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

[The Jopp]

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?

[Traul]

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.

[CanRay]

And now I'm reminded why I failed physics.

[Miri]

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.

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?

[Yerameyahu]

There is no volume:Body connection, as it stands. Annoying. (IMG:style_emoticons/default/smile.gif)

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. (IMG:style_emoticons/default/biggrin.gif)

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.

[Traul]

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.

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 (IMG:style_emoticons/default/nyahnyah.gif) 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.

[Yerameyahu]

Hey, don't look at me. I don't care. (IMG:style_emoticons/default/smile.gif) I just know that Arsenal says it's non-flammable gas, presumably Helium.

[Miri]

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 (IMG:style_emoticons/default/smile.gif)

[Yerameyahu]

Depends on where you're looking, and camo is its own mod. As is distance. (IMG:style_emoticons/default/nyahnyah.gif)

[Miri]

It takes a modslot to slap some white/blue paint on the underside of your drone?

[suoq]

But what would be an aproximate logical size multiplier?

The vehicle is a sustaining focus for a levitate spell cast on the vehicle.

[SpellBinder]

He might've been thinking of the chameleon coating.

[Yerameyahu]

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. (IMG:style_emoticons/default/smile.gif) As does distance (in this case, altitude).

[Halinn]

nothing is less dense than vacuum.

I don't know about that. Some of the people I've met...

[CanRay]

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.

[Yerameyahu]

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.

[CanRay]

*Inhales* "We represent the Lollypop Guild, Lollypop Guild, Lollypop..." *Is beaten by random group of dwarves*

[KarmaInferno]

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

[Traul]

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.

[Yerameyahu]

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. (IMG:style_emoticons/default/nyahnyah.gif)

[suoq]

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?

[Traul]

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. (IMG:style_emoticons/default/nyahnyah.gif)

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.

[KarmaInferno]

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

[suoq]

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.

[Angelone]

I'm gonna go with strings. Strings that are edited out before the run hits theaters. I suppose nanites would work as well.