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Experimental Fuel-Cell Airplane Begins NASA Test
gilgsn writes "Planenews.com has a NASA press release from their Dryden Flight Research Center about the first large fuel-cell powered airplane to fly. The Helios prototype took-off Saturday at 8:43AM from the Hawaiian island of Kauai, using solar panels to power its 10 electric motors for takeoff and during daylight portions of its 20-hour shakedown flight. As sunlight diminishes, Helios switched to a fuel cell system to continue flight into the night. I wonder how long it will be before fuel cells are used on homebuilt experimentals."
Yes, well, cost per kg of a satellite is atleast $4600/kg (~$10,000/lb, and that's to low earth orbit which is only over the horizon for a few minutes at a time- GEO sats are visible all the time but are 3x more expensive). But you usually don't get these satellites back again, and if anything goes wrong up there, you're screwed. With Helios you can bring it down, fix it and send it back up.
The biggest problem is that it's still more or less a solar powered craft -- and solar energy just doesn't have the density to do anything useful and still be mobile.
Well, it's 1.5kw/m^2. That's more power than a 1 bar electric fire. Ok, so solar panels at the moment are at most getting to around 40-60% efficient (for lab samples, small production/expensive ones are more like 20%, cheap ones are 10% or so), but that's still quite a bit of power.
Although... maybe something like this could make a reasonable alternative to those Broadband Broadcasting Balloons (say that three times fast!), since these craft can fly at higher altitudes and make roam to areas where they may be needed more.
Yes, very probably would work. That's the point of the fuel cell; they can keep it up there 24 hours a day; previously it was coming down at night. 762 pounds of radio equipment should be plenty; provided it doesn't suck too much juice. It might even be possible to build a passive system- just bounce the radio waves off the underside of the vehicle.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"We aren't going to run out of oil. We're only going to run out of petrochemicals. There's always going to be oil; you can run diesel engines on vegetable oil for example.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"Not to be a wet blanket, but while Helios is really neat it's not terribly useful.
You're not a wet blanket, just wrong. They have already completed HDTV trials, lots of other applications to follow. Cell towers will be replaced by these. Cell towers have been unpopular in most areas. No one wants to live next to one. These can be easily launched and can be made cheaply.
It might be cheaper than launching a satellite in some cases,
It's definitely cheaper than launching a satellite
For the cost to build and operate the vehicle it clearly doesn't have any commercial potential
Oh really, can you provide some facts to support that claim? You simply just don't know what you are talking about. Have a look at Skytower Global and look at Aerovironment too.
http://tinyurl.com/3t236
If the entire planet converted to wind power in 30 years, it would take another 300 years to remove the extra heat from the last 300 years of fossil fuel use. Until we get control of it, we won't be able to pick an optimal CO2 concentration value for the planet.
May 29 Press Release
June 7 Press Release
If you click on that Kauai picture from the Dryden home page, look at the window title: the payload is denoted as "amphitech radar" -- which I surmise means something that weighs about the same as what they think they would need for a sufficiently suitable unmaned AWACS drop-in replacement.