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how do you make a trapezoidal aero panel?

When I try to make an aero panel, I only get a rectangular option that lets me pick the 1-4 corners of a rectangle. But many surfaces need a trapezoidal panel shape.

 

I looked through all the manuals and online, but couldn't find an explanation. The other flutter software packages I've seen have a 4 point pick.

 

Thanks in advance,

flyboy2160

4 REPLIES

Re: how do you make a trapezoidal aero panel?

When creating an Aero panel in FEMAP, you enter the 1-4 points for the leading edge of the panel, and then the chord length at both ends.  Different chord lengths will result in a tapered panel.  These four inputs should get you any shape panel you need.

 

Mark.

Re: how do you make a trapezoidal aero panel?

Mark,

Thank you!

But I want to attach the corners of the aero panel to structural nodes. I tried doing it using both the 'on node' option for the chord edges and 'offset from node' option with the offset set to 0., but neither will hook the panel to the node.

I think I need that hook: Won't the air loads be calculated from a deformed mode shape?

Steve

Solution
Solution
Accepted by topic author flyboy2160
‎12-20-2016 04:17 PM

Re: how do you make a trapezoidal aero panel?

In the Aero Panel dialog box, put the cursor in "X" entry for "Point 1", in the graphics window, right click the mouse and change the snap mode to "Node", you can then pick any node on screen it's X,Y,Z values will fill in the Point 1 Selection.  Do the same for Point 2.  You will then have to measure the chord length using the little "Ruler" button to define the two chord lengths.  Air loads are calculated by several methods, one example being a Doublet-Lattice method.  These are working on the panels as defined.  These aero panels are then splined to the structural model to make the connection.  I've always though of NASTRAN aeroelasticity as the aero model providing aerodynamic damping to the structural mesh.  It's not CFD.  I suggest you take a look at the Webinar produced by SDA for some more info -

 

https://structures.aero/software/nx-nastran/aerodynamic-flutter/ 

 

Mark.

Re: how do you make a trapezoidal aero panel?

Thanks again Mark,

 

I owe you a beer or food!

 

I'm aware of the splining connection, but was trying to avoid it (you have this option in some other software.)