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The Birdcage Corsair center section is coming together nicely at Vultures Row Aviation. (image via Vultures Row Aviation)
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Back in July, we published a report concerning the extremely rare ‘birdcage’ variant of the Vought F4U-1 Corsair (BuNo.02449) undergoing restoration to flying condition at Vultures Row Aviation in Cameron Park, California. Quite a lot has taken place in the interim, and we thought our readers would be interested in seeing some photographs describing the latest efforts. Work has focused primarily upon completing the fabrication and installation of skins for the wing center section. Of these, the lower inner center section skins have been finished, painted, and installed and, just last week, the so-called ‘valley skins’ for the upper center section have undergone spot-welding, painting, and installation too. We also have some photographs showing work being performed on another very rare Corsair variant, an FG-1A which once flew during the 1946 Cleveland Air Races!
The following images describe the manufacturing and installation process for the lower wing center section skins on the Corsair.
An over view of the starboard side of the wing center section – showing the midribs installed. (photo via Vultures Row Aviation)
A view between the main spar (right) and the auxiliary spar (left) standing inside what will become the starboard main undercarriage wheel well. This is during the preparations for fitting and attaching the skin assemblies
. (photo via Vultures Row Aviation)
Anoter view between the spars, this time from inside the port side of the wing center section. You can see the trailing edge ribs have already been installed to the right. (photo via Vultures Row Aviation)
Stiffeners for the wing center section lower skins being prepared for spotwelding. (photo via Vultures Row Aviation)
Stiffeners undergoing assembly. (photo via Vultures Row Aviation)
The spotwelding machine beginning to attach the lower center wing section skin stiffeners. (photo via Vultures Row Aviation)
A view of the lower wing center section skin during assembly. Note the copper-colored spotelding probe at the center top of the screen. During the spotwelding process, this probe pushes down against the two sheet metal pieces waiting to be joined, sandwiching it against a probe pushing up from the other side. When the parts are in position, a powerful electric current flows from one probe to the other, passing through the two pieces of aluminum sheet. Since the aluminum isn’t a particularly effective conductor, its internal resistance heats up the sheetmetal to melting point and fuses them together. Obviously, there is a fair degree of testing which needs to occur ahead of time to make sure that just the right amount of current flows for just the right amount of time to create an acceptable weld. The probe tips also need cleaning after every few welds to ensure consistency as well. While the setup time isn’t insignificant, the process is a lot quicker than traditional riveting, and can usually be performed by one person rather than two. The bonded structure is also somewhat lighter than it would have been had rivets been employed too, while maintaining similar rigidity and strength. (photo via Vultures Row Aviation)
Spotwelding is complete for the lower skin section. (photo via Vultures Row Aviation)
Spotwelding the lower wing skin assembly for the opposite side of the Corsair’s center section (photo via Vultures Row Aviation)
The fully-assembled left hand lower skin assembly for the Corsair’s wing center section. (photo via Vultures Row Aviation)
The fully-assembled right hand lower skin assembly for the Corsair’s wing center section. (photo via Vultures Row Aviation)
Both wing center section lower skins are now fully spotwelded. Each panel involves some 1,100 spot welds! (photo via Vultures Row Aviation)
The airfoil side of the two lower wing center section skin assemblies. Note the acid-etched lines along the spotwelded rows. This is done prior to spotwelding to ensure maximum surface conductivity for optimal weld-strength consistency. (photo via Vultures Row Aviation)
One of the lower skins, now respelendent in its salmon-colored primer, is nearing completion. The two perforated brackets at the far left are for holding some of the myriad hydraulic lines in place in the wing center section. (photo via Vultures Row Aviation)
After primer-painting, the lower wing center section skin is undergoing preparations for riveting onto the airframe. (photo via Vultures Row Aviation)
The lower skin stiffeners are now riveted into mating components on the Corsair wing center section, although the edges have yet to be bolted against the airframe. (photo via Vultures Row Aviation)
Bolting the lower wing skins into the main spar cap. Note the traditional Type I silver-colored cadmium plated hardware, which is typical of a WWII-era manufacturing process. The post-WWII AN standard hardware and it’s modern MS equivalent is typically finished with a Type II gold-colored Cadmium plating process, so this seemingly minor detail of using Type I hardware is another sign of strict attention to authentic detailing. (photo via Vultures Row Aviation)
The lower skin during its installation. Note the two hydraulic line brackets are now also fixed in position. (photo via Vultures Row Aviation)
The lower skins insalled for the right side of the wing center section. (photo via Vultures Row Aviation)
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Wing Center Section – ‘Valley Skins’
These images reveal some of the details for how the so-called ‘valley skin’ assemblies are fabricated and installed. The term ‘valley’ is a term of convenience and refers, obviously, to the dip in the gull-wing profile.
The assembly process for the upper wing center ‘valley skins’ begins. Note how the stiffeners are Clecoed onto the skins in certain places. This helps keep the parts aligned during spotwelding although, obviously, the Clecos will eventually be replaced with rivets. (photo via Vultures Row Aviation)
The ‘valley skin’ assembly during the spotwelding process. (photo via Vultures Row Aviation)
Another shot showing the stiffeners for the wing center section valley skin following the spot-welding process. (photo via Vultures Row Aviation)
A closeup of the spotwelds affixing the stiffeners to the ‘valley skin’. (photo via Vultures Row Aviation)
Getting the salmon colored primer paint ready in the paint booth. (photo via Vultures Row Aviation)
For obvious reasons, it is impossible to paint the stiffeners and skin prior to the spotwelding process, which makes ensuring that the entire assembly receives a proper coat of primer paint difficult. To ensure part longevity against potential corrosion issues, the technician here is threading a paint brush through the obscured cavity between the stiffener and wing skin to coat the interior with a layer of paint. The exposed areas of skin, however, can be painted more traditionally with a spray gun. (photo via Vultures Row Aviation)
The two ‘valley skins’ and accompanying parts prior to assembly and installation. (photo via Vultures Row Aviation)
The wing center section prior to the ‘valley skin’ assembly installation. (photo via Vultures Row Aviation)
The wing center section trailing edge prior to the flap hinge going in. (photo via Vultures Row Aviation)
A view of the wing fold bulkhead with the outer hinge assembly for one of the flaps going in. (photo via Vultures Row Aviation)
Setting the starboard ‘valley skin’ assembly into position prior to affixing it to the airframe. (photo via Vultures Row Aviation)
The ‘Valley Skin’ sitting in place, prior to cinching down
. (photo via Vultures Row Aviation)
The ‘valley skin’ assembly is Clecoed into position on the wing center section prior to final bolting/riveting. (photo via Vultures Row Aviation)
The port ‘valley skin’ assembly Clecoed into position. (photo via Vultures Row Aviation)
Another view of the Corsair center section with the valley skin undergoing installation. (photo via Vultures Row Aviation)
The ‘valley skin’ assembly undergoing installation. (photo via Vultures Row Aviation)
The starboard ‘valley skin’ undergoing installation. (photo via Vultures Row Aviation)
The ‘valley skin’ for the port side of the wing center section during the installation process. Note the hydraulic line mounting brackets in the background are now almost completely populated with the appropriate interface hardware (the blue anodized connectors). (photo via Vultures Row Aviation)
Another view inside the main gear wheel well showing the ‘valley skin’ during its installation process. (photo via Vultures Row Aviation)
Another shot of the valley skin from inside the wheel well. Note the beefy construction of the main spar web to the lower right of the image. (photo via Vultures Row Aviation)
Another view of the interior of the wheel well. Note the four large bolts along the top of the main spar web. These attach the two hinges (on the opposite side of the spar) for the undercarriage bracing structure. Oddly, two bolts for each hinge attach from one side of the spar, while the others (not installed yet) attach from the reverse side. (photo via Vultures Row Aviation)
The ‘Valley Skin’ in place on the Corsair’s wing center section. (photo via Vultures Row Aviation)
Wing Center Section – Leading Edge and Air Ducts
Two Corsair center section skins drying in the paint booth. These components are located at the wing join, just ahead of the main spar. The scalloped shape allows the upper edge of the outer wing panel to clear the center section during wing-fold operations. (photo via Vultures Row Aviation)
The leading edge endplates for the wing center section which we saw hanging in the paint booth earlier. (photo via Vultures Row Aviation)
Riveting in the leading edge skins. (photo via Vultures Row Aviation)
An interior shot of the leading edge, showing the freshly-bucked rivets for the leading edge skin (note the blue annodized tails). (photo via Vultures Row Aviation)
Another view of the freshly-bucked leading edge rivets from inside the assembly. (photo via Vultures Row Aviation)
Freshly installed leading edge rivets now firmly in place. The endplates shown earlier will mount just behind the auxiliary wing fold hinge you can see jutting out at the left. The exposed screws/nuts seen here are obviously just temporarily in place to firmly cinch the skins close together during the riveting process and will be replaced with the appropriate fasteners in due time. (photo via Vultures Row Aviation)
Assembling a leading edge wing rib. This particular rib mounts very close to the fuselage, right beside the leading edge air intake assembly. (photo via Vultures Row Aviation)
Clecoing the leading edge wing rib together. (photo via Vultures Row Aviation)
Assembling a Corsair wing leading edge air duct assembly. These ducts guide incoming air to both the wing-mounted oil coolers and the fuselage-mounted intercoolers. (photo via Vultures Row Aviation)
The leading edge air intake during assembly. (photo via Vultures Row Aviation)
Offering up one of the center section leading edge wing ribs to the air intake assembly to check the fit. (photo via Vultures Row Aviation)
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Horizontal Stabilizers – Attachment Fairings
Working on the horizontal stabilizer root fairings. (photo via Vultures Row Aviation)
Trial-fitting the as-yet un-drilled skins for a root fairing which will cover the mounting points for one of the Corsair’s horizontal stabilizers. (photo via Vultures Row Aviation)
Working on the root fairing skins for a horizontal stabilizer. (photo via Vultures Row Aviation)
Another shot of the root fairings coming together. Note that the parts are just clamped into place, and have yet to be fully trimmed and drilled. (photo via Vultures Row Aviation)
Outer Wing Panel – Ribs, Flaps and Fuel Tank
The early Corsairs featured a number of unique details which later variants didn’t carry. For instance, the outer wing panels through the -1A included wet-wing fuel tanks in the leading edges just outside of the main armament. Furthermore, they also featured outer wing panel flaps which had fabric-covered trailing edges, instead of sheet metal airfoils. But uniquely, the first 325 ‘birdcage’ Corsairs had a feature which “drooped” the ailerons by 9 degrees to provide additional wing flap performance if needed. Since BuNo. 02449 came off the production line as construction number 297, it also had this capability, which Vultures Row is presently involved in replicating. There are images below which show the work to refabricate the outer wing panel rib at Station 3.25 which has vestigial details of this aileron droop hardware. Incidentally, the station number for a Corsair is a simple reference point describing the distance (in inches) from the datum point. So Station 3.25 for the outer wing panel is essentially the physical plane 3.25″ from the datum point at the wing fold.
Early Corsairs from the F4U-1 ‘birdcage’ through the -1A variants had auxialiary fuel tanks in the leading edge of the outer wing panels. It was a so-called ‘wet-wing’ – meaning that the airfoil structure actually formed the tank. This image depicts the wet wing section during the assembly process. It is a relatively small tank, running along about three feet of the leading edge just outboard of the guns. For many reasons, this tank option was deleted in later Corsair variants, and often wired-off in the field. They were prone to leaks, especially at the vulnerable swivel joints linking the tanks to the fuel system at the wing fold. Even so, it is an interesting feature being installed in the aircraft. There are just a handful of surviving Corsairs today which have these tanks installed. (photo via Vultures Row Aviation)
Assembling the leading edge skins for the outboard flap. (photo via Vultures Row Aviation)
The leading edge section of the outer wing flap. Unlike the metal-covered inboard flaps which attach to the Corsair’s wing center section, early Corsairs (birdcage through the -1A) had outer wing flaps with fabric-covered trailing edges. (photo via Vultures Row Aviation)
An original trailing edge rib (Station 3.25) which essentially forms the wing fold bulkhead for the port outer wing panel. (photo via Vultures Row Aviation)
A closeup of the attachment point for Station 3.25. The large mounting holes on the upper and lower skins at the right mark where it would bolt to the trailing edge of the outer wing panel’s main spar cap. (photo via Vultures Row Aviation)
An interior view of the same trailing edge wing rib assembly. On the right-most diagonal bracing panel, you can see a circular hole with four smaller holes surrounding it. This is where a bearing for the aileron droop mechanism once mounted. (photo via Vultures Row Aviation)
Another view of the wingfold bulkhead. (photo via Vultures Row Aviation)
The original wing fold bulkhead shown beside a newly-fabricated skin assembly. (photo via Vultures Row Aviation)
The interior side of the newly-fabricated skin assembly for the wing panel, replicating the same structure on the original component also in view. (photo via Vultures Row Aviation)
Lucky Gallon
Vultures Row Aviation is working on several Corsair projects simultaneously in addition to the BuNo.02449. One of the most exciting of these is the ultra-rare FG-1A BuNo.13481 which the legendary Cook Cleland flew in the 1946 Cleveland Air Races as #92, Lucky Gallon. Walt Soplata saved this aircraft from certain scrapping, and while he was only able to preserve the center fuselage section, this will now form the basis for a resurrection of the airframe, which will be completed in the same livery it once wore during the races in 1946. This is an exciting development, and one which we look forwards to following in the coming years.
The original center section from FG-1A Bu. which Cook Cleland flew in the 1946 Cleveland Air Races as Lucky Gallon. Sadly, the center section of this airframe is all that survives today, but is about to undergo restoration back to flying condition. (photo via Vultures Row Aviation)
The disassembly process begins for Lucky Gallon’s center fuselage section. Note the original red paint from Lucky Gallon’s livery to the left. While this has mostly pealed away from the dark blue finish the aircraft left naval service in, it provides the crucial information for the appropriate colors for her eventual repaint into Cleland’s famous livery. (photo via Vultures Row Aviation)
More work on Lucky Gallon’s central fuselage assembly. (photo via Vultures Row Aviation)
Removing the firewall assembly from Lucky Gallon’s surviving fuselage section. (photo via Vultures Row Aviation)
The skin subassemblies being detached from Lucky Gallon’s surviving fuselage section. This area once housed the aircraft’s main fuel tank. (photo via Vultures Row Aviation)
Deriveting the fuselage skin assemblies from Lucky Gallon. (photo via Vultures Row Aviation)
The interior floor of Lucky Gallon’s fuselage fuel tank bay following the removal of most attaching rivets. (photo via Vultures Row Aviation)
Born in Milan, Italy, Moreno moved to the U.S. in 1999 to pursue a career as a commercial pilot. His aviation passion began early, inspired by his uncle, an F-104 Starfighter Crew Chief, and his father, a military traffic controller. Childhood adventures included camping outside military bases and watching planes at Aeroporto Linate. In 1999, he relocated to Atlanta, Georgia, to obtain his commercial pilot license, a move that became permanent. With 24 years in the U.S., he now flies full-time for a Part 91 business aviation company in Atlanta. He is actively involved with the Commemorative Air Force, the D-Day Squadron, and other aviation organizations. He enjoys life with his supportive wife and three wonderful children.
Great article, excellent photos! One thing has me confused, though: in one of the photo captions, number 7 if I recall correctly, you say that “aluminum isn’t a particularly effective conductor” of electricity. That seems backwards to me, as I’ve always been told that aluminum is one of the better conductors of electricity, behind silver, copper, and gold.
Awesome work, guys. Spending a few years rebuilding a famous warbird seems like time well spent imo. I hope everything goes smoothly and I would love to see a mini series produced about it.
God Bless the dedication that you all are doing and wish the young could understand how these machines,the builders and brave pilots help save the world from madness 70 years ago. Home of The Blue Angels
Awesome work guys! My Dad was a Marine Infantry vet on Okinawa. He turned me on to the bent wing bird as a child. It was love at first sight!. Hopefully once your finished you’ll fly her to New Century Airport in Gardner Kansas? Would love to check her out! Good luck with your restoration!
Labor of love. Keep up the good work.
Great article, excellent photos! One thing has me confused, though: in one of the photo captions, number 7 if I recall correctly, you say that “aluminum isn’t a particularly effective conductor” of electricity. That seems backwards to me, as I’ve always been told that aluminum is one of the better conductors of electricity, behind silver, copper, and gold.
Well done gentleman, excellent work with unsurpassed craftsmanship!
It’s really incredible the work you guys are doing. Tks so much for keeping Corsairs alive.
Awesome work, guys. Spending a few years rebuilding a famous warbird seems like time well spent imo. I hope everything goes smoothly and I would love to see a mini series produced about it.
God Bless the dedication that you all are doing and wish the young could understand how these machines,the builders and brave pilots help save the world from madness 70 years ago. Home of The Blue Angels
lookin good. are you in need of gun doors. my friend makes them has made them for Ezells. let me know
Awesome work guys! My Dad was a Marine Infantry vet on Okinawa. He turned me on to the bent wing bird as a child. It was love at first sight!. Hopefully once your finished you’ll fly her to New Century Airport in Gardner Kansas? Would love to check her out! Good luck with your restoration!