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kojax
Post  Post subject: Zeppelins: Misunderstood Sky Tanks  |  Posted: Mon Mar 12, 2012 11:02 am
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I've discussed this before with people, but it didn't turn out pretty. I'm hoping this time to obtain a different result by putting all the pertinent data in the OP. That way the rest of the thread isn't all taken up just trying to dispel all of the misconceptions.

First off, zeppelins are not like the helium balloons you may encounter at a child's birthday party. They don't "pop" the moment you punch hole in them. The air pressure inside of the Zeppelin is kept almost exactly the same as the outside air, so even when it starts to get holes in it, the helium/hydrogen doesn't leak out quickly. It just sort of gradually seeps out over time, giving the zeppelin plenty of time to complete its mission and return to base for repairs.

Even hundreds and hundreds of bullet holes won't cause it to crash.

wiki wrote:
A series of structural vulnerability tests were done by the UK Defence Evaluation and Research Agency DERA on a Skyship 600, an earlier airship built by the Munk team to a similar pressure-stabilised design. Several hundred high-velocity bullets were fired through the hull, and even two hours later the vehicle would have been able to return to base. The airship is virtually impervious to automatic rifle and mortar fire: ordnance passes through the envelope without causing critical helium loss. In all instances of light armament fire evaluated under both test and live conditions, the vehicle was able to complete its mission and return to base. The internal hull pressure is maintained at only 1–2% above surrounding air pressure, the vehicle is highly tolerant to physical damage or to attack by small-arms fire or missile


http://en.wikipedia.org/wiki/Airship#Safety

One accurate criticism is that they move somewhat slowly. However, depending on what kind of propellers you use to move them, they may or may not have a strong heat signature for rockets to lock onto. And of course, if they attack from up wind, then they don't have to turn the propellers on at all, so no heat signature in that event. They're capable of reasonably high altitude flight (which was one of their chief advantages in WW 1, because few planes at that time could climb high enough to engage them.)

Possible interesting applications would be things like night attacks and/or extractions. The ability of a zeppelin to move quietly, and drift slowly through the air would make it hard to spot at night. In theory, the underside could be cooled by placing panels with pipes in them, and pumping some kind of coolant through them, making it invisible to infrared imaging. Light intensification might still work I guess, depending on how dark a night it is. Most terrorists/insurgents/etc don't have radar.

One thing I'm very curious about, and can't seem to find data on, is the question of how stable/unstable a platform a zeppelin gives you to fire from. Most aircraft can only hit ground targets by using bombs and missiles, or extremely rapid fire machine guns, because any kind of gun that requires careful aiming would probably get jolted around too much to actually hit anyone. I don't know if zeppelins would be different in that respect. It would be really awesome to be able to put sniping turrets on an aircraft, to make precision kills. Put some kind of silencer on the weapon, and I imagine the psychological effect to the enemy would be quite chilling.


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kojax
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Mon Mar 12, 2012 11:06 am
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For the sake of discussion, the question is: would it be worth the trouble to try and resurrect this technology, or would the technical obstacles and basic impracticality be so overwhelming that the gain ends up being overshadowed by all the costs.

What I see in zeppelins primarily is an invincible extraction vehicle. Say you've got a chopper pilot down deep within enemy territory, surrounded on all sides by hostiles. Why not send a rescue vehicle that's virtually impossible to shoot down to get him/her?

The down side is that there may exist ways to defeat them that haven't been thought of yet, by which a low tech enemy could still bring them down. They're almost totally impervious to small arms fire, but all it takes is some creative weapons designer to come up with one munition that defeats them, and the whole project, including any investments into engineering ... etc.... becomes a total waste.


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iNow
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Mon Mar 12, 2012 11:32 am
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I see slow speeds as the critical point of failure. Even with super fast propellors, a jet could still wipe them out with essentially zero need for chase. Even if the bullets don`t destroy the craft itself, they could easily decimate the pilot compartment and any materials or people being transported. I`m no expert, but I definitely feel that WWI technology would be easily wiped out by even 1960s technology, let alone that which is available to us today in 2012.

Perhaps I am dismissing it too quickly, though?

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marnixR
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Mon Mar 12, 2012 8:09 pm
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i too see slowness as a major issue
that, and the fact that it is quite visible on a radar screen

therefore, any attack just needs visual clues, can approach quite closely and is able to outmanoeuvre without too much challenge to its own survival

if you want to make things a bit more challenging from the point of view of the attacker, you could always aim for the gondola, and its destruction would make the integrity of the balloon immaterial

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iNow
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Tue Mar 13, 2012 2:46 am
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I realize I could challenge the "virutually indestructible" comment, too. Just shoot some sort of incendiary device towards it... Hydrogen likes to react with flames. :)

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Ophiolite
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Tue Mar 13, 2012 9:42 am
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It would seem a more suitable use might be in logistical support, moving large quantities of materiel to locations clos to, but not at, the front line.


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kojax
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Tue Mar 20, 2012 12:58 pm
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marnixR wrote:
i too see slowness as a major issue
that, and the fact that it is quite visible on a radar screen



Yeah. It would be nearly useless against an enemy that had radar. But insurgents in a place like Afghanistan don't have radar.

Quote:

therefore, any attack just needs visual clues, can approach quite closely and is able to outmanoeuvre without too much challenge to its own survival



The problem is actually hitting it with a rocket. At any reasonable height, an unguided rocket would be overwhelmingly likely to miss. A guided rocket would have very little to lock onto, since a zeppelin puts off such a small heat signature compared with a plane or helicopter.

Prior to engaging the enemy it could circle around to position itself upwind and attack from that direction, so as not to need to be running its engines.

Also, if it's not a rigid zeppelin, a lot of rockets trigger their detonation by the force of the impact, and a soft outer balloon may prevent them from experiencing that impact so they don't even blow up.

Quote:
if you want to make things a bit more challenging from the point of view of the attacker, you could always aim for the gondola, and its destruction would make the integrity of the balloon immaterial


How much armor do you think we could put on that gondola? Since weight has no effect on fuel consumption, the only limiting factor is how big a balloon -to - gondola size ratio do you want?

iNow wrote:
I realize I could challenge the "virutually indestructible" comment, too. Just shoot some sort of incendiary device towards it... Hydrogen likes to react with flames. :)


This is an interesting problem. I see only two solutions.

1) - Use Helium instead of Hydrogen. However, this carries the problem that Helium is very expensive, so it might simply cost too much to have people shooting holes in the canopy and causing it to leak out.

2) - Build a balloon within a balloon. The inner balloon is filled with Hydrogen. The outer balloon is filled with an inert gas like Nitrogen. The outer buffer should prevent oxygen from reaching the Hydrogen in sufficient quantities for combustion to take place. It doesn't matter how hot the Hydrogen gets if it has nothing to react with.


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iNow
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Wed Mar 21, 2012 3:10 am
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Couldn't one get past that by puncturing the first layer with a standard projectile, then once it had leaked a bit you use the incendiary after?

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marnixR
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Wed Mar 21, 2012 8:07 am
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let's assume for argument's sake that current weaponry is not ideal for attacking zeppelins
how hard do you think it would be to develop more appropriate weapons - like the equivalent of an armour-piercing shell for tanks ? or rip-claws ?

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kojax
Post  Post subject: Re: Zeppelins: Misunderstood Sky Tanks  |  Posted: Sun Mar 25, 2012 5:16 pm
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iNow wrote:
Couldn't one get past that by puncturing the first layer with a standard projectile, then once it had leaked a bit you use the incendiary after?


Except you're forgetting that the air pressure inside the balloon is only slightly greater than the air outside. Punching a hole in it causes it just to seep very slowly out. You'd have to either wait a long time or punch quite a lot of holes to get enough of the gas in the outer layer to leak out so that oxygen could get past it in meaningful quantities.



marnixR wrote:
let's assume for argument's sake that current weaponry is not ideal for attacking zeppelins
how hard do you think it would be to develop more appropriate weapons - like the equivalent of an armour-piercing shell for tanks ? or rip-claws ?


The one real possibility I can think of would be explosives that go off inside the blimp to temporarily increase the pressure of the air in there to something higher than ambient pressure, so the gas would be forced to expand outward through the holes you're ripping in the balloon. If using hydrogen, perhaps it could contain a chemical that might mix with the hydrogen. Like, maybe a canister that contains lots of oxygen for the hydrogen to react with. If Helium is used instead of hydrogen, then Helium is very non-reactive. It would be hard to come up with a chemical that could make it do much.

However the main problem for a weapon like this still remains: how do you target it? Any kind of canister or bomb would have to be delivered somehow. Rockets are usually heat guided. Radar guided ones are possible but I think that would be expensive. Unguided weapons face the problem that the blimp is likely to attack from a reasonably high altitude. They are capable of altitudes higher than intuitively one might expect.

Insurgents can't really afford to use stationary fortifications, like a big AA flak cannon battery, because we'd blow it to bits the moment we saw it. That's also why they can't use radar. The moment they turn on the array, we'd see it lock in on it (remember radar isn't passive - it has to emit a signal to work). Their only option for shooting down aircraft is hand held weapons.


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