Overview:

A major accomplishment took place in the SBD's restoration in recent weeks, with the trial-fitting of the aircraft's wing leading edges in the Wing Center Section jig. This was a momentous achievement, as it marked the first time that the Dauntless has worn the correct forward profile to its wing since the dive-bomber ditched in Lake Michigan during WWII!

While this article covers the process of matching up the leading edges to the adjacent wing structure, we will begin with a description regarding the remanufacture of one of the components fitted to the wheel well edging to emphasize the myriad complex details which restoring this aircraft actually involves—and the deft skills required of those performing its rebuild.

Wheel Well Stiffener Fabrication:

A length of extrusion circumscribes the wheel well cutouts in the SBD's Wing Center Section, adding rigidity to the overlying skin. Due to the nature of the contour they must follow, these seemingly simple parts require significant finesse to remanufacture correctly—Pioneer Aero's Chief Engineer, Martin Hedley taking on the task.

Rather than order a custom-designed extrusion to match the required cross-section, Hedley was able to modify an existing right-angle bulbed extrusion by milling off the flat leg to leave a length of flat extrusion with a bulbed edge. He then stretched the flat edge to approximate the wheel well cutout radius, after-which he ran the part through a rolling machine so that it lay snuggly against the wing skin interior—with the bulbed edge matching the skin's edge. It must be noted here that the rolled profile and cutout radius change constantly along the part due to the curve it must match in the leading edge skin. Once the parts were in the correct shape, Hedley trial-fitted them against the skin, then drilled them off in preparation for riveting.

This image shows the partially formed stiffener following the use of a rolling machine to match its curvature to the wing’s complex profile. The area near Martin Hedley's finger is close to the correct profile, whilst the ends require further manipulation to achieve the required shape. (image via Pioneer Aero Ltd.)
This image shows the partially formed stiffener following the use of a rolling machine to match its curvature to the wing’s complex profile. The area near Martin Hedley's finger is close to the correct profile, whilst the ends require further manipulation to achieve the required shape. (image via Pioneer Aero Ltd.)

Another view of the same, partially fabricated leading edge stiffener to further demonstrate how much curve has been applied in the initial shaping stage. (image via Pioneer Aero Ltd.)

The underside of the lefthand leading edge for the Wing Center Section, with the section of modified extrusion offered up to it, following the new part’s initial shaping to match the wheel well cutout. Hedley accomplished this by stretching the outer edge, without doing anything to the bulbed edge. (image via Pioneer Aero Ltd.)

While it may be difficult to discern to some, this closeup image shows how the whole length of extrusion, including the previously flat area, has been rolled to fit snuggly against the curve of the leading edge skin. (image via Pioneer Aero Ltd.)

The underside of the righthand leading edge for the SBD’s Wing Center Section showing the trial-fitting of its newly-made wheel well skin stiffener. The piece of modified extrusion has been stretched and rolled to closely match the wheel well cutout. It is sitting in its final position, with the edge of the bulb tracing the skin’s edge. (image via Pioneer Aero Ltd.)

A view of the same setup as the previous image, albeit from a different perspective, showing how the newly-fashioned stiffener closely fits the contours of the wheel well skin. (image via Pioneer Aero Ltd.)

A view of the wheel well skin stiffeners for the left and righthand wing leading edges following shaping and trial fitting. Note that the rivet holes have also been drilled off. (image via Pioneer Aero Ltd.)

A reverse-side view of the parts depicted in the previous image. This shot attempts to highlight the extrusion’s final, rolled profile. Note how the rivet holes have also been countersunk to match the dimples in the wing skin. (image via Pioneer Aero Ltd.)g

An underside view of the lefthand leading edge for the SBD’s Wing Center Section after the rivet holes for mounting the wheel well skin stiffener have been marked out, drilled and dimpled around the edge of the cutout. (image via Pioneer Aero Ltd.)

The underside of the lefthand leading edge for the SBD’s Wing Center Section with the newly-fabricated and painted skin stiffener offered up against the wheel well cutout. The part is now ready for riveting. (image via Pioneer Aero Ltd.)

A similar view to the previous image, albeit with the stiffener now sitting snugly in place against the wheel well cut out skin. (image via Pioneer Aero Ltd.)

A similar view to the previous image, albeit from a different perspective showing how the now-painted stiffener fits sitting snugly in place against the interior surface of the skin around the wheel well cut. (image via Pioneer Aero Ltd.)

The underside of the righthand leading edge for the SBD’s Wing Center Section showing the same close fit of its stiffener to the wheel well cutout skin. (image via Pioneer Aero Ltd.)
The underside of the righthand leading edge for the SBD’s Wing Center Section showing the same close fit of its stiffener to the wheel well cutout skin. (image via Pioneer Aero Ltd.)

Trial-Fitting the Lefthand Leading Edge:

With the leading edges more-or-less complete, it was then time to offer them up against Spar #1 for trial-fitting in the SBD's Wing Center Section jig for trial-fitting.

The restoration team initiated this effort with the lefthand unit—marking and positioning the newly-fabricated leading edge attachment angle in the jig, then drilling and reaming the holes to match those in the jig. They then fabricated the skin doubler which wraps around the leading edge at Station #66 (beneath the attach angle).

Next, they aligned the leading edge assembly with the adjacent structure in the Wing Center Section, positioning it for match-drilling against the interconnecting structure. First they drilled off the leading edge rib at Station #10 (the inner-most rib) to its associated Spar #1 attach angle. They then drilled off the wing attachment angle against the leading edge at Station #66. With the two ends of the lefthand leading edge now locked in place, the team proceeded to drill off the skin against the underlying spar caps for Spar #1, trimming the skin edges to their final size as well.

A closeup view of the SBD’s Wing Center Section jig showing the replacement lefthand leading edge attachment angle in the process of being drilled and fitted to the jig. The angle’s position sets where the leading edge is located, so it is important to get it situated correctly. Pioneer Aviation’s engineers were able to accomplish this via the use of a damaged original part from a donor airframe, along with dimensional details from the manufacturing drawings. (image via Pioneer Aero Ltd.)
A closeup view of the SBD’s Wing Center Section jig showing the replacement lefthand leading edge attachment angle in the process of being drilled and fitted to the jig. The angle’s position sets where the leading edge is located, so it is important to get it situated correctly. Pioneer Aviation’s engineers were able to accomplish this via the use of a damaged original part from a donor airframe, along with dimensional details from the manufacturing drawings. (image via Pioneer Aero Ltd.)

A similar view to the one shown in the previous image, albeit from a different perspective. As already noted, the attachment angle’s position sets where the leading edge is located. Although it is at a constant 90° with respect to the jig face aft of Spar #1, the angle changes constantly as it sweeps around the front of the wing to account for its sweep back, reaching its sharpest taper at the leading edge apex. (image via Pioneer Aero Ltd.)

Here we can see the lefthand wing leading edge attachment angle after most of the holes linking it to jig have been drilled in—these, of course, will eventually attach to a matching wing attach angle on the outboard wing panel when the two are eventually mated together. (image via Pioneer Aero Ltd.)

A view of the lefthand inboard wing leading edge assembly on the workbench, with the outboard edge at Station #66 closest to the camera. A doubler has been fabricated to fit over skin in this area, and we can see it in the process of being final-fitted, clecoed to the underlying skin and internal structure. Like the leading edge attachment angle, this doubler is a complex shape to fabricate due to the constantly changing taper between the leading edge and Spar #1. (image via Pioneer Aero Ltd.)

Another view of the lefthand inboard wing leading edge skin doubler during the process of trial-fitting it to Station #66—as seen from the top side of the wing. The rivet holes for the section aft of the clecos will be drilled in once the skin’s aft edge has been trimmed to its final size. (image via Pioneer Aero Ltd.)

The lefthand wing leading edge subassembly during the process of positioning it on the SBD’s Wing Center Section jig. This is a momentous step, because it is the first time since the aircraft’s wartime accident that the the front shape of the wing has been correct! (image via Pioneer Aero Ltd.)
The lefthand wing leading edge subassembly during the process of positioning it on the SBD’s Wing Center Section jig. This is a momentous step, because it is the first time since the aircraft’s wartime accident that the the front shape of the wing has been correct! (image via Pioneer Aero Ltd.)

Another view of the SBD’s lefthand inboard leading edge being positioned on the Wing Center Section jig. The wooden support near image center is bearing the subassembly’s load while the attachment angle at Station #66 (outboard end) and the angle at the aft end of the rib at Station #10 (inboard end) are being positioned for trial-fitting against Spar #1. (image via Pioneer Aero Ltd.)

A closeup of the lefthand leading edge, showing the process of positioning the rib at Station #10 for trial fitting. Note that the rib’s attach angle has been clecoed to Spar #1, and is about to be drilled off against the rib itself. (image via Pioneer Aero Ltd.)

Another view of the lefthand leading edge during its positioning in the Wing Center Section jig—the inboard face of the rib at Station #10 is the primary focus of this image. Note that the angle attaching the rib to the forward face of Spar #1 has now also been drilled off against the rib. A close look along the rib’s lower edge, towards the left of the image, will reveal a plumb bob line (running close to the cleco tops) being used to ensure that the wing reference line at apex of the leading edge curve matches the same point on Spar #1. (image via Pioneer Aero Ltd.)
Another view of the lefthand leading edge during its positioning in the Wing Center Section jig—the inboard face of the rib at Station #10 is the primary focus of this image. Note that the angle attaching the rib to the forward face of Spar #1 has now also been drilled off against the rib. A close look along the rib’s lower edge, towards the left of the image, will reveal a plumb bob line (running close to the cleco tops) being used to ensure that the wing reference line at apex of the leading edge curve matches the same point on Spar #1. (image via Pioneer Aero Ltd.)
A lower side view of the SBD’s lefthand leading edge during its trial-fitting onto the Wing Center Section jig. The wheel well and undercarriage leg opening are clearly evident. (image via Pioneer Aero Ltd.)
A lower side view of the SBD’s lefthand leading edge during its trial-fitting onto the Wing Center Section jig. The wheel well and undercarriage leg opening are clearly evident. (image via Pioneer Aero Ltd.)

Another revealing view showing the lower side of the SBD’s lefthand leading edge during the subassembly’s trial-fitting onto the Wing Center Section jig. (image via Pioneer Aero Ltd.)

Another revealing view showing the lower side of the SBD’s lefthand leading edge during the subassembly’s trial-fitting onto the Wing Center Section jig. (image via Pioneer Aero Ltd.)

A view of the outboard side of the lefthand wing leading edge during its trial-fitting to the SBD’s Wing Center Section. Here the leading edge and outer doubler have been positioned in the jig with the wing attachment angle. Holes from the skins and internal structure have been transferred through into the attachment angle, locking all of these components together. This allowed the restoration team to mark and drill-off the final group of holes between the structural components. Note how the shiny surface of the skin doubler appears to show a gap in the structure near the attachment angle—this is an optical illusion. (image via Pioneer Aero Ltd.)
A view of the outboard side of the lefthand wing leading edge during its trial-fitting to the SBD’s Wing Center Section. Here the leading edge and outer doubler have been positioned in the jig with the wing attachment angle. Holes from the skins and internal structure have been transferred through into the attachment angle, locking all of these components together. This allowed the restoration team to mark and drill-off the final group of holes between the structural components. Note how the shiny surface of the skin doubler appears to show a gap in the structure near the attachment angle—this is an optical illusion. (image via Pioneer Aero Ltd.)

Lefthand Leading Edge Nose Ribs Trial-Fitted:

With the SBD's lefthand leading edge locked in position against the Wing Center Section,  it was then possible to trial-fit the inter-spar ribs linking the Nose Spar to Spar #1. After positioning, the ribs were drilled off against their associated structure. While most of these particular ribs were of new manufacture, the skin support bracket beside the rib at Station #32 is original to B-22, although it did need a small repair, which Pioneer effected during its trial-fitting.

A view inside the lefthand wing leading edge looking from the outboard side along the gulley for the undercarriage leg into the wheel well. With the leading edge in position, it was then possible to trial-fit the inter-spar ribs (seen here) which link the Nose Spar to Spar #1. Closest to the camera is the rib at Station #56, followed by those at Stations #49 and #42 in the leg well. Inside the wheel well itself, we see the ribs at Stations #32 and #19, with the interior bulkhead at Station #10 at the far end. The fabrication of these ribs was discussed in Restoration Update #58. (Image via Pioneer Aero Ltd.)
A view inside the lefthand wing leading edge looking from the outboard side along the gulley for the undercarriage leg into the wheel well. With the leading edge in position, it was then possible to trial-fit the inter-spar ribs (seen here) which link the Nose Spar to Spar #1. Closest to the camera is the rib at Station #56, followed by those at Stations #49 and #42 in the leg well. Inside the wheel well itself, we see the ribs at Stations #32 and #19, with the interior bulkhead at Station #10 at the far end. The fabrication of these ribs was discussed in Restoration Update #58. (Image via Pioneer Aero Ltd.)

A closeup of the inter-spar ribs for the lefthand wing leading edge mentioned in the previous image. The unpainted rib seen here is positioned at Station #32 while the other is at Station #19. (Image via Pioneer Aero Ltd.)

This is another view inside the lefthand wing leading edge, looking from the wheel well through the lefthand undercarriage leg well towards the outboard edge of the SBD’s Wing Center Section. We can see the inter-spar ribs which lie between the Nose Spar (lower) and Spar #1 (upper) spar, with the rib at Station #32 being closest to the camera, followed by the ribs at Station’s #42, #49 and #56. These ribs are in the process of being drilled off against the interconnecting structure. (Image via Pioneer Aero Ltd.)

A closeup of the rib (unpainted) at Station #32 which links the Nose Spar and Spar #1 in the lefthand wheel well. The bracket between the forward face of Spar#1 and the upper skin is an original B-22 component. It has been bead blasted and inspected, with only a repair to the flange where it attaches to Spar #1 requiring replacement. Here the damaged section has been removed, with a replacement piece in the process of being positioned and drilled off. (Image via Pioneer Aero Ltd.)

Another, albeit broader, view inside the lefthand wing leading edge looking from the wheel well through the undercarriage leg trough towards the outboard edge of the SBD’s Wing Center Section. Closest to the camera is the rib at Station #19 followed by those at #32, #42, #49 and #56 respectively. Also visible is the original B-22 skin-to-spar bracket, inboard of the rib at Station #32. (Image via Pioneer Aero Ltd.)

Trial-Fitting the Righthand Leading Edge:

With the lefthand leading edge (and its newly-fitted inter spar ribs) now in place, it was time to move on to the righthand side. The process of trial-fitting the righthand leading edge to the Wing Center Section followed a nearly identical path to the lefthand example.

They began by marking and positioning the newly-fabricated leading edge attachment angle in the jig, then drilling and reaming the holes to match those in the jig. Then the skin doubler which wraps around the leading edge at Station #66 (beneath the attach angle) was fabricated .

The restoration team offered up the leading edge assembly to the Wing Center Section and positioned it for match-drilling against the interconnecting structure. First they drilled off the leading edge rib at Station #10 (the inner-most rib) to its associated Spar #1 attach angle. Then they positioned the leading edge at station #66 and drilled it off around the wing attachment angle. With the two ends of the righthand leading edge now locked in place, the team could then drill off its skin against the underlying spar caps for Spar #1 and trim the skin's outer edges to their final size.

A closeup of the lower side of the righthand leading edge attachment angle seen here attached to the SBD’s Wing Center Section jig. All of the holes have been drilled for holding this component both to the Wing Center Section and the outer wing panel. Looking closely, one can see both the leading edge datum wire and the wing reference line—the latter being held vertically by a bolt. (image via Pioneer Aero Ltd.)

Another close up (from the topside of the wing) of the righthand leading edge attachment angle bolted to the SBD’s Wing Center Section. Note the leading edge datum wire leading to the right near the bottom of the image. This line helps Pioneer’s engineer’s ensure that the wing’s leading edge is lined up correctly. (image via Pioneer Aero Ltd.)

Trial-fitting the skin doubler at Station #66 of the righthand leading edge for the SBD’s Wing Center Section, as seen from the top side. This doubler has a complex shape due to the changing taper between the leading edge and Spar #1, so it required significant skill to refabricate. (image via Pioneer Aero Ltd.)
Trial-fitting the skin doubler at Station #66 of the righthand leading edge for the SBD’s Wing Center Section, as seen from the top side. This doubler has a complex shape due to the changing taper between the leading edge and Spar #1, so it required significant skill to refabricate. (image via Pioneer Aero Ltd.)

The righthand leading edge positioned in the SBD’s Wing Center Section jig. Much like with the trial-fitting of the lefthand wing leading edge, a wooden support was used to bear the weight of the subassembly while the attachment angle at Station #66 (outboard end) and the angled extrusion at the aft end of the rib at Station #10 (inboard end) are positioned and drilled off. (image via Pioneer Aero Ltd.)

A similar view of the work involved with positioning the righthand leading edge on the SBD’s Wing Center Section, albeit from a slightly different perspective. (image via Pioneer Aero Ltd.)

Pioneer Aero’s Tyler Bailey is seen here positioning the righthand leading edge on the SBD’s Wing Center Section jig—aided by Craig Cunha, partially obscured on the reverse side. This is another momentous step, because the wing’s complete forward shape is revealed for the first time since the aircraft’s wartime crash. (image via Pioneer Aero Ltd.)

A topside view of the SBD’s righthand leading edge being positioned on the Wing Center Section jig for trial fitting. Note that the lefthand leading edge has already undergone this process and is seen temporarily clecoed in position, while the righthand unit still requires support from the wooden former before everything is lined up and the rivet holes are drilled off. (image via Pioneer Aero Ltd.)
A topside view of the SBD’s righthand leading edge being positioned on the Wing Center Section jig for trial fitting. Note that the lefthand leading edge has already undergone this process and is seen temporarily clecoed in position, while the righthand unit still requires support from the wooden former before everything is lined up and the rivet holes are drilled off. (image via Pioneer Aero Ltd.)

Here we can see Pioneer Aero’s Craig Cunha bolting the aft end of the replacement righthand leading edge attachment angle to the Wing Center Section jig, locking the subassembly’s outboard end in place. (image via Pioneer Aero Ltd.)

A view of the righthand leading edge positioned in the SBD’s Wing Center Section jig; the wheel well and undercarriage leg opening are clearly evident. (image via Pioneer Aero Ltd.)

A view of both leading edges after being positioned in the SBD’s Wing Center Section jig. The righthand leading edge still needs to be fully drilled off, whilst the inter-spar ribs between the Nose Spar and Spar #1 need to be mounted as well. (image via Pioneer Aero Ltd.)

Another nice view of the leading edges after being positioned in the SBD’s Wing Center Section jig. (image via Pioneer Aero Ltd.)

Another nice view of the leading edges after being positioned in the SBD’s Wing Center Section jig, albeit from a different perspective to the previous image. (image via Pioneer Aero Ltd.)

A full-on view of the SBD's Wing Center Section jig during the process of trial-fitting and drilling off the righthand leading edge. (image via Pioneer Aero Ltd.)
A full-on view of the SBD's Wing Center Section jig during the process of trial-fitting and drilling off the righthand leading edge. (image via Pioneer Aero Ltd.)

Righthand Leading Edge Nose Ribs Trial-Fitted:

With the SBD's righthand leading edge locked in position against the Wing Center Section, it was then possible to trial-fit the inter-spar ribs linking the Nose Spar to Spar #1. After positioning, the ribs were drilled off against their associated structure. While most of these particular ribs were of new manufacture, the skin support bracket beside the rib at Station #32 is original to B-22, although it did need a small repair, which Pioneer effected during its trial-fitting— much like that on the lefthand leading edge.

A closeup showing the underside of the SBD’s righthand leading edge, with the undercarriage leg well running from the right of the image through to the wheel well on the left. With the leading edge in position on the Wing Center Section jig, it was then possible to trial-fit and drill off the inter-spar ribs linking the Nose Spar (bottom) to Spar #1 (top). The rib at Station #56 is closest to the camera (at right), with the ribs at Stations #49 and #42 further down the leg well, leading to the ribs at Stations #32 and #19 in the wheel well. The rib at Station #10 is visible, partly out of shot, at the far side of the wheel well. The refabrication of these ribs was discussed in Restoration Update #58. (image via Pioneer Aero Ltd.)

A closeup inside the righthand leading edge from within the wheel well, looking right through the trough for the undercarriage leg. The Nose Spar is towards the bottom of the image, whilst Spar #1 is just visible at the top. At the left of the image, the inter-spar rib at Station #32 is just visible, with the ribs at Stations #42, #49 and #56 following progressively to the right. (image via Pioneer Aero Ltd.)

Another image of the inter-spar ribs during their trial-fitting in the righthand leading edge, looking from the wheel well at left down towards the righthand wing join. Closest to the camera is the rib at Station #19 followed by those at Stations #32, #42, #49 and #56. (image via Pioneer Aero Ltd.)

A closeup inside the righthand wheel well of the rib linking the Nose Spar and Spar #1 at Station #32. The unpainted bracket between the forward face of Spar#1 and the upper skin is an original B-22 component. It has been bead blasted and inspected, with only a repair to the flange which attaches it to Spar #1 requiring replacement. Here the damaged section has been removed and a replacement piece is being positioned and drilled to fit. (image via Pioneer Aero Ltd.)

A view inside the SBD’s righthand wheel well. To the left is the rib at Station #19 followed to the right by the ribs at Station #32 and #42 respectively. Also visible is the original B-22 skin-to-spar bracket inboard of the rib at Station #32. (image via Pioneer Aero Ltd.)
A view inside the SBD’s righthand wheel well. To the left is the rib at Station #19 followed to the right by the ribs at Station #32 and #42 respectively. Also visible is the original B-22 skin-to-spar bracket inboard of the rib at Station #32. (image via Pioneer Aero Ltd.)