High-Tech Blimps Earning Their Wings 200
coondoggie writes "The US Army this week showed off its latest high-tech blimp laden with powerful radar systems capable of detecting incoming threats 340 miles away.
The helium-filled blimps, or aerostats, are designed to hover over war zones or high-security areas and be on guard for incoming missiles or other threats. The Army wants them to reduce some of the need for manned and unmanned reconnaissance flights.
The aerostat demonstrated this week is known as the Joint Land Attack Cruise Missile Defense Elevated Sensor System (JLENS), which is designed to fly up to an altitude of 10,000 feet. According to GlobalSecurity.org., the $1.4 billion JLENS is a large, unpowered elevated sensor moored to the ground by a long cable. From its position above the battlefield, the elevated sensors will allow incoming cruise missiles to be detected, tracked, and engaged by surface-based air defense systems even before the targets can be seen by the systems."
Re:Blimps (Score:4, Informative)
Shoot down at 10,000 feet is easy (Score:4, Informative)
I hate to pop your balloon (pun intended) but 10,000 feet is not that high. In World War 2 the Germans had anti-aircraft guns that could easily get to much over 20,000 feet. Many cheap modern shoulder held anti-aircraft missiles can easily shoot this high and a blimp would be easy to hit. It might be safe from small arms fire but a few small holes wouldn't hurt it much. An anti-aircraft missile is another matter.
Irresponsible waste of nonrenewable resources (Score:5, Informative)
The amount of Helium on the Earth is very small (though there is lots in space). Helium is needed for medical MRIs and scientific research, but we are going to run out in a few decades. My lab is already suffering from increased Helium prices. Helium has a nasty way of escaping from containers (we're only able to recycle about a third of what we use), so these blimps are likely to waste a lot. Just like the rest of the missile defense systems, they'll never be used for their intended purpose.
Re:Overpriced wrong price (Score:5, Informative)
That billion dollar price includes the communication system between the aerostats radar and the targeting radar of other systems like anti-aircraft missile systems. So it is a very misleading number. I would guess the "blimp" or really aerostat part is less than 5% of the total cost. This is really an integrated detector system that happens to use a blimp as one of its inputs.
Re:Why Helium and not Hydrogen? (Score:3, Informative)
Hydrogen is not actually much lighter than helium. What matters is not the molar mass, but the difference between the molar mass and the average mass of air - this is what generates buoyancy. Hydrogen is 2 g/mol, helium 4 g/mol, air approximately 29 g/mol (it is a mixture, so that's the average value). Ths means that 1 mol (about 22,4 l) of helium will lift 25 g, and 1 mol of hydrogen - 27 g. Therefore hydrogen is only 8% better than helium.
Re:Why Helium and not Hydrogen? (Score:4, Informative)
No. Two protons. Atomic hydrogen is pretty much never seen in nature. It's always bonded as H2. I think that's actually a slightly bigger molecule than mono-atomic He.
Re:Blimps (Score:1, Informative)
Re:1.4 billion? What is that describing? (Score:2, Informative)
Regarding the aerostats floating over Iraq and Afghanistan now, these are likely the Persistent Threat Detection System [lockheedmartin.com].
Re:Blimps (Score:2, Informative)
There are no satellites in orbit that can do this job right now. To put new one up would cost quite a bit more.
A drone with enough radar power to do the job would be called an E-3. This requires huge airports and infrastructure to support.
Re:Irresponsible waste of nonrenewable resources (Score:3, Informative)
I eagerly await somebody's explanation of how the Free Market will conjure up a substitute...
As the price of helium goes up it will become worth it tap more expensive supplies of helium, and people will use less of it. This is pretty basic free market economics.
I had no idea (Score:3, Informative)
So except for the US, who has a huge cruise missile fleet that needs to be guarded against?
Re:Irresponsible waste of nonrenewable resources (Score:3, Informative)
Liquid helium is pretty unique as a coolant - it boils at 3-4 K, and is needed to cool the core in superconducting magnets. Everything else has a much higher boiling temperature (quickly scanned off of wikip) - 20 K (hydrogen) 77 K (nitrogen) or 90 K (oxygen, paramagnetic - no good for superconducting magnets anyway).
It's also pretty standard to measure well below 20 K - down to mK in some experiments - and you can't do this without sucking hard on LHe. I'm not an expert but I use LHe a lot and I don't know of any alternative. Already the price of (very) high purity He gas has gone up - we're not able to do as many experiments as we would like. As much He as possible is recovered and re-liquified but you always lose some to atmosphere when doing transfers, and so have to buy more (as well as pay for the liquification).
Re:blimps (Score:3, Informative)