[HN Gopher] Flying Only with the Heat of the Sun
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Flying Only with the Heat of the Sun
Author : john-doe
Score : 75 points
Date : 2021-07-24 12:08 UTC (1 days ago)
(HTM) web link (www.notechmagazine.com)
(TXT) w3m dump (www.notechmagazine.com)
| tdeck wrote:
| When I was a kid at science camp we demonstrated this effect.
| They had a very long sausage-shaped black plastic bag that we all
| rand around filling up and laid out in the sun until it rose. I
| always assumed this strange bag was designed for such demos. In
| our case something happened (a person let go, a tether broke; I
| don't recall), and the "solar sausage" flew away completely until
| we could no longer see it.
| elif wrote:
| I'm no balloon expert, but it seems like they could have absorbed
| more heat with a translucent top.
|
| Then the solar rays would enter the chamber before hitting the
| black fabric and reflecting back into the chamber.. more
| frequencies of light, more chances to catch the heat.
|
| Like the SHGC effect observed by closing/opening curtains
| ramraj07 wrote:
| Isn't almost anything that's not powered by nuclear energy flying
| only with the heat of the sun with extra steps? If you include
| the definition of "some sun" then even nuclear energy is the
| same, just with a multi billion year cycle.
| phreeza wrote:
| Just to counter your nitpick with another nitpick, geothermal
| is also not solar with extra steps :-)
|
| Edit: tidal power would also seem to fall into that bucket
| because it comes from the gravitational forces of the solar
| system.
| unishark wrote:
| Imagine the climate change problems if we used up too much
| gravitational energy from the solar system.
| [deleted]
| devenson wrote:
| Slowing the rotation of the earth.
| [deleted]
| dimman wrote:
| Oh noes, not longer working hours...
| Robotbeat wrote:
| Sailplanes also do this. "Gliders" get a brief mention as an
| aside, but it's somewhat glossed over, but fundamentally the
| sport of flying depends on the same solar thermal phenomenon
| except instead of producing black material to absorb sunlight,
| sailplanes rely on existing low albedo features of the landscape
| to generate the solar heated air.
|
| Sailplanes air often towed to the air by powered aircraft in the
| US, but higher performance sailplanes usually carry their own
| motor for self launch (often electric) and in Europe are often
| winch-launched. Gravity launch (rolling down hill) and auto tow
| (a car pulls the sailplane into the air, usually with a pulley)
| are also fairly common, and the former would meet this "low tech"
| qualification.
| m4rtink wrote:
| I really recommend anyone flying a glider as a passenger (in
| Europe this is often possible on regional air shows run by the
| local aeroclub) it's totally different experience to engine
| powered aircraft!
|
| It's much quieter than small general aviation aircraft so you
| can talk to the pilot without a headset, the only noise being
| the air flowing around the plane.
|
| The whole plane is also usually much lighter and has better
| visibility, not to mention being very graceful. At least for me
| the experience felt much more direct and elegant.
|
| And the experience of being powered pretty much directly by
| nature _and_ the pilots skill in finding the invisible rising
| thermals is priceless! Its the perfect metagame, the pilot uses
| their extensive meteorogical experience to guess where the
| thermals are and flies there. If the guess was right you are
| rewarded by the sweet sweet positive altitude value on the
| variometer. If the guess was wrong the altitude budget is spent
| and you have to land and try again.
|
| And lastly, it all feels so safe! Like, really - the aircraft
| has no engine that can fail and is pretty much built to land on
| any reasonably flat field. And the pilot is trained to always
| look for a landing area in case they don't find thermals and
| have to land early.
|
| And what happens if a glider lands in a field ? Gliders have
| detachable wings so that they can be loaded on trailer
| dispatched from the airfield. In favorable conditions sometimes
| a tow aircraft can be dispatched to land near the glider on the
| same field and tow it aloft again.
|
| Really, gliders are so much different than "normal" aircraft
| yet so fascinating! :)
| vitro wrote:
| Yep, we have an airport nearby and anytime you can pay and go
| for a flight.
|
| As for thermals, also search for gliding birds as they may
| have found them first!
| ZeroGravitas wrote:
| I find these and the low tech magazine articles fascinating,
| though I sometimes feel that either I'm a) falling victim to an
| elaborate prank, b) unknowingly supporting the output of
| someone's mental health issues (though I feel that about some of
| my best loved musical acts too).
|
| Now that's there's two sources, I'm further confused as to
| whether one is mocking the other, but if they are it's possibly
| too subtle for me to catch.
| spodek wrote:
| I consider No and Low Tech Magazine among the best sites on the
| web. He's living by different values than mainstream. He loves
| technology and he loves sustainability. For many those loves
| conflict. They keep seeing attempts to make things more
| efficient lead to more pollution. They don't think in systems.
|
| His values are more in line with history, particularly before
| the industrial revolution. He finds out and shares how people
| did things without burning fossil fuels that we can learn from.
|
| The site has changed my life. One example: his articles on how
| power grids become insecure and expensive with higher uptimes,
| making using just renewables harder
| https://www.lowtechmagazine.com/2018/12/keeping-some-of-
| the-..., combined with an article on fermentation in Vietnam
| https://www.lowtechmagazine.com/2017/02/vietnams-low-tech-fe...
| led me to try unplugging my fridge. Using my windowsill for
| cold and fermenting, my first try two winters ago, I made it
| three months. My next try, last winter, I started earlier and
| made it 6.5 months. My food was as delicious as ever and my
| electric charges dropped to under $2.00 per month. More
| importantly, I live more resiliently. If more people lived this
| way, large parts of the country could go with just renewables,
| barely any batteries, no peaker plants, no nuclear, more
| health, longevity, prosperity, stability, energy security.
|
| With that little energy use, I'm going to try taking my
| apartment off the electric grid for a few months this winter.
| That's living in Manhattan. I'll also start earlier as I
| developed more skills to store and ferment without a fridge, so
| starting in October or maybe September, I figure I can go 8 or
| 9 months without a fridge -- that is, living resiliently.
|
| To clarify, my power reduction is a side point. Divided by 7.9
| billion it's a rounding error. It's the value shift from
| dependence to independence, from relying on burning fossil
| fuels to learning from my neighbors, family, and ancestors. The
| cause of our environmental problems isn't CO2 and plastics.
| They result from our behaviors, which result from our culture.
| He comes from a culture that doesn't cause these problems, or
| at least orders of magnitude less.
|
| Such solutions are practical, affordable, immediately doable
| and most available to those with the least resources. His
| philosophy focuses on improving human life, community, and
| Earth's ability to sustain life.
| Robotbeat wrote:
| Man, we still need industrial scale clean energy solutions
| (to make your apartment, etc). Solar balloons are terribly
| inefficient & impractical compared to, say, a solar aircraft.
| asymmetric wrote:
| What's the relationship between No and Low tech magazine?
| spodek wrote:
| No tech magazine posts short quotes from other sources.
|
| Low tech magazine posts longer, original articles.
|
| Same people behind them, as best I can tell.
| aaron695 wrote:
| Here's a toy one, good reviews, but fragile (have tape) and prob
| use once -
|
| https://www.amazon.com/TEDCO-Tedcotoys-Activity-50-foot-Ball...
|
| Practically perhaps you could use the principal to manage
| buoyancy on lighter than air... unlikely though, to much added
| complexity.
| lovemenot wrote:
| At the end of the article:
|
| >> The problem remains that fully solar balloons need sunlight,
| and it is rare for the sky to remain unclouded for long journeys.
|
| Above 6,000 metres, it is rather rare that any cloud blocks the
| sun in daylight hours. This method of transport has potential for
| freight.
|
| Rather than black, you'd want a transparent skin or layers of
| skins. Focus sunlight with internal reflectors onto an engine.
| Usefully, waste heat is not a problem here, but valuable, when
| captured in the envelope.
|
| The engine should use more than just heat energy. Visible light
| for PV power generation. Maybe ultraviolet can be used to
| elecrolyse environmental water vapour to hydrogen. To provide
| both lift and energy storage for night time.
| m4rtink wrote:
| Similar system (partially transparent baloon) can be used in
| space for the solar thermal engine concept:
|
| http://www.projectrho.com/public_html/rocket/enginelist.php#...
| lovemenot wrote:
| Nice. Space lacks a key drawback of the atmospheric solar
| concentrating balloons. Namely wind. It is difficult to point
| reflectors at the sun when the whole craft is slightly
| changing orientation all the time.
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(page generated 2021-07-25 23:02 UTC)