Overview:
For this our 75th Update describing the restoration journey of our Douglas SBD-5 Dauntless, we are excited to say that, after finishing up Spar #1, Pioneer Aero Ltd.'s engineers have begun the process of reassembling the historic dive bomber's wing center section. It began with the trial-fitting of Spars #1 and #2 into the jig, along with numerous interconnecting parts. While these parts will need to come out again for adjustments before everything is final-fitted together, this does mark a major milestone in the aircraft's restoration!
Finishing Spar #1:
We covered the completion of Spar #2 and much of Spar #1 back in mid-March. We cover the remaining work on Spar #1 here. Pioneer Aero's Craig Cunha led this effort. As was related previously, most of the parts for this spar are replacements, since the originals were too damaged for airworthy refurbishment, either because of the wartime ditching incident, or the subsequent corrosion which took place after decades of immersion in Lake Michigan. That being said, a few original cross members from this major subassembly were reusable, and these have been fitted back into the rebuilt spar.
At the time of the last update, Pioneer was awaiting the arrival of the replacement upper spar cap, which has since arrived. Cunha was then able to position it on the partially reassembled spar and drill it off against the web plate and associated structure. The replacement undercarriage mounts were then positioned and drilled off against the web and spar caps.
Replacement lower spar caps were also fabricated, positioned and drilled off against the web plate. The undercarriage jack shaft support brackets were positioned and drilled off too, then sent off for cadmium plating. All components were prepared and painted with primer. Cunha then assembled the spar and riveted everything together as far as practical. All five of the primary Wing Center Section spar assemblies are now essentially complete and ready for mounting back into the jig!
Another view of Spar #1 ready for riveting together. While most of these components are replacements, the cross rib outboard of the wheel well is original. For reference, this is the aft face looking toward the lefthand end, with the upper spar cap being to the right. (image via Pioneer Aero Ltd.)
Another view of Spar #1 ready to be riveted together. Most of the components seen here are replacements, however the three cross ribs between the wheel wells are original. For reference, this is the aft face between the wheel wells looking toward the lefthand end, with the upper spar cap to the right. (image via Pioneer Aero Ltd.)
The righthand end of Spar #1 during the process of being riveted together. Both of the replacement undercarriage mounts have been positioned and drilled off, the originals being too corroded for reuse. (image via Pioneer Aero Ltd.)
These are the replacement jack shaft support plates which mount onto Spar #1. At the time this image was captured, the plates had been drilled and cut to shape and were awaiting bead blasting before being sent of for cadmium plating. (image via Pioneer Aero Ltd.)
Spar #1 in the process of being riveted together while strapped to the workbench. For reference, this is the spar’s forward face, with the lefthand end being closest to the camera and the upper cap resting on the bench. The large rectangular cutouts make space for the wheel wells. The lefthand undercarriage mount is closest to the camera. The bearing sits in the circular hole, which currently has strap looping through it to tie the assembly down to the workbench. (image via Pioneer Aero Ltd.)
Here we see the upper spar cap for Spar #1 in the process of being riveted to the web plate. For reference, this is the forward face between the wheel wells, with the upper spar cap resting on the workbench. (image via Pioneer Aero Ltd.)
Another view of Spar #1 in the process of being riveted together. For reference, this is the aft face, with the lefthand end being closest to the camera and the upper spar cap resting atop the workbench. A whole host of components make up the spar, with some of them already riveted together at the time this image was captured. Other parts will have to wait for riveting until the spar is installed in the wing. This ensures that all of the rivets can be accessed for forming up. (image via Pioneer Aero Ltd.)
Trial-Fitting Spars in the Jig:
With all five primary Wing Center Section spars now complete, it was time for Pioneer Aero to mark another major milestone in the Dauntless project by beginning the process of mounting them back in the jig for trial-fitting purposes.
Another view of Spar #2 being trial-fitted in the Wing Center Section jig. On the left, William Lowen can be seen taking a photo from an elevated position standing on the workbench while on the right, Martin Hedley is tightening one of the retaining bolts in the spar’s righthand end. Prior to placing it in in position, Lowen and Hedley made sure to check that the jig was was perfectly vertical. There are four plumb bobs permanently mounted to the jig which indicate whether it remains in true, allowing changes to be made to ensure the jig remains vertical at all times. A careful scan of the image will reveal that the lines for all four of these plum bobs are visible in this shot. (image via Pioneer Aero Ltd.)
Another view of Spar #2 in the jig. In the background, the SBD's upper fuselage can be seen sitting in its jig, whilst the rebuilt main spars are visible stacked vertically at the far left. (image via Pioneer Aero Ltd.)
Looking down at the aft side of Spar #2 following the trial attachment of the left and righthand lower sections of Fuselage Frame #3 to the web plate and their respective hard points on the jig. The lefthand end is closest to the camera. (image via Pioneer Aero Ltd.)
This effort began with the team fitting Spar #2 in the massive, vertical jig, which had been empty of components for a while now as each subassembly underwent restoration independently. Now the process of making sure these components fitted together properly could begin. With Spar #2 in place, the lower sections of fuselage frame #3 were assembled and test fitted between Spar #2 and the respective jig points.
A view of the Wing Center Section jig following the addition of Spar #1 below Spar #2. While it is difficult to see in this image, the original inter-spar ribs at Stations #32 (left and right) and at Station #0 have been fitted temporarily fitted here to prevent Spar #1 from sagging. This view shows the wing’s lower surface. A close look will reveal that the station 32R rib is coated with primer paint, which means that it is airworthy. The other two, unpainted, non-airworthy ribs will be swapped out for their replacements once the surrounding ribs are positioned. This will allow the new ribs to be drilled off against the spars while properly oriented. (image via Pioneer Aero Ltd.)
Another view of the jig following the attachment of Spars #1 & #2 along with some of their interconnecting ribs. This view allows a better look at these ribs. Note that the rib at Station #32R rib is primed, meaning that it is airworthy, whilst the other two are not. The latter two will be swapped for their replacements once the surrounding ribs are positioned. (image via Pioneer Aero Ltd.)
Spars #2 and #1 trial-fitted to the jig, with a better view of the original inter-spar ribs at Stations #32 L & R and Station #0 temporarily fitted to prevent Spar #1 from sagging. This is looking at the wing’s lower surface with the righthand end closest to the camera. The airworthy, primer-painted Station 32R rib is more easily spotted here. (image via Pioneer Aero Ltd.)
The previously mentioned spar assemblies and ribs are pictured here from another perspective, with the wing’s upper surface being visible as seen from the righthand end of the Wing Center Section. (image via Pioneer Aero Ltd.)
A similar view to the previous image, only this time it is almost square on from the righthand end. This view shows how the jig plates hold the spar ends. (image via Pioneer Aero Ltd.)
Spar #1 was then added to the jig, after which it was possible to trial-fit the inter-spar ribs linking the forward two spar assemblies together. Most of these ribs are replacements, as described in previous posts, so the trial-fitting allowed more of the rivet holes at the spar web plate interfaces to be drilled out. Of course, all of these components will be removed and trial-fitted a few times as various components attached to them undergo their own trial-fitting, and as the access requirements change. This is the beginning of the phase where visible signs of major forward progress begin to take hold! Bravo to the entire team at Pioneer Aero Ltd!
A closeup view between Spars #2 and #1 in the jig as seen from the wings lower surface, towards the lefthand edge. This image shows that additional ribs have been trial-fitted between the two spars. Looking from left-to-right at the ribs, we see Rib #42L (original), the replacement rib at Station #32L (temporarily clamped in place for positioning and back-drilling), and the replacement rib at Station #10L, which is already positioned. (image via Pioneer Aero Ltd.)
A different perspective to the previous image showing Ribs #42L (original) and #32L (clamped replacement) mounted between Spars #1 & #2, as viewed from the wing’s lower surface looking out to the lefthand wing join. (image via Pioneer Aero Ltd.)
Here we see Craig Cunha about to drill the attachment holes for mounting replacement Rib #10L to Spar #1. He has already drilled and positioned Rib #10R (at left) while Rib #0, canted sideways between them, is about to be positioned and drilled. Each of these three ribs, viewed here from the top surface, is a replacement. (image via Pioneer Aero Ltd.)
Another view of the middle section of the wing showing Craig Cunha using a right angle drill to cut rivet holes for affixing Rib #10L to an attach angle mounted on Spar #1. (image via Pioneer Aero Ltd.)
Another view from the lower surface of the wing showing the three central ribs described in the previous images being trial-fitted between Spars #1 and #2. (image via Pioneer Aero Ltd.)
A view of Spars #1 and #2 with the inter-spar ribs being trial-fitted, seen here from the wing’s lower surface (lefthand end closest to the camera). These ribs (#10L, #0 and #10R) have all been successfully positioned and are awaiting the trial-fitting of the remaining ribs linking the two spars together. (image via Pioneer Aero Ltd.)
All of the inter-spar ribs seen here sitting between Spars #1 & #2 from the topside of the wing have been successfully drilled into their correct positions. (image via Pioneer Aero Ltd.)
A view of the correctly-positioned ribs depicted in the previous image, only this time viewed from the lower side of the wing. Note, some ribs remain to be trial-fitted, as evidenced by the empty attach angle on Spar #1 seen here in the foreground (image via Pioneer Aero Ltd.)
A closeup view showing the forward fitting of Rib #10L where it mounts to Spar #1, as seen from the wing’s lower surface. (image via Pioneer Aero Ltd.)
A closeup view showing the forward fitting of Rib #10R where it mounts to Spar #1, as seen from the wing’s lower surface. (image via Pioneer Aero Ltd.)
