The SBD-3 was a “quick and dirty” adaptation of the SBD-2 to the recognized requirements of the modern war. This is something strange, because I cannot find any evidence of this significant, 6 inch difference between SBD-3 and SBD-2 on the photos! The same sources specify the length of the SBD-2 as 32’ 2”. The reason was the different engine mount, modified in the SBD-5. In the previous post I described how the photos confirmed the different length of the SBD-5 (33’ 1/ 8”) and the SBD-3 (32’ 8”), listed in their specifications.
In the effect, the length of the airplane often vary between subsequent versions. The fuselage shape is not so important, so it is often modified. Thus, once “debugged” in the prototype (the stall characteristics etc.) it remains unaltered between subsequent versions. This is a typical case, because the wing geometry determines the aircraft behavior. When you look into Dauntless specifications, you will find that all its models have the same span, but they often differ from each other in the length. (Here are the links to the high-resolution profile images of: SBD-2, SBD-3). Within two weeks I will present the corrected/verified top view. I will discuss where are the differences in the length of the SBD-5 and SBD-3, 4, as well as the mystery of the “missing 7 inches” of the SBD-2. On the next week I will present side views of two earlier Dauntless versions: the SBD-2 and SBD-3. In the effect, the leading edge of the center wing section has a small downward inclination. Note that this airfoil was a specific modification of the NACA-2415 shape: the part of the wing that houses the main landing gear was reshaped. I draw the latter element just to mark the exact position of the first rib of the wing. That’s why you can see around this silhouette some auxiliary sketches: the front view of the engine cowling, and the contours of the center wing section. While drawing the side view you still have to think “in 3D”. The airfoils of the tailplane were specified nowhere. I still have to verify this detail when I build the wing. Because I did not observe such an effect on the photos, I decided to use the thicker airfoil of NACA-2409. However, the bottom contour of the NACA-2407 seems to be a little concave. Two different sources specifies different wing tip profiles: NACA-2409 (Performance Test Report, 1942) or NACA-2407 (BuAer drawing, 1944).
I draw three profiles: first of the wing root, then the root of the outer wing section, and then the wing tip. their airfoils as well as the incidence angles and spar locations). To build them, on the side view I need the precise contours of their key sections (i.e. For these parts the most important drawing is the top view. I prepare these plans to build a model: that’s why I removed the outer wing section and horizontal tailplane. The dotted lines mark the rivet seams, but size and spacing of these dots does not match the real rivets. This is not an ultimate drawing: I suppose that it will be updated during my work, following the new findings about the airframe shape and/or details. The good news is that the wing and the tailplane arrangement on the KAGERO plans and the BuAer drawing match each other: On the other hand, the BuAer top view is a little bit asymmetric, and the firewall line is moved forward a little. It seems that the part of the vertical tail contour was shifted). (The positions of the wing and horizontal tailplane match in the side and top view match each other. While the aspect ratio of the top view matches the span and length specified in the dimensions, the actual fuselage length on the side view is somewhat shorter.
#Dauntless builder manual
You can also find here some manual errors, made by its draftsman. This BuAer drawing isn’t an ideal source: it does not contain such details as panel seams. From the side view you can read the exact length: 33’ and 1/8“. From the front view you can read the precise wing span: 41’ and 6 5/16“. I have found on the Internet a BuAer Navy drawing of the SBD-5, from 1944. They do not show many details, but contain the key dimensions. Maybe the textual data contains an error? In such a situation I try to find an “official”, archival drawing of the aircraft. However, in this monograph they have the same length! The airframe after the firewall was the same in all Dauntless versions). Most probably it has slightly different engine cowling and the propeller. (The SBD-5 and SBD-6 fuselage was 33’ long. According the monograph data, SBD-5 fuselage was 4 inches (about 10.1 cm) longer than SBD-3.