Modeling the Empennage (3)

I started the vertical tailplane of the SBD by forming its root airfoil (Figure 35‑1). I had no description nor a direct photo of the airfoil used here. However, the reference photos reveal that it could have similar shape to the airfoil of the horizontal tailplane. Thus I copied that curve into this mesh.

Figure 35-1 The root airfoil of the rudder/fin

Note that I used here a thin strip of the faces instead of a single curve (which I used in the case of the horizontal tailplane or the wing). The reason is simple: on the single subdivision curve I cannot mark a “sharp corner” at a control point (original mesh vertex). On the face “strip” I can mark the corresponding edge as sharp (increasing its Crease coefficient to 1). I marked in this way the edge at the split between the rudder and fin. Simultaneously I can form such a face strip in the top view as easily as a single curve. (I just have to remember to select its vertices using the group select commands (Border-select or Circle-select), instead of the simple mouse click). Why didn’t I use this method in the previous cases? Well, good ideas require some time to emerge…

Once the root airfoil was ready, I extruded it into the basic trapeze (Figure 35‑2):

Figure 35-2 Extrusion of the mesh into the basic trapezoid

Then I split this mesh into the rudder and fin (i.e. into separate objects, as in Figure 35‑3):

Figure 35-3 Mesh details of the separated fin and rudder

Note that I added additional “rib” edges to the mesh of the fin. They will be useful in forming the forward fragment of this part.

Initially, I extruded the first approximation of the dorsal fin from the bottom edges of the lower ribs (Figure 35‑4):

Figure 35-4 Extrusion of the dorsal fin

However, I decided that the resulting topology of this mesh differs too much from the original layout of the panel seams (and the original ribs and spars). To make a better approximation, I used the fin shaped in the previous step as the reference object (in Figure 35‑5 it is in red):

Figure 35-5 Cutting out the forward part of the mesh

I cut out the forward part of the original fin, forming in this mesh the first vertical edge. Then I extruded it into next segment (Figure 35‑6):

Figure 35-6 Extruding anew the forward part of the fin

The next segments were extruded in similar way (Figure 35‑7):

Figure 35-7 Extruding next fin segment

In each new segment the vertical cross section is significantly smaller than in the previous one. I had to compensate it by cutting out its bottom fragment (using the Knife tool — as in Figure 35‑7) and reducing the number of remaining faces.

Figure 35‑8 shows the resulting dorsal fin:

Figure 35-8 The extruded dorsal fin

The tip of this fin was formed in an unusual way — it was stamped in the cover of a fuselage hatch (as you can see on the photo). I will form this cover later.

Figure 35‑9 shows the objects created in this posts:

Figure 35-9 The rudder and the fin objects, created in this post

You can examine them in this source *.blend file.

In the next post I will describe my work on the fairing of this fin (it seems quite simple, but occurred more difficult than I expected!).

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