Closing an eliptical wingtip

[Micho]

Hi. I've just created the account here. To come to the point: I have a problem with closing a surface on an eliptical wing/horizontal/vertical stabilizer. I have searched all the internet and tried many options but still couldn't find satisfactory sollution, that makes both leading and trailing edges smooth and left no visible boundries between each surfaces. The problem is pictured below:







This is vertical stabilizer of PZL-38 "Wilk", part of my engineer work Thank You in advance for any tips.

 

[MrCATIA]

I'd try a Multi-Section Surface from the top edge of the wing surface (with tangency to the surface) to the outside curve. Then repeat for the bottom portion. That should work if the curves are good.

Another method is a Fill surface between the two curves, again with tangency to the wing surface.

(this looks familiar - did you ask about this maybe a month ago?)

 

[Micho]

I have already tried Your method. This is what I get using Multi-Section:
View attachment 1950
View attachment 1951

The effect using fill is even worse. Best sollution I got was to divide both surfaces into 2 with a guide (extremum of the surfaces) and then use Multi-Section for the part including leading edge and Fill for the rest (both with tangency to the wing) . It makes nice surface but still I couldn't get smooth trailing edge. I also tried to extrude the outside curve and then use tangency to this. It improves trailing edge but makes "waves" on the surfaces.

(No, I have not asked about this before. I suppose this is a common problem with closing wingtips )

 

[MrCATIA]

Here's a different approach:

1. Use Extrapolate to extend the top and bottom wing surfaces out beyond the wing tip. They should be as smooth as the wing surfaces. Depending on your geometry, Tangent continuity may be fine but Curvature continuity is usually better.
2. Use the elliptical wingtip curve to make a Extruded surface extending thru the wing surfaces. Trim the wing surfaces to the extruded surface.
3. Add some fillets to round off the sharp edges.

 

[Micho]

This is what I also tried It makes nice continuity, smooth edges, but... the thinckness of the wing is different at the very tip (the vertical part of the extruded surface is adjusted to the airfoil shape). Thank You anyway. What I did was to use the method I mentioned before. However, It doesn't work with all the surfaces too. I had to divide the upper and lower surface into (even) 3 pieces with splines and then use multisection/fill between them a few times. After that I was editing tangency of the splines to fit the best sollution. Sometimes it's good to create a separate multi-section surface only for the edges along the outside eliptical curve, but sometimes it is useless. I am aware this is not the best sollution, but good enough for my project. As You can see there is no rule Thanks for help. Now I have another problem with volumes, but I will create another topic for this