Ok, we have the option of making most of our vehicles and drones into lighter than air, which is useful. But what would be an aproximate logical size multiplier?
Let's take a large drone of today, the US HK drone. If that one would have been built with a LTA body how much bigger in volume would be logical?
Size X2m, Size X3, Size X4?
Since the actual technology of lighter than air hasn't changed (ie no übergas that gives off more efficient lift) then they should be fairly large. Sure, lighter and smarter materials have arisen but even those have limits.
Lets take the description of a large drone, about the size of a normal car, it should not be impossible to say that it would be 4 times the size of a normal car should it be a LTA drone.
What do you think?
EDIT!
This also raised another question.
Depending on the maximum flight ceiling of the drone the type/amount/temperature of the lift gas . Would this increase or decrease possible heat signature of the vessel?
Full Version: The size of vehicles - and making them LTA...
The best you can do is not use gas at all: just assume they have über-strong and über-light materials that can resist loss of pressure and use them to build a vacuum balloon.
Density of air: 1.22521 kg/m3
Density of iron: 7.874 t/m3 (according to Wikipedia)
Your drone is not pure solid iron, should have plenty of empty space and lighter materials in there. Let's say the drone is 10 times less dense than iron. That still makes it about 500 times denser than air. So to build an LTA you are looking at a 500x volume increase, that is about 8x size increase in all dimensions.
It should be less for vehicles since they have a lot more empty space around passengers.
Density of air: 1.22521 kg/m3
Density of iron: 7.874 t/m3 (according to Wikipedia)
Your drone is not pure solid iron, should have plenty of empty space and lighter materials in there. Let's say the drone is 10 times less dense than iron. That still makes it about 500 times denser than air. So to build an LTA you are looking at a 500x volume increase, that is about 8x size increase in all dimensions.
It should be less for vehicles since they have a lot more empty space around passengers.
And now I'm reminded why I failed physics.
QUOTE (Traul @ Jul 22 2011, 09:58 AM) 
The best you can do is not use gas at all: just assume they have über-strong and über-light materials that can resist loss of pressure and use them to build a vacuum balloon.
Density of air: 1.22521 kg/m3
Density of iron: 7.874 t/m3 (according to Wikipedia)
Your drone is not pure solid iron, should have plenty of empty space and lighter materials in there. Let's say the drone is 10 times less dense than iron. That still makes it about 500 times denser than air. So to build an LTA you are looking at a 500x volume increase, that is about 8x size increase in all dimensions.
It should be less for vehicles since they have a lot more empty space around passengers.
Density of air: 1.22521 kg/m3
Density of iron: 7.874 t/m3 (according to Wikipedia)
Your drone is not pure solid iron, should have plenty of empty space and lighter materials in there. Let's say the drone is 10 times less dense than iron. That still makes it about 500 times denser than air. So to build an LTA you are looking at a 500x volume increase, that is about 8x size increase in all dimensions.
It should be less for vehicles since they have a lot more empty space around passengers.
So your basically saying.. build a lot empty space sacs that are rigid.. pump the air out of them.. and the vehicle will rise up because the air sacs want to find a spot where the air pressure inside the sacs and outside are equal?
There is no volume:Body connection, as it stands. Annoying. 
It's safe to assume that LTAs are not super-materials vacuum things, because Arsenal *tells* us: it's Helium, or another LTA non-flammable gas.
AFAIK, all the LTAs are 'cold', so there's no change in (heat) Signature. Their size Signature is much bigger (visually, at least), but you'd have to ballpark that.
Using the (pretty awful) Signature table, I'd say say they automatically get the +3 mod for Zeppelins and other 'oversize' vehicles, but *added* to whatever they used to be—an LTA-modded drone would be -3, +3 = 0. Maybe.
Using the Perception mods table, I'd either use the Thresholds (bump a notch), or use a simple modifier (+2 or 3 at least?), again for visual.
It's safe to assume that LTAs are not super-materials vacuum things, because Arsenal *tells* us: it's Helium, or another LTA non-flammable gas.
AFAIK, all the LTAs are 'cold', so there's no change in (heat) Signature. Their size Signature is much bigger (visually, at least), but you'd have to ballpark that.
Using the (pretty awful) Signature table, I'd say say they automatically get the +3 mod for Zeppelins and other 'oversize' vehicles, but *added* to whatever they used to be—an LTA-modded drone would be -3, +3 = 0. Maybe.
Using the Perception mods table, I'd either use the Thresholds (bump a notch), or use a simple modifier (+2 or 3 at least?), again for visual.
QUOTE (Miri @ Jul 22 2011, 07:19 PM)
So your basically saying.. build a lot empty space sacs that are rigid.. pump the air out of them.. and the vehicle will rise up because the air sacs want to find a spot where the air pressure inside the sacs and outside are equal?
No, I'm saying the LTA will fly if the average density of the balloon+the drone is lower than air density. The drone density is fixed so the balloon density needs to be as small as possible, and nothing is less dense than vacuum.
QUOTE (Yerameyahu @ Jul 22 2011, 07:26 PM)
It's safe to assume that LTAs are not super-materials vacuum things, because Arsenal *tells* us: it's Helium, or another LTA non-flammable gas.
YOU do the computation for an Helium filled balloon
Or you say it is worse than vacuum, settle for 10x size increase and call it a day. Does not look too far-fetched when you look at an actual zeppelin picture.
Hey, don't look at me. I don't care. I just know that Arsenal says it's non-flammable gas, presumably Helium.
I just know that Arsenal says it's non-flammable gas, presumably Helium.
QUOTE (Yerameyahu @ Jul 22 2011, 01:26 PM)
Using the Perception mods table, I'd either use the Thresholds (bump a notch), or use a simple modifier (+2 or 3 at least?), again for visual.
I'll see you your +2 or +3 to spot threshold and raise you 804m altitude. Half a mile high with a basic camo paint job should do plenty to hide it from visual sight
Depends on where you're looking, and camo is its own mod. As is distance.
It takes a modslot to slap some white/blue paint on the underside of your drone?
QUOTE (The Jopp @ Jul 22 2011, 08:44 AM)
But what would be an aproximate logical size multiplier?
The vehicle is a sustaining focus for a levitate spell cast on the vehicle.
He might've been thinking of the chameleon coating.
Not a vehicle mod, a dice pool mod. We're talking about Perception Thresholds and dice pool mods. Incidentally, I didn't say '+2 or 3 Threshold', but +2 or 3 to the Perceiver's dice pool.
Although, yes, camouflage paint job is certainly a vehicle mod (though probably not one that costs *slots*). That, or indeed the chameleon coating, would give their own *Perception dice pool mod* against detection, per the rules. As does distance (in this case, altitude).
Although, yes, camouflage paint job is certainly a vehicle mod (though probably not one that costs *slots*). That, or indeed the chameleon coating, would give their own *Perception dice pool mod* against detection, per the rules.
As does distance (in this case, altitude).
QUOTE (Traul @ Jul 22 2011, 08:36 PM)
nothing is less dense than vacuum.
I don't know about that. Some of the people I've met...
I worked tech support. I've dealt with people denser than depleted uranium, and ones that were as dense as vacuum. Honestly, if nature abhors a vacuum so much, how do their heads not assplode?
The options for LTA craft are many, and Shadowrun SUPERSCIENCE (Which includes the study of magic) might have given us something better than Helium.
The options for LTA craft are many, and Shadowrun SUPERSCIENCE (Which includes the study of magic) might have given us something better than Helium.
Except, again, we know for sure that whatever it's given us is a simple, non-flammable, lighter-than-air gas in a puncturable gas bag. Probably helium.
*Inhales* "We represent the Lollypop Guild, Lollypop Guild, Lollypop..." *Is beaten by random group of dwarves*
QUOTE (Traul @ Jul 22 2011, 01:36 PM)
No, I'm saying the LTA will fly if the average density of the balloon+the drone is lower than air density. The drone density is fixed so the balloon density needs to be as small as possible, and nothing is less dense than vacuum.
I would point out that materials strong enough to prevent the outside air pressure from crushing the vacuum container are going to be heavier than the "lift" from the vacuum can overcome. The bigger the container the more such material is needed, making the whole thing heavier still.
I imagine there MIGHT be a break-even point where the vacuum's lift capacity finally exceeds the weight of the container, but at that point you have a vehicle so large as to blot out the sun.
Much more practical to use a gas that's merely somewhat less dense than air, so you can use much lighter balloon materials. Which is why modern balloons and dirigibles use stuff like helium or just heated air.
-k
QUOTE (KarmaInferno @ Jul 23 2011, 04:13 PM)
I would point out that materials strong enough to prevent the outside air pressure from crushing the vacuum container are going to be heavier than the "lift" from the vacuum can overcome. The bigger the container the more such material is needed, making the whole thing heavier still.
Same as before: feel free to provide your own estimate based on a more acurate model.
I'm not sure why the only valid way to dispute the feasibility of vacuum lift-cells is to estimate the lifting ability of helium.
QUOTE (KarmaInferno @ Jul 23 2011, 10:13 AM)
I would point out that materials strong enough to prevent the outside air pressure from crushing the vacuum container are going to be heavier than the "lift" from the vacuum can overcome.
If a "molecular wall" is used I don't see why it would have an overall greater density than air. Could you explain what the weight to surface area requirement is for a molecular structure designed to keep it's internal space a vacuum?
QUOTE (Yerameyahu @ Jul 23 2011, 05:13 PM)
I'm not sure why the only valid way to dispute the feasibility of vacuum lift-cells is to estimate the lifting ability of helium.
It is the only way to answer the original question: what's the size of an LTA? The feasibility of vacuum lift-cells is off-topic, no one has claimed that they were feasible and it does not matter because feasible or not, they are the best that can physically be done and provide a useful lower bound of the size. That's all.
QUOTE (suoq @ Jul 23 2011, 11:49 AM)
If a "molecular wall" is used I don't see why it would have an overall greater density than air. Could you explain what the weight to surface area requirement is for a molecular structure designed to keep it's internal space a vacuum?
Are we discussing some new magic structural material here?
Because as far as I know pretty much all vacuum containers are pretty hefty structures.
-k
QUOTE (KarmaInferno @ Jul 23 2011, 11:58 AM)
Are we discussing some new magic structural material here?
Currently we have structures such as carbon nanotubes ( http://nanoall.blogspot.com/2010/11/carbon...s-in-brief.html ) and graphene ( http://nanoall.blogspot.com/2011/05/graphe...plications.html ).
I'm not making a claim that such structures or structures based on such structures can. in our universe, be used to create LTA objects by being built to be wafer thin, strong, and contain a vacuum. However, using such a material in-game is no more mind bending than the working of the matrix, magic, technomancers, dragons, and the creation of the NAN. We already have nanohives and nanites that do all sorts of amazing things in-game, so clearly the science in this direction has progressed incredibly.
I'm gonna go with strings. Strings that are edited out before the run hits theaters. I suppose nanites would work as well.
"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!"
Well, I'll forget about the vacuum thingy as we do not HAVE that technology and WONT have that technology in 70 years.
QUOTE
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.
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.
QUOTE (The Jopp @ Jul 24 2011, 05:43 AM)
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.
Twenty years from having webservers that filled a room to one that can be held in the palm of a hand.
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.
Traul, I don't understand. We *know* how the LTA mod works, because Arsenal says it's a bag of non-flammable gas.
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
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
QUOTE (KarmaInferno @ Jul 24 2011, 01:15 PM)
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".
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
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
QUOTE (KarmaInferno @ Jul 24 2011, 02:18 PM)
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.
QUOTE
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.QUOTE
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.
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.
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.
QUOTE (Yerameyahu @ Jul 24 2011, 07:18 PM)
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.
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.
QUOTE (Mayhem_2006 @ Jul 25 2011, 02:07 AM)
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.
QUOTE (Mayhem_2006 @ Jul 25 2011, 01:07 AM)
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.
"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."
Honestly something else was on my mind when I made that post, but that works too.
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