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San Francisco, 12:02 AM
Mon Nov 30
11 posts in the last 24 hours
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03/09/09
O, O, O... O'Rei
03/09/09
03/09/09
I'm CSI:LV, Miami & NY trained. Even though I couldn't use Luminol or DNA or even polycyanoacrylate fingerprint lifting, my scientific analysis indicates that there is a great probability that the burned rims and engine parts once formed an internal combustion powered person or cargo vehicle normally found on roads and highways.
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11/10/08
Can't be the pictured item -- it's using a propeller.
All the electric fans in my house will testify that electric prop fans are anything but quiet -- especially at high RPM.
Now if you really want 'quiet'....either a very LARGE rotor with low RPM's (or...the VERY SLOW RETURN of the dirigible.) Since the dirigible's cabin isn't mounted in the same place as the propeller, vibration is less than in a blimp.
Secret fantasy -- return of large dirigible travel as replacement for 18-wheelers and ships. Possible? Could we go back to using Hydrogen for weight or maybe some H2/He mix? The Hindenburg has a flammable super structure as well as supposedly a nitro-cellulose type paint that would have been VERY flammable.
But now days -- some ultra light planes are using paper with glue and a carbon-skin -- could walls build of those substances be used to build a *vacuum* powered dirigible? 15lb/sq in? Sheet....we are talking 10.5 metric tons/meter. of max pressure resistance.
If I am vaguely remembering H.S. chem, H2(=2) weighs ~1/7.3 as much as atmosphere? (N2=14,O2=16). So a vacuum of ~15% could provide similar lift -- that's still a high 14lb/in^2 or 9.8Metric tons. How much
inter-spacial support would a vacuum powered dirigible need?
If it was Vac.-powered, another option would be heating H2 or H2 using the gas laws to change relative density...if outside temp was 70F (273+21.1->295), then if He2 was heated to 600C ~1112F, could achieve same lift factor as H2.
Perhaps there is some *useful* mixture of H2+He2? that would not be flammable and it used to heat?
Advantages of Vacuum-powered lift -- wouldn't have to worry as much about ballast issues. Reduce vacuum -> gain weight, increase vacuum, reduce weight.
Perhaps I'm misguided in my thoughts, but it *seems* that much of jet and airplane's fuel inefficiency stems from having to use to much fuel to provide lift.
If lift could be provided for little or no energy, (obviously a vacuum pump would have to count against a vacuum container's efficiency, then you only have wind-resistance against the dirigible -- perhaps a streamline design could allow pointing the longitudinal lift portion in the direction of wind flow, even while rudders /vanes or sails would move to ship foward...for that matter -- would it be
conceivable to use sail-boat technology to supply travel power to dirigibles?
Main use would be cargo transportation or slow luxury liner ship? Fantasy? or Sci Future?
11/12/08
I'd venture to say that from the ground, it would seem totally silent. Of course in the cabin, you would have some engine and prop noise, not to mention the din caused by the respiration of the pilot and passenger.
11/10/08
The functional problems with hydrogen cars involve the fact that hydrogen is an energy-storage medium (in practice), not a fuel.
Currently, in the US, a hydrogen powered car is nothing more than a car inefficiently powered by coal.
-Kle.
11/10/08
It was conviently pre-stored for us, but thats never going to happen again, ever.
From now on, its *always* going to be looking for ways to store energy generated elsewhere.
Unless you honestly think we are going to get nuclear fussion cars, your pretty much stuck with "generated one place, then used". (or, instead, we have a transport system run where the fuel is delivered on the fly....like trams)
Hydrogen is a pretty darn good store of fuel, and it can be made from many sources.
Coal, yes, but also Solar, Wind and (imho) the best; Directly from sunlight by growing special algea.
Of course, theres other options aside from hydrogen.
But hydrogen...which can be powered by many things...is certainly a lot better then oil, which *has* to come from a finite resource being used up.
The efficiancy point is wrong too...show me a car more efficiantly powered by coal directly! Coal is big and heavy. I bet if you made a coal car it would have a lot less range.
11/12/08
Coal is non-renewable, and we need to be careful, we only have 3-500 years worth left.
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