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250-Foot Hybrid Airship To Spy Over Afghanistan
Toe, The writes "Gizmodo details the Long Endurance Multi-intelligence Vehicle (LEMV) (based on the P-791), a spyship from US Army's Space and Missile Defense Command capable of hovering at 20,000 feet. Planned for deployment in Afghanistan, the ship can float for three weeks and carry well over a ton of payload, apparently surveillance equipment. The video on Gizmodo of the P-791 shows that these ships are a hybrid not only of both buoyancy and propulsive lift, but also of both awe and hilarity."
It seems that there is a limit on slashdot article title length. Many submission in the firehose section also have missing endings in their titles.
1) Are they really more efficient?
They're certainly better than helicopters for hovering and slow patrolling, but for transporting lots of people or stuff to a definite destination I doubt it. Given the typical shapes used, I can imagine them spending lots of fuel just fighting the wind or air resistance. Not going to be easy to beat ships or trains, or even normal planes.
Airships are fuel efficient if you don't mind going wherever the wind blows you.
2) What gas to use though?
I don't think there will be enough helium to go around:
http://www.wired.com/wired/archive/8.08/helium.html
http://www.usatoday.com/news/nation/2007-12-02-Helium_N.htm
So the options are hot air (which doesn't produce as much lift) or hydrogen (which has significant PR problems for airship usage).
I suppose this would be a smaller problem. Could use hydrogen both for fuel and for lifting.
No. When used in the attributive position, the unit labels on such quantities are given in the singular form, whether it's a 250-foot airship, a seven-mile trip, a twenty-dollar entree, or a three-day conference.
Now, if you put it in the predicate, then you use the plural form: the airship is 250 feet long, the trip is seven miles, the entree costs twenty dollars, or the conference lasts three days.
If you have more questions like this about English grammar and usage, I'm available on Lang-8 (same username as here). HTH.HAND.
Cut that out, or I will ship you to Norilsk in a box.
Thankfully, as the article states, the military isn't planning on making this aircraft to open a speedy and luxurious cruise line over Afghanistan. The airships will be used for aerial surveillance, where staying in one place for long periods of time is the main goal. They are designed to remain aloft for a few weeks at a time, something that ordinary aircraft can't do.
True but then again this thing will have a long slant range as well. At 20,000 ft it's sensors will have a very long line of site. Well outside of the range of those guns and probably the SA-2.
In a limited theater type war if anybody was to light up one of these with radar I am sure that it would get catch a HARM very quickly.
Think of this as a supplement for the E-3 and the P-3.
The P-3 is big and slow and so far none of them have been shoot down over Afghanistan. And yes they are actually popular sensor platforms in that theater.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
The real problem is speed, or rather the lack thereof. Air travel became as popular as it is because it's so much *faster*. People might book an airship flight once a decade for the novelty, kind of like a cruise ship trip, but they're not going to hop on the blimp whenever they need to get to the other side of the country. The trip would take too long. Jets are faster, so they win.
People still use cars for cross-country travel. It appears that there's a serious misconception about airship speed here. Maybe we're used to seeing blimps lumbering around stadia (yeah, I typed stadia). These limp airships are only about 1/4th the size of classic rigid craft, and are intended to cruise around 30 knots. The Hindenburg made 85 mph on 4 diesel engines. The USS Akron could do 83 and the Macon 87. These were all built in the 1930s, and were designed to be much faster than surface vessels with much longer range than heavier-than-air ships. Assuming a modern passenger airship could do 100-200 mph, it could easily compete with high speed trains and cars -- even jets for trips under 500 miles or so. People use jet travel not for the speed advantage over airships, but rather for the all-weather availability. It would seem the military picked 20000 ft operational altitude to mostly avoid the problem of weather closer to the surface.
I am not a crackpot.