Any idea how to approach this?

Brian,

I have attached a model of my method.

The center fuselage is a revolved surface. Then the front fuselage is a boundary surface from the existing revolve to a sketched circle. I used a "Curvature To Face" to keep it nice and smooth. Then, to cap off the nose, I used a surface fill with Curvature for the edge. I added a constraint curve, which only consists of a sketched point (and a reference line), this way I can control the height of the fill. I then trimmed off the back edge, and also replaced it with a fill. I knitted it all together, and since the model is symmetric, I trimmed it in half.

Next I created the wings with a boundary surface. Notice that the top and bottom are seperate sketches. Generally, open splines work better than closed splines, so this is good. Note that for the second (bottom) surface I used a tangent constraint on each of the secondary direction edges. This ensures good tangency between the new and old surfaces.

Now for the good stuff, and the answers to your questions. I trimmed away the fuselage using a single closed spline. note that at the front, it is not symmetrical (top to bottom). This is an artifact of using a closed spline, and why I generally avoid it. They are just harder to control. In this case, to match your question, I need to keep it as a single spline. So ignore the error and lets take a look at what I did.

I did it in two parts, top and bottom. For the top, I needed to only select half of the fuselage edge. But as it is a whole, single edge, I cannot select that. It wants to select the whole edge, which isn't what I want. So I made a 3D sketch, used convert entities to make the edge a sketch object, and then trimmed the sketch line back to just the top half. Now I can use that for the boundary surface. I also added sketched transitions from the wing to the fuselage (I discuss how to do that more below in bold). I didn't just want sketches, though, I want to make sure that the entire leading and trailing edges are perfectly vertical along those lines. So I extruded those sketches with the surface extrude tool. Then, when I made the boundary surface, I can select those edges, and make the surface tangent. So I created the boundary surface, made the Dir1 curves Curvature to Face with 100% tangency influence, and made the Dir2 curves with just Tangency to Face and 0% influence. Then, I added connectors (right click on one of the green lines, and select "add connector") to help control the flow.

Then, to make the bottom transition surface, I just hid the hold reference surfaces, and used the new edge of the top half boundary surface for that Dir2 curves. I knit the existing surfaces (that way I don't have to do the 3D sketch thing again). Then just repeat the same method as the top.

To make the wing tips I just made a transitionary sketch on the Front plane. I used a 2 point spline (just the endpoints). This makes for a very sharp transition, but you may want to make it come out more. To do that just make it a three point spline, and move that centerpoint out as far as it takes. Instructions for face-to-face transitions: To make the sketch also maintain good curvature, you need to select: the spline, the edge, and the face. This will bring up the constraint Equal Curvature, which is what you want. Do this for both the top and the bottom faces.

Now, use this to make a boundary surface from the top to the bottom. This is a bit tricky. I actually created a video, so let me just show that here (it will take about 30 minutes from when I post it for vimeo to process it, so please be patient).

So. Does that give you the results that you want?

Brian,

Looking at your zebra stripes, I would reinforce what Charles said about curvature continuous transitions. It looks to me like you didn't even set the transitions up with tangency, let alone curvature continuity.

Jerry Steiger