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Help Me Pick An Airfoil.

Old 09-05-2007, 03:16 AM
  #1  
fr4nk1yn
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Default Help Me Pick An Airfoil.

I keep trying to post a coherent question. So far it's not working.

I'm building a new plane to replace the one I nose planted today by having my TX set to the wrong model.

MKi climbed a lot under power but floated really well and was REALLY maneuverable.

The wing was bend out of 3mm CellFoam so the chord, minus aileron, was 5".
Wingspan was 32", thickness 13% 40% from leading edge.

I'm thinking of just reducing the thickness but with all the airfoils I'm looking at in MotoCalc I figure I'd better ask for opinions before I start bending.

The new wing will also be bent out of 3mm CellFoam.

The plane will probably weigh in between 10-12 ounces, MKi was 11 with 2s battery and 1oz of lead for balance.

Opinions Please.

Added some photos of the fuse being assembled just for giggles.
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Old 09-05-2007, 03:23 AM
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Water Boy
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When you say "bent" are you refering to the KF airfoil? If not have you read about it? Its a really great and effective foil. I have 2 bipes built with it, one of which is in my sig.
There have been many threads on it on here and RCG. Great flight charateristics. Nice slow flight, great lift and god penetration. I am using it on most of my foamies for now on.
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Old 09-05-2007, 03:28 AM
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fr4nk1yn
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I was thinking of using one of the 9% 2 step KF foils but I think a symmetrical is easier to bend. I've used the KF a few times on some builds but they were simply cut from the edge of blu-core.

I like the top step KFm wing but inverted the KFm becomes a bottom step which I don't like the stall characteristics of.

hey! alt+f4 closes the browser (;
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Old 09-07-2007, 04:38 AM
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I'm bored so I'll post some photos of the planes progress.

The airfoil was fubar. It came out as 13%, again, max thickness is aprox 18% of chord and it's somewhat semi-symmetrical. Oh well.
My 1st attempt a an Eppler 168 resulted in the foam cracking near the spar.

Elmer ProBond, lots of it as you can see in the wing, and CA is being used for most of the assembly.
This time I used Monokote covering before bending and also added some scribe the inside in " increments to help the bend.
Inside of the blue foam spars is a bamboo spar. It formed somewhat of an I beam.
Servo tray is 5mm Cellfoam.
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Last edited by fr4nk1yn; 09-07-2007 at 05:29 AM.
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