The size of vehicles - and making them LTA..., My drone can go *pop* Options

[CanRay]

"Truth is we have no idea how we did it, we programmed the computer after drinking... Um, some stuff we found in the chem lab. It was green. Or... Red. I can't remember. But it works great!"

[The Jopp]

Well, I'll forget about the vacuum thingy as we do not HAVE that technology and WONT have that technology in 70 years.

Air density at sea level is about 1.2 kg/m^3, so each cubic metre of vacuum gives us 1.2 kg (times gravity) of lift. This is only about 10% greater than hydrogen, and 20% greater than helium, but with tens of thousands of cubic metres of cell volume this can be a substantial gain in lifting capacity.

Assume a roughly cylindrical vacuum cell, say 100m long and 10m radius, that holds 31,400 m^3 (or 1.1 million cubic feet) of vacuum. That generates 37,700 kg (or about 83,000 pounds) of lift. Surface area of the cell is 6911 m^2, so your vacuum cell structural material is limited to a maximum mass of about 5.4 kg/m^2.

The density of steel is 7800 kg/m^3, so the maximum thickness of steel plate you can use is 0.7 millimetres (1/36 inch). Obviously this isn't going to be anywhere near strong enough! And it needs to be even thinner if you want any appreciable usable lift (as opposed to lift merely used to keep the vacuum cell itself aloft).

To get an idea of the strength required from an ultra-tech material, the vacuum cell has an air pressure equivalent to just over 10 tonnes on every square metre of its surface. This is like taking a sheet of that 0.7 millimetre thick steel, using it to bridge a 100 metre wide chasm, parking 500 cars on it (you'd have to stack them about 10-high to fit them on), and expecting it to not even *bend* appreciably - let alone collapse.

[suoq]

Well, I'll forget about the vacuum thingy as we do not HAVE that technology and WONT have that technology in 70 years.

It took less than 70 years to go from pre-WWII technology to posting on dumpshock from a gps enabled smartphone.

[CanRay]

Twenty years from having webservers that filled a room to one that can be held in the palm of a hand.

[Yerameyahu]

Not all tech moves at the same rate. Today, we can't go to the Moon, and we (USA) can't get to orbit.

Traul, I don't understand. We *know* how the LTA mod works, because Arsenal says it's a bag of non-flammable gas.

[KarmaInferno]

Technology changes rapidly.

Physics does not.

You would need a materials science advancement so profound as to be nearly magical or miraculous.

And taking the big picture into account, if you are capable of creating such a material, you are likely FAR beyond the development level that Shadowrun posits.

I can see something like this in a far future setting, but not anything in the next 100 years.

And at the end of the day, why would you bother? Helium doesn't have quite the lift capacity of vacuum, true, but it also does not have the rigid containment requirements because it's self-supporting. You just need a thin membrane.

Tech develops from a need, not just because it's possible. There's plenty of examples of experimental tch that never gets past the prototype phase because it's simply not practical.




-k

[suoq]

Physics does not.

Of all the places Shadowrun diverges from reality as we know it, you've chosen physics to draw your line in the sand?

If you really want helium gasbags in your world, instead of some unexplainable type of negatively charged molecule that resists all other identical molecules to create a near vacuum gasbag over a vehicle composed of magitanium, that's fine, but that's your vision. It's not canon or raw anymore than the world that uses such molecules and materials.

In the end, the real answer to the OP, in direct contradiction to the answers in this thread is "Until someone gives you a page number, it as big as you want and works in whatever way makes your table fun".

[KarmaInferno]

It would be nice if people would address the main thrust of an argument instead of picking at only parts of the whole.

Shadowrun physics diverge from reality in specific, pretty well defined ways. Mostly, physics act like real world physics unless actual Magic is involved. Helium is helium. Vacuum is vacuum. Metal is metal.

Am I saying that it is impossible to create a material that could be light enough for vacuum to lift, yet provide the rigidity to withstand the outside air pressure? No.

What I am saying is that any culture advanced enough to create such a material is going to be far more advanced than the tech level presented in Shadowrun.

If you have such materials, you might, for example, be able to create armor clothing that can shrug off tank shells. Or entire floating cities. It's not an insignificant thing to introduce the ability to create super-materials into a world-building exercise. Technology does not develop in a vacuum. Such technological abilities would permeate every level of a given society, not just be limited to the lifting structure of a blimp.

My other main point is that trying to develop vacuum based lifting mechanisms is simply impractical when there's existing gas-based lifting tech that works almost as well but with far far less in the way of resource and tech requirements.




-k

[suoq]

the tech level presented in Shadowrun.

What, exactly, is the tech level in shadowrun?

We have better flying jetpacks today than they do. Their food, quite frankly, sucks. And they can't even get a decent hologram going. Heck, I'm pretty our our predator drones are better than their drones. On the other hand, in shadowrun characters can get biotreatments that help them notice stuff and think more logically and for 250 nuyen and a single injection a shadowrun character can get programmable tattoos that store data.

Such technological abilities would permeate every level of a given society, not just be limited to the lifting structure of a blimp.

And yet, in shadowrun, that doesn't happen. There's bioware out the wazoo and people eat soy instead of biocow. They can shove a ton of visual processing in a cybereye and jack all visual processing on an entire van. They have climate control orthoskin and no clothing based climate control.

My other main point is that trying to develop vacuum based lifting mechanisms is simply impractical when there's existing gas-based lifting tech that works almost as well but with far far less in the way of resource and tech requirements.

What gets developed is often not what people are trying to work on. Money dumped into hypertension angina pectoris resulted in viagra. Exploration into space made possible lightweight wheelchairs. The greatest porn delivery vehicle in history started out in the military industrial complex. Tech for one sector is often created in another sector with other goals.

[The Jopp]

Perhaps the question is not about how much extra lift we can get from future LTA designs, but rather what ultralight materials will exists that would allow us to make strong and durable yet very light LTA vehicles.

We have memory plastics and monowire which means that you could design a hull made out of buckytube/monowire tech which would be very lightweight, thin and durable and several parts where conventional steel is replaced with lightweight plastics.

Less weight would then means less requirements for lift, thus also less requirements for additional mass to aquire lift.

[Mayhem_2006]

Not all tech moves at the same rate. Today, we can't go to the Moon, and we (USA) can't get to orbit.

Just as an aside, the US does still have unmanned launch capability for the orbital insertion of satellites etc (pegasus and Atlas). And the non-moon-visiting isn't due to lack of technology, but lack of will.

[Yerameyahu]

Heh, that's true. Still, my point was that we have tiny supercomputers with touch screens, GPS, and video… but not jet packs and flying cars (no, not really), and barely electric cars! Things move differently, and it's hardly relevant to point out the advances computers have made in comparison to pretty breathtaking materials science-fiction.

[CanRay]

Just as an aside, the US does still have unmanned launch capability for the orbital insertion of satellites etc (pegasus and Atlas). And the non-moon-visiting isn't due to lack of technology, but lack of will.

And budget.

[SpellBinder]

Just as an aside, the US does still have unmanned launch capability for the orbital insertion of satellites etc (pegasus and Atlas). And the non-moon-visiting isn't due to lack of technology, but lack of will.

And motivation.

[CanRay]

"All right, we're on the moon! Where's the oil deposits we can exploit?" "Um... We got rocks. That's it." "Screw this noise, let's plan to invade the Middle East in a few decades! Give 'The World' the Moon to make them think we're being nice."

(IMG:style_emoticons/default/nyahnyah.gif)

[SpellBinder]

Honestly something else was on my mind when I made that post, but that works too.