Bigelow for Falcon Heavy

[alexterrell]

So the BA-330 was aimed at the EELV launch market, with a mass of some 25 tons.

There is model of a BA-2100 aimed at the SLS market, with a mass of some 100 tons.

What would a Bigelow for Falcon Heavy look like? Broadly speaking, double all dimensions and you quadruple the mass and increase the volume 8 fold (less a little to account for stronger walls.

So that implies a Bigelow 900 for Falcon Heavy. This could support 12 to 18 crew. It would need to fit inside the FH fairing - which might go up to 6m?

A second flight could take a segmented heat shield solar panels and other external gear. Could it be suitable for Mars Aerocapture?

[Jason1701]

A 6m fairing on the 3.66m core might pose stability problems. Does anyone know the fairing-to-core ratio on the hammerhead ELVs?

[mlorrey]

So the BA-330 was aimed at the EELV launch market, with a mass of some 25 tons.

There is model of a BA-2100 aimed at the SLS market, with a mass of some 100 tons.

What would a Bigelow for Falcon Heavy look like? Broadly speaking, double all dimensions and you quadruple the mass and increase the volume 8 fold (less a little to account for stronger walls.

So that implies a Bigelow 900 for Falcon Heavy. This could support 12 to 18 crew. It would need to fit inside the FH fairing - which might go up to 6m?

A second flight could take a segmented heat shield solar panels and other external gear. Could it be suitable for Mars Aerocapture?

FH puts a 25 ton Bigelow module in lunar or Mars orbit, not just injection trajectory. Can you say Phobos Base and L1 solar sat construction shack??

[alexterrell]

A 6m fairing on the 3.66m core might pose stability problems. Does anyone know the fairing-to-core ratio on the hammerhead ELVs?

Or in indeed the inflated diameter to fairing ratio for a Bigelow module?

The relatively small payload fairing of the Falcon Heavy does seem to be it's major drawback compared to Shuttle derived launchers (or any LH2 based rocket). But that's an argument for inflatables. 

[ugordan]

FH puts a 25 ton Bigelow module in lunar or Mars orbit, not just injection trajectory.

No.

[alexterrell]

FH puts a 25 ton Bigelow module in lunar or Mars orbit, not just injection trajectory. Can you say Phobos Base and L1 solar sat construction shack??

Not quite.

I was thinking a VASIMR would lift the Base and fuel to L1. Then chemical propulsion and aerocapture to Mars and Phobos.

Haven't done the numbers, but I think 3 FH launches would put a BA-900 plus service module on the surface of Phobos.

[docmordrid]

The Engineer in Progress blog has some interesting speculations  about the kg/m3 of Bigelow modules, basically 45-60 kg/m3. For 50 mT to LEO that gives -

45: 1,110 m3
50: 1,000 m3
55: 909 m3
60: 833 m3

Give it a read....

[tnphysics]

Wall mass is proportional to volume.

[MP99]

FH puts a 25 ton Bigelow module in lunar or Mars orbit, not just injection trajectory.

No.

Agreed, won't even put that much through TLI.

cheers, Martin

[mlorrey]

FH puts a 25 ton Bigelow module in lunar or Mars orbit, not just injection trajectory.

No.

Falcon Heavy sends 35 tons to TLI and 30 tons to Mars trajectory.

[mlorrey]

FH puts a 25 ton Bigelow module in lunar or Mars orbit, not just injection trajectory.

No.

Agreed, won't even put that much through TLI.

cheers, Martin

You havent watched the video then. Elon stated: Falcon Heavy puts 35 tons in TLI.

[Nomadd]

Wall mass is proportional to volume.

 Why would it be? Wall thickness and composition is partially determined by penetration resistance, which wouldn't change with volume.

[MP99]

FH puts a 25 ton Bigelow module in lunar or Mars orbit, not just injection trajectory.

No.

Agreed, won't even put that much through TLI.

cheers, Martin

You havent watched the video then. Elon stated: Falcon Heavy puts 35 tons in TLI.

You're wrong and he didn't.

YOU need to watch it again.

cheers, Martin

[e of pi]

The Engineer in Progress blog has some interesting speculations  about the kg/m3 of Bigelow modules, basically 45-60 kg/m3. For 50 mT to LEO that gives -

45: 1,110 m3
50: 1,000 m3
55: 909 m3
60: 833 m3

Give it a read....

Heheheh. Nice to see I didn't even have to flaunt my model--someone else did it for me. The full model also does some diameter and length guessing, though my dataset is small and rough. I should mention that expansion from fairing size to inflated diameter is something the model currently does not predict at all, and I that tend to consider 60 kg/m^3 a better estimate for equivalent density than 45. This is especially true in my mind with the fairing constraints on the Falcon Heavy's current fairing, since they may load the module up a bit more than my estimates are based on with extra supplies, the proverbial water, T-shirts, and such--they did something similar with the Genesis units (with experiments and stuff), and those were more like 112 kg/cubic meter. Basically, they designed the largest module that would fit the fairing, then loaded it until it massed out at the same time it bulked out.

[joek]

The Engineer in Progress numbers look about right based on other data...

The last NASA Inflatable Module Mission presentation* contains a good breakdown of some of the numbers.  It shows 40-50kg/m3 (core, shell, avionics, ECLSS, power fluids/air, etc.). Also gives an idea of ratios for packed/inflated size.

However, it's fairly small at 200 m3 and doesn't have some of the capabilities of Bigelow's version (solar, radiators, etc.) so 40-50 kg/m3 may be at the low end for an independent unit (not docked to the ISS).

Some older NASA studies on long duration HSF looked included inflatables and IIRC they used 50-55kg/m3 (sorry, can't find a link at the  moment).  Never mind; not comparable, was looking at:
http://ston.jsc.nasa.gov/collections/TRS/_techrep/CR-2004-208941.pdf

* http://www.nasa.gov/pdf/458816main_FTD_InflatableModuleMission.pdf

[alexterrell]

Wall mass is proportional to volume.

 Why would it be? Wall thickness and composition is partially determined by penetration resistance, which wouldn't change with volume.

Predominantly determined by penetration resistance.

A small part of the wall thickness is determined by pressure, so thickness of this scales with diameter, and hence mass scales with volume.

However, this is a few mm only. It will only dominate where D > 100m.

For Bigelow modules, wall mass should be mostly a square function, not a cube function.

[rklaehn]

If your target is not LEO but something like EML1, then falcon heavy is just the right size to send either a fully outfitted and provisioned sundancer module, or an empty BA330 module on a belbruno trajectory. See this http://forum.nasaspaceflight.com/index.php?topic=15878.msg718931#msg718931 as an example of what you can do with that.

If you really want to go just to LEO, just send two BA330 and maybe a node in a very long fairing.

We have to get away from the notiion that you have to adapt the payload exactly to the launcher if we want to use the low cost provided by falcon heavy and maybe others. What if falcon heavy does not meet it's performance goals? With a smaller module you just put in less provisions to compensate. With a module using exactly the performance you're screwed.

[blasphemer]

What if falcon heavy does not meet it's performance goals? With a smaller module you just put in less provisions to compensate. With a module using exactly the performance you're screwed.

Thats a big if. I am sure that if Falcon Heavy sized Bigelow module is to be developed, actually fitting into its mass budget is essential. Not to mention that the performance numbers would probably be validated by test flights before.

Do we know how costly it is to develop rescaled Bigelow modules? There are plenty of heavier than BA 330 module concepts around. This seems to indicate that Falcon Heavy sized one will be probably developed, too.

If FH suceeds, it will be with us for a long time, so adapting a Bigelow module to make the most of it is the most optimal choice.

[Ben the Space Brit]

To me, at least, the obvious payload is the first section of CSS Alpha: a Sundancer with the propulsion node already attached.  Use the rest of the spare payload capacity to launch with as much as the materials needed for outfitting as possible.  The advantage is that you have decreased the lead time to get the station to IOC by two or three launches at least.

If Raptor ever happens, a similar payload could be launched to LEO with the Raptor acting as the EDS for a LEO-to-LLO/EML transfer vehicle.

FH is also pretty much perfectly proportioned for a cargo delivery or crew transfer mission to an EML space station.  In fact, I would suspect that cargo to EML and other cis-lunar orbital and surface destinations was the market that the LV was designed to encourage.

Think of FH being the CaLV for the F9 as CLV.

[Lampyridae]

Wall mass is proportional to volume.

 Why would it be? Wall thickness and composition is partially determined by penetration resistance, which wouldn't change with volume.

Predominantly determined by penetration resistance.

A small part of the wall thickness is determined by pressure, so thickness of this scales with diameter, and hence mass scales with volume.

However, this is a few mm only. It will only dominate where D > 100m.

For Bigelow modules, wall mass should be mostly a square function, not a cube function.

The original Transhab development indicated the wall mass was about 12kg/m^2.

[joek]

---snip---
The original Transhab development indicated the wall mass was about 12kg/m^2.

Based on ISS inflatable mission numbers that appears to have grown to ~20-24kg/m^2... inflatable shell ~2916-3499kg; inflatable surface area ~143m^2 (~158m^2 total - ~14m^2 core ends).

[alexterrell]

By comparison, 1cm of Aluminum would mass 27kg/m2.

The Transhab wall looks a good 30cm thick.

[docmordrid]

And Bigelow has said their modules are 16" (40.64 cm) thick.

[joek]

That's consistent with NASA's numbers with MMOD bumper layers (which appear to account for a significant portion ) stated variously as "<16in" and "<0.5m".

[alexterrell]

so if we assume carbon based materials (like Kevlar) at about 1.5g/cm3, then the Bigelow wall is 2cm of material and 38cm of vacuum or air. I assume there's one air tight membrane near the inside and most of the mass is out side of this.

Would most of the filler therefore be vacuum? If it's air, there's a problem with outgassing. If it's vacuum, there's a problem with expanding it?

[docmordrid]

There are several redundant air bladders and IIRC the walls are foam filled.

[joek]

so if we assume carbon based materials (like Kevlar) at about 1.5g/cm3, then the Bigelow wall is 2cm of material and 38cm of vacuum or air. I assume there's one air tight membrane near the inside and most of the mass is out side of this.

Would most of the filler therefore be vacuum? If it's air, there's a problem with outgassing. If it's vacuum, there's a problem with expanding it?

There approximately "two dozen" layers (see attachment), multiple bladders, thermal and MMOD protection, and several different materials.  Most the volume appears to be MMOD protection layers.  TransHab used Nextel + open cell foam; assume Bigelow's structure is similar.

From TransHab: NASA's Large-Scale Inflatable Spacecraft, AIAA 2000-1822:

On orbit, in the vacuum of space, the foam regains its original standoff thickness due to the resilience of the foam.

So in a sense, yes, the outer shell is largely vacuum.

edit: add image.

[joek]

A 6m fairing on the 3.66m core might pose stability problems. Does anyone know the fairing-to-core ratio on the hammerhead ELVs?

The "How big a fairing?" seems to be a recurring question in several threads.  I don't have a simple answer for FH, but a couple points of reference...

Atlas V Launch Services User’s Guide, ULA, Mar 2010 (pg 8-1):

ULA has considered payload fairings as large as 7.2 m (283 in.) in diameter and up to 32.3 m (106 ft long), as shown in Figure 8.1-1. These larger fairings, which are limited to flying on Atlas V configurations of up to four solid rocket boosters (SRBs), require moderate vehicle changes and modifications to the launch pad, limited mostly to secondary vertical processing facility structure.

http://www.ulalaunch.com/site/docs/product_cards/guides/AtlasVUsersGuide2010.pdf

Delta IV Payload Planners Guide, ULA, Sep 2007 (pg 10-11):

Payload fairings as large as 6.5 m (255 in.) in diameter and up to 25.9 m (85 ft long), as shown in Figure 10-13, have been evaluated and appear feasible. Larger fairings would require modest vehicle changes and modifications to the launch pad, limited mostly to secondary MST structure.

http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdf

...I'll leave it to someone with more chops in aerodynamics to elaborate.

[docmordrid]

3.66m core for F9 and a 3.81m core for Atlas V - less than 6" difference.  Do our engineers think that if kept in proportion to core diameter something akin to the above could work?

[joek]

3.66m core for F9 and a 3.81m core for Atlas V - less than 6" difference.  Do our engineers think that if kept in proportion to core diameter something akin to the above could work?

Maybe for F9, but FH is very different.  Note:
1. Atlas V (smaller core) but larger PLF than Delta IV (larger core).  Counterintuitive?
2. Atlas V larger PLF caveat on number of SRB's.
3. Delta IV larger PLF is shown only on Delta IV Heavy.  Significance is unknown.

I can only opine that my past (limited and dated) experience suggests that simple core/PLF rations are inadequate, and that when the the booster is anything other than relatively clean cylinder such as with strapons larger PLFs can be much more of a problem.  Will leave elaboration to someone with more aerodynamic chops and/or better CFD tools.