Vertical Shunting Arches- A New AWES
Kite shunting is a cyclic reversal of flight direction,
with leading-edge and trailing-edge alternating. Four-line kites shunt,
but most do it poorly. JoeH's Rev kites are good shunters. AWE shunters
are a general category of wingmill. KiteLab Ilwaco has shown by small
experiments that horizontal shunting by a suspended wing is a workable
Vertical shunting, with a One Stick Diamond Kite set as a Kite Arch, is
now also shown to be an effective AWES mode, with advantages in stability
and control. Besides potentially driving ground-based electrical
generators, this general method has high promise for high-speed,
precision, and heavy-lifting applications.
This particular discovery came about by accident; i accidentally flipped
an arch-rigged "billowing set" one stick diamond kite, and it took on a
reflex shape and parked totally stable at its zenith without a tail. I
then put a sheet line on it and was able to whiz up and down powerfully.
It seems more than ever that staking kites out crosswind is a key to large
JoeF will link us the videos and collect the new kite arch variations on
one link page. They are closely related even, if they look different. One
image shows a recycled arch made from seven random diamond kites, but with
seven sticks eliminated. 2KiteSam fitted grommets to the empty corners to
rig a drawline furling arch. The furling worked, but excess friction was
evident and a new frictionless furling rig is pending. Other upcoming
demos will integrate multiple shunting kites and arches in variations,
with large tarp arches making a special debut.
~Dave Santos 22Feb2012 AWES5898
Comment and development of this topic will be occurring here.
All, send notes, drawings, and photographs!
- Video Vshunt_demo.avi
- Landing video of Vertical
shunting kite arch
Vertical shunting with a One Stick Diamond Kite is hereby shown to be an
effective AWES mode, with advantages in stability and control. Besides potentially driving
ground-based electrical generators, it has high promise for high
speed and heavy lifting applications.
Recycled Kite Arch with Furling
Note of March 24, 2012: "One more small test toward filling the sky with
kite lift someday; the attached JPEG shows an arch of misc. kites simply
rigged, showing once again how kites can be aggregated to scale up as a
"metakite". Next studies are with multi tarps for megapower, but diamond
kites thirty feet tall would be pretty powerful.
Flies real nice, at about 60 degrees; had to wait for a lull to
photograph it low enough to catch the harbor landscape, it actually self
landed and relaunched several times during a couple hour session, very
tamely. This is a good kite arch and the basic methods have great
Learned a lot about how to avoid making a mess stowing and setting up
(by making a mess). Tested without tails, and then with tails, and they
definitely helped greatly to make this very stable and tame with no loss
in flying angle noticed.
The Furling 1.0 barely worked, with too much friction in the drawline
passing thru all the grommets, but I see a nice way to furl with no
friction and balanced forces, so will re-rig for that and do video.
Sam and I flew this arch in a near gale, and it flew, but with very
distorted sails and spars." Dave Santos
- [ ] Other experiments are
on the way ...
Terms and aspects:
- Distinguish between a kite arch that is not shunting and those that
are vertically shunting.
- shunting kites, kite shunting See related matter:
Vertical Shunting Arches- A New AWES Architecture
- shunting kite arches (long and short stroke).
- Two sorts: rotating always in one rotational direction for edge
exchange is one type; other type is AoA change just enough to cause role
exchange of leading edge for trailing edge in alternation.
Variation occurs win long strong where exchange of roles is by either
method of same direction rotating or reverse AoA just enough to achieve
role changes for the edges. JpF
- flip-wing kite arches and flip-wings also alternate leading edge to
trailing edge to leading edge, etc. The rotating ribbon SkyBow is
a flip-wing kite arch with short stroke.
- kite shunting
- AWE shunters are a general category of wingmill.
Related links and concepts:
Commentary is welcome:
- A kite arch may have continuous wing material or wing elements with
raw-tether segments between the units.
- A kite arch may be a flip-wing sort or not.
- Non-flip-wing kite arches may be of two sorts:
1. Shunters (being explored by KiteLab, Ilwaco, Washington, USA, and
topic of this file.)
2. Non-shunters. Notice that the old art of AoA changes to guide
non-flip-wing kite arches up or down vertically has the extreme of
full shunting where driving leading edge is role exchanged by leading
edge-trailing edge without continuous same-direction rotating, but of
long stroke AoA alternations.
- Notice that, especially on long-stroke AoA changing, there is
cross-winding occurring (but vertically); the extreme advantage occurs when full flip of
role changes in long vertical stroke with high time in cross-winding,
i.e., occurring in the climb up and in drive down.
- We do not forget the whale tail items in windpower where drive
exchange occurs in a wing that drives up and then later drive down by
AoA severe changes at turn points.
arch of trains :: Consider a system that has two
anchors spread far left and right of the power window; the arch is
maintained by a series of elements where each element is not just one
wing, but a train of kite wings; the whole is a series of trains that
lift an arch. Those trains might be stable lifters for some niche
uses. Also, those train elements that form an arch might be
vertically-shunting trains for some niche uses.
2, 2012 by Dave Santos of KiteLab,
Ilwaco and Austin:
Kite Arches for Crosswind Power
Here are some notes toward a formal theory of operation for Kite Arches,
extending Loyd's crosswind power concept to crosswind arches, and
equating the flight characteristics with Culp's "staked-out" stability
principle. Basic geometric proof, covered elsewhere, applies in showing
that arched structures far outperform single tether AWECS by
airspace/land-footprint scope to power ratio.
Miles Loyd famously coined the term "Crosswind Power" to describe
crosswind sweeping wings like a HAWT blade or looping kiteplane, but the
essence of Crosswind Power is broader than that, as every WECS requires
a crosswind extent to operate. Crosswind Power is really a continuum,
from high-speed sweep to static lift. A parachute decelerator works by
spreading area across its apparent wind, and so is seen as the lower
tech boundary of Crosswind Power. Decelerator-based AWESs exist, from
spin-canopies to pulsing varidrogues. The lowly varidrogue is wrongfully
objected to as more downwind than crosswind in operation, but a close
look at virtually all AWES concepts reveals considerable
depth-of-section downwind. There is seemingly no purely crosswind WECS.
The unique virtue of Kite Arch engineering physics is to resist
cross-field forces by a balanced minimal geometry of catenoids, a set of
curves. To compute an ideal compressive arch, merely hang a chain and
use that catenary curve upside-down.
A Kite Arch essentially eliminates common tether drag, by being quasi
all-wing. By contrast, a static single-line kite tether is fairly high
drag, with some down force (negative lift). Worse, a looping
single-tether kite inscribes a
the form encompassed by a jump-rope, "harvesting" high drag.
Vertical Shunting Arches is the latest Kite Arch method. A VSA inscribes
minimal-surface in the sky. Special magic emerges when mathematical
perfection is approximated in the real world. Catenoids may prove to be
the optimal wind harvesting geometry, using the least material for
maximal output. KiteLab had been for years hanging WingMill arches from
lifter kites and shunting or tacking them crosswind horizontally, also
inscribing a catenoid.
Suddenly the Kite Arch emerges as a competitive AWES architecture, but
there are key antecedents. We first note primitive arches from
multi-line kites from traditional Polynesia, then into the 19th Century
Kite Golden Age, with even manlifting accomplished (Baden-Powell), but
it seems only in recent decades did the Kite Arch emerge as a well
defined category. The first Kite Arch that I learned about was my net
friend Anders Ansar's Ribbon Arch, followed by Peter Lynn and Dave
Gomberg's kite show arches flying multiple theme soft-kites closely
together off a common gangline set crosswind. George Peters also did
great work on Ribbon Arches, before Anders.
The World Kite Museum then opened up to me a whole world of special Kite
Arches, seemingly tracing from Ohashi's 1980s discovery that he could
bend a certain kind of Kite Train (diamond kites) almost 180 degrees
into an arch set crosswind, and it would continue to fly. Some unknown
person at about that time seems to have figured out how the diamond
kites could be fully integrated into the arch line, eliminating all the
cross-sticks. Since then hundreds of kitemakers have made such arches,
generally without tinkering with the design. Other arch variants
emerged, from rotating SkyBows. In all cases Kite Arches set crosswind.
When Dave Culp at KiteShip first informed me in 2007 that "staking out"
a large kite tames it, i did not make the connection to Kite Arches. It
was only last week that this mentally clicked into place. Not only is
the Kite Arch a Crosswind Power device, but it incorporates a powerful
kite stabilizing principle, that the ground surface itself is the most
robust and stable kite structure possible. One even sees this principle
in the common arched traction kite parked at zenith off its control bar.
A fantastic advantage to Kite Arches is the ability to kill them in a
controlled progressive linear fashion by slacking on side. The arch lays
down from its windward point. By contrast, "kite killing" single tether
AWES is always more complex or risks retract winch saturation.
Kite arches and trains naturally combine by setting the trains across
the arches, from lower to upper. Multiple arches sum tremendous lift,
while also stabilizing close-set trains from interfering. Fry and Hines
naturally envisioned trains of WECS in their rigid wind power arch
structure, set crosswind. We now see how a Kite Arch can do the job
cheaper and better by going higher. A growing list of methods exists to
rotate a Kite Arch to match wind direction-- Hauling and Belaying around
an Anchor Circle, Anchor (ground) Vehicles, Giant Carousel, Giant
Control Bar, Circular Track, Circular Cableway, Buddy Boats, etc.
In summary, there are many bulk advantages to Kite Arches. The
challenges with arches are mostly in the details. An "anchor field" is a
key arch requirement. Kites in a network can tangle badly if poorly
designed and carelessly operated. The Bow-Tie failure mode is most
characteristic of a high AR arch wing; deep-section bridling, foil
section reflex, and/or tails constrain a wing arch from flipping; local
swivel sections can recover a BowTie flip.
April 2, 2012
by Dave Santos of KiteLab, Ilwaco and Austin