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Inflatable Space Stations

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Re: Inflatable Space Stations

#41

Post by m4rtink »

nkoren wrote: post #20
zackmorris wrote: post #14

Earlier quoted context omitted.

Ya I really like their airship to orbit concept. I asked AI about lift to drag (L/D) ratios in plasma at 10,000-17,5000 mph (5-8 km/s) and it suggested that lifting bodies achieve between about a 1:1 and 3:1 L/D ratio. If we assume the generous 3:1 L/D ratio, that would seem to make a single-stage to orbit space plane possible. A bit off-topic, but an aerospike engine is half of a rocket nozzle, with a virtual half c…

Airship To Orbit is JP Aerospace, not Bigelow. It seems like an utterly bonkers and fairly implausible concept and I'm definitely not equipped to analyze its merits. But the JP team have some legitimate accomplishments in the rockoon world, and appear to be honest, hardworking people. Definitely not grifters. I've been following their work on ATO since they first announced it at a Space Access conference in ... 2003,…

Yeah, airship to orbit might still be a question mark, but there is a significant overlap in other useful areas.

You should be for example totally able to build an inflatable frame for a launch loop, making it possible to launch payloads from above most of the atmosphere.

Also for re-entry the more you lower the density of something, the less re-entry stresses there will be. So you could construct a giant low-pressure inflatable decelerator device and have it essentially float down all the way from orbit, incrementally shedding energy as it comes down over a longer period of time, taking care to balance the rate of descent, heating and internal/external pressures.

Re: Inflatable Space Stations

#42

Post by m4rtink »

estimator7292 wrote: post #32
JKCalhoun wrote: post #27

Love the painting of the huge toroidal space station—with the houses and forests inside. I had a thought experiment: if you could ride a bicycle (motorcycle?) against the direction of spin of the station you would essentially be "stationary". You would still have a velocity into the always-sloping-up wheel. What if you rode up a gentle ramp? Could you break away from the surface of the wheel then and become "weightle…

Important to note that while the station has angular velocity it is not usually accelerating. If you decelerate and cancel your own angular velocity relative to the station hub, you do indeed simply stop experiencing gravity. Imagine instead jumping off the 'stationary' hub of a rotating station. You simply float under no gravity until you hit the ring. The angular velocity imparted on you by the ring is the gravity…

If there is an atmosphere inside, it will presumably rotate with the structure & will start imparting the rotation velocity on you as you close to the surface from the hub.

Also the surface rotates at potentially quite a high speed compared to you, with likely various structures sticking out, that might smash to you as you get closer, so better watch for that. :)

Re: Inflatable Space Stations

#43

Post by schiffern »

maxcan wrote: post #5

I never understand why the rotating station concepts seem to all have rigid tethers, either in the form of a central boom or a rigid circular structure. It would seem like you could get a much larger diameter, so less rotational velocity and more comfort, by attaching rigid, or inflatable in this case, structures with a tether. Compressive loads are non existent, you just need to resist tensile loads. Maybe I'll go a…

  >Maybe I'll go ask the AI
I never know if, when people say this, they mean

  Maybe I'll go ask the AI oracle, it's only slightly fallible
Or

  Maybe I'll go poke an ML model a few different ways to see if it emits interesting word sequences, that I'll then fact-check and study to develop real, deep knowledge.
I'm actually optimistic we can increase the second one, but it requires everyone to help educate our less-technical friends, family, and colleagues.

This isn't new. It's the same person who used to say "but Google said...!" This is a solvable education problem, because we've solved it before.

Re: Inflatable Space Stations

#44

Post by m4rtink »

ceejayoz wrote: post #6
aDyslecticCrow wrote: post #3

I suspect without ISRU production of bulk orbit sheet metal, the most feasible solution is to repurpose rockets in their whole. Building a station this large is gonna be costly even within the cargo hold of starship. But six of them, gutted of insides as welded end to end could provide the vast majority of the bulk mass. This assume rather sophisticated orbital welding and object manipulation; but its feasible we cou…

This was considered with the orange Space Shuttle fuel tanks; they went almost all the way to orbit anyways.

I think something would have to de done about the thermal isolation - it looked like to be quite flimsy & I guess a couple months on low orbit with all the UV light and atomic oxygen could easily result in cloud of dark orange stuff slowly departing the tank or any construction built from them.

Re: Inflatable Space Stations

#45

Post by m4rtink »

avmich wrote: post #34
xavxav wrote: post #11

Earlier quoted context omitted.

aren't rockets like the starship almost the opposite of what you want in a space station? They want to minimize the integrity of the rocket as much as possible (without blowing up) to reduce the mass while for a station you want robustness (for pressure & impacts).

Starship tanks likely hold several bars of pressure and survive transportation to orbit...

Starship is also meant to be reusable, so there is an additional margin already built in.

Re: Inflatable Space Stations

#46

Post by aperrien »

hinkley wrote: post #12

One of the problems with space stations is that we can make them longer, or we can pull off pieces and replace them with bigger ones. We don’t have a way to make them larger around. And the way contact points work, I don’t think we have a way to even inflate a new section around an existing one.

We could just leave them up there and add more stations nearby. It may even be possible to use tethering lines to travel from one to another.

Re: Inflatable Space Stations

#47

Post by maxcan »

schiffern wrote: post #43
maxcan wrote: post #5

I never understand why the rotating station concepts seem to all have rigid tethers, either in the form of a central boom or a rigid circular structure. It would seem like you could get a much larger diameter, so less rotational velocity and more comfort, by attaching rigid, or inflatable in this case, structures with a tether. Compressive loads are non existent, you just need to resist tensile loads. Maybe I'll go a…

>Maybe I'll go ask the AI I never know if, when people say this, they mean Maybe I'll go ask the AI oracle, it's only slightly fallible Or Maybe I'll go poke an ML model a few different ways to see if it emits interesting word sequences, that I'll then fact-check and study to develop real, deep knowledge. I'm actually optimistic we can increase the second one, but it requires everyone to help educate our less-technic…

When its such for my personal edification and idle wonderings, usually the former. If its something that is any way critical to a meaningful decision or something I'm going to publicly share, its the latter.

Re: Inflatable Space Stations

#48

Post by stoneforger »

schiffern wrote: post #43
maxcan wrote: post #5

I never understand why the rotating station concepts seem to all have rigid tethers, either in the form of a central boom or a rigid circular structure. It would seem like you could get a much larger diameter, so less rotational velocity and more comfort, by attaching rigid, or inflatable in this case, structures with a tether. Compressive loads are non existent, you just need to resist tensile loads. Maybe I'll go a…

>Maybe I'll go ask the AI I never know if, when people say this, they mean Maybe I'll go ask the AI oracle, it's only slightly fallible Or Maybe I'll go poke an ML model a few different ways to see if it emits interesting word sequences, that I'll then fact-check and study to develop real, deep knowledge. I'm actually optimistic we can increase the second one, but it requires everyone to help educate our less-technic…

If it had been solved before we would not be in the predicament we are now, i.e. people might be able to learn but that doesn't mean everyone does. In fact, most do not because we are too busy figuring out how to die leading less fulfilling, more angst-ridden lives.

Re: Inflatable Space Stations

#49

Post by Doxin »

estimator7292 wrote: post #33
maxcan wrote: post #5

I never understand why the rotating station concepts seem to all have rigid tethers, either in the form of a central boom or a rigid circular structure. It would seem like you could get a much larger diameter, so less rotational velocity and more comfort, by attaching rigid, or inflatable in this case, structures with a tether. Compressive loads are non existent, you just need to resist tensile loads. Maybe I'll go a…

There are compressive forces. If mass inside the ring is not balanced, it can drag the ring into an ellipsoid. The inner sides of the ellipse are compressed. A rigid ring can resist some of this inherently, but a rigid spoke to the hub cleanly takes up all the inward forces. If your ring is not rigid, any perturbations can cause oscillations that throw the whole thing out of balance. Like a gas leak in one compartmen…

I don't think your reasoning here is correct. Take a bicycle wheel for example. The spokes on a bicycle wheel do not take any compressive forces due to the way they are attached to the rim, and yet bicycle wheels can take surprising compressive loads without going oblong.

Re: Inflatable Space Stations

#50

Post by zackmorris »

nkoren wrote: post #20
zackmorris wrote: post #14

Earlier quoted context omitted.

Ya I really like their airship to orbit concept. I asked AI about lift to drag (L/D) ratios in plasma at 10,000-17,5000 mph (5-8 km/s) and it suggested that lifting bodies achieve between about a 1:1 and 3:1 L/D ratio. If we assume the generous 3:1 L/D ratio, that would seem to make a single-stage to orbit space plane possible. A bit off-topic, but an aerospike engine is half of a rocket nozzle, with a virtual half c…

Airship To Orbit is JP Aerospace, not Bigelow. It seems like an utterly bonkers and fairly implausible concept and I'm definitely not equipped to analyze its merits. But the JP team have some legitimate accomplishments in the rockoon world, and appear to be honest, hardworking people. Definitely not grifters. I've been following their work on ATO since they first announced it at a Space Access conference in ... 2003,…

Oh hah, thanks, I don't usually make mistakes like that! I guess the two were wired together in my brain.
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