Posted on 03/05/2004 12:35:42 PM PST by Calpernia
The dirigible, or airship, may be employed as a tool to detect potential attacks against the United States, DoD officials told House subcommittee members March 4.
"We believe the best way to protect Americans is to defeat terrorists as far away from our homeland as we can," Air National Guard Maj. Gen. John A. Love said in his prepared testimony before the House Terrorism, Unconventional Threats and Capabilities Subcommittee. Love is a senior officer with U.S. Northern Command, the unified command charged with defending the United States from land, air and sea attack.
Paul McHale, assistant secretary of defense for homeland defense and National Guard Bureau chief Lt. Gen. H. Steven Blum also provided testimony.
While U.S. troops are taking the fight to terrorists in places like Afghanistan and Iraq, Love asserted it's also important "to win the 'home game' by protecting, defending and defeating threats against our nation."
Recent technology demonstrations, Love said, point to the potential use of airships to patrol a 500-mile "buffer zone" established outward from the American coastline.
High-altitude airships, Love continued, could provide "over-the-horizon" surveillance across North America "and out from our coastal waters for air, ground and maritime threats."
Use of airships for homeland defense purposes, McHale explained, is consistent with DoD's charter to provide "the military defense of our nation from attacks that originate from abroad." Testing of prototype dirigibles, he said, demonstrated they "could provide wide area surveillance and communications capabilities."
McHale pointed out DoD's partner role with the Department of Homeland Security in its mission of protecting the nation against, and preparing for, acts of terrorism. DoD, McHale said, stands ready to "provide assets and capabilities in support of civil authorities, consistent with U.S. law."
National Guard Bureau chief Lt. Gen. Blum told House committee members the Guard "is uniquely suited for operational missions inside the U.S. to help protect both the American people and our critical infrastructure."
In fact, there are now 32 certified Weapons of Mass Destruction Civil Support Teams, the three-star general said, noting, "More are on the way." Blum said each team features 22 Army and Air National Guard specialists trained to detect and identify chemical, biological or radiological hazards, and assist in follow-on activities.
Another initiative involves the reinforcement of WMD civil support teams, Blum noted, with "existing medical, engineer and security forces from either the Air or Army National Guard."
The result, Blum pointed out, is "a more robust capability in response to a WMD incident."
Oddly enough, a friend and I were almost decapitated by a '34 Chrysler Airflow, 'way back when. We were leaning over the engine looking at this and that, straightened up, and the hood fell shut all by itself about a second after our heads were clear. Very solid clunk!
What kind of global 'coverage'?
True, but buoyancy comes from the difference between the density of the vessel and that of the surrounding fluid. So if hydrogen weighs 1 and helium weighs 2 and air weighs 100, then in air the lifting power of hydrogen is 99, while that of helium is 98.
I've forgotten the actual values involved, unfortunately.
This seems to be a common misconception ... the real relationship according to www.flyingkettle.com/jbfa.htm is:
and from www.sfu.ca/~howardc/delta/operations/operations.htm
- Hydrogen offers the best lifting performance of 11.19 N/m3 in the ISA (International Standard Atmosphere), but its high flammability makes hydrogen politically unacceptable nowadays.
- Helium provides 10.36 N/m3 lift and is completely safe, but it is very costly, and is difficult to transport and supply.
- Methane provides only 5.39 N/m3 lift and has no particular merit because it offers no safety advantages over hydrogen.
- Ammonia provides 4.97 N/m3 lift and is cheap, non-explosive, and quite easy to transport and supply, but it is somewhat corrosive, toxic and malodorous, and has not found favor in practice.
- Hot air must be kept hot by burning fuel, and buoyancy control can be performed by varying the fuel burning rate. Hot air is very cheap and easy to supply, and is completely safe, but it provides rather poor lift. In practice the temperature of the air in a hot-air balloon envelope varies between 100oC and 120oC, and thus the lift provided is between 2.7 N/m3 and 3.2 N/m3.
Helium gas has 92% of Hydrogen's lifting capacity even though it is twice of its density
Did you miss that part about 'surveillance' (or detection) in the article?
From the article: "The dirigible, or airship, may be employed as a tool to detect ..."
GPS provides radiolocation services to the user base - not surveillance or detection services ...
Incidentally, for future reference, the GPS NAVSTAR radiolocation system contains 24 satellites.
Detailed info available from these authoritative sources (IOW - don't just take my word for it):
www.aero.org/publications/GPSPRIMER/WhatisGPS.html
Funny ... John H K mentions 'recon' in the first sentence of his post ... if you want to be specific about it - simple 'coverage' is dependent on a number of factors, and, theoretically could be achived via just one geosynchronous bird ...
You don't see one good physics-based reasons why this might be undoable?
I do. In fact, I see several ... one has to do with the inverse square law as it relates to the expansion of a propagating 'radio' (EM) wave ...
1 satellite in geosynchronous orbit can't do the reconnaissance job of even one balloon, because of its distance from Earth. Trying to, say, photograph Earth from geosynchronous orbit is not likely to be terribly successful.
I think I saw something about that on the History Channel. But once the external fabric caught on fire, it was inevitable that the hydrogen gas bags would also ignite.
True, though hydrogen rises so quickly that the flames shoot up and away. Looks spectacular, but much less dangerous to people on the ground, and it's over quickly. The Hindenburg's hydrogen did catch on fire, but what you see in the film is its fabric burning.
Just the usual. Technology marches on. The one satellite needn't have just a small antenna, nor even just one antenna.
Effectiveness is proportional to funding, which beats the inverse square law. How much money you got? Enough to build 1000 balloons and equip, maintain, and operate them?
Let's try a 'fer instance' using a relatively modern, more or less common example of what we're looking at here -
- let's take the NWS's WSR-88D which employs a 28' dish, an S-band freq of 2.4 GHz (thereabouts) which results in 45 dB of gain and a 3 dB beamwidth of just under a (1) degree ...
... do you know what kind of distance an arc of 1 degree covers at 35,786 kilometers (19,323 nautical miles or 22,241 statute miles) above the earth's surface?
The problem that arises is that - MULTIPLE 'targets' would be indicated with a beamwidth at that distance - and I've not consdered the path-loss that would be encountered *both* directions - with a poor reflection/reflector (the bogey aircraft) as the source for the return (signal) ...
A better solution might be increased use of land-based OTH (Over The Horizon) HF (High Frequency) RADAR rather than a) balloons or b) an impossible satellite solution ...
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