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elliptical lift distribution

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elliptical lift distribution

Old 03-25-2020, 09:18 AM
  #1  
kantibo
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Hello guys,
Could someone help me with this document: Lift Superposition and Aerodynamic Twist Optimization for Achieving Desired Lift Distributions (see attachment)
I have a straight wing and i want to twist it geometrically to get an elliptical lift distribution.
I read the document below but i don't really understand what the matrice A and the vector x (respectively at equations 5 and 7) represent.
I understand the first column of the Matrice A but not the others one.
Is it possible to have any examples to help me to understand the concept?
My wing:
span: 1214.36 mm
chord: 202.39 mm
airfoil: Eppler E197.
Thanks in advance.

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Old 06-14-2020, 02:31 AM
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JacoS
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Originally Posted by kantibo View Post
Hello guys,
Could someone help me with this document: Lift Superposition and Aerodynamic Twist Optimization for Achieving Desired Lift Distributions (see attachment)
I have a straight wing and i want to twist it geometrically to get an elliptical lift distribution.
I read the document below but i don't really understand what the matrice A and the vector x (respectively at equations 5 and 7) represent.
I understand the first column of the Matrice A but not the others one.
Is it possible to have any examples to help me to understand the concept?
My wing:
span: 1214.36 mm
chord: 202.39 mm
airfoil: Eppler E197.
Thanks in advance.
I don't fully understand the document. It is a little above my comprehension of just pushing levers and turning fuel into noise.

Anyhow, I do know that washout is incorporated to prevent wingtip stalling. It has some negative side effect in that it decreases lateral stability. Think of hanging a painting on the wall with two strings. If the two strings are far apart the painting should hang much more stable compared to when you put the two strings right next to each other in the middle of the painting. By incorporating more washout into the wing you will 1. Decrease the possibility of tip stall and 2. Decrease lateral stability. This is why designers have come up with other methods to prevent tip stalling such as leading edge stall strips and a changing aerofoil section from root to tip.

So a balance has to be found and I guess this is what your document tries to explain. I reckon only a couple of degrees twist should do as model planes generally have very light wing loadings and your wing is of straight cord.

Hope this helps a little bit.
Old 09-08-2020, 12:19 PM
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SkyersJet
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That article is very complex. Why don't you get the distribution by changing the shape instead? Seems like that would be simpler.

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