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):
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.
In this case I discovered that the fixed segment of the cockpit canopy was mounted on the pilot’s canopy rails. (In the previous post I assumed that this rail was placed between the pilot’s canopy and this fixed canopy). If I did not find this error now, it would cost me much more work during the later stages of this project! Now I could quickly fix it (see Figure 51‑2b).
In the rear part of the SBD cockpit you can find a double (two-beam) rail (Figure 51‑2a). The forward segment of the gunner’s canopy slides along the outer rail, while the rear (i.e. the last) segment — along the inner rail (Figure 51‑2):
In Figure 51‑2b) you can see that this rail protrudes from the last segment of the canopy. It’s OK — in the real aircraft they cut out a half of its bottom edge, to make room for it (Figure 51‑3a):
Frankly speaking, these rails forced a lot of small modifications along this “canopy sequence”. Their presence allowed me to fix various small differences between the reference photos and this model. In particular, now the roundings on the canopy rear edges match the photos, as well as the clearance between these canopies.
The typical cockpit canopy frame of a WW II airplane was a structure made from duralumin (or steel) tubes. In the SBD these tubes had rectangular cross sections, and were riveted to each other. They formed frames, which were covered with relatively thin (2-3mm) transparent organic glass plates. These plates were attached to the tubular “skeleton” by rows of small bolts (Figure 51‑4):
The heads of these bolts had flat (conic) heads, which were “sunken” in the thin sheet metal strips placed over the organic glass plates. (There was also a seal layer under these thin duralumin strips). In this post I will recreate these external sheet metal elements. The internal tubular frame of the canopies will appear during the last, detailing stage.
As the first I created the windscreen frame (Figure 51‑5a). The general method is always the same: I copied the mesh from the “glass” object, then cut out the frame stripes (Figure 51‑5b):
Of course, the subdivision surface generated by these strips in some places does not lie on the reference “glass”. Thus I had to adjust this mesh a little (Figure 51‑6a):
Finally I obtained the result as in Figure 51‑6b). Note that I created the frame of the hinged windscreen part as a separate object (just in case).
I formed the further canopy segments in a similar way. First I copied the mesh of the corresponding “glass” object. If it was required, I shifted it along its rails to match it against the reference photo (Figure 51‑7a):
Then I inserted into this mesh additional, sharp (Crease = 1) edges along the borders of the frame strips that are visible on the reference photo. Finally I removed the unnecessary faces from the areas between these strips (Figure 51‑7b).
When the frame shape matched the reference, I shifted it back onto the corresponding “glass object” (Figure 51‑8a):
Finally I made this frame thick (by the “sheet-metal thickness” — about 0.02 or 0.03”). I did it using a Solidify modifier. It is directed outside, so it creates an illusion of thin stripes lying on the “glass” surface (Figure 51‑8b).
In a similar way I created frames of the all other segments of this cockpit canopy (Figure 51‑9):
In this source *.blend file you can evaluate yourself the model from this post.
As you can see, this Dauntless model starts to resemble the original aircraft. However, it still misses the propeller. I will work on it in the next post.
Airplanes in 3D 