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Kf airfoil or wing shaping?

Discussion in 'Scratchbuild Talk' started by wingman94, Jan 25, 2011.

  1. wingman94

    wingman94 Cadet

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    I need to build a new high wing plane and I was thinking a pod and boom plane would be easiest. I need a plane that goes a little slower than the parkjets so I thought I would build something with lift. Would a kf airfoil work on a high wing plane? I've only seen them on jets. Also, would you recommend curving the wing? I read somewhere that those don't like to go inverted though.
    Thanks
  2. JettaManDan

    JettaManDan Administrator

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    If you do an undercamber (curved wing) it is true it will not like inverted at all...cannot be flown inverted really....so your only 2 choices are a Kfm style wing or try to actually shape an airfoil what you can do is do a curved top wing plate..and then glue it to a flat bottom to make a upper airfoil....probably would need cross ribs for strength...

    attached is the Kfm airfoil "cheat sheet" so you can see what you can make...

    Dan

    Attached Files:

  3. wingman94

    wingman94 Cadet

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    Thanks! i might try the kfm2
  4. JettaManDan

    JettaManDan Administrator

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    if you are looking at good inverted performance i'd go Kfm-4 - it gives you more stability and equal lift top and bottom...if you are just doing rolls than the Kfm-2 is fine...but if you want to fly upside down then that will give you a high negative angle of attack to stay up inverted...
  5. Dredogol

    Dredogol M0DERATOR - (aka "Dred")

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    For your wing plane design, I would go with KFm-2.
    You could try #3... but I doubt you'll need it.

    Jetta is correct on all the other stuff.
    Make sure to read the thickness + step chord distances... those are crucial.

    It's pretty hard to do a curved wing shape that WORKS correctly.
    If you go this route... be prepared for a lot of trial/error.
  6. rodrigo

    rodrigo Ace Pilot

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    the KF2 airfoil works great in my C119 (upper wing) WS93cm, 18cm chord
    Lot of lift, strength and flight gentle.. I flew inverted but not for too long because I don´t have to much practice...the plane responded great ,straight and level( a little elevator input )
    Anyway, I don´t know if the upper wing are good for inverted flight, so I do not know whether it would recommend a KF4
  7. JettaManDan

    JettaManDan Administrator

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    if i have the ability later i'll do a short vid on bending depron with heat...an undercamber wing is good for a slow high wing trainer...and you can use the technique to make an airfoil top wing with a flat bottom glued on...
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