Airborne Harmonic Nodes
This is ongoing clarification of
FlipWings (membrane wingmills) are anti-nodes, the moving part of a
harmonic AWES system. Because they are less obvious, we have hardly
considered the static harmonic nodes as such; like the ground/anchor
point, the pilot-lifter kite, and corner-block drogue, as a simple
Ideal AWES harmonic nodes are solid and stiff, so as to dissipate as
little harvested and transmitted energy as possible. Therefore, the ground
is an ideal AWES node, but kite-lift and drogue-tension node design needs
to be optimized to present as much embodied mass and aero inertia as
possible in the direction of motion. Natural kite-and-wind mass and
elasticity are inherent to self-oscillation.
In practical terms, this means that a larger lifter kite and drogue is
better (up to a point). They should be made with low-stretch low-porosity
material. Node mass and sail area directly opposed to antinode motion both
count. Pure ballast mass can even be a useful airborne node.
A static-nodal wing is tensile balanced at its static CE. An antinodal
wing is LE attached, like a flapping-flag. Its CE moves fore-and-aft and
flips sides with each flap. Mass-spring resonance of both the hardware and
flow regulates the action.
As an example of what might be possible, consider a "laddermill"
consisting of alternating nodes and anti-nodes in a powerful stable
"ladder" oscillation of standing waves tapped at the base. It would not
need to rotate weakly in an endless loop; instead the antinode wings would
sweep crosswind in well ordered passive harmonic synchrony. A test will be
devised to see how well this sort kite train does.
Comment and development of this topic will be occurring here.
All, send notes, links, drawings, papers, videos, plans, safety-critical
findings, and photographs!
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