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#26 2008-02-09 00:14:34

samy
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From: Turku, Finland
Registered: 2006-01-25
Posts: 180
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Re: Shipyard?

What about them?

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#27 2008-02-09 06:07:54

Terraformer
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From: Ceres
Registered: 2007-08-27
Posts: 3,531
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Re: Shipyard?

Use them to build a Shipyard?


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#28 2008-02-09 18:52:15

samy
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From: Turku, Finland
Registered: 2006-01-25
Posts: 180
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Re: Shipyard?

So...if they could be used to build a shipyard...then couldn't they also be used to build ships? Making them, by definition, a shipyard?

So, in essence, you want to build the shipyard out of Bigelow modules. Okay, I suppose there's nothing in principle preventing that.

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#29 2008-02-10 04:56:59

Terraformer
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From: Ceres
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Posts: 3,531
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Re: Shipyard?

Would a Falcon 9 be able to take a Bigelow module up? And would one be able to take a DreamChaser up?


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#30 2008-02-10 10:17:06

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,291
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Re: Shipyard?

Let's see. A real habitat will be bigger than the demonstraton module that Bigelow flew. TransHAB was designed to be the length and diameter of the Shuttle cargo bay, but would inflate to 3 times diameter making it 9 times the cross-section area. Since the length would remain the same, that means 9 times the volume. To be this big, a Bigelow habitat would have to be about 5 times the diameter and 4 times the length of the Geneisis I or II demonstration modules. At 5 times diameter it would be 5*5=25 times the area, and at 4 times the length that means 100 times the mass. Genesis massed about 1360 kilograms, so a full-size habitat module would mass about 136,000 kilograms or 136 metric tonnes. Falcon 9 can lift 10,400kg to a 185km circular orbit if launched from Kwajalein. That launch site has 9° longitude, so the inclination would also be 9°. That's not good enough.

If you scale-down a full-size module to twice the diameter and same length of the Destiny laboratory module, it would still have 4 times the volume. That would be 8.4m diameter and 8.4m length, or 3.36 times the diameter of Genesis and 1.9 times the length. That would be 3.36*3.36*1.9=21.45 times the mass. So 29,172kg launch mass. Still too big for Falcon 9.

If you make the Bigelow module the same size as Destiny, it would be 1.68*1.68*1.9=5.36256 times the mass, so 7,293kg launch mass. That Falcon 9 could lift.

Of course if you launch Falcon 9 from Cape Canaveral AFS instead of Kwajalein, and launch it to ~390km altitude instead of 185km, you could reach ISS. The higher your orbit, the less atmospheric drag. To get completely out of the atmosphere so the orbit just won't decay, you have to get at least 800km which is medium orbit. The Van Allen radiation belts are around there. Higher launch latitude results in higher orbital inclination, which results in lower launch mass. Falcon 9 can lift 9,900kg to 185km circular orbit at 28.5° inclination if launched from the Cape. ISS is at 41.6° inclination, so reduce launch mass. Higher altitude also means lower launch mass. So the question is just how big do you want the hab, and where will it go?

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#31 2008-02-10 12:57:06

cIclops
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Registered: 2005-06-16
Posts: 3,230

Re: Shipyard?

The mass of an inflatable module scales much closer to its area than the volume, that is to the square of the size not the cube.


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#32 2020-10-09 16:57:10

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 26,002

Re: Shipyard?

Using what we have to leverage the big build of a ship for mars...

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#33 2020-10-11 07:27:10

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 26,002

Re: Shipyard?

Terraformer wrote:

GW has posted before about a dry dock using aluminium framing and mylar sheeting. It wouldn't be pressurised, but it would be well lit and free of temperature extremes, allowing the workers to use simple mechanical counter-pressure suits rather than the bulky suits they have today.

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