Seamless Joining of Two Objects

This post is a small digression about a modeling technique that you may find useful.

There is a detail on the bottom surfaces of the SBD center wing: an opening, made partially in the cover of the fuselage belly (Figure 72‑1):

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Figure 72-1 The detail that I have to recreate

The difficult part of this detail is its flange, stamped in the fuselage cover. I just have two photos of this element, both of average resolution. On both of them you can see a typical circular recession, made around the opening in the belly cover. In fact, such a feature is quite common in the sheet metal design (you can see plenty of such stamped flanges in various places inside your car). This is a minor detail, too small for any serious modeling, but too large for recreating it with the textures.

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Using Panel Lines to Verify the Fuselage Shape

In every creative process, after each “big step forward” you have to stop and carefully examine the results. Usually you have to make various corrections (sometimes minor, sometimes major), before taking the next step. This post describes such minor corrections that I had to make after mapping the key texture of the panel lines.

In my first post published in October, I drew the panel lines on the model, then compared them with the photos. Sometimes a minor difference between their layouts can lead to a discovery of an error in the fuselage shape. I in that post already found and fixed an issue in the shape of the tailplane fillet.

I also mentioned (see Figure 65‑9 in previous post) that I can see a difference in the bottom part of the wing fillet. Now I would like to resume my analysis at this point (Figure 67‑1):

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Figure 67-1 Difference in the shape of the wing fillet bottom seam

Continue reading Using Panel Lines to Verify the Fuselage Shape

Unwrapping Meshes of the Alternate Dauntless Versions

After a long break in August and September (I had to finish a demanding project in my daily work) I am back. This week I made a “slow start”: because in my last July post I finished mapping the SBD-3, now I mapped in the UV space parts that are specific to the alternate Dauntless versions: SBD-1 and SBD-5.

Let’s start with the SBD-1: when you switch into its scene, you can immediately see the gray elements that are not mapped in the UV space (as in Figure 62‑1a). These parts are specific for this version:

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Figure 62-1 Unwrapping elements that are specific to the SBD-1

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Final Adjustments of the Model Shape

While working on the cowling details, I discovered that the SBD-5 from the Commemorative Air Force (“white 5”) uses a non-original Hamilton Standard propeller. It has larger hub and a pair of bolts in the middle of the hub barrel edges. (As I wrote in this post, the original Hamilton Standard hubs used in the SBDs were smaller, thus they had a single bolt in the middle of each barrel edge). What’s more, I also noticed that the centerline of my model does not precisely pass through the tip of the propeller dome visible in this photo. When I corrected this mistake, I also noticed that the edges of certain cowling panels in my model are minimally below their counterparts on the photo. I examined this difference and decided that I should fix it by rotating the camera of this projection around the fuselage centerline. It was really a “cosmetic” adjustment — the rotation angle was about 0.7⁰. However, suddenly everything in this model matched better the reference photo — except the horizontal tailplane (Figure 58‑1):

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Figure 58-1 Improved matching of my model to the largest reference photo

Continue reading Final Adjustments of the Model Shape

Details around the Gunner’s Cockpit

The last details that I create in this project stage are the gun doors behind the gunner’s cockpit. In the SBD-1 they covered a single Browning gun. Fortunately, they were wide enough for stowing the double guns, which were mounted in the SBD-2 and SBD-3 by the Navy workshops (Figure 57‑1):

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Figure 57-1 Evolution of the SBD gunner’s cockpit

Note that stowing the ammunition belts of this double gun required additional cutouts in the cockpit rear border. They were covered by slide plates on both sides of the gun doors (Figure 57‑1). In this post I will recreate these details.

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Updating the SBD-5 Model

I continue updating the Dauntless versions that I am building in parallel to the basic SBD-3. In the previous post I updated the one important element of the SBD-5 model: its propeller (SBD-3 used an older version of the Hamilton Standard propeller). In this post I will continue this update.

While I already recreated the SBD-5 NACA cowling (see Figure 46-8 in this post), now it is time to adapt the panels behind it. I started by copying the corresponding cowling from the SBD-3. When it appeared in the place, I discovered a 1” gap between this cowling and the SBD-5 inner cowling panel (Figure 56‑1a):

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Figure 56-1 Fitting the rear cowling from the SBD-3 into SBD-5

Continue reading Updating the SBD-5 Model

Updating the Model of the SBD-1

As I described it in one of my previous posts, in parallel to the SBD-3 I build a SBD-1 model and a SBD-5 model. They are in the same Blender file, but in separate scenes. Since I completed the SBD-3 model for this project stage, now it is time to take care of these other versions. These models share all the common objects with the SBD-3, so I have to recreate a few different details. I already modified their NACA cowlings. In this post I will update the SBD-1, because there is just a single remaining difference: the ventilation slot in the side panel of the engine cowling.

The SBD-3 had this slot much wider than the SBD-1 and SBD-2 (Figure 54‑1):

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Figure 54-1 Comparison of the ventilation slots in the SBD-3 and the earlier versions

(I used here an archival photo of the SBD-2, because it had the same side cowling as the SBD-1. There were only 57 SBD-1s ever built, so the photos of this version are not as numerous as the later ones).

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Cockpit Canopy Details

Before I start forming the frames of the Dauntless canopy (which I created in the previous post), I had to conduct yet another verification of its shape. I placed the canopy rails on the cockpit sides, and verified if they fit the corresponding canopy segments. First I tested the rails of the pilot’s canopy (Figure 51‑1a):

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Figure 51-1 Tracing the rails of the pilot’s canopy

They were formed from open-profile beams (Figure 51‑1b). Why these rails are such an important test tool? Because they always have to be parallel to the fuselage centerline! It sounds obvious, but it can reveal various unexpected errors in the canopy shapes.

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Forming the Cockpit Canopy

Like many contemporary designs, the SBD had a long, segmented (“greenhouse”) cockpit canopy. In this post I will show you how I recreated it in my model. I will begin with pilot’s canopy, then continue by creating the three next transparent segments.

I formed the pilot’s canopy by extruding the windscreen rear edge (Figure 50‑1). (I formed this windscreen earlier, it is described in this post). The high-resolution reference photo was a significant help in precise determining its size and shape:

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Figure 50-1 Forming the pilot’s canopy

Generally, the canopy shape in the SBD is quite simple. The tricky part was that each of its segments slides into the previous one. (Oh, well, the pilot’s canopy slides to the rear, but it does not matter in this case). This means that there were clearances between each pair of neighbor canopies that permitted such movements. If I made them too small or too wide, the last (fourth) canopy segment would not fit into cockpit rear border (i.e. the first tail bulkhead)! In such a case I would have to adjust back all the canopy segments. Well, I will do my best to avoid such error.

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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):

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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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