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.
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.
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.
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
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Flying turbines can hunt & eat these energy bundles. DS . Source.