
Solar Impulse lands in California after Pacific crossing - frgewut
http://www.bbc.com/news/science-environment-36122618
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barney54
The Solar Impulse is really cool technology. It also shows why oil use has
been so prolific. the energy-to-weight ratio of jet fuel is a marvel when you
consider the size of today's jet aircraft and the distances they fly with
hundreds of passengers.

~~~
barrkel
Indeed. I expect we'll synthesize jet fuel or a close equivalent (something
that burns and reduces airframe weight) from electric or bio sources long
after most other engines have moved to electric. Perhaps we'll generate
electricity on board, but it will be with a dense, wasting fuel.

And we certainly aren't going to use solar to power commercial human air
transport any time this millenium; it will always be better, for people, to
compress energy before a flight and travel faster, than try to make the flight
itself self-sustaining and travel slower. The only exception could be
recreational flyers.

~~~
cmsmith
We've been synthesizing one liquid hydrocarbon fuel for thousands of years;
ethanol is pretty similar to jet fuel in energy density and combustion. I
think the possibility that in the future we'll have cheap solar/wind grid
power and use that to produce ethanol, rather than charge batteries, is more
likely than people think. Ethanol production isn't terribly efficient, but if
your input power is sustainable it doesn't really matter.

~~~
elithrar
Ethanol is about 70% of the energy density of Jet A-1:
[https://en.m.wikipedia.org/wiki/Energy_density](https://en.m.wikipedia.org/wiki/Energy_density)

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cubano
I am surprised that no one has been developing (or I haven't heard of) fully
autonomous airplane pilot systems. Something like that tied to a fleet of
solar planes like this for shipping stuff could be a real game changer for
certain types of cargo.

Flying actually seems like a much "cleaner" environment for the AI to navigate
then roads do, to be honest, and the dependence on instrumentation and not
visual cues as much is of course a natural fit.

~~~
zubiaur
There are several autopilots able to follow a route untethered with just
waypoints. Apm (ardu pilot mega) and pixhawk come to mind. From what I've read
it is still highly recommendable by the RC community to have telemetry links
and if range allows, manual control. These modules are used mostly as flying
aides but some companies are building RC planes with autopilot capabilities
and market them towards the mapping and surveying industries, charging a hefty
premium for it.

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brianmcconnell
Pilot here. I agree with other posts about energy density being an important
factor here. I don't expect to see all-solar aircraft anytime soon. The best
way to get aviation to become carbon neutral will be via biofuels, which
several airlines are already experimenting with.

That said, I can see a couple of areas where solar will contribute.

While it will be very difficult to generate all of the power needed for an
airliner via solar, there's no reason not to cover the aircraft in high
efficiency (triple junction) solar cells. A large airliner will have a usable
sky facing surface area of 1,000 square meters or so (rough estimate). Enough
to generate a few hundred kilowatts of power. If the aircraft has hybrid
gas/electric engines, that power can reduce the fuel burn a bit (even a small
reduction is a big deal).

I can also see where a serial hybrid design could be workable (e.g. lots of
fuel cells generating electric power that in turn drives electric fans). This
would be attractive, especially in smaller planes, due to the potential to
reduce the risk of mechanical failure.

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ruffrey
Impulse propulsion flown by Piccard? Checks out

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harwoodleon
"He predicted that, 50 years from now, electric aeroplanes would be
"transporting up to 50 people"."

Shame the mega storms that are swirling the planet at that point will probably
rip the planes out of the sky.

50 years too late if you ask me.

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chinathrow
What megastorms? Did I miss anything?

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throwaway5752
To busy to find links, but the gist is that Greenland Ice Sheet melting
disrupts the conveyor currents that transport heat energy between the equator
and the poles. Coupled w/ greater warming, the higher temperature differential
would support stronger and more frequent cyclonic storms (supported by models,
current trends, and archeological evidence).

~~~
stevetrewick
"The total number of hurricanes (particularly after being adjusted for
improvements in observation methods) and the number reaching the United States
do not indicate a clear overall trend since 1878"

[https://www3.epa.gov/climatechange/science/indicators/weathe...](https://www3.epa.gov/climatechange/science/indicators/weather-
climate/cyclones.html)

"Trends in tropical cyclone activity in the Australian region (south of the
equator; 90–160°E) show that the total number of cyclones appears to have
decreased to the mid 1980s, and remained nearly stable since. The number of
severe tropical cyclones (minimum central pressure less than 970 hPa) is
dominated by variability with periods of lower and higher frequencies of
occurrence."

[http://www.bom.gov.au/cyclone/climatology/trends.shtml](http://www.bom.gov.au/cyclone/climatology/trends.shtml)

"Similarly, the trend in intense tropical cyclones (minimum central pressure
below 970 hPa) is not significantly different from zero."

[https://www.ipcc.ch/ipccreports/tar/wg1/091.htm](https://www.ipcc.ch/ipccreports/tar/wg1/091.htm)

Or did you mean current trends in something else?

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gozur88
Yep. All the falsifiable predictions have turned out to be, well, false.

