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Wing AOA on Kolb MK III?

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grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Mon Feb 11, 2008 5:50 am Post subject: Wing AOA on Kolb MK III?

Why is the Kolb MK III wing set at 9 degrees positive when the plane is set level for the weight and balance?



Does the plane fly with a 9 degree AOA in level cruise?



I guess this is confusing to me because I build radio controlled airplanes and I set the wings and horizontal stabilizers at 0 degree AOA in relation to the fuselage and thrust line. These fly fine. I have experimented with raising the AOA of the wing and it doesn’t seem to make much difference other than changing the trim settings.



I know the faster you fly the wing has to lower AOA and the slower the AOA increasing until about 14 to 16 degrees before a stall occurs. 9 degrees seems fairly close to the stall AOA.



What would happen if the wing was readjusted on the Kolb to have a Lower AOA?

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slyck(at)frontiernet.net
Guest

Posted: Mon Feb 11, 2008 7:25 am Post subject: Wing AOA on Kolb MK III?

Grant,  that is close to the cruise angle.  Sure looked funny to me  

too at first, sort of plowing

through the air.  The SS has a different setup.  I wonder  at what  

angle the CG is checked on it?



The main reason for the angle in cruise is the shape of the leading  

edge.  -The most forward point is near

the bottom of the wing surface.  On most common GA wings like the  

Clark Y and the Aeronca NACA 4412

the leading edge has a much larger radius so the streamlining into  

the wind results in a more

level angle.  I'll guess that taping a large radius cuff (1/2 slice  

of foam pipe insulation)  on a Kolb leading  

edge                                                                     

                                                          would  

result in a faster cruise.

BB



On 11, Feb 2008, at 8:50 AM, grantr wrote:



 	  Quote: 	
		   

 <grant_richardson25(at)yahoo.com>



 Why is the Kolb MK III wing set at 9 degrees positive when the  

 plane is set level for the weight and balance?



 Does the plane fly with a 9 degree AOA in level cruise?



 I guess this is confusing to me because I build radio controlled  

 airplanes and I set the wings and horizontal stabilizers at 0  

 degree AOA in relation to the fuselage and thrust line. These fly  

 fine. I have experimented with raising the AOA of the wing and it  

 doesn’t seem to make much difference other than changing the trim  

 settings.



 I know the faster you fly the wing has to lower AOA and the slower  

 the AOA increasing until about 14 to 16 degrees before a stall  

 occurs. 9 degrees seems fairly close to the stall AOA.



 What would happen if the wing was readjusted on the Kolb to have a  

 Lower AOA?





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=163454#163454

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rowedenny(at)windstream.n
Guest

Posted: Mon Feb 11, 2008 7:38 am Post subject: Wing AOA on Kolb MK III?

\Grant asked:

 	  Quote: 	
		   Does the plane fly with a 9 degree AOA in level cruise?


	




Yes, maybe a little less.

Grant also asked:

 	  Quote: 	
		   What would happen if the wing was readjusted on the Kolb to have a Lower 

 AOA?


	


If you lowered the angle of insidence of a Mk-3s wing you would have to go a 

lot faster to take off and land as you would not have enough angle of attack 

to rotate at the Mk 3s low stall speed without dragging the tail.  Also the 

horizontal tail angle would have to be changed accordingly, and you would be 

flying around with your nose higher in the air to get the wing back to the 

correct AOA.

Homer got it right, these planes are a nice balance for light, low speed 

flying.

 	  Quote: 	
		  



 Denny Rowe, Mk-3 N616DR

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grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Mon Feb 11, 2008 10:36 am Post subject: Re: Wing AOA on Kolb MK III?

I think I know what your talking about however I don't see how the leading edge  effects wing AOA that much.



What kind of airfoil does the kolb have?

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Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Mon Feb 11, 2008 4:25 pm Post subject: Wing AOA on Kolb MK III?

At 01:36 PM 2/11/2008, grantr wrote:



 	  Quote: 	
		  I think I know what your talking about however I don't see how the leading 

edge  effects wing AOA that much.



What kind of airfoil does the kolb have?


	


The leading edge of the Kolb airfoils are formed by the front spar, which 

is a relatively small diameter tubing tangent to the lower surface.  AOA 

is, of course, measured from the chord line, which is the line running from 

the frontmost point on the wing (about the middle of that tube) to the 

trailing edge.  On a more conventional airfoil, the leading edge radius is 

both larger, which puts that frontmost point higher relative to the lower 

surface, and additionally the lower surface usually starts to curve up to 

meet the leading edge radius, so angle between the chord line and the lower 

surface is greater.  The upshot of all this is that at the same lower 

surface angle, the Kolb airfoil's AOA will be less than a more conventional 

airfoil, or, conversely, at the same true AOA, the Kolb _looks_ like it's 

at a higher AOA.



I could be wrong, but I'd guess the Kolbs use a TLAR airfoil ("That Looks 

About Right"), with its shape based as much on the materials and 

construction technique used as on aerodynamics.  The result is a high 

camber airfoil, good for low speed and climb, not so great for speed.



FWIW, the early Quicksilvers had a "670-15" airfoil, which was made by 

bending a thin aluminum tube for one-half of it's length over a 670-15 car 

tire; it was about 12% camber.



-Dana



--

  Nowadays only a lawyer can tell legal from illegal, and the lawyers don't 

know the difference between right and wrong.

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grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Mon Feb 11, 2008 4:36 pm Post subject: Re: Wing AOA on Kolb MK III?

Well just take all those aerodynamics and throw them in the trash! LOL  TLAR usually works very well. It does on my R/C airplane.



Wow I didn't know that about the Quicksilvers.



I looked at my wing on my MK III  when I got home and it appears to be a completely flat bottom wing. Its hard to tell in the trailer. 



I think flat bottoms do make more lift than cambered bottom wings. It also adds more drag I think.

Thanks

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