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Notice: Improved two-anchor persistent flight demonstrated by back-flipping and back bridling:        >>   AWES6946  Sep 5, 2012

Earlier today I was able to keep a toy Delta Kite (Gayla Sky Spy) flying by towing it in brief cycles back and forth between two spread anchors. The back of the kite was bridled just like the front and the kite simply "back-flipped" faces at each end of travel.

This is improved short cycle two-phase pumping, without an earlier problem of reliably "turning the corner". Last year effective three-phase pumping was demonstrated in public (WKM Windless Kite Festival). The latest design is further evidence that persistent flight is simple and practical by pumping inputs from the ground, for AWES and other applications. Video and a public demo pending.

High value persistent flight was long considered one of the hardest problems in aerospace, but it is not.  Thanks  goes to the AWES Forum for helping solve real world challenges by freely shared knowledge.

~ Dave Santos

[Recall the two-point disclosure: AWES1389 in 2010 by JoeF 
and  the tri-tether cranking and pumping: May 27, 2009: Tripod Tether by Dave Santos
AWES151 of May 27, 2009]

 11 October 2011
Testing Persistent Kite Flight by Pumping (Stability Factors)

After several trial sessions of two-line persistent kite flight (toy kite on a leader line towed by horizontal pumping line) the following picture emerged: It is possible to sustain quasi-circular flight by this means, but its too sensitive to the timing of the to-and-fro motion for reliable passive flight. To fly a nearly circular pattern for an extended session, a brief pumping tug must be skillfully applied each way. Too little or too much of a tug, too soon or too late, and the kite leaves the pattern, often entering towed "lock-out", with no easy way to get back in the pattern. Often the lockout was a wandering loop sliding off to the side. Passive feedback methods will be tested to solve the instability.  

By changing the geometry to long-stroke towing, a kite tows stably in either direction. To make the turn entails a brief unstable period as the kite once again finds its stable flight attitude. Setting a small tack (turning input) into the kite allows a tilted tow that sets up a smooth turn, for an over all ovoid path, but a long tilted tow is less stable in the real world than a long straight tow.   T

he early conclusion from testing is that higher phase (more lines) kite tugging is far more stable and practical for persistent flight, with three-phase tri-tether tugging offering good passive stability.

CoolIP                       ~Dave Santos            11 October 2011        AWE4454

Note- A sufficiently high quality kiteplane skillfully enough controlled can be maintained aloft on one line from one location. The kite glides down to the end of its tether and regains altitude by a sharp tug, to set up another glide phase. Skilled kite fliers already perform this flight mode-
Alan Flying Zero Wind Kite .Thomas K Horvath, Hybrid 200 - YouTube

First glance on two unbaked methods              > AWES1389
Posted By: joe_f_90032    Wed Mar 24, 2010 2:47 pm

The moment of first glance sometimes brings a gem of value, 
sometimes not.   The following two glances of enthusiasm
would not get posted if I passed away in an hour and thus 
unable to develop the glance.  So, I risk sharing the two 
glances that may or may not be inventive, but for the moment
seem to have a kernel of something that someone might want
to explore (I hope I will be here tomorrow to invest on the 
development of these two sparks):

Step-tall-launch method: Pedal a kite left and right and left and right etc.  between two pulleys while the kite climbs higher in each cycle between  the pulleys that spread further apart also. Keep letting out line at each cycle until the kite is in higher winds enough to sustain the kite. Then operate the system as an effective AWECS.  The details of the let-out mechanism have not been given attention yet.   Pedal in insufficient wind until kite reaches working winds; then convert to AWECS for gains. 

Spread-line center pulls up a third line when the two kites are spread, one left and one right. Then guide the two spread kites back to center which lets the spring-loaded central line back down. The sprag clutch (driven by the central line) operates during the spread and the release.  The two kites stay flying: spread, center, spread, center, spread, center, etc. The kites have their main tether that does not get let out or in. This is not a reeling method of kite tether as is a common AWECS method.    I have not seen this method. Note how a lateral line of many kites could be worked in a kind of peristaltic rhythm with most kites (not the far left or the far right kite) operating to release as it goes to relative center with one of its adjacent neighbors while relative to the other adjacent neighbor kite is spreading (and thus lifting central down lines).

If there is any novelty in these two glances, I offer such into public domain without need for reference.     CoopIP          And if such glances hold prior art, then I hope to be around past this hour to uncover and credit those who have come before this moment with their findings and instructions.  


Comment and development of this topic will be occurring here.       
All, send notes, drawings, and photographs!

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  • It does help to "(leave) the desk", just as Dog insists, to empirically easily confirm that by power-to-weight for AWE flight, kiteline beats "electricity" "to transmit power over a distance" (to the surface). Or we can just sit at a desk, like Einstein, and still get results.

    Lets "pretend", which is Einstein's Gedanken Method. We tow a toy kite in circles (use a tri-tether) in still air with a watt of tow energy. Then we put a motor/propeller on the kite and make it lift up a conductive tether. Now we find that more than a watt of electricity is needed to fly just as high in the same circle. The extra energy goes into waste heat of the motor and tether, more aerodrag by a thick tether, higher AoA for the same airspeed; induced drag of the propeller, and so on. Of course there are some fancy physics to explain exactly why bare kite and line rocks, but a child can see and feel that the kite and line is lighter (flying weight), lower drag, and does not resistively heat up so readily as a motor and electrical conductor.

    Anyone who denies this is "in denial of what is already known" in AWE. Of course electrical transmission is very practical along the earth's surface and at small scales, where power-to-weight and safety does not dominate the engineering.                     ~~DaveS