> - Can handle any size/wheight cargo, as opposed to underground
> tunnelsystems. A complete factory or offshore rigg would pose no
> problem for a large airship.
A *very* large airship. That's definitely a niche application.
> Because of their low-noise propulsion
> this should not bother anyone.
But an airship will be much larger than an equivalent fixed-wing aircraft
and fly lower, will therefore produce more drag, and hence require more
power to sustain the same speed *and* be lower so the noise will be worse.
You only save on power by reducing speed and increasing the travel time.
> Besides all that the idea is that they replace at
> least some airplanes (lower operating cost, less noise, less pollution...)
Then why haven't they? As you said, we can build them today, but we're
not. The most probable answer is that a) they're too slow and b) they're
too expensive. As far as I'm aware, the major expense in operating a
modern jet is the cost of leasing it, and this is why airlines fly them as
often as possible. An airship travelling at 150 mph would have to be far
cheaper to lease per ton-mile than a 747 at 500 mph, even if it did use
less fuel.
Airships are cool, but I really doubt they're economically feasible on a
large scale. One thing I have been impressed by lately is the 'Moller
Skycar', at http://www.moller.com; a four-seat VTOL aircraft somewhat
larger than a four-seat sedan, which should get 15 miles-per-gallon at 350
mph. They claim the prototype will fly soon, but the $1 million price-tag
is a bit annoying.
Mark
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