Wind shear powered flight of binary kite

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TLDR a pair of kites flown at different heights would not need an anchor to stay aloft if there is sufficient wind speed difference between the lower and higher kite levels.

This is just for fun/curiosity although it might have some practical applications as small aerostat balloons have.

How it works:

Assume at a 20m height wind blows from east at 3m/s and at 200m altitude it blows from west at same 3m/s. Yeah its implausible to have an 180degree change, but for explaining purpose the point is there-s a 6m/s delta-v aka wind shear between 20 and 200m altitudes. Even greater gradients are found in low jet streams over a ~200-300m altitude difference.

Assume the two kites are anchored at same point and both have the same pull force - the lower kite pulls its line westwards with e.g. 500grams line tension the high kite pulls the same force and same angle eastwards. The horizontal components cancel each other which means the anchor point is pulled vertically, so a simple weight in a nacelle (carrying ballast or payload) with the weight twice the vertical pull of each kite will simply float in the air without a ground anchor.

In actual low level jet streams both low and high altitude winds are (mostly) in the same direction, yet a vertical shear of at least 5m/s is sufficient to keep aloft a decent payload.

An interesting feature of this system is it does not need very strong lines - if wind shear increases the system would just gain altitude until it finds a level where pull force balances the nacelle’s weight.

There-s also potential for steering, e.g. the lower kite can be a two line steerable kite like a NPW and an autopilot within the nacelle could search for the higher delta-v, similarly with a glider seeking thermals except here there are only three choices the stronger gradient is either left or right or the binary kite is already within the strongest stream.

A variant with two lower kites each a couple hundred meters apart (lines drawing an inverted, tilted V) would automatically steer towards the higher delta-V stream.

PS the low kite can be a very light drogue/parachute (made of e.g. garbage bag foi)l while the full lift is provided by the high kite. The whole thing is disposable.

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Did you have a look to “dual aircraft platform”? To my limited knowledge , only simulation were done, no proof of concept. I once asked to board a balloon trip with a kite to test it, but they refused !

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Thanks that’s cool I didn’t knew the idea was given consideration.

They probably aim for jet stream surfing which probably makes more sense. The tether length in the video seems ridiculously small - I guess for illustration purposes. I doubt however the jet stream is sufficiently reliable or predictable to really implement a pseudo satellite this way.

For fun however.. launching it could be tricky indeed. And there-s no fun without a radio tracker and sensors to be able to tell how successful the flight was. I wonder how low the cost can be to satisfy this kind of curiosity.

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Design of Flight Control Laws for a Novel Stratospheric Dual-Aircraft Platform (PDF)

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Wow, “disaster relief” - one of the classic symptoms of the wishful world of wannabe AWE! Of course, almost nobody reading this was at the first world HAWP (AWE) conference in Oroville/Chico, California.

Wayne German, closely aligned with Santos and Joe Faust, kept interrupting every speaker to reiterate his idea of two kites connected by a reeling tether, at least one of which would lift a generator and a microwave gun that would beam the power to a waiting microwave receiving station capable of converting the power to electricty on the ground. No mention was made of why we have power lines, if it were that easy to beam electricity by microwaves.

His position was that his idea was so overwhelmingly superior, being the only answer, that nobody else should be allowed to speak. Of course I recognized the typical newbie approach where all the “little complications” had yet to be considered, such as the fact that there was no proven kite-reeling system using even a single kite operating from the ground, that there was no microwave power beaming system ready for use either, that both might be too complicated, expensive, failure-prone and dangerous, and weigh too much, with no mention of the danger of such a microwave power beam being mis-aimed and frying people alive across the landscape, if such could ever be built at all, within even the next century.

Meanwhile, since then, we had Santos telling us that Wayne had been Director of Research at Boeing. Anyone who had experienced Wayne’s stammering, meandering, dismissive interruption of every speaker at the conference could see that Wayne would be unlikely to hold such a position. As it turned out, Wayne had not even been employed at Boesing at all, and had simply been associated with some kite-flying club in the Seattle area. Nonetheless, Santos and Joe Faust tended to place Wayne on a pedestal over the years, even after Santos’ original claim that he had been director of research at Boeng had fallen apart.

OK, so now, some current wind energy wannabes (not even newbies) have stumbled cross a watered-down version of this now-ancient idea, for “wifi” and “disaster relief”. Oh like Altaeros supposedly “pivoted” to, with no result?

Looks like one more “gamechanger” press-release breakthrough to me. Sounds great as long as nobody ever has to actually build and run one, rather than just issuing renderings and press-releases! :slight_smile:

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Thanks Doug, but I think Blimpyway was just talking about staying up in the air. Not very kind to compare him to who you know. Dave Santos claimed some proofs of concept exist without complete references but some guidance. I found this link which might help System and method for wind. Dale Kramer.

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Abstract:
A system and method for wind-powered flight, comprising a low-speed, high-drag leading aircraft such as a kite, tethered to a low-speed, low-drag trailing aircraft, such as a glider. The leading aircraft is launched, and when the leading aircraft ascends into winds which are significantly greater than winds at the ground level and the takeoff velocity of the trailing aircraft, the leading aircraft begins to tow the trailing aircraft. The trailing aircraft becomes airborne and can be flown at a low air speed to maintain a constant drag on the leading aircraft, which in turn provides thrust to maintain the trailing aircraft aloft at the lower altitude.

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I was replying to the topic itself, not anything Blimpyway said, which I did not even read anyway. At this point we have ample confirmation that the basic concept is not entirely new, which conflicts with the reference provided by Pierre, above, that calls it “a novel concept”. I never said anything about Santos claiming any proof existed of this concept, only that he had placed Wayne on a pedestal, and insisted Wayne had been Director of Research at Boeing, which to me was absurd and could not have been true. Yes the history of wannabe AWE is not always pretty, not always logical, but those who ignore history are doomed to repeat it! :slight_smile:

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Thanks, the image in this patent makes an interesting suggestion: the “nacelle” hanging between the two kites can be a small fixed wing rc aircraft with autopilot (aka drone) and a release mechanism that can be remotely triggered.

A RC plane with Inav or Ardupilot includes almost everything needed: radio receiver with telemetry, instruments (altitude, attitude, gps) and has return home capability. The only extra part is a small servo drone release that can be triggered manually or automatically on receiver signal loss as part of autopilot’s recovery procedure.

Thus costs for experimenting can be quite low - hopefully only the two kites get lost.