
Alexander Graham Bell’s Tetrahedral Kites - flannery
http://publicdomainreview.org/collections/alexander-graham-bells-tetrahedral-kites-1903-9/
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GnarfGnarf
The kites were part of his exhaustive investigations into aerodynamics. There
is an amazing display of his experimental propellers at the Bell Museum in
Baddeck, Nova Scotia. They show how he methodically varied attributes to
derive optimal pull. Well worth the visit.

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hawski
I once built a simple box kite. It was remarkable for me how easy it was and
how it could somehow perform even when there seem to be no wind. It was easier
to built than a diamond kite.

It was years ago and sometimes I'm thinking about building one again and
placing some action camera up there. To make a few drone-like shots, but for
much less money. But also because it's fun.

I built mine with a few wood slats, two shopping bags, some string and glue.

~~~
baldfat
I built a diamond kite with my dad and it is one of my favortie childhood
memories. For some reason I have never done it with my kids yet (Finding that
awesome kite paper has been elusive) but I have built dozens with kids I
worked with. Such a great learning experience.

[http://www.my-best-kite.com/kite-paper.html](http://www.my-best-
kite.com/kite-paper.html)

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jszymborski
This one looks like a Sierpinsky Triangle :)

[https://c1.staticflickr.com/5/4226/35286566316_65bcda7d3f_b....](https://c1.staticflickr.com/5/4226/35286566316_65bcda7d3f_b.jpg)

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kmill
That'd be a Sierpinski tetrahedron, but it's the same idea. I think it's
pretty interesting that these were made about ten years before Sierpinski
described the fractals, but then again the design appeared in mosaics from
much earlier:

[https://s-media-cache-
ak0.pinimg.com/originals/52/98/75/5298...](https://s-media-cache-
ak0.pinimg.com/originals/52/98/75/529875deedb52ebe7adad4a29d4dea48.jpg)

[https://s-media-cache-
ak0.pinimg.com/600x315/7b/7c/06/7b7c06...](https://s-media-cache-
ak0.pinimg.com/600x315/7b/7c/06/7b7c0653e7c82e33dddf7898e70baf2c.jpg)

~~~
jlg23
Where were those pictures taken?

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jszymborski
Reverse google image sleuthing leads to a pinterest board[0] that alleges they
are of the Cosmatesque style[1], which means they maybe originate from
somewhere in medieval Italy?

[0] [https://www.pinterest.com/paulettecadic/pavements-des-
cosmat...](https://www.pinterest.com/paulettecadic/pavements-des-cosmates/)

[1]
[https://en.wikipedia.org/wiki/Cosmatesque](https://en.wikipedia.org/wiki/Cosmatesque)

~~~
kmill
Thanks for the sleuthing. I found them myself by searching for Cosmati
mosaics, since Wikipedia mentions them in the article about the Sierpinski
triangle.

Captions for the two images:

Francesco De Comité took this photograph in the Church Santa Maria in
Trastevere, Rome,

Civita Castellana - Santa Maria Maggiore - Motivo detto "setaccio di
Sierpinski"

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VA3FXP
It's really inspiring and impressive the stability of these kites. The weight
to lift ratios are also fantastic. The linked National Geographic articles are
very informative and interesting.

Methinks this would make an excellent platform for a kite-antenna.

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cma
Do SpaceX's grid fins operate on similar principles?

[https://i.stack.imgur.com/rnHbB.jpg](https://i.stack.imgur.com/rnHbB.jpg)

(edit: and these:
[http://www.aerospaceweb.org/question/weapons/q0261.shtml](http://www.aerospaceweb.org/question/weapons/q0261.shtml)
)

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samstave
I'm sure that those are designed such to eliminate as much drag as possible
while also providing steering capabilities on descent?

~~~
digikata
On descent, one might think that increased drag is something of a useful
feature.

~~~
samstave
True, except if it has an uncontrollable effect on the overall steering of the
system.

Drag will vary greatly based on weather and wind, so it is likely not
something one would want to count on.

~~~
digikata
I believe that variability would be the domain of the control system and
launch/recovery parameters to handle no matter what the fin design. The
shorthand way to think about it is that the fin should not add any variability
that the control system does not have the authority to overcome (and by some
margin above that) - else one would not choose that combination of design
elements; apoligies if im retreading something you already know...

~~~
samstave
Yes, true - I just wasn't articulating that as clearly as you have.

I was thinking of "we don't want to rely on drag as a function of descent"
rather than "drag doesn't matter, because the control system is fully advanced
and capable enough to deal with any variance brought on by drag"

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dmd
We built one in my company's lobby a few months back!
[https://c2.staticflickr.com/6/5332/30663005756_793b436f73_k....](https://c2.staticflickr.com/6/5332/30663005756_793b436f73_k.jpg)

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perilunar
Inspired apparently by (the under-appreciated) Lawrence Hargrave's box kites:

[https://en.wikipedia.org/wiki/Lawrence_Hargrave](https://en.wikipedia.org/wiki/Lawrence_Hargrave)

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diggernet
I had a tetrahedral kite growing up. That thing was amazing. It would lift off
in a light breeze. And boy did it pull when the wind picked up. Great fun.

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wizardforhire
Is that a Sierpinski's triangle kite almost ten years before Sierpinski wrote
about it!? Regardless truly awesome.

~~~
gjm11
Yup. But (at least according to Wikipedia's article about the ST) the pattern
was around -- in art -- _centuries_ before Sierpiński!

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pencotts
Let us not forget Samuel Franklin Cowdery:
[http://www.atlasobscura.com/articles/man-lifting-kites-
cody](http://www.atlasobscura.com/articles/man-lifting-kites-cody) (not
tetrahedral, but impressive)

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amelius
What's with that last picture?

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qubex
The one of them kissing? I thought that was really cute and somewhat
challenges my prejudices about people of that era being repressed, cold,
unemotional and reluctant to exhibit public displays of affection.

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JoeAltmaier
Its amazing anyone thought it feasible to risk life and limb at the vagaries
of the wind. Unpowered flight is fundamentally dangerous.

