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Post by Pawel on Jun 5, 2023 6:06:06 GMT
Oh wow, suberb work yet again, Allie! Your Jumbos made me realise I definitely don't give enough attention to spacecraft and orbital traffic in my campaigns. Here's hoping we'll get the equipment/vehicles preview doc soon, for proofreading, and you'll be able to freely polish up the stats of your newest creations. Hehe, but yeah, using existing references is definitely a good idea too!  |
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Post by lupmet on Jun 5, 2023 8:20:11 GMT
What does the spaceships use for fuel? Do they drill for oil on Poseidon?
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Post by Pawel on Jun 5, 2023 8:50:16 GMT
What does the spaceships use for fuel? Do they drill for oil on Poseidon? Liquid hydrogen. I'm pretty sure anybody who tries to drill for oil on Poseidon might as well sign their death warrant.  |
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Post by allie on Jun 5, 2023 16:03:09 GMT
Thank you! Prosperity Jumbos have been rattling around in my brain for awhile now, like jumpcraft tenders and for a lot of the same reasons. Your Jumbos made me realise I definitely don't give enough attention to spacecraft and orbital traffic in my campaigns. Don't sweat it too hard; spacecraft mostly only matter as much as the time the players will spend in space. (During the mockup phase I ended up wondering if a Jumbo could go from Prosperity to Proteus. I ended up dropping the idea because the math was too much of a headache, but if it turns out to be possible I'll let y'all know.) I didn't even try to give the Jumbo game stats, because there's nothing in-setting I can compare them to for reference! But it'll be very cool if I can turn them into something players can pilot. |
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Post by allie on Jun 6, 2023 0:23:32 GMT
What does the spaceships use for fuel? Do they drill for oil on Poseidon? Hydrogen for both logistical and design reasons. I'm honestly not sure if Poseidon has petroleum; it takes geological time to form, and fast fungus recycles biomatter too well. |
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Post by lupmet on Jun 6, 2023 7:51:43 GMT
What does the spaceships use for fuel? Do they drill for oil on Poseidon? Liquid hydrogen. I'm pretty sure anybody who tries to drill for oil on Poseidon might as well sign their death warrant. My thought as well, too many would object to it, but I didn't want to pore over all the books to find the reference. Now I instead pored over some of the NASA and Wikipedia pages on the topic... Liquid oxygen is also needed, would it be possible to produce hydrogen and oxygen in some way in space with the technology available? The obvious source would be water but that is heavy to transport. What amounts are needed? Would mining an asteroid for ice and then use sun energy to split the water into hydrogen and oxygen be reasonable? I am looking for a more energy efficient way of producing fuel then transport it up from planet side, then they could refuel the Jumbos and other spacecrafts in space. |
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Post by allie on Jun 6, 2023 11:05:54 GMT
Liquid hydrogen. I'm pretty sure anybody who tries to drill for oil on Poseidon might as well sign their death warrant. My thought as well, too many would object to it, but I didn't want to pore over all the books to find the reference. Now I instead pored over some of the NASA and Wikipedia pages on the topic... Liquid oxygen is also needed, would it be possible to produce hydrogen and oxygen in some way in space with the technology available? For what it's worth my assumption is that LOX isn't needed, and that Prosperity Jumbos (and probably most spacecraft that have to break orbit) use some variant of nuclear thermal rocket built around a McClusky reactor. (Also that Jumbos are streamlined and winged for better in-atmosphere performance, so they probably do require runways as opposed to belly-landing on water like most of Poseidon's orbital shuttles; but that's neither here nor there.) My smartest guess is that Proteus and Nereus probably have some byline in remass mining, which can be moved very slowly across the astronomically tiny distances necessary to keep it viable. My wise guess is that Blue Planet's always been wildly optimistic about space infrastructure (there are 2.3 million spacer genies in the Solar System, and they've only been around a century; how many kids are they having?) and I should just trust that it works. |
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Post by allie on Jun 6, 2023 12:23:28 GMT
Also worth mentioning that surface landers always have the worst fuel consumption in their weight class, because they need high-thrust engines to lift off. The tugs, runabouts, and Grissom-class patrols are probably built on low-thrust fusion rockets and can probably stretch a fuel tank for weeks; I wouldn't be surprised at all if Dundalk and Atlas both have higher-performance designs in the works that use water for reaction mass.
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Post by michaelsd on Jun 8, 2023 15:30:03 GMT
If I remember correctly hydrogen is used. It is harvested mostly in the belt and brought to the stations at the wormhole entrances.
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Post by neil on Jun 8, 2023 19:56:05 GMT
An ex-physicist's comment on the energy needed to get to various places. People don't realise just how fast orbit is.
Back of the envelope calculations, for Earth. A sub-orbital lift to 400km (about ISS height) requires leaving the ground at about 2.8 km/s.
Getting to a stable orbit at about the same altitude (needed to dock with something in orbit) requires leaving the ground at about 9 km/s. (Orbital velocity is around 7 km/s.)
Escape velocity for Earth is about 11 km/s.
There's a reason Gagarin's first flight, to orbit, was a much greater achievement than Glenn's sub-orbital flight.
As for the type of engine (chemical or nuclear-thermal), I've not seen any clear description on the minimum viable size of a fusion reactor in the setting. We know that it powers a torchship, but those are massive. There are a few large settlements that have fusion power, but most don't. Perhaps they're similar to nuclear fission power plants now: they power cities, some large military vehicles, and nothing smaller.
Perhaps that's why the jumbos are so large: they're at the minimum size of a vehicle that can have a fusion power plant.
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Post by neil on Jun 8, 2023 19:58:28 GMT
Also worth mentioning that surface landers always have the worst fuel consumption in their weight class, because they need high-thrust engines to lift off. The tugs, runabouts, and Grissom-class patrols are probably built on low-thrust fusion rockets and can probably stretch a fuel tank for weeks; I wouldn't be surprised at all if Dundalk and Atlas both have higher-performance designs in the works that use water for reaction mass. Don't discount ion drives for orbital manoeuvring. Power comes from solar panels, and the reaction mass is low-mass gas. Thrust is low, but the "burn" times are very long. |
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Post by Pawel on Jun 8, 2023 20:15:11 GMT
An ex-physicist's comment on the energy needed to get to various places. People don't realise just how fast orbit is. Back of the envelope calculations, for Earth. A sub-orbital lift to 400km (about ISS height) requires leaving the ground at about 2.8 km/s. Getting to a stable orbit at about the same altitude (needed to dock with something in orbit) requires leaving the ground at about 9 km/s. (Orbital velocity is around 7 km/s.) Escape velocity for Earth is about 11 km/s. There's a reason Gagarin's first flight, to orbit, was a much greater achievement than Glenn's sub-orbital flight. As for the type of engine (chemical or nuclear-thermal), I've not seen any clear description on the minimum viable size of a fusion reactor in the setting. We know that it powers a torchship, but those are massive. There are a few large settlements that have fusion power, but most don't. Perhaps they're similar to nuclear fission power plants now: they power cities, some large military vehicles, and nothing smaller. Perhaps that's why the jumbos are so large: they're at the minimum size of a vehicle that can have a fusion power plant. Is an ex-physicist someone who has discovered the error of their ways and now pursues the path of deeducation? 😆 |
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Post by allie on Jun 12, 2023 16:34:06 GMT
As for the type of engine (chemical or nuclear-thermal), I've not seen any clear description on the minimum viable size of a fusion reactor in the setting. We know that it powers a torchship, but those are massive. There are a few large settlements that have fusion power, but most don't. Perhaps they're similar to nuclear fission power plants now: they power cities, some large military vehicles, and nothing smaller. No idea if the numbers were based on anything, but old PHBs suggest that fusion reactors tend to be 2-225 tons, and most of the reactor-equipped vehicles were civilian ones. Definitely agree they're far from widespread, though. Personnel requirements are probably a factor: reactor-certified nuclear technicians don't grow on trees, and if you can't persuade at least one to move to Poseidon's Armpit for a five-year work contract then Poseidon's Armpit isn't getting fusionized, full stop. |
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Post by michaelsd on Jun 16, 2023 12:52:13 GMT
Most vehicles have hydrogen fuel cells according PG.
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