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Re: [AWES] Re: [kitegen] BarretinaHyperlite (Lift/Drag)

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  • dave santos
    Another reason, besides cleanness, thatĀ advanced HAWTs have high L/D, is variable-pitch blades. Careful load matching and a narrow wind rangeĀ is also
    Message 1 of 6 , Jan 7, 2012
      Another reason, besides cleanness, that advanced HAWTs have high L/D, is variable-pitch blades. Careful load matching and a narrow wind range is also required to artificially get the highest L/D. In ordinary use wings are often flown at higher overall lift and a lower L/D, than at a perfect airspeed perfectly load-matched for highest L/D. Bottom line, highest L/D is a weak basis for determining best ROI of a working wing.
       
      Its also worth remembering that a crude wing very lightly wing-loaded (depowered during recovery phase) can have a surprisingly high L/D. This is how a cheap wing with a "floaty" depower mode can compete overall with a high L/D wing forced to often work at high AoA in loaded mode, with a lot of drag developed anyway. These are key insights for an AWES designer.
       
      Tubercules in principle reduce drag and maximize lift across a usefully wider range of semi-stalled and turbulent conditions, but the fabrication implementation is probably overkill. We are more likely to see small tab turbulator add-on-kits perform this role on modern blades, just as as they do on modern aircraft.
       
      Thanks for keeping the posts serene... 
          
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