Dirigible returns to military relevancy

[Ahriman238]

Not quite sure where this should go. to be honest.

Turns out the US navy, in it's wisdom, is wrapping up a 5-year multimillion dollar study into the military value of dirigibles. Now, airships have been used before, in both world wars as sub-spotters, but the last Navy Airship was retired in the early 1962.

Specifically the study has focused on the possibilty of outfitting airships with radar, cameras etc, on the theory that they can stay up for a long time with a fraction the fuel costs of an AWACS. Their prototype MZ-3A wnet on it's first flight back in October.

The Army has expressed interest in lighter than air flight as a mobile command platform, and there is talk about reducing the radar profile enough to use dirigibles as transport vehicles for covert forces. I suppose at least we won't have to worry about black helicopters any more.

read all about it.

EDIT: naturally, the program is run out of Lakehurst Naval Air Station, the center for LTA for as long as the Navy has done it but more famously the site of the Hindenberg crash.

[madd0ct0r]

I wonder if they're looking to integrate them with drones?

Either as an airship carrier, or simply a drone that's silent and doesn't need to come down for weeks.

[Knife]

Meh, I could see it if it was a UAV or something. Deploy as the air version of a buoy or something. It would have to get pretty high to be out of AAA threat or SAM threat if they ever used it in an actual war zone. 10k feet doesn't seem that high to me, but anti aircraft systems are hardly my specialty.

[Mr Bean]

Meh, I could see it if it was a UAV or something. Deploy as the air version of a buoy or something. It would have to get pretty high to be out of AAA threat or SAM threat if they ever used it in an actual war zone. 10k feet doesn't seem that high to me, but anti aircraft systems are hardly my specialty.

They work fine over friendly airspace, especially since they can be even more disposable that usual since a weather balloon style UAV can be immune from ground fire but expensive to shoot down. Sucks to use your 200,000 dollar a pop missiles to down 5000$ mini-Airship UAV's which can loiter forever. And if you take the simple and cheap spam route you can throw up in times of trouble two hundred of the things for anything from surveillance to jamming to repeater platforms to simple decoy's designed to look like something useful and even cheaper.

[Sea Skimmer]

Multiple airships are now being worked on by the navy, air force and DARPA and Lockheed as an independent effort, but the most promising ones are hybrid airships which generate some lift aerodynamically. Relying purely on lifting gas remains shitty for most military purposes, all the more so now that helium prices have skyrocketed and conventional airships have to blow off as they burn fuel; though the DARPA pelican project intends to solve that by sucking the helium back into pressurized storage tanks. Transport, and all the endless takeoff and landing problems that creates is only being heavily pushed by Lockheed as far as I can tell, and they have lifting fans on the P-791 demonstrator so landing can be accomplished by reversing them and sucking the thing onto the ground. ISR and communication relay roles are much more viable since they seek to land as little as possible.

[Simon_Jester]

For unmanned airships, hydrogen might actually work. Any obvious problem with that? It's hazardous on the ground, but not vastly more so than the explosives and avgas people routinely store on the ground at airbases anyway.

[Sea Skimmer]

Hydrogen makes the thing much more readily able to burn if its struck by lighting, which happened to several hydrogen filled airships in the distant past, and becomes an increasing risk if you want an airship to stay airborne for as long as a year for ISR missions. It also undergoes more thermal expansion and contraction as I recall; though it is lighter and lets the airship lift more weight. Some of these airships are intended to fly above the ceiling of conventional, though not all lighting so that'd be much less of a problem. Hydrogen may win in the end merely because the military can't get helium in the required amounts at forward bases; this has already been a problem with tethered aerosats in Afghanistan.

[madd0ct0r]

manufacturing hydrogen is easier certainly. I seem to recall it being difficult to store - the atoms just pass straight through the aluminum skin of the balloon. I don't think helium would be any better though.

[Lord of the Abyss]

For unmanned airships, hydrogen might actually work. Any obvious problem with that? It's hazardous on the ground, but not vastly more so than the explosives and avgas people routinely store on the ground at airbases anyway.

It's my understanding it's actually less dangerous in many ways; since it's a gas it doesn't flow outward in flaming pools, and since it's so light a hydrogen fire tends to send its flames and heat mostly straight up.

[Shroom Man 777]

Didn't most of the people on the Hindenburg die from falling from heights, while those who stayed on board and rode it down were less-killed?

[KhorneFlakes]

I think so. I remember this documentary talking about the Hindenburg's fires, saying that they mostly burnt outwards from the fuel tanks/whatchamacallits, so the floors (according to evidence they had, anyway) actually burned under the feet of people on certain decks. Other people actually fell through the floors and died from impacts with other decks.

Sadly I watched it when I roughly six or so, so I don't remember much of it. I will see if I can find it though.

A definite thing I do know is that some people actually jumped out of the Hindenburg as it got closer to the ground.

[Alkaloid]

I actually remember reading about these a while ago, and one of the advantages was that they are really hard to shoot down because SAMs have difficulty tracking them because they don't have much in the way of an RCS or emissions, and even if you hit them the only way to bring them down is really to set them on fire because modern AA weapons will only normally puncture a few gas envelopes even with a direct hit. So they're unlikely to use hydrogen because it takes away about the only measure of survivability they have.

[Sea Skimmer]

Most blimps, let alone rigid airships have hoards of metal on them. The only reason a radar might have problems tracking them is because they could potentially be moving too slow to be noticed by pulse Doppler systems. That is a very very limited kind of invisibility when you are a giant object high in the sky with no ground clutter to hide among. As for resistance to damage, mythical against missiles, it has some real truth against small caliber machine gun bullets. German zeppelins came back with hundreds of .303 holes in them; as the gas pressure is very low the rate of leakage is also very low. But you put even a small missile into one of these and it’s going to blow a giant hole. Engage one with a modern automatic cannon and it’s game over as well.

The main survivability aid, for the ones that seek survivability is simply that by flying at 60,000 feet or so, you can fly above the effective ceiling of most mobile SAMs. Only relatively heavy systems, which in no way means they must be modern systems, or decently capable jet fighters will be able to attack in the first place.

Making a stealth blimp should well be possible, some people think it was already done for ELINT, but it’d be pointless for most of the intended roles. Particularly now that thermal cameras have become incredibly capable, and making a loitering blimp hide from thermal imaging or UV sensors would be more or less impossible.

[eyl]

Unmanned blimps carrying sensors (over a stationary point) have been used for years - what's the difference here? (beyond the stealth variant)

[Sea Skimmer]

The fact that a tethered object is not in fact a blimp. By definition a blimp is a form of airship and thus self propelled. The camera and radar balloons in use are called tethered aerostats. Also by being rigid the dirigible type airships in development now can carry much greater payloads then would ever be possible with blimps or balloons in a realistic manner. None of the current tethered aerosats carries over 1 ton.

[Irbis]

Making a stealth blimp should well be possible, some people think it was already done for ELINT, but it’d be pointless for most of the intended roles. Particularly now that thermal cameras have become incredibly capable, and making a loitering blimp hide from thermal imaging or UV sensors would be more or less impossible.

To play a little Devil's Advocate here - is there a good reason why, exactly? On a soldier, or vehicle, good thermal isolation is problematic due to heat accumulation, but good isolation and heat retention should be a good thing on airship, no?

Of course, even if you reduce it a great deal it would be probably detectable at such height, but as far as stealth vehicles go, stealth blimp would be the one that could use IR masking the most and would be easiest to actually implement one on.

[Sea Skimmer]

The problem is to be stealthy for long periods the blimp is going to have to fly higher then airliners cruise in the 35-41,000 foot bracket, which means almost anyone looking at it is looking at it against the near absolute zero background of space. Fly lower and someone will just end up seeing it physically, or worse crash into it. It will also be above 99% of the atmosphere. That's going to make even the most fractional change in temperature noticeable, and on top of that the airship has a massive solar heating area... all day long. Hiding that isn’t going to be remotely easy and you have a major weight limit if the airship is to be a reasonable size. The requirement for hangers is a BIG limit to how big a covert self propelled airship could actually be, few hangers exist that could actually hold large airships and fewer still that aren’t on military or civilian airfields at which airship operations would be blatant. Drifting spy balloon are easier since you just inflate them in the open, and known to have been used, but they were not very stealthy.

Meanwhile the UV hole issue is basically impossible to solve. You cannot change the fact that you are blocking the UV rays from the sun unless you had a system on the skin of the airship to generate UV light, which seems rather unlikely. This is one of many reasons why stealth aircraft only really work at night. Many modern infrared guided missiles already have a secondary UV sensor to help them discriminate against decoys, and UV optics are not uncommon for reconnaissance sensors.

Hiding stuff from IR on the ground is actually much much easier than at high altitude. First of all, skin heating from moving in the air is greatly reduced (unless you drive around at 100mph all the time) and solar heating is at least partly reduced by solar heating of the surrounding ground. Even on the coldest day the ground is far warmer then space is. Your big problem comes at dusk and dawn when metal heats up and cools off differently than dirt, but that’s life. You are meanwhile not forced to run engines all the time to maintain a fixed position as an airship must meaning you are not forced into a heat buildup situation, and generally its just easier to get rid of heat in an unnoticeable manner.

Also the dense atmosphere actually absorbs several large bands of the infrared spectrum. This is vital. Infrared camouflage works by converting the wavelengths that easily pass through the atmosphere into ones which are easily absorbed. The heat still exists… it’s just enemy sensors will not detect it at useful ranges. Paints, dyed cloths and now active converter systems are extensively in use and in development in this field. On the ground weight is not nearly so critical, so it’s much easier to implement this technology. The paints aren’t light, and cloths and converters are worse. But if you fly above most of the air, against space, tech like this really starts to break down in effectiveness anyway.

[Sarevok]

For some reason I feel I am going to look incredibly dumb for asking this but will go ahead anyway...

Airships can carry dozens or even hundreds of tons of payload. Can't they be armed with some CIWS guns and Pantsyr-S1 type missiles which knock out high speed missiles. Unlike naval vessels there is no real radar horizon problems to deal with for missile intercept. So with a good sensor setup an airship see missiles while dozens of kilometers away and react with plenty of time to spare.

Obviously this is just my uninformed thinking and won't work in reality...

So what is wrong with this idea and why ?

[Simon_Jester]

Size. You could build an airship with its own built-in missile defenses, but it's going to be really big, Hindenburg sized or bigger. And it'll still be slow, which means it's very easy to do dickish things like send up whole squadrons of planes to ripple-fire a volley of dozens of missiles at the thing at once. So saturating the missile defense would be relatively easy, and concentrating air defense assets against it would be easy, and that's not a good combination.

For aircraft to be survivable against competent air defense that can get into range of them, they need to have other advantages like speed, maneuverability, and stealth. You survive a lot longer if you can cross the width of an enemy's radar coverage in ten minutes than if you need an hour; longer if you can turn out of the way of a surface-to-air missile that still needs a minute or more to reach your position; longer if the radius at which the enemy can detect you is cut to 20% of normal by stealth measures.

An airship has neither speed, maneuverability, nor stealth. Active defenses are just no substitute for those things, except in a very contrived one-on-one duel between one airship and one SAM, or one fighter plane, or something like that.

[Sarevok]

Won't a big airship be cheaper than a hundred million dollar gen 4.5-5 fighter ? So you can counter enemy fighters one for one ? (assuming insane amounts of landspace available to park 300 meter behemoths)

[Simon_Jester]

Sarevok, you can't.

For one, to make it capable of defending itself in a fight, you have to pile it down with all sorts of expensive radar and weapons and communications gear, which is not cheap. Sure, the airframe of the airship would be pretty cheap- but then, the airframe of something like an F-35 would probably be pretty cheap too, if it didn't have to fight at all.

For another, we're not even talking about making this thing a match for an advanced fighter in a fight. Being able to shoot down incoming missiles doesn't give you that ability. At most, it gives you the power to defend yourself against attack; even if the enemy fighter shoots every last one of its missiles, and you shoot all the missiles down, the fighter can just go "well, shit," land, reload, and come back for another go at you. Also, it would be easy to concentrate dozens of fighters from all over a whole country against a small knot of these airships, and fire off scores or hundreds of air to air missiles at once to shoot them all down.

And third, to make these things complicated enough to defend themselves in air to air combat, we'd pretty much have to put crewmen on them to handle the weapons. Drones are all very well for firing a missile at a fixed target on the ground from a remote controller's orders, but they're not flexible enough to handle air warfare- not yet. Which means you're also risking the crew of the airship in this kind of "OK, you throw bombs at me and I'll see if I can catch them all out of the air and throw them back" contest.