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NSS
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Solar Sail

11/29/2009 2:12 PM

Can anyone answer this.

Imagine a solar sail. in the shape of a half sphere, or at the worst say a Pyramid.

say set up like a wind anemomenator.

I know regular "Wind" with this has different "Wind" resistances be it blowing across the open end of the half spheres, or around the round end.

But would the equivalent of "Solar Wind" behave the same way? I know the force would be extremely small. but does a "Solar Wind" behave in a similar way as regular air "Wind' and cause different pressures?

Thanks
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Tornado
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#1

Re: Solar Sail

11/29/2009 6:05 PM

I doubt that the cupped effect would make much if any difference on how the solar wind impinges on either side of this. However, there used to a science kit toy called a "radiometer." The vanes were silver on one side, black on the other. The difference between absorbing and reflecting the incoming radiation results in different forces on either side, hence rotation of the wheel. It would take a rather sizable unit to get much out of it, however.

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ffej
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#2
In reply to #1

Re: Solar Sail

11/29/2009 10:45 PM

This has been a topic of discussion before.

If the light (photons) were the cause of the rotation you'd expect it to rotate away from the mirrored side. This isn't what happens. It rotates away from the mat black side.

There are explanations of what really happens available on the web.

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mjb1962853
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#3

Re: Solar Sail

11/29/2009 10:45 PM

Space fairing solar sails use photon momentum.

Radiometer is nice proof-of-concept demonstrator.

This link should answer your question more thoroughly...

http://en.wikipedia.org/wiki/Solar_sail
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ffej
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#4
In reply to #3

Re: Solar Sail

11/29/2009 11:00 PM

No, a radiometer is not a "proof of concept", it works on a different principle. see post 2

http://en.wikipedia.org/wiki/Crookes_radiometer.

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mjb1962853
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#5
In reply to #4

Re: Solar Sail

11/29/2009 11:35 PM

Interesting. Crookes radiometer does NOT demonstrate the solar sail concept. Last remaining shred of respect for my physics teachers has just left the building.
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ferquiza
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#6
In reply to #4

Re: Solar Sail

12/01/2009 12:44 PM

I heard both opinions before.Is one more subject to know,( by research) about when i get retired or if you are kind enough tell us what you know and not "available in the web".Thanks in advance...
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