Lifter-kite overview
Self-flying lifter-kites are a basic tool for current AWE. They even
lift sweeping fly-gen hot-wings without resort to fancy avionics. Three
kinds of lifter-kites are the workhorses: Parafoils, Morse Sleds, and
Deltas. Each has advantages and faults as listed below. The sled and
foil were discussed extensively in previous posts, so the Delta
description is more detailed.
Parafoils
Jalbert began as an early American aviator who then worked on
barrage balloons, inventing the kytoon. Late in life he invented his
real masterpiece, the ram-air soft-wing known as the parafoil. What
makes the parafoil revolutionary is that the faster its driven the
harder its structure pressurizes. All other designs are speed-limited
by acting progressively floppier at higher speed. In his final years
Jalbert developed flapper-valve inlets that hold pressure in during
upset. This is the most advanced of all soft kites, even suitable as a
water-kite.
Great parafoils exist in both self-flying single-line & powerful
fast-sweeping multiline traction versions. As a lifter it can pull very
hard for its area.
Parafoils are formed into high quality airfoils at super-low
weight-to-wing area (double-skin). A defect of parafoils is that
relaunching from the ground usually requires assistance, but lifted
up by a wingtip from a Morse Sled (as a self-looping parafoil) bypasses
the problem. Parafoils may be the ultimate scalable design; stock
versions have bigger wing area than a 747--and
the largest kite ever was far bigger still.
Morse Sled
No kite is more capable with such cheap light "untailored" (flat)
construction. The quality of the airfoil is not so high, so the sled is
not suitable for high-speed sweeping, but being single-skin gives the
kite the lowest wing-loading of any, a key virtue.
While prone to temporary collapse in dirty wind, the kite is so light it
seldom crashes due to collapse, but re-inflates promptly. An
extraordinary quality of the type is its reliable ability to
self-relaunch. It can scale greatly by its tensarity principle (whisker
on a ram-airbeam), but not so much as a parafoil.
While most Morse Sleds have tails, some do well without them by
being cut a bit longer; I use a tailless Kayak Kite for kayaking
here on the Lower Columbia River with good results.
Delta
Tailless Delta Kites are a modern type developed on the Texas Coast.
They are the dominant toy kite design; exceptional fliers in a very wide
wind range; cheap and simple to produce. These qualities make them
attractive as lifters in small-to-medium scale AWE. The design is
practical up to "hang glider scale" before stick construction becomes
too fragile and unwieldy. Beyond that size, soft kites like the sled and
parafoil are better.
A delta's frame is somewhat floppy to make it compliant to small-scale
turbulence. Loose wingtip fabric flaps contribute to its snowplow
stability, where a leading wing's drag pulls it back to align
the kite with shifted wind. The prominent fabric keel damps yaw
oscillation. While tails are common on small deltas to delay the onset
of looping in rising wind, the tailless original is ideal
for aggregation into vast robust structures like close-packed arches and
trains, without the bother of tails hung up on adjacent lines.
A quality delta makes a fine addition to any kiter's quiver. I've flown
a Gomberg Spotlight
Delta for several years now, souped up with a water-relaunch
nose float, ram-air stub-tail, and elastic aft-bridle. It is flyable
up to gale conditions. A little delta (18 in (46 cm) wingspan) I
happened across has a very long integrated flat tail (20 ft; 6 m) giving
it the form of a
planarian worm. Verily it is
Hargrave's vision of future worm kites. With a bit of ballast far
down the tail and long ribbons added, it will fly in a gale even though
it is so small.
For light-wind flying, X-Kites makes a great PVC-and-fiberglass delta
that sells for about $4. It flies as well as "pro" ultralight kites
costing 20 times more. Gayla
is the original delta maker (the dimestore kite of my childhood) and
still makes vast quantities of variants selling as cheap as a dollar or
two. I harvest them for array experiments from trees with a long pole
after Austin's Zilker Kite
Festival. which is even cheaper and reduces litter.
FairIP/CoopIP ~~Dave Santos May 22, 2010 M1554 Comment and development of this topic will be occurring here. All, send notes! Terms and aspects: Related links:
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Flying turbines can hunt & eat these energy bundles. DS . Source.