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String Variloops Made Easy
Sorry to Brooks for not posting this to JoeF's string variloop thread earlier, but this is a topic i have worked for several years now. The finding is that string variloops are a practical AWE power transmission option.

All you need is a fixed spool that the loop is wound onto over the top of the spool. As the loop is launched the take-up side of the loop is passively unwound off the spool. The turbine capstan or bull-wheel is allowed to roll out the slack return side of the loop as it grows. Once the loop is fully extended & unwound the turbine then pulls the loop powering the groundgen capstan or bull-wheel. To retract the process reverses but the slack side of the loop is now taken up until the loop is fully wound & landed. Interestingly the loop reverses direction each session. A detail is that the loop is reverse threaded on the capstans or bull-wheels each session. One could design to reverse the turbine to rewind.

A string loop requires a splice or connector fitting. To add to or hotswap a loop merely requires adding sections by connecting in. To work on a moving loop is not that hard, may industrial conveyor systems have sidetrack capabilities, think of train yard operations as a mega example.

This is how KiteLab's successful KiteMotor 1 variloop is manually handled & automation seems practical. There are many possible variations in handling variloops & Brooks approach is also workable. Ideas involving many always-engaged pulleys do stink, but Daniel's idea of using terrain suspension to hide long side-pulled sections is cool. A single pair of added split-pulleys suffices & any number of such pulleys can be completely disengaged for zero added friction during power generation.

Comment and development of this topic will be occurring here.       
All, send notes, links, drawings, papers, videos, plans, safety-critical findings, and photographs!

  • Terms and aspects:  
  • Related links and concepts:  
  • Commentary is welcome:
    • So far, the entry in the AWE Glossary:
      string variloop       
       Two general considerations: 
      1. loop not-working while let out or hauled in   and 
      2. loop works during variation of let-out skied portion.   
      See discussions:          M945     M1021
       
    • Sorry to DaveS for me not explaining my reasoning more clearly. I see much advantage to having the loop to be variable length as with any AWE system the goal is to find the wind energy and harvest it. Its not always in the same place all the time. I have several different designs scratched out involving connectible segments but for simplicity of automated unmanned operation(MY requirement for AWE to reach a significant level of operation) the winder arm was my best bet and easiest to CAD up.
       ~ brooks
       
    • This LTA HAWT flymill concept is nice and simple, and could even be simpler by tapping power from the nose, eliminating the tail-lines.                          [[  Tails  ]]

      Surely we have seen this configuration before (?)...its like an LTA version of KiteLab KiteMotor1.

      On Saturday, February 1, 2014 6:23 PM, joefaust wrote:
      http://www.piclist.com/techref/idea/flymill.htm
      Drive loop for groundgen by global rotation of a finned LTA kytoon?

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