Nice video of the Rev. Under active control the Rev may fly down; and if on a high bridge, the flying down could continue toward the 6 o'clock direction on a 12 hr clock in the full semi-spherical wind window with half of such below the horizon.   The aim of the topic thread is to find stable passive constructs. Stunt-kite pilots are confident in the down-going flying legs of stunts; and some may fly off bridges and well know the paths below the horizon; yet they are not using a passive control of a stable down-going wing.   Aim: Off the bridge fly a wing that stays stable in the down-flying mode (no turning to go back up). 

As tethered Super Turbine seems difficult for flying, as AWE looks difficult to generate some economic wind energy, what are other possibilities, knowing two rotors tilted at an angle of 30° have a same swept area as a vertical rotor?

PierreB

Still laughing! Thanks for the boot idea, Rod! Get your magnet soles here at the kite chandlery!  Walk on the underside of the iron bridge while managing an inverted kite system!

Dig up?   Facing some tailing challenges gave nix to the bag drogue for some purposes; rather, full stable negative low-mass  and low sail loading negative kiting seems to fill the bill. I well know unstable negative kiting as do most parents: slam ... the wing dives in lock-out into the ground as they first kite with the kiddies following a plan from a book. But those ground eaters will also rarely sit toward the 6 o'clock station if flown from a bridge; rather the wing will spin and loop. 

     Rotate the SkyBow in the wrong direction and eat dirt fast; but the same from a two-anchor point on a bridge will fly with a declination stably of about 45 degrees or so.  The art of single-tether for stable single-station-keeping negative kiting is little developed; most people want to fly wing up into the sky and not down to eat dirt.  The negative kiting of the Rev is under active control and is dependent on very precise holding of the control lines... all four lines.   The aim of the topic: single-line to a bridled wing that then locks fairly stably to the 6 o'clock station  at a declination of say 45 degrees or so or more below the horizon ... and with low sail loading.   Tailing will be only one of the uses of such negative kiting. Energy kites of some makes will use negative kiting. 

Thought I posted this sketch, but do not see the message. Sorry if delays bring on duplication, but I waited 15 min or so. 

    One-tether hold of wing. Wing is to stay fairly quiet in the 6 o'clock station of a full wind window of semi-spherical shape. Low-mass and low sail loading. Note the approximate inverted catenary of the tether of the negative kiting situation.     

DaveS,

Light structure like latticework structure being able to assume some airborned component by tilted turbines, and also to assume some borned component in case of lack of wind. Tethered structure assumes only airborned component. Note: I try to see possibilities for mix airborned-borned structure, thinking in reallity the next future of wind energy will be probably assumed by offshore HAWT and their new field of searches.

AWE like you practice enters a new discipline of kite-art, but does not go towards generating wind energy. Please stop to see despair when you do not agree: for me kite-art is interesting and fun, generating wind energy is another problem.

PierreB

Great, Baptiste; thanks! =============================================Posting an archival copy of the file to date:  

Negative Kites negative-lifting kites, stable down-going kites  [File start date: January 21, 2014] "inverted kiting"   "upside-down kiting" that fly negatively stably passively with low wing loading with substantial negative lift

Motivations and applications Solutions, plans, specifications Discussion: Stable Down-going Kites (11012) and its following posted messages. Mass/|negative lift|  ratio kept low.  |negative lift| is the absolute value of the negative lift of the kited wing. Have low-mass give substantial stable down-going flying of the wing.      Baptiste Labat reminds us below that the matters in FFAWE include negative kiting. We are recalling the trolling of objects in water where the powered upper hull tows a negative-kiting wing (paravane) down deep in the water. Included in such space are the deep diving fishing lures and trawling-net-gate-opening paravanes.. An effective easy experimental "tower" is a flying kite system; then from the main tether place negative-kiting experiments with their dedicated branching tether. Note that historical kite trees or branching trains have positive-lifting sub-kites from main tethers, whereas here we are in focus on branches that negative kite stably, passively, and with low wing loading and substantial negative lift.  We know well looping wings and spinning wings; but what is far less explored are strongly negative-lifting wings that stay downing. The mixed media of air and water has been a continuing exploration as Baptiste Labat reminds us.   Yet to be in visual portfolio are air-only negative kite plans and videos; the transient negative kiting of stunt kites and circling or looping kites is a category of itself and set aside a bit from the focus of stable-station-keeping negative kites where the station is fixed at points say from 3 o'clock to 9 o'clock on a 12 hr-clock face. Say, choose 6 o'clock; have a strongly negative lifting single-tethered kite wing fly staying near that station stably and passively.    Plans and video are sought. Analysis as researchers may produce will be featured.    Patents are robust for paravanes that dive down; but as yet patents are nearly quiet on air-only matters in focus in this folder. Kiting literature has not shown much on the matter either, as the giant thrust is to fly positively-lifting wings upward!

In post of http://groups.yahoo.com/neo/groups/AirborneWindEnergy/conversations/messages/11040 You probably know l'aile d'eau http://www.youtube.com/watch? v=1tEw_mlUh7g http://www.augredelair.fr/ joomla/recits/luc_armant/ ailedeau.pdf  http://www.energykitesystems. net/WPGA/Wings/index.html (Sorry it is in French, and I don't know any translation.) Luc Armant did a nice study of stability and station keeping not at zenith.   Another potential application would be traveling in the sky with two kites (one up, one down), a bit like Kramer patent Germain Beltz and Armand Torre are as well designing nice kite which are able to station keep (anywhere?) on the side of the window. I think this is based on a balance between weight of the kite and asymmetrical force due to bridling.  I forwarded your question to Emmanuel du Pontavice which is doing a PhD on kite stability at Ecole Polytechnique.  ~~ Baptiste Labat                                January 22, 2014 [[Ed:  cerf-volant (thèse d’Emmanuel du Pontavice)   Related: https://www.polytechnique.edu/accueil/actualites/publications/les-empreintes-de-sous-marins-294226.kjsp        We recall the winners of The 2011 Wayne German Award for Kite Energy  where negative kiting is involved in some of their works, especially the negative kiting of paravanes. ]]

Videos of solutions:

Explorations Investigation of Negative Lifting Surfaces Attached to an Open-Wheel Racing Car Configuration When on a high bridge, envision the wind window expanding from the quarter-spherical shell to a full semi-spherical shell. Instead of flying a kite to the zenith, set the kite's wing to fly stably and emphatically to the anti-zenithal pole. We seek passive formats of bridling and shape that will stably fly to the anti-zenithal region of a semi-spherical wind window. Keep the mass cost low compared to the negative lift being effected. One motivation in kite energy regards tailing of lifting wings with negative kites as tails.  Veer fully downward stably and passively.   Also, the full circle of stable-station veering may be explored.  Different than looping wings, the wing is to stay veering in just one station of the wind-window full circle. It is common and easy to fly stunt kites downward, but not so easy to stably fix the system to the downward direction. Kitists are used to using gravity in their designs for upgoing-wings kited.  In "inverted kiting" or "negative kiting" when stability is wanted for downward direction, especially when stability is sought and low-mass costing is wanted, then gravity plays a different role. http://en.wikipedia.org/wiki/Tailplane    But note, most common tailplanes with negative lift are fixed rigidly, not flying on tether as kites. downward-lifting  is "negative lifting" Flip-wing rotating opposite to normal flip-wing kiting. Reverse the S  and have bottom going downwind to effect a negative-lifting resultant. How to stabilize the rotation direction and the wing attitude? Reflex in flying-wing hang glider is integrated with the wing, not tethered behind the wing. Our topic here is about detaching the "reflex" and flying the "reflex" stably at the end of a tether, thus a stable negative kite system. Horizontal stabilizers on many common rigid aircraft frequently have the stabilizer flying with downloading; but again such stabilizer is integrated rigidly with the aircraft fuselage.  Differently, our topic hereon would look towards tethered downloaders, especially with low mass per negative lift. DIVERGENT SINKER SINK http://www.vedette.it/ecoing5.htm Paravane:  US1320804  (A)   Trolling Line Sinker http://www.pescastore.it/catalogo/product_info.php?products_id=7301 Notice the stark absence of air kites that fly negatively stably passively from high anchor points (bridge, tower, balloon, conventional kite tether,

World's smallest windmills to power cell phones

Oh really, is that a fact?   Mmmm Hmmmm.  If not, what is it?  Another lie.

So if this idea never ends up powering anyone's cel phone, can we flag it as one more big clean-n-green lie?  The article mentions Betz, as any beginner might, but they don't seem to understand the implications of a slightly more subtle wind-energy-buzzword: Reynolds Number.  Airfoils don't work at that scale.  Even insect wings operate on a different principle than airplane wings or wind turbine blades.  ("Bumblebees can't fly.")  Dare I say they'd be better off with a drag-based device in the micro-realm? A Savonius perhaps?  Just a guess.  

Anyway, I invite anyone to begin to see the commonality between most wind energy "press-release-breakthroughs". It always starts with a lie.  That's your first clue.  What amazes me is how many times we can read of these types of "breakthroughs", always believing each new one, and somehow never going back to check what percentage of these lies ever come true!  If only people would go back and check, after the fact, they would realize that almost every such article is nothing but a complete lie!  After a while, you can see it in real time.  They all sound the same.  Always sensational claims, never anything to back it up.

Have a day!  Long live Whale Bumps!

:)

Yes, DougS, and with Rod, we have a great plenty of wings and tethered wings that do go downward; your review of spinner and actively controlled wings and HAWT blades match such as looping blades, looping parafoils, circling kiteplanes, figure-pathing stunt kites; yes those go downward and yet are not the topic of this thread.  The topic regards tethered wings that stay going downward essentially near 100% of the time; that is, the subject wings kiting would simply kite essentially all the flight session passively controlled in a generally anti-zenithal direction robustly stably.  The subject solutions are not simple hung streamers (that are actually still positively lifting even if the streamer seems to be pointing downward).  The dynamically changing dive downward indicates that a kited wing may fly downward; that is not the topic. Half-the-time in various stations of the enlarged window's lower half is not the target topic. Rather, have the kited wing fly with robust negative lift in approximately one station, say the 6 o'clock station on a 12-hr clock face. 

Note that on level ground one cannot experience having the target topic solutions; the four-line controlled Rev eating its way into the water going downward teases the topic, but is not the topic as it uses four (not one) tethers in active (not passive) control; the shown Rev video indicates how twitchy the Rev is (its high plus asset) and so such Rev would not supply the target passive stability sought. 

Rather, notice a stabilized passively controlled sled kite anchored to the ground and achieving about L/D of approximately 2. Have it symmetrically balance so that we see it generally ever seeking approximately a flight in the projection of the 12-o'clock plane of the wind window (quarter-spherical shell). Such scene is generally the mirror image of the target subject; but notice that things must definitely change for the wing and its bridle and detail arrangement, as the said kite is definitely as written ... a positively-lifting stable passively-controlled kite; so direct mirror-reflection does not work for this said example to obtain a negatively-lifting kite of close blood-line to the said example. The art of having working stay-always-going-downward in totality is not often practiced in atmospheric kites (paravane realm is another matter where more instances of down-going paravanes are regularly operating).   

I find yet no video on the Internet of a kiting scene that meets the target topic (one or more might be there, but such is not yet in my view).   We have many kited wings being shown that fly downwards into crashes, fly downwards during dynamic stunts. fly downwards during a positive L/D movement in special moves, fly downwards during the following of circle paths and other curves with a downward-path segment, fly downward in rotation as you indicated.    Notice that a kited wing that moves downward might still be having a positive L/D with positive lift occurring, but just less than moments before, as in a down moving Rev that is controlled to simply have lower positive L/D than a moment before, and so a settling to a lower altitude results; such movement is off the target topic.   Rather, what is sought is to have the wing have negative lift and positive drag for a net negative L/D, relative to the zenith. 

Notice the following experiment: have a 1 oz lead ball at the end of a 30 m tether; hang that ball from a bridge. Let there be steady wind impacting the lead ball; the ball will be pushed in the direction of the wind; it will stream somewhat. Finally there is a little interference with the ball surface and the connection of the tether that will give fine asymmetry to the scene aerodynamically. There are many ways to bridle such a ball; the resultant fine dynamics would depend on the bridle choice. One simple choice is to have the tether meet the surface of the ball at one point and let that be the end of that bridle story. In that case, the interference of the tether with the surface of the ball will be giving a net turbulence because of the tether; such will slow the air on the connection upper side of the ball; L/D for the ball wing will not then be zero; rather the average L/D will be positive or negative. I vote for negative, as the smoother stream will be on the bottom side of the ball, not on top where the tether meets the ball.  If all is so, then we would have a negative-flying kite system in this example; and the station keeping will generally be near the 6-o'clock plane. Realities will have the position of the ball changing some, but the average position with be fairly symmetrical at the said plane.  This example has high wing-loading relative to conventional ultralight kite systems and so moves it a bit away of the target topic; what is sought is low wing loading.  OK, use a ping-pong ball or lighter-yet an inflated sphere of skin of the lightest known inflatable film that could hold a bridle connection and stay shaped during intended wind impacting. Then in the lower wing-loaded ball situation, the drag would move the ball more downwind in the 6-o'clock plane on average, yet I suspect we would still have the negative L/D, with absolute value of the L smaller than the absolute value of the drag; the drag would have more dominance. 

    The topic target aims to have wings that have negative L, but where the absolute value of the negative lift is dominant over the wing's drag.  And yet the system remain with a single main tether, stay passively controlled, stay robustly station-keeping stably.   The solutions will not be leaving the station very much except by the result of gusts; but the stability intended has the wing return to the defined low station; hence, the topic is aside of circle rotating blades except in the case when the rotating blade is the full global object that stays globally in the low station-keeping position (distinguish from your suggested turbine that has blades in its integrity going up and then returning going down while presumably you had the global blade-set in undefined positions of the wind window relative to the tether-anchor position). 

    A conventional three-blade towered turbine has during normal operation generally with a global L of zero so that it does not globally try to fly vertically to zenith off the tower, even while each blade is a lifter relative to its apparent wind.   Differently a kited gyrokite's blades globally conventionally have a positive L; one may explore negative gyrokite where the L is negative ... and such would tend to meet the target topic; the topic thread is open to receiving design and proof video of negative gyrokite that meets the stable down-flying station-keeping nature and the passively-controlled nature sought. 

Thanks for the moment. 

Cheers, 

JoeF

"Your opinion that "for me kite-art is interesting and fun, generating wind energy is another problem" neglects the common root of art and technology as Techne (ancient Greek single word for art-tech, See Heidegger on techne)."

Fog! 

PierreB