Dakota Territory Air Museum’s P-47 Update – March, 2020

Here is the March 2020 update for the Dakota Territory Air Museum's P-47D restoration at AirCorps Aviation. Pictured here is a possible sister-ship to P-47D 42-27609, this being P-47D-23-RA Thunderbolt "Miss Lorraine" (s/n 42-27886) from the 341st Fighter Squadron, 348th Fighter Group, 5th Air Force, at Morotai airfield, in January 1945. (image via wikipedia)
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Warbird Digest has just received the March, 2020 report from Chuck Cravens concerning the restoration of the Dakota Territory Air Museum’s P-47D Thunderbolt 42-27609 at AirCorps Aviation in Bemidji, Minnesota. We thought our readers would be very interested to see how the project has progressed since our last article on this important project. So without further ado, here it goes!


The turbo supercharger oil tank is an assembly that has been moved from its standard location because of the Christmas tree tank installation. It is mounted on the back of the Christmas tree tank support structure, which is composed of parts original to 42-27609.. (photo via AirCorps Aviation)

Update 

Progress on fabricating and fitting wing skins for the P-47 was evident in February and March. Some of the more complex curved wing skins had to be stretch formed. The fuselage also continued to receive attention as Aaron worked on wiring and plumbing of hydraulic and brake systems. He also wired and plumbed the instrument panel. 

Wing Assembly 

The wings continue to get most of the attention this month. Making the leading edge skins was a big part of the effort. 

The leading edge skin has been clecoed to the front section of the wing ribs. (photo via AirCorps Aviation)

Brad is removing ribs from the aft spar in preparation for painting and eventual permanent assembly. (photo via AirCorps Aviation)

Further out toward the tip on the tapered wing, the leading edge skin curve is tighter. (photo via AirCorps Aviation)

This is the same section of the leading edge, viewed from the root end. (photo via AirCorps Aviation)

In this image of the wing rib leading edge, the standard flange reliefs are visible. These pressed in indentations allow the flange to conform to the curve of the rib. (photo via AirCorps Aviation)

This is another view from the underside of the wing skin. (photo via AirCorps Aviation)

Brad deburs rivet holes in the spar 1 webbing. (photo via AirCorps Aviation)

Cory deburs rivet holes on one of the spars. (photo via AirCorps Aviation)

Republic named this part “gun trough frame”. It is located under the leading edge skin and reinforces that area. (photo via AirCorps Aviation)

Randy works at fitting rib sections into the leading edge skin. (photo via AirCorps Aviation)

Parts 

The Thunderbolt is a complex fighter, and parts continue to be fabricated as they are needed in the restoration process. 

AC fittings used in the engine installation have been machined. The darker one is an original used as a pattern. (photo via AirCorps Aviation)

On the bench is a landing gear downlock cylinder. (photo via AirCorps Aviation)

Robb forms an outer leading edge skin using the stretch former. (photo via AirCorps Aviation)

As more hydraulic pressure is applied, the skin conforms to the REN form. (photo via AirCorps Aviation

Fuselage 

More and more fuselage system installations happened this month. While it isn’t always obvious visually, these installations comprise some of the most critical tasks in a restoration like this one. 

Aaron has spent quite a bit of time wiring and plumbing the instrument panel. (photo via AirCorps Aviation)

This is what the panel looks like from the back side. It is remarkable how many of the instruments require plumbing connections. (photo via AirCorps Aviation)

Aaron has installed the radio mast for the SCR 274 radio. (photo via AirCorps Aviation)

The natural aluminum part is half of the turbo supercharger case. The tube and lever assemblies make up the intercooler exit door actuators. (photo via AirCorps Aviation)

One of the components that is in a different place than the Republic drawings indicate, is this junction box for the SCR 274 radio. It is one of the parts moved when the Christmas tree tank was field installed. (photo via AirCorps Aviation)

The natural aluminum tubing in this photo is the auxiliary fuel tank vent. (photo via AirCorps Aviation)

This tube carries pressurized air from the turbo supercharger forward to the carburetor. (photo via AirCorps Aviation

Pappy Gunn, the 5th Air Force’s Great Innovator 

No historical discussion of the 5th Air Force and its air war in New Guinea would be complete without mentioning Paul I. Gunn. In his early 40s during WWII, Lt. Col. Gunn was known as “Pappy” because of his “advanced age”. He had a profound influence on how the war was conducted by using his ingenuity to modify non-ideal equipment which had the virtue of being available. 

Paul Irvin”Pappy’ Gunn, USAAF service photo. (photo via AirCorps Aviation)

Gunn was responsible for adapting aircraft, particularly B-25s and A-20s, to the combat conditions they met in the New Guinea campaign. Lt. Col. Gunn took bombers and attack aircraft that were designed to bomb from medium to high altitudes, and converted them into low level strafers and skip-bombing planes.

First were the A-20s. Pappy installed a field modification that mounted four fifty caliber guns in the nose so both skip bombing and strafing could be done by the same aircraft.

The A-20’s range was a limitation, so Pappy had extra fuel tanks installed in the bomb bays. While this addressed the issue of range, it also had the disadvantage of reducing the bomb load.

The strafer gun installation on the first B-25 to be converted. USAAF photo. (photo via AirCorps Aviation)

Fourteen gun installation in Dakota Territory Air Museum’s B-25J, Betty’s Dream, photo. (photo by Chuck Cravens)

Since B-25s had already been used for skip bombing, and had better range and bomb loads than the A-20s, they were the next to be modified with forward-firing guns. Since a bombardier wasn’t needed for low level attacks, the space he would have occupied was freed up for gun installations.

Several configurations were tried, including a forward firing 75mm cannon. The eventual setup used most frequently consisted of all fifty caliber guns. Four were installed in the nose, four more as side blisters on the forward fuselage and two firing forward from the top turret.

Some later field conversions, like the B-25 Betty’s Dream, had as many as fourteen .50 cals firing forward with eight nose guns, four in side blisters, and two more in the top turret. 

From the early part of 1943, the “commerce raider” B-25s and A-20s damaged and destroyed Japanese shipping vessels, and made too costly the resupply of Japanese airbases and ground forces in New Guinea. By the summer of 1944, when P-47 42-27609 was in combat, the Japanese were falling back toward the northern end of New Guinea; they were effectively driven out by the fall of 1944.

Photo series of one of Pappy Gunn’s “commerce destroyer” B-25s sinking a Japanese escort destroyer. USAAF photo. (photo via AirCorps Aviation)

In addition to attacks on shipping vessels, skip-bombing was soon employed in conjunction with ‘parafrag’ bombs on enemy airfields. P-47s and other 5th Air Force fighters flew air cover for these raids. 

Space precludes a complete discussion of Pappy Gunn’s amazing accomplishments, so this is just a brief historical mention of Pappy Gunn’s better known innovations. 

His remarkable story is well worth further reading. Much more in-depth information on Pappy Gunn’s life and service can be found in General George Kenney’s book The Saga of Pappy Gunn, and in John Bruning’s book Indestructible: One Man’s Rescue Mission That Changed the Course of WWII. 

A 345th bomb group, 499th Bomb Squadron B-25 lays a string of 23 pound parafrag bombs on Clark Field in the Philippines. USAAF photo. Dakota Territory Air Museum’s B-25 Betty’s Dream is painted to honor Captain Charles E. “Pop” Rice, operations officer of this squadron. (photo via AirCorps Aviation)


And that’s all for this month. We wish to thank AirCorps Aviation, Chuck Cravens (words and images) as well as John LaTourelle  (images) for making this report possible! We look forwards to bringing more restoration reports on progress with this rare machine in the coming months, although it will likely be some time before we can do so given how the present pandemic has suspended almost all non-essential activities around the globe at the moment. Be safe, and be well!


Is the P-47 Thunderbolt your favorite airplane? Make sure to purchase issue #73 of Warbird Digest featuring the beautiful “Dottie Mae”

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