Modeling the Upper Cowling of the Fuselage

In this post I will form the fuselage panels in the front of the windscreen. In the SBD there were two hinged cowlings, split in the middle. They allowed for quick and easy access to the M2 gun breeches and the internal cabling behind the instrument panels (Figure 49‑1):

Figure 49-1 The hinged cowling in the front of the windscreen

The parts of the fuselage around the cockpit are always tricky to model. It especially applies to the panel around the windscreen. When you obtain the intersection edge of these two objects, it can reveal every error in the windscreen or the fuselage shape.

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Modeling the Rear Part of the Engine Cowling

In this post I will create the next section of the engine cowling. I copied its forward edge from the rear edge of the inner cowling panel. Then I extruded it toward the firewall (Figure 48‑1):

Figure 48-1 Initial shape of the engine cowling behind the NACA ring

I am going to split this object into individual panels, thus I already marked their future edges as “sharp” (as you can see in the figure above). It allowed me to preserve continuity of the tangent directions around these future panel borders from the very beginning.

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The Old-Fashioned Curves of the SBD Engine Cowling

This relatively short post contains a digression about the aircraft shape. It was sparked by a suggestion that I received. Some time ago Alan from SOARING pointed me that the SBD NACA cowling was not as smooth as in my model (thanks, Alan!). He suggested that its contour was created from a combination of two or three arcs and a straight segment (Figure 47‑1):

Figure 47-1 A different concept of the NACA cowling contour

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Engine Cowling Details

In this post I will finish the engine cowling of the Dauntless (of course, for this stage of the project). In the previous posts I formed its outer panels. In the case of the air-cooled radial engines like the one used in the SBD, there is always another, inner panel: the central part of the cowling. It is located behind the cylinders and exhaust stacks. In the classic arrangement of the NACA cowling it is nearly invisible. In the SBD-1..-4 you could see only its outer rim. That’s why I had to use all available pictures of the Dauntless engine maintenance or the wrecks, to learn about its general shape (Figure 46‑1):

Figure 46-1 The central cowling panel, behind the engine

This panel had two variants. The first one (let’s call it “flat”) is visible on the photo above. It was used in the SBD-1..-4. In the SBD-5 and -6 the engine was shifted forward by 4”, so the central panel became a little bit longer (“deeper”).

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Modeling the Carburetor Scoop

The carburetor scoop passed significant evolution in the subsequent Dauntless versions. In the SBD-1 there was a rather large air duct placed on the top of the NACA cowling (Figure 45‑1a):

Figure 45-1 Evolution of the carburetor scoop in the first Dauntless versions

However, it was quickly discovered that it obscures one of the most important spots in the pilot’s field of view: straight ahead and slightly below the flight path. That’s why it was somewhat corrected in the next version (SBD-2). In this aircraft the designers lowered the scoop, increasing the field of view from the cockpit. Such a solution persisted in the SBD-3 and -4. In the SBD-5 they completely redesigned it, placing the carburetor scoops inside the NACA cowling (more about this — see in this post the paragraphs around Figure 11-6).

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