This post is dedicated to a minor feature, which I have found surprisingly demanding: modeling the grooves pressed in the curved surfaces of the aircraft panels. In the SBD you can see some of such reinforcements on the inner cowling, behind the cylinder row (Figure 95‑1):
They are 0.7-1.0” wide (Figure 95‑1a) and span over the inner cowling along its radial directions (Figure 95‑1b, c). In the SBD-5 and -6 these reinforcing grooves occur only on the lower part of the cowling (Figure 95‑1b), while in the earlier versions (SBD-1, -2, -3, and -4) they are also present on the upper part (Figure 95‑1c).
Even when the flaps on the NACA cowling are closed, you can still see rounded endings of these grooves around the cowling rear edge (Figure 95‑2):
In the earlier versions (SBD-1..SBD-4) they appear on the narrow strip behind the NACA cowling (Figure 95‑2a). You can see more of the upper grooves when the NACA cowling flaps are set wide open. In the SBD-5 and -6 the engine and the NACA cowling were shifted forward by 3.5”, and the gap between the NACA ring and the inner cowling is wider. Thus, in these versions you can see even longer fragments of the grooves behind the NACA cowling (Figure 95‑2b).
Such grooves appear on many sheet metal elements, so I decided to write this post as a small tutorial that teaches how to recreate these elements. Thus, do not be surprised when I list the detailed Blender commands in the text below.