
Atlas: A Human-Powered Helicopter - yurisagalov
http://www.kickstarter.com/projects/1156290643/atlas-a-human-powered-helicopter-for-a-historical
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joachimd
Wow competition is heating up as there is already a well established group
called Upturn going after the prize. They also have a Kickstarter campaign and
are much further along with a working model that is now getting tuned.
[http://www.kickstarter.com/projects/1594333219/make-
aviation...](http://www.kickstarter.com/projects/1594333219/make-aviation-
history-with-a-human-powered-helicop)

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yurisagalov
This project is from the same team that recently set the Guinness World Record
by building a Human Powered Ornithopter
(<http://www.youtube.com/watch?v=0E77j1imdhQ>)

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Tichy
That video seems weird: since apparently they launched the ornithopter with
some machine, how is it even clear that it stayed afloat by using human power
after launch? Where is the difference to a glider?

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pygy_
_> Where is the difference to a glider?_

It sustained altitude _and_ speed for a while (short of 20 seconds).

See this: <http://www.youtube.com/watch?v=0E77j1imdhQ>

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jrockway
Gliders can gain altitude and speed. There are plenty of spots on the surface
of the earth where air is rising quickly enough to support a plane.

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pygy_
True.

I guess we can dismiss the possibility of ascending currents in this case,
since the test was performed on uniform land, at dawn.

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marvin
Glider pilot here. That does make it less likely, but it is no guarantee that
there were no rising air currents. Thermals are sustained by an atmospheric
temperature differential, not "hot air rising". They are usually _triggered_
by the local temperature differences caused by the sun, but can also be
triggered by a gust of wind.

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pygy_
Thanks for teaching me something. I was referring to this[0] which is indeed
hot air rising and only occurs at low altitude, you're talking about this[1].

Is there a possibility for the phenomena you describe to occur 10 meters above
flat land at dawn?

[0] <http://en.wikipedia.org/wiki/Thermal>

[1] <http://en.wikipedia.org/wiki/Thermal_wind>

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marvin
Hi, sorry for the late reply. I only briefly read the second link, but I don't
think it's what I was talking about. I read the Wikipedia article on thermals
a week ago, and it seems a bit brief. I was a bit quick with my first reply as
well. This is a pretty big subject.

Thermals can be triggered by any perturbation in the atmosphere - a gust of
wind, a truck on the highway or a temperature differential caused by the sun.
But they are _sustained_ by vertical temperature differences in the
atmosphere: As an airmass rises, it expands due to the lower atmospheric
pressure. This expansion causes the airmass to cool adiabatically,
approximately one degree Celcius per 100 meters of gained altitude.

However, meteorological conditions can cause the temperature distribution of
the _surrounding_ air to be different. For instance, after a clear night with
no clouds, perhaps the air from the ground up to 2000 meters altitude actually
decreases in temperature 1.1 degrees Celcius per 100 meters of altitude
gained. If an airmass on the ground starts moving upwards in these conditions,
it will still cool adiabatically - but slower than the rest of the atmosphere
cools due to the meteorological conditions. So a rising airmass will actually
accellerate, because the airmass grows hotter relative to the surrounding air
as it rises. This is a thermal. It will keep moving until the temperature of
the atmosphere starts rising with altitude. Condensation (cloud formation,
cumulus clouds are caused by thermals) can increase its vertical speed.

But to answer your initial question: Yes, they can and do. But when the
atmosphere is so _unstable_ (unstable atmosphere == temperature falls very
quickly with altitude) that thermals are spontaneously triggered without help
from the sun, it will usually mean bad weather or thunderstorms later in the
day. So if the air seems calm at the surface, it will pretty much be
guaranteed to be calm at 10 meters altitude. You can detect thermals at ground
level by rapidly changing wind direction, often on nice summer days. In the
air at low-ish altitudes (less than 2000 meters), thermal activity is
indicated by turbulence.

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starpilot
Wow. I spent most of my undergrad extracurricular effort working on my
university's HPH team. Incredibly difficult challenges in aerodynamics and
structures. The goal is to go for a whole minute and reach 3 m altitude. In
the few decades the prize has been offered, the record has been _seconds_ and
centimeters high.

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option_greek
I can understand the altitude limitation but whats limiting hover time..
losing balance ?

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archangel_one
Presumably the pilot must be pedalling pretty hard to get this thing in the
air, so they're not going to be able to keep that up forever.

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suhastech
Interesting. The first project they seem to have funded on Kickstarter.

[http://www.kickstarter.com/projects/1594333219/make-
aviation...](http://www.kickstarter.com/projects/1594333219/make-aviation-
history-with-a-human-powered-helicop?ref=users)

~~~
joachimd
That is a different project, different set of people.

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reledi
Cameron and Todd backed the Upturn project on Kickstarter, they didn't create
it. NTS Works (the organization behind Upturn) is in competition with AeroVelo
(the organization behind Atlas).

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alagu
On some guesses of how future will be, I definitely see jetsons-type
single/two person local commute micro-aircrafts.

Curious, who else is working on micro-aircrafts with engines for local
commute?

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netrus
I always fail to see the market there. Why is it superior to the car,
considering the higher costs for fuel, that will be unavoidable?

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alagu
Market is where land commute takes time. Eg., in Bay area, there are lot of
people who commute from South Bay to San Francisco. Slow traffic is common
during peak hours and it is frustrating. I see this area as one of the best
places to try local air-commute.

It would add the third dimension to the commute space. Like the fast-lanes in
freeways, lanes could be formed by altitude.

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suby
I think a far more likely solution / scenario is that we'll have cars that
drive themselves. It'd also be a hell of a lot safer.

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SagelyGuru
It seems a bit pointless when it would be relatively easy with a dirigible
(i.e. add a bag of hydrogen or helium). On a windless day, your pedalling
should propel you quite a distance anywhere you want to go. Problem solved,
with technology that is at least hundred years old.

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WestCoastJustin
The goal is to win the American Helicopter Society (AHS) prize of 250k. The
regulations ([http://www.vtol.org/awards-and-contests/human-powered-
helico...](http://www.vtol.org/awards-and-contests/human-powered-
helicopter/hph-rules)) specifically outlaw your suggestion -- although it was
a good one ;)

4.1.1 The machine shall be a heavier-than-air machine. The use of lighter-
than-air gases shall be prohibited.

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SagelyGuru
OK, thanks. So how about I use strong carbon fibre shell with air pumped out.
There is no lighter than air gas involved and the whole machine can be (just
slightly) heavier-than-air. I bet they would outlaw that too, under the 'catch
all' rule mentioned below. Nothing but extremely hard work will do ;)

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leoedin
It'd have to be a very strong shell to actually give you buoyancy above simply
not having anything. Carbon fibre is strong in tension, while a material which
can support a vacuum must be strong in compression. The weight of any shell is
going to be much greater than the buoyancy you'd gain.

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K2h
More pictures of the streamlined high-speed recumbent bicycles at
<http://www.flickr.com/photos/adamince/page2/>

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grannyg00se
It looks like the state of the art right now gives us absolutely huge devices
that barely even make it off the ground. Does anybody have any confidence that
a human powered helicopter could ever be practical for real transport? Unless
we humans somehow manage to multiply our sustained power output by several
times, I don't see this happening.

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SagelyGuru
I suggest at least eight strong men in a row. You get aerodynamic and scaling
benefits, just like with rowing boats.

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xyzzyz
Air vehicles are light, men are heavy.

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Tichy
Why aim so low? I say kickstart a perpetuum mobile!

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crazy_eye
Neat, but this idea can only go so far on this planet (gravity, etc). Maybe on
our next planet...

