Affordable habitats means more Buck Rogers for less money says Bigelow

[Go4TLI]

most spacecraft use diaphrams

Indeed.  And many of those have a not to exceed reverse dP on them from an engineering/requirements perspective. 

Again, could this all be done?  Probably.  Would it have to be thought about and be complex?  Probably.

Would it operationally be easier to dock them externally and have them ready for a variety of possible reasons?  Probably. 

[mfck]

OK Go4TLI, thanks for the insight and the patience. I am grasping the extent of the challenge here.

[A_M_Swallow]

{snip}
I'm not sure what you mean by "decontaminating".  There was none of that done ever to the system unless we were intentionally breaking into the system.

In '2001 A Space Odyssey' the pods were kept inside the mother ship.  The ISS keeps its visiting vehicles outside, providing access via a berthing or docking port.

IMHO Future space stations are likely to keep visiting vehicles outside except when repairing the vehicle.  If one of the engines or valves is being repaired in a shirt sleeves environment then the fuel pipes will need "decontaminating".

A room lined with say Velcro where the mechanic can walk all the way round the vehicle being repaired may be useful.  If the room is in vacuum then a small suit port can be used rather than an enormous airlock.

[a_langwich]

From the article:

Mr. Gold also noted that Bigelow is currently in negotiation with NASA for further activities and is cautiously optimistic that they will be able to make an announcement soon.

This is interesting if true. What near-term "further activities" might they be discussing?

My guess, probably the Asteroid Mission that the president seems so fixated upon.

During the November press conference, Gerst was asked if the Bigelow tugs could be useful for the asteroid capture mission, he said no, NASA is trying to push SEP and improved solar arrays technology for the asteroid capture mission, so they are not looking for a commercial tug. 

Perhaps NASA and Bigelow have been discussing an inflatable capture mechanism for the asteroid?  That seems like a capability Bigelow could contribute toward, and perhaps is distantly related to the Olympus carrier.  ("What else could we capture...?")

[dcporter]

Go4TLI, am I correct in assuming that your work next to a hypergol system would not have been possible if the system had recently fired and not been decontaminated?

No.  I was standing next to the orbiter within an hour or so of the engines (OME and thrusters) after they last fired.  I was certainly standing next to them within several hours to a day after we went into the OPF and did not have plugs installed, etc.  We did of course verify there were no gross leaks.

I'm not sure what you mean by "decontaminating".  There was none of that done ever to the system unless we were intentionally breaking into the system.

That's quite different than what I imagined from descriptions of toxicity! Thanks much for the first-hand accounts.

[docmordrid]

How likely is it that Draco/SD could be adapted to use H2O2/alcohol?

[manboy]

How likely is it that Draco/SD could be adapted to use H2O2/alcohol?

I don't know if anyone besides SpaceX could answer that. But I hope they eventually move away from hypergols.

[dkovacic]

How likely is it that Draco/SD could be adapted to use H2O2/alcohol?

That would be great development especially because it would be useful for long duration BEO missions. H2O2 has many purposes which would increase options in emergency scenarios. And I wonder who would be the first to decompose a little peroxide and mix it with ethanol...

[Jim]

How likely is it that Draco/SD could be adapted to use H2O2/alcohol?

Like converting a diesel into a gas engine.  Requires different injectors, requires a ignition system/catalyst, different valves, different combustion chamber.  Better to start from scratch.

[dcporter]

Better to start from scratch.

The phrase "methane superdracos" pops up pretty regularly round these parts. I have a feeling that people think of superdracos as any engine that fits in the side of a Dragon and works as both a LAS and as landing engines. Is it realistic to expect an engine to be developed that isn't hypergolic (assuming still that having hypergols in an enclosed zero-g space station is bad) but can handle the (very different) needs of a LAS and landing engines?

[guckyfan]

Better to start from scratch.

The phrase "methane superdracos" pops up pretty regularly round these parts. I have a feeling that people think of superdracos as any engine that fits in the side of a Dragon and works as both a LAS and as landing engines. Is it realistic to expect an engine to be developed that isn't hypergolic (assuming still that having hypergols in an enclosed zero-g space station is bad) but can handle the (very different) needs of a LAS and landing engines?

For that purpose it would have to be a pressure fed engine. I would guess that a turbo engine cannot spin up fast enough to do a launch abort. It would need a very efficient ignition, maybe laser initiated? Methane, because it is what they would use for MCT. But what about the oxidizer? Could H2O2 be used? I imagine it would be difficult to store LOX in a Dragon at ISS doing life boat function.

[Go4TLI]

Better to start from scratch.

The phrase "methane superdracos" pops up pretty regularly round these parts. I have a feeling that people think of superdracos as any engine that fits in the side of a Dragon and works as both a LAS and as landing engines. Is it realistic to expect an engine to be developed that isn't hypergolic (assuming still that having hypergols in an enclosed zero-g space station is bad) but can handle the (very different) needs of a LAS and landing engines?

For that purpose it would have to be a pressure fed engine. I would guess that a turbo engine cannot spin up fast enough to do a launch abort. It would need a very efficient ignition, maybe laser initiated? Methane, because it is what they would use for MCT. But what about the oxidizer? Could H2O2 be used? I imagine it would be difficult to store LOX in a Dragon at ISS doing life boat function.

This is going really off-topic.  There has been no direct evidence that SpaceX is going to anything but hypers for Dragon.  And Jim is very much correct that it would be a completely new design and development. 

Trying to retrofit this into dragon, would likely alter the mass properties of the vehicle leading to even more design changes. 

I highly doubt this is being considered just to validate a conceptual picture of a couple of *notional* Dragon vehicles sitting inside a TBD giant balloon in space. 

[Jim]

Trying to retrofit this into dragon, would likely alter the mass properties of the vehicle leading to even more design changes. 

Just clarification for others, he means the H2O2/alcohol tanks would have different mass properties than the current NTO/MMH tanks due to different mixture ratios and fluid densities.   

[jongoff]

I highly doubt this is being considered just to validate a conceptual picture of a couple of *notional* Dragon vehicles sitting inside a TBD giant balloon in space.

Wholeheartedly agree. I think some of the other readers have a hard time differentiating "FauxCAD"/concept art from well researched plans with solid engineering to back them up. I still have hopes that Bigelow Aerospace, via the BEAM project, will progress from FauxCAD to real CAD to real hardware to flying hardware, but so far I think these pictures are mostly begging for the appropriate sized grain of salt.

~Jon

[PS: not trying to throw stones in a glass house--we're also mostly at the fauxCAD/ground test article point on our technologies, I just try to make sure that people know that my fauxCAD is fauxCAD.]

[jongoff]

Trying to retrofit this into dragon, would likely alter the mass properties of the vehicle leading to even more design changes.

Just clarification for others, he means the H2O2/alcohol tanks would have different mass properties than the current NTO/MMH tanks due to different mixture ratios and fluid densities.

Yeah, swapping propellants on a tightly intregrated vehicle like Dragon would be very tough.

IIRC while NTO/MMH results in tanks that are close to the same size, HTP/Alcohol should have a very high O/F ratio, and with how much denser HTP is than Alcohol to start with would result in very different tank size, valve sizes, etc. Even for an open-frame vehicle like Xombie that would be a nontrivial change, but for a tightly structurally integrated vehicle like Dragon, you'd like be redesigning very significant parts of the vehicle.

What Jim and GO4TLI said--ain't likely to happen.

~Jon

[daveklingler]

I still have hopes that Bigelow Aerospace, via the BEAM project, will progress from FauxCAD to real CAD to real hardware to flying hardware, but so far I think these pictures are mostly begging for the appropriate sized grain of salt.

To be fair, it's been so long since Genesis I and II went up that we tend to forget their existence.  But they're still there, and they do certainly qualify as flying hardware.  In some respects BEAM is a big step forward, but it's only slightly larger than either of the Genesis modules.

[daveklingler]

Yeah, swapping propellants on a tightly intregrated vehicle like Dragon would be very tough.

IIRC while NTO/MMH results in tanks that are close to the same size, HTP/Alcohol should have a very high O/F ratio, and with how much denser HTP is than Alcohol to start with would result in very different tank size, valve sizes, etc. Even for an open-frame vehicle like Xombie that would be a nontrivial change, but for a tightly structurally integrated vehicle like Dragon, you'd like be redesigning very significant parts of the vehicle.

What Jim and GO4TLI said--ain't likely to happen.

~Jon

A move to a nitrous monoprop or biprop would also fulfill the artist's conception.  SpaceX is certainly aware of NOFBX, if it doesn't turn out to be an explosive.

[jongoff]

To be fair, it's been so long since Genesis I and II went up that we tend to forget their existence.  But they're still there, and they do certainly qualify as flying hardware.  In some respects BEAM is a big step forward, but it's only slightly larger than either of the Genesis modules.

Oh, I didn't forget about the Genesis modules at all. The fact is that almost all of the people who were involved with Genesis have since left Bigelow. Knowledge and experience reside in people not in the walls of a building. To me, BEAM is a chance for them to reboot (Bigelow v2.0) and reestablish real flight hardware cred.

~Jon

[jongoff]

A move to a nitrous monoprop or biprop would also fulfill the artist's conception.  SpaceX is certainly aware of NOFBX, if it doesn't turn out to be an explosive.

Sure, that's could be an easier switch (from a Dragon integrated packaging/redesign standpoint) if NOFBX pans out. But seriously, I doubt SpaceX has put more than a couple of man-hours of feedback into that concept. It's a concept that's probably a decade out. It's interesting, but we shouldn't read too much into it yet.

~Jon

[mmeijeri]

IIRC while NTO/MMH results in tanks that are close to the same size, HTP/Alcohol should have a very high O/F ratio, and with how much denser HTP is than Alcohol to start with would result in very different tank size, valve sizes, etc.

I really liked the idea of HTP/IPA until someone (Ben Brockert?) pointed out that if you mix them, you get what's called a Sprengel explosive.