[JoeF]

Imagine two (or more) wings that step-tow each other. Two PG or HG would tow themselves upward by towing toward each other, On close approach, they would turn away and glide, paying out line. Anyone knowledgeable in aerotow can understand how sustained flight is feasible by this simple method. Cordless power tools might serve as prototype winch-motors, to get started. Its not hard to envision the basic flight patterns to navigate at will, and consider various schemes to provide power, especially by operating the winch-motors in gen mode to charge batteries, by known free-flight AWE principles.

Acronym legend:
AWE airborne wind energy Main file site: http://www.energykitesystems.net
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Off land: two tether-coupled HGs
Off water: tether-coupled HGs

Note: Notes in that forum easily show understanding that three or more coupled wings may be envisioned in "polygonal" step towing to altitude.
https://groups.yahoo.com/neo/groups/AirborneWindEnergy/conversations/topics/20060

In USHawks forum there as been some notes close to these matters. Jack Lambie identified using Earth soil as one wing and a sailplane for the other wing; the winch would be in the sailplane; the Earth-sailplane tether coupling would fly each other with aim to have the sailplane lofted to altitude while the other wing: Earth : would approximately stay at its same original "altitude." Replace "Earth" with a second HG in the system. Actually, without doing the search, this topic may have been mentioned in our forum. However, this topic thread aims to focus on the two-wings-coupled step-towing where a winch is in at least one of the wings or perhaps remotely controlled and centered in the coupling tether (which may or may not be a good idea). See: http://www.ushawks.org/forum/viewtopic.php?f=2&t=2470

FFAWE has been mentioned in USHawks forum and elsewhere. Tether-coupled wings may exploit wind gradients and thermals for generating energy and for soaring XC. Focus on the two-HG scenario as a means for step-towing two HGs at a time over say flatland is the core of this topic thread. Alternative to Dragonfly tugs?

[Frank Colver]

I also seem to remember this topic in this forum some time ago.

Frank

[Rick Masters]

Imagine two (or more) wings that step-tow each other.

Imagine running off a mountain and soaring up to the clouds. Its called hang gliding...
Yeah, aerial step towing is an interesting idea.
It's too complicated, though. Something is sure to go wrong.
Run a chaos simulation on a slack line in thermal turbulence.
People with too much time on their hands should try it with UAV hang gliders.
Maybe Jeff Bezos could use it to get to outer space using Elon Musk's lithium batteries and DeWalt power tools.         

[Bob Kuczewski]

Run a chaos simulation on a slack line in thermal turbulence.
People with too much time on their hands should try it with UAV hang gliders.
Maybe Jeff Bezos could use it to get to outer space using Elon Musk's lithium batteries and DeWalt power tools.