISP of ~13,000 seconds, so looking at the Medusa (Which is more efficient), I'd say between 33,000 seconds Dry mass: 10,000 tonnes, Wet mass (bombs): 20,500 tonnes. Medusa is only more efficient due to mass savings, really. .08c cruise, and braking? .16c total Dv Let me run up the numbers... Sorry to say, but you're mass ratio is looking like 2.88 times 10 raised to the 64th. According to your numbers you only have a few hundred kps. You're gonna need better engines. Also, if you know your mass values, you already have your answers. Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Just now, Bill Phil said: Also, if you know your mass values, you already have your answers. Yeah... I was a stupid there. 3 minutes ago, Bill Phil said: Sorry to say, but you're mass ratio is looking like 2.88 times 10 raised to the 64th. According to your numbers you only have a few hundred kps. You're gonna need better engines. Okay, so less mass or more mass? Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 (edited) 20 minutes ago, Spaceception said: Yeah... I was a stupid there. Okay, so less mass or more mass? Neither. More ISP or less speed. Let's say your mass ratio is exactly "e". The Ln of e is 1. That means that you need an exhaust velocity of .16c to get .16c of DeltaV. Now, in space, ratios like 10, 15, or 20 are more possible, and it really depends on a bunch of factors. But your ship doesn't need to survive 1g, so a lot more is possible. Maybe inflatable Graphene tanks? Idk. Edited February 28, 2016 by Bill Phil Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 2 minutes ago, Bill Phil said: Neither. More ISP or less speed. Alright, new ISP 45,000 seconds speed 11% light speed. Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 9 minutes ago, Spaceception said: Alright, new ISP 45,000 seconds speed 11% light speed. That won't change much. You need ISPs thousands of times of that to not have enormous masses. I mean masses larger than Jupiter, here. Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Just now, Bill Phil said: That won't change much. You need ISPs thousands of times of that to not have enormous masses. I mean masses larger than Jupiter, here. Oh, well than what would be your ISP/Bomb mass/Speed? Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 (edited) 4 minutes ago, Spaceception said: Oh, well than what would be your ISP/Bomb mass/Speed? You need at least .001c ISP to get a DV of 1% light speed with a mass ratio of e. Preferably faster. Medusa may not even work. I messed up with my analogy. It's galactic masses, not jupiter masses. And if not that, solar masses. Edited February 28, 2016 by Bill Phil Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Just now, Bill Phil said: You need at least .001c ISP to get a DV of 1% light speed with a mass ratio of e. Preferably faster. Medusa may not even work. I messed up with my analogy. It's galactic masses, not jupiter masses. Wait, GALACTIC masses!? So how was the original Orion (On paper) able to get to 10% ls if it requires so much mass? Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 (edited) 1 minute ago, Spaceception said: Wait, GALACTIC masses!? So how was the original Orion (On paper) able to get to 10% ls if it requires so much mass? They had high ISPs, like, millions of seconds. Orion gets better as it gets bigger. They also had 8 million tons of total (wet) mass. Edited February 28, 2016 by Bill Phil Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Just now, Bill Phil said: They had high ISPs, like, millions of seconds. Orion gets better as it gets bigger. So if I increase the size of the spacecraft to 150,000 tonnes, and do a mild switch to Orion, with a ISP of 250,000, would 6% ls be doable? Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 (edited) 4 minutes ago, Spaceception said: So if I increase the size of the spacecraft to 150,000 tonnes, and do a mild switch to Orion, with a ISP of 250,000, would 6% ls be doable? Let's be really nice: you get to use a mag sail to brake. Only need 6% DV. You're mass ratio is in the thousands. Maybe multiple stages? With three stages, each one with 2%c deltaV, you can have a lower double digit mass ratio. Edited February 28, 2016 by Bill Phil Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Just now, Bill Phil said: Let's be really nice: you get to use a mag sail to brake. Only need 6% DV. You're mass ratio is in the thousands. Maybe multiple stages? Use asparagus staging to release empty mass? Both Bombs and resources? Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 Could do this even easier with laser sails, braking with mag sails. Just now, Spaceception said: Use asparagus staging to release empty mass? Both Bombs and resources? Look at the Daedalus/Icarus designs. Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 1 minute ago, Bill Phil said: Could do this even easier with laser sails, braking with mag sails. You need to build the lasers first, and this is in the middle of the end of world, where we have 15 years to build the spacecraft. Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 3 minutes ago, Spaceception said: You need to build the lasers first, and this is in the middle of the end of world, where we have 15 years to build the spacecraft. Easy: Launch a fleet of Orions to build the lasers in low solar orbit. Could probably get there in a month or two, bring an asteroid and make some lasers. Build the laser sail and bam! You have a laser starship. What's happening to Earth? Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Just now, Bill Phil said: Easy: Launch a fleet of Orions to build the lasers in low solar orbit. Could probably get there in a month or two, bring an asteroid and make some lasers. Build the laser sail and bam! You have a laser starship. What's happening to Earth? That would work, but how big/heavy will the sail be? I heard that in order to get to 8% ls, you need a sail the size of Texas (Alright, not that big, maybe 1/3 the size). A Black Hole is gonna wreck some $#!t. And the plot is gonna be big, at least near the end Link to comment Share on other sites More sharing options...
Bill Phil Posted February 28, 2016 Share Posted February 28, 2016 (edited) 6 minutes ago, Spaceception said: That would work, but how big/heavy will the sail be? I heard that in order to get to 8% ls, you need a sail the size of Texas (Alright, not that big, maybe 1/3 the size). A Black Hole is gonna wreck some $#!t. And the plot is gonna be big, at least near the end But you may not even need to go to another star system. Orbital colonies seem much more doable, unless the whole solar system is exploding. And you could just build a bunch and go a bunch of AU out... The speed of the sail depends on size and power of the laser. Edited February 28, 2016 by Bill Phil Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 Just now, Bill Phil said: But you may not even need to go to another star system. Orbital colonies seem much more doable, unless the whole solar system is exploding. Well, it's a Black hole entering inside the orbit of Jupiter, It'll either fall into the Sun, the Black hole, or become rogue. Link to comment Share on other sites More sharing options...
Spaceception Posted February 28, 2016 Author Share Posted February 28, 2016 23 minutes ago, Bill Phil said: Look at the Daedalus/Icarus designs. That's too theoretical, even today, I need something near-term, like NPP, or maybe laser sails. Link to comment Share on other sites More sharing options...
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