|Aggregate Flight Stability
with High AirSpace Infill Demonstrated
AirSpace Infill Factor- The effective density of AWECS elements in a given airspace.
KiteLab Ilwaco is successfully demonstrating super-effective aggregate flight stability and high airspace infill factor with arches of tailless kites on swivel leaders. This is a foundational AWE method with great scaling potential. Description of the experiments follows background information below.
A major technical divide in AWE is between designers who endow flying elements with as much embodied inherent stability as possible & those who intend for active control to prove adequate as the stability principle. The inherent stability school originates in mainstream aviation where human pilots require an aircraft to generally recover & fly itself upon any lapse of active control. Except for a few military/aerobatic types, modern aircraft still seek & maintain stable attitude if there is a control gap. The AWECS theory is that if human pilots require inherent stability for safety & reliability, so do emergent autonomous flight agents.
The traditional single line kite offers high inherent stability to the designer, but it is not perfect. Windfield turbulence eventually overpowers recovery forces & a kite crashes without an expert kiteflyer to save it. Fortunately, inherent stability can be increased & expert pilotage obviated by aggregating kites into trains & arches. These methods also allow a designer to more densely pack airspace with working wings than single-wing/single-tether configurations.
A kite train is a wonderful thing, but its tall skinny format poorly utilizes airspace. Kite arches are promising maximizers of airspace as they stretch across the wind without the weedy height of a train. Anders Ansar (an old net friend) tried arches a decade ago consisting of one long ribbon wing across the wind, but they underperformed as much of the ribbon flew out of trim. Kite festival arches fly better by breaking up the wing into many smaller cells with pitch freedom to self trim, but such arches are fairly sensitive to wind direction & must be reset periodically. Kite masters developed arches to close-pack show kites where each kite has full freedom on a leader line & such arches well tolerate veering wind as each kite weathercocks independently. Other kite masters hit on spectacular trains of normally unstable kites like fighter kites. The kites need have just a bit of inherent stability to average out as a stable system. While the aggregate train flies stably sub-kites are free to go nuts.
The latest KiteLab experiments combine the best features of all these methods as an arch of toy tailless delta kites on swivel leaders. Such kites are stable in smooth moderate wind but begin to loop as conditions kick up. Eight to sixteen deltas are tethered along an arch in the strong turbulent breeze off of the hills surrounding Ilwaco & the flight dynamics observed during extended sessions.
At any given moment several of kites might be looping & swooping, but the overall arches have not yet been seen to falter. The kites at each end of the arch show a greater tendency to come down in lulls or conflict with the arch line, but so far always relaunch or shake free. A lone delta must be launched skillfully & does not easily self-relaunch, but the arch self-launches & relaunches kites reliably. The arch also launches sequentially in a cascade as an initial kite takes to the air & pulls its neighbors up.
The kites look weirdly alive as they subtly interact. Tag lines & halyards are placed between the lifter kites to loft AWE power elements like membrane wing-mills. Even flygen AWECS with heavy conductive tethers are easily raised & lowered under total control with the reliable powerful lift available by multiple kites.
The next step is to fly kite "cupolas" (i.e.- string tripod) to accept wind from any direction without intervention. The ultimate expression of this development path is robust 3D layered meshes of AWEC elements. There does not seem to be any major barrier to rapid success.
CoopIP/FairIP ~Dave Santos
Development of this article will continue. M1494
Slowly catching up on old documentation:
May 28, 2010
Terms and aspects
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