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Old 02-25-2019, 03:30 PM   #106
Urwumpe
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Originally Posted by markp View Post
 I don't see why not. A basic approach could be to set the lifting gas mass and the structural masses could be set from the scenario file. Then by setting the lifting gas mass to zero you could have a vacuum airship. Mmm I wonder if it's really that easy. I can check if you like.
Would be nice, I still have about 3 hours of work left on my shift before can test it at home.

I suspect a few control functions like venting gas should no longer work. But controlling altitude by ballonets should be the same as for a hybrid.
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Old 02-25-2019, 08:45 PM   #107
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So the code is designed to calculate the size the airship mesh and calculate structural masses depending on the pressure ceiling requested in the scenario file. Ballast mass is also used in the calculation.

It's possible to put in a line of code to override the lifting gas mass in the calculation of the total mass.

Code:
  liftgasmass     = 0.0;
  airshipmass    = m_structure+envelopemass+liftgasmass+ballgasmass;
The size of the airship would be calculated assuming that the lifting gas is helium though.
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Old 02-25-2019, 08:49 PM   #108
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Originally Posted by markp View Post
 So the code is designed to calculate the size the airship mesh and calculate structural masses depending on the pressure ceiling requested in the scenario file. Ballast mass is also used in the calculation.

It's possible to put in a line of code to override the lifting gas mass in the calculation of the total mass.

Code:
  liftgasmass     = 0.0;
  airshipmass    = m_structure+envelopemass+liftgasmass+ballgasmass;
The size of the airship would be calculated assuming that the lifting gas is helium though.

well - then it should be better to fork it for vacuum with vacuum pumps. The size of the ship should rather depend on payload mass, as far as I understand the physics.
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Old 02-25-2019, 09:09 PM   #109
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It's also possible to set the gas density to zero in the initialisation routine that calculates the size of the airship.

Not sure that's any help. Things will become clearer over the next few days I guess.

Last edited by markp; 02-25-2019 at 09:23 PM.
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Old 02-25-2019, 09:20 PM   #110
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 It's also possible to set the gas density to zero in the initialisation routine that calculates the size of the airship.

Yes, but it shouldn't be zero.... only close to zero.
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Old 02-26-2019, 12:38 PM   #111
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Originally Posted by Urwumpe View Post
 Yes, but it shouldn't be zero.... only close to zero.
Yes quite.

Setting the gas density to 'zero' seems to work although the ballonet size remains fully inflated as the airship rises because the pressure on the envelope is negative.

Do you have any idea of the equivalent areal density for the envelope of such a vacuum airship on Mars? From terrestrial rigid airships I get around 5-6 kg/m2 for a very crude calculation of an areal density (surface area / structural mass).
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Old 02-26-2019, 12:49 PM   #112
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Not what you expect likely, but does this fairly new paper help you?

https://ntrs.nasa.gov/archive/nasa/c...0180006789.pdf

Its about how to estimate the masses and its pretty interesting in terms of design.

But it does not contain sample data.
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Old 02-26-2019, 01:07 PM   #113
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Yes that looks very interesting, thanks!

There seems to be some numbers from their study on page 37 that might help.
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Old 02-26-2019, 01:13 PM   #114
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Oh yes, did not see them when going over the pages. The deployment also looks interesting there.
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Old 02-28-2019, 02:28 PM   #115
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So I get about 0.2 kg/m2 for their areal density which is very good compared to non-rigid airship numbers of 0.35-0.52 kg/m2 quoted on page 5 of a paper available online called, "A methodology for determination of baseline specifications of a non-rigid airship".
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Old 02-28-2019, 02:30 PM   #116
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Also working on a cargo container for delivering the airship to different places

airship_box.jpg

Last edited by markp; 02-28-2019 at 02:34 PM.
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Old 02-28-2019, 02:44 PM   #117
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 Also working on a cargo container for delivering the airship to different places

Attachment 16437
Not "Airship inside"?

If you want to know a real joke: Thieves managed to steal a trailer with a registered hot air balloon near my place. I really wonder where they want to sell it.
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Old 02-28-2019, 03:24 PM   #118
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Originally Posted by Urwumpe View Post
 Not "Airship inside"?

If you want to know a real joke: Thieves managed to steal a trailer with a registered hot air balloon near my place. I really wonder where they want to sell it.

That's pretty bizarre.
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Old 03-01-2019, 09:47 PM   #119
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OK so now an airship has been delivered to Mars packed up nicely in some cargo containers. Who's going to unpack and assemble it though?

Click image for larger version

Name:	container1.jpg
Views:	12
Size:	51.6 KB
ID:	16438

Click image for larger version

Name:	container2.jpg
Views:	8
Size:	37.7 KB
ID:	16439
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Old 03-12-2019, 02:43 PM   #120
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I now have a version of the airship that can be created in a stored configuration. The properties of the assembled airship can be set during the simulation from a 'master' cargo container. The size of the airship will depend on the amount of extra cargo containers have been delivered nearby.

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