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   Post on Strut Cuffs for MK4 in Technical tasks

   By skypics, posted 2 Sep 2018

   I have flown the model B and now have the MK4 with under camber STOL wing.
   For many hours I had been bugged by the fact that there is severe turbulence just behind the leading wing struts at the wing juncture. If you place yarn tell tails in that area you will see that during climb the yarn is streamlined, but as you level off the yarn will actually turn 180 degrees and face forward.
   I used 6061 T0 to form the cuff and attached it with common bathroom bath tub calking compound for a test, thinking I would switch to something better later. Turns out the calking has held up very well.
   To fill the hollow inside the cuff I used air dry modeling clay. Again thinking temporary. It's still in there. 
   There are a couple videos at You Tube skypics234, but they don't show it as well as I would like.
   Here are some photos. I was using tape to hold them in this shot and later changed to the calk.
    
   No off the shelf cuff available I tried various modifications .
   
   
   
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   Post on Wing Strut Cuffs in Avidfoxflyers General Hangar

   By skypics, posted 22 Jul 2018

   I have flown the model B STOL and now the MK4 STOL and had noticed when flying that I could see a vibrating ripple in the fabric just behind the leading wing strut.
   I placed yarn telltales in that area and was amazed and mystified at what was revealed.  
   When climbing out the yarns were flowing back in a streamlined fashion as expected. However, when I leveled out the yarns actually turned 180 degrees and faced FORWARD!
   Finding a wing cuff for an Avid is impossible so I went through many iterations until I hit on the right combination. 
   Now the yarns stay streamlined al all AOA. Can't say how much drag was eliminated, but it should be substantial.
   To see this change check out skypics234 on YouTube. 
    
   John M