Adjusting the Tail Tip Shape

In the previous post I formed the shape of the SBD Dauntless tail tip. In this post I will finish its “closing strip” that contains the running light frame. I will also verify the overall shape of the tail tip using the available photos.

There is one thing I didn’t mention in the previous post, just to keep the narration focused on the pure modeling. Before the modeling I carefully studied the reference photos. In the result I found differences in the shape of the curved trailing edges of the fairing behind the elevator. On the photos you can see a straight fragment of this edge (Figure 39‑1a). Its presence means that the curve of the trailing edge was smaller, and the fuselage was somewhat thinner here. You can see the differences between the real shape and my reference drawing in Figure 39‑1b):

Figure 39-1 Another mistake that I found on my scale plans

I did not notice these detail before. As you can see, I applied this modification when I started to model this part.

Modeling the Tip of the Tail

The tip of the SBD tail was a light fairing, attached to the last bulkhead (at station 271 — see Figure 38‑1b). That’s why you can see “NO PUSH” label on the photo in Figure 38‑1a). The tail wheel was attached to the bulkhead 271, which transferred the resulting loads forward, via the tail structure. The tail tip fairing was always free of any significant loads. However, the shape of this part is a combination of the empennage fairing and the last fuselage segment. What’s worse, there is a large opening at the bottom — for the eventual tail wheel deflection (Figure 38‑1b):

Figure 38-1 The tip of the tail — from the top and bottom

Modeling Empennage Details

After the previous post I decided to simplify the empennage fairing. Originally I created it from two separate objects: the fin fairing and the tailplane fairing, split across their fillet. Now I decided to eliminate this troublesome seam by joining these two meshes into single object (Figure 37‑1):

Figure 37-1 Initial merge of the two fairings

I will split it later, along the bottom rib of the fin (there was another panel seam in the real airplane). To simplify creation of the original overlapped panels, I simultaneously split the fin into the forward and the rear part, along one of the original seams.

Modeling the Fin Fairing

In the SBD Dauntless the fillet along the fin and the fuselage was formed from the bent bottom edges of the fin panels. I am showing it in Figure 36‑1:

Figure 36-1 Details of the fin fairing

(To make some of these panel seams more visible on thee photos, I sketched along them thin lines). You can observe that each fin panel overlaps the next one, starting from the tip stamped as the part of one of the fuselage doors (see Figure 35‑8 in the previous post). The outer contours of these panes are not perfectly aligned: you can see small overlaps on the photos (Figure 36‑1). Surprisingly, such a detail makes the modeling more difficult. However, the most difficult part will be the seam between the fin and the horizontal tailplane fairings (see Figure 36‑1). It runs along the fuselage longeron, across the fillet between the stabilizers and fuselage.

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

Modeling the Tailplane Fairing

In the previous post I formed horizontal tailplane of the SBD Dauntless. In this part I will describe how I created the fairing between this tailplane and the fuselage. It is an easier part than the wing root fairing, because it is smaller and most of its cross sections are not circular.

At the beginning I cut out from the stabilizer its middle segment, along the root rib (Figure 34‑1):

Figure 34-1 Initial elements of the fairing

Then I “draw” the outer contour of this fairing in the side view. I also checked it in the reference photo (as you can see in Figure 34‑1).

Modeling the Empennage (2)

After some verification of the reference contours that I described in the previous week, I am coming back to modeling of the horizontal tailplane.

In the previous post I created the reference airfoil of its root rib. Now I copied it into a new object, straighten along the fuselage centerline, and finally extruded spanwise (Figure 33‑1):

Figure 33-1 Forming the basic contour of the horizontal tailplane

Modeling the Empennage (1)

The horizontal tailplane has similar structure to the wing — but it is simpler. Thus I started it in the same way as the wing, by forming its root airfoil (Figure 32‑1):

Figure 32-1 Modeling the root airfoil of the horizontal tailplane

In the most of the aircraft the tailplane has a symmetric airfoil. So it was in the Dauntless. I did not find its signature (family) in any of the reference materials, thus I carefully copied its contour from the photos (its rear part — the elevator — seems to have modified shape, anyway). It has incidence angle of 2⁰, so I rotated the rib object and used a Mirror modifier to generate its bottom part.