CoolIP index           

 

 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. To 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

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

Terms and aspects:   

  •          

Related links:

Commentary is welcome:

  • 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                    AWE4923