[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.

[Maarten88]

I'm sure that kite design will be very stable in the air. But I guess the triangular wings are not very efficient and disturb each others airflow.

I wonder how the tetrahedral design compares with the Cody kite design, from the same era. That design looks more efficient to me, and has been proven to scale big enough to lift people in the air.

As a kid I built several small Cody kites and they fly amazingly well. We combined several and flew with up to 1km of line, hundreds of meters high.

https://en.wikipedia.org/wiki/Samuel_Franklin_Cody

[Retric]

"tetrahedral beings were flown both unmanned and manned during a five year period from 1907 until 1912" So, according to the article they did carry people.

An important consideration is these kites where lighter per lifting area so they needed less wind and would also fall slower without wind making them somewhat safer. The added redundancy is also an important consideration.

PS: It's actually fairly easy to build a kite that can lift a person in a strong wind as even a simple parachute will work. see: parasailing which can work at even 15mph. The problem is finding a design that fails safely.

[cma]

Do SpaceX's grid fins operate on similar principles?

https://i.stack.imgur.com/rnHbB.jpg

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

[theoh]

AFAIK, grid fins are made the way they are to circumvent the problems of supersonic shockwaves rendering conventional fins useless. So it's a different situation.

[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"