# Question about reference values --> Area (multi element wing)

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March 28, 2010, 08:39
Question about reference values --> Area (multi element wing)
#1
Member

smith
Join Date: Apr 2009
Posts: 75
Rep Power: 17
Hello everybody!

I have a question about the reference values for an 3D multi element rear wing.

First of all, if i analyse a single element airfoil under different angles of attack, my reference area of my wing is always the chord-line times the length of the airfoil right? doesn't matter which angle of attack my airfoil has?!

But what happens in the case of an multi element rear wing? (attachment)
my logical thoughts say me that i just have to summarize all the single element areas by calculating the single elements as described above.

Is this right or i am doing an mistake there?

Kind regards!
Attached Images
 123123.JPG (16.5 KB, 115 views)

 March 28, 2010, 10:42 #2 Senior Member   Jouke de Baar Join Date: Oct 2009 Posts: 127 Rep Power: 16 Hi, A common choice is the planform area. This is the area of your wing projected on the ground when the wing is in horizontal position. In this definition it does not depend on AoA. You might use: report > projected areas Good luck!

 March 28, 2010, 10:46 #3 Member   smith Join Date: Apr 2009 Posts: 75 Rep Power: 17 so, if my wing is in horizontal position where this is the x direction, you mean i should use the projected area in x direction?

 March 28, 2010, 11:16 #4 Senior Member   Jouke de Baar Join Date: Oct 2009 Posts: 127 Rep Power: 16 Hi, that is correct, only to my understanding your projection should be in the z-direction. (Or in the y-direction for a 2d case.) So for a 3d case let fluent do the projection along the z direction. Make sure to have the resolution small enough. For a 2d case simply take the difference between the x-coordinates of the first leading edge and the last trailing edge of your wing.

 March 28, 2010, 11:22 #5 Member   smith Join Date: Apr 2009 Posts: 75 Rep Power: 17 hm, if my chord-line is in the x direction, the thickness is in the y direction and the depth is in the z direction i thought i should chose the y direction for the 3d case?

 March 28, 2010, 11:23 #6 Senior Member   Jouke de Baar Join Date: Oct 2009 Posts: 127 Rep Power: 16 your right

 March 28, 2010, 11:25 #7 Member   smith Join Date: Apr 2009 Posts: 75 Rep Power: 17 okay, thanks a lot!

 March 28, 2010, 11:29 #8 Senior Member   Jouke de Baar Join Date: Oct 2009 Posts: 127 Rep Power: 16 Good luck!