/sci/ - Science & Math

>>7530757
>>That's not entirely true.
No it is very true:
http://blogs.scientificamerican.com/guest-blog/helium-hokum-why-airships-will-never-be-part-of-our-transportation-infrastructure/

To answer your question: air pressure at 6,000 feet and air pressure is 81 kPa so air density is 1 kg/m^3.

So this means if you had 1 cubic meter of vacuum you could just lift 1 kilogram of ship.

at this pressure hydrogen has a density of 0.06696 kg/m^3, so if you use hydrogen then you can just lift 0.93 kg per cubic meter of hydrogen.

The interesting thing is gravity really doesn't matter here. Though if you really want flying battleships(you're writing a sci-fi novel aren't you), you should increase the density of the air. If you make your planet have an atmosphere that's like a combination of titan and venus. Dense, at high pressure, but cold so people don't get fried. Admittedly, you'd need to do some crazy world building to find an atmosphere that humans could live in.

To get you started there's this:
http://selenianboondocks.com/2013/11/venusian-rocket-floaties/

empty Rocket stages can pretty much just float on venus.