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New Wing design.

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Posted

There has been some real intelligent wing talk lately so I want to run this by you guys  anybody see any reason this could cause problems. Adding 2 inches to the rear and total of 1/4 to the top. Black doted line is the new shape. Starting about the center of lift is zero.  Ill go into detail what its for later.

0119201404_resized.jpg

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Posted

Actually doesn't appear to be a major impact on lift or airflow so unless  its for a special use then it wouldn't change much of anything.

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Posted

If you are going to do that why not go to a newer flat bottom style rib? You have me curious now. 

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Posted

If you are going to do that why not go to a newer flat bottom style rib? You have me curious now. 

I just acquired a partial set of M4 ribs to have a pattern for them. A model 2 with model 4 wing ribs, HUH?

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Posted

If you are going to do that why not go to a newer flat bottom style rib? You have me curious now. 

Its the model 4 rib but to get the flaperon to enter the air-frame that I am working on It needs to be 2 inches further back. I will be making all wing ribs from scratch everything brand new.  This is a special air-frame that is my baby.  And its gonna be sweet more details to come in the next year.

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Posted

If you are going to do that why not go to a newer flat bottom style rib? You have me curious now. 

Its the model 4 rib but to get the flaperon to enter the air-frame that I am working on It needs to be 2 inches further back. I will be making all wing ribs from scratch everything brand new.  This is a special air-frame that is my baby.  And its gonna be sweet more details to come in the next year.

You’re going to keep us turkeys in suspense for a year? Sounds like something fun is in the works. Hope you do a full build thread like last time. 

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Posted

I'm not an expert, but from what I understand, a sharp leading edge can get you into trouble with nasty stall characteristics and it's best not to mess with the leading edge unless you know what you're doing. Extending the trailing edge shouldn't make much of a difference. With that said, the KF4 uses the Ribblett GA30U-612 airfoil and the coordinates are posted on the internet. Why not plot the airfoil with a 2" longer chord and you will have a known airfoil and not be left wondering how your changes will affect the flight characteristics? I can plot it out in CAD if you need. Just get me the chord length.

 

 

-Brett

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Posted

For what it's worth, if a designer is going to use a constant-chord, constant section shape wing (the old Hershey bar) it's important to NOT have out at the tip an airfoil that at nearly zero lift is crawling up the inside of it's drag bucket!  This highly recommends against the undercambered airfoil section shapes.  Even some of the flat-bottomed shapes are starting to edge up the inside of their drag buckets at zero lift.  The spanwise lift distribution is, according to Otto Schrenk, about halfway between the chord distribution and an elliptical distribution.  There's also a modification to this due to wing washout, which further contributes to unloading the wingtip.  So at very minimum, I would have to chime in and say if you're going to put an all-new airfoil section shape on there, ditch the undercambered lower surface, at least out approaching the tip.  Otherwise you will suffer an unnecessary drag penalty.   - Turbo

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