Initial Approximation of the Fuselage

Before I start forming the mesh of the SBD fuselage, I will prepare an auxiliary object: the simplified version that will help me to grasp the general concept of its shape. I will describe it in this post.

In the first step, I created the three key bulkheads (Figure 22‑1):

Figure 22-1 The key bulkheads of the SBD fuselage
Figure 22-1 The key bulkheads of the SBD fuselage

First one — the firewall — seems to have an elliptical shape (Figure 22‑2):

Figure 22-2 The shape of the firewall
Figure 22-2 The shape of the firewall

The contour of the station 140 on my plans is copied from one of the photos which I have found on the Vultures Row Aviation web site (Figure 22‑3):

Figure 22-3 Station 140
Figure 22-3 Station 140

For this conceptual shape I replaced the bottom part (after the trailing edge) with the curve extrapolated from the further tail cross sections.

Finally, in station 271, which closes the main fuselage structure, I had to extrapolate its upper part (Figure 22‑4):

Figure 22-4 Station 271
Figure 22-4 Station 271

Then I extended between stations 140 and 271 a mesh, forming in this way the simplified tail (without the wing root fairing) (Figure 22‑5):

Figure 22-5 The first approximation of the tail
Figure 22-5 The first approximation of the tail

I put another edgeloop in the middle of this tail to fit its contour in the side and top views.

In the next step I recreated the mid-fuselage (Figure 22‑6):

Figure 22-6 Forming the mid-fuselage
Figure 22-6 Forming the mid-fuselage

In this concept object I entirely skipped the wing root fairing — because it requires a lot of work. I will recreate it directly in the final fuselage object. Note that the fuselage contours along the cockpit are straight lines. This detail is visible on many photos.

I added in the middle of the cockpit another “bulkhead” edgeloop, and used it to determine shape of the bottom part of this fuselage (Figure 22‑7):

Figure 22-7 Fitting the bottom part of the fuselage
Figure 22-7 Fitting the bottom part of the fuselage

I fitted the contours of the fuselage that protrudes from the wing bottom surface into the contours in my reference drawings. It took some iterations to fit them. (The contour you can see in the bottom view was copied from original Douglas photo, so it is an important reference. The side view is not based on such a confirmed information). To preserve the straight edges on the cockpit sides, I had to move this central bulkhead along the fuselage centerline using the Edge Slide command. I was able to move or scale this edge only along the Z direction.

Finally, when I finished this element, I checked if the cockpit sides are still straight, like before. They were not (Figure 22‑8):

Figure 22-8 Small deformations in the middle of the fuselage
Figure 22-8 Small deformations in the middle of the fuselage

As you can see in the picture above, I used an auxiliary horizontal plane set in the contrast color to see the effective shape of the fuselage mesh. I placed it just above the “longeron” edge that runs along the maximum width. The fuselage contour you can see on this plane is bent in the front of station 140. I think that such a shape is the effect of the “saddle”-like shape of the fuselage in this area. I am glad that I identified this issue on this simplified model. I will try to avoid such an effect in the final fuselage by directing all the lengthwise (“longeron”) edges along their real-life counterparts (upper-left to bottom-right on the side view).

In this source *.blend file you can check all details of the model presented in this post.

In the next post I will continue working on the fuselage. (I will use the object crated in this post as the reference).

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