Restored: Pima’s Peacemaker | HistoryNet MENU

Restored: Pima’s Peacemaker

By Dick Smith
10/25/2017 • Aviation History Magazine

Transporting and restoring a mammoth B-36J called for special equipment—and ingenuity.

It Air and Space Museum’s newly restored Convair B-36J dominates the 80-acre outdoor display area. In fact, its nearly 47- ’s no exaggeration to say that the Pima foot-high tail towers over the other exhibits at the sprawling complex in Tucson, Arizona.

The B-36 holds the record for being the largest mass-produced piston engine airplane ever built. Pima’s Peacemaker was the last of 385 (including one XB-36 and one YB-36) of the Cold War–era intercontinental bombers, which were operated by the U.S. Air Force between 1949 and 1959. The Pima museum’s aircraft, B-36J-10-CF no. 52-2827, was constructed under the Air Force’s “Featherweight” program, indicating that all defensive armament had been eliminated except for the dual 20mm cannons in the tail’s “stinger.”

The B-36J was manned by a crew of nine. Although the Peacemaker never actually dropped armed bombs, unarmed nuclear and thermonuclear weapons were periodically carried on training missions, which could last in excess of 50 hours. The bomber was the “big stick” wielded by Curtis LeMay, commander in chief of Strategic Air Command, who played the aircraft’s long-range deterrence card to its utmost in Cold War negotiations with Eastern Bloc nations.

Production models of the B-36 were powered by six 28-cylinder Pratt & Whitney R-4360 Wasp Major radials, each generating 3,800 hp. Their reverse positioning with pusher props turned out to be the bomber’s Achilles’ heel. Poor air circulation around the engines and carburetors contributed to overheating and—in combination with persistent fuel leaks—resulted in many in-flight fires.

Starting with the B-36D, four General Electric J47 turbojets were slung in dual pods under the outer wings, giving the aircraft an additional 5,200 pounds of thrust from each engine. That modification enabled the Peacemaker to reach altitudes in excess of 50,000 feet and a maximum speed of more than 400 mph. In the late 1940s and ’50s, most of the world’s straight-wing interceptors had a service ceiling of 40,000 feet, making the B-36 invulnerable to attack by fighters. Even if the opposing fighters could reach the bomber’s altitude, their engines would lose thrust in the thin atmosphere, allowing the B-36 to maneuver out of danger. Those advantages evaporated with the appearance of the Mikoyan-Gurevich MiG-15 during the Korean War. The sweptwing Soviet fighter’s service ceiling of 50,800 feet meant the B-36 was no longer safe from enemy interception.

The Pima museum’s aircraft rolled off the Convair production line at Fort Worth, Texas, and was delivered on August 14, 1954. Less than five years later, on February 12, 1959, the huge bomber was struck from active duty. It was initially put on display at Fort Worth’s Amon Carter Field, which later became the Greater Southwest International Airport. In the late 1970s, City of Fort Worth, as the bomber was christened, was moved to the Southwest Aero Museum, located between the former Carswell Air Force Base and the Lockheed Martin assembly plant. When that site morphed into a business park in the early 1990s, the mammoth airframe was disassembled and transported to a building donated by Lockheed Martin.

A group of former Convair employees and volunteers subsequently devoted more than 40,000 hours to restoring the aircraft. Eventually, however, the National Museum of the United States Air Force, which actually owned the B-36, determined that the Convair group did not have the means to fully restore and display the aircraft, and that effort came to a premature halt.

In 2005 Scott Marchand, director of collections and restoration at the Pima museum, went to Fort Worth with a colleague to look over the plane and figure out how to move the airframe to Tucson. “This was no small undertaking,” Marchand said. “We quickly realized it would take numerous trucks and some creative loading and rigging.”

The real problem was how to move the gigantic main wing center section, which spans 148 feet, measures 29 feet at its widest and, when resting on a storage jig, is 12 feet tall. Tucson’s Southwest Industrial Rigging Company took it on, telling the museum, “We are not sure how to do it just yet, but a job has never defeated us, and this one isn’t going to!”

In early July, the museum sent four staffers to Fort Worth to load the disassembled B-36 onto 11 trucks. Lockheed Martin aided the Pima team by loaning several pieces of specialized equipment used to handle the huge airframe parts. Members of the local B-36 association were also on hand to offer their expertise. July in Fort Worth, of course, means temperatures above 100 degrees and humidity in excess of 80 percent. Marchand recalled, “We consumed gallons of sports drinks and hundreds of popsicles.”At the end of a backbreaking week of work, the convoy was ready to start for Arizona. Moving the main wing center section, however, would have to wait for special arrangements.

In late September 2005, Southwest Industrial Rigging finalized plans and secured all the permits required to move the wing section. The massive part was loaded on a specialized trailer, a custom rig that measured 100 feet long and consisted of a “triple goose neck, double rear steerable, double drop trailer.” Even then, nearly 40 feet of the section hung off the trailer. The entire load measured 170 feet long, 29 feet wide and 13 feet high, and took up both lanes of the interstate. Police agencies and state departments of transportation escorted the massive load, and since the vehicle could travel at no more than 55 mph, traffic got backed up for miles. The wing’s 29-foot width became a critical factor east of Tucson, where an underpass narrowed the highway to 30 feet, allowing only 6 inches to spare on either side.

The restoration began with the exterior being cleaned, repaired and stripped to bare metal. The team had particular difficulty working with the magnesium skin. Specialists said the high humidity and intensity of the ultraviolet light in the Fort Worth area had clearly taken a toll on the bomber’s skin.

“Putting everything back together was a real challenge,” said Marchand. “It was obvious where everything had to go, but with an airplane of this size and weight, it was a tenfold order of magnitude greater than any other project that we had ever tackled.” The wing center section alone weighed 68,000 pounds. Most of the lifting equipment at the museum was never intended to deal with items of that scale, and considerable ingenuity and creativity were involved in the reassembly.

The B-36 is constructed from thousands of parts machined to very close tolerances, held together with hundreds of mechanical fasteners. During the restoration, the crew of staff and volunteers often remarked that building an aircraft of this size within the confines of the Convair plant must have been a monumental undertaking. Putting together a B-36 outdoors, on uneven surfaces, and dealing with wind gusts beneath the searing Arizona sun turned out to be another daunting task. Major milestones involved lining up and attaching the front fuselage to the wing center section, lowering the main and front landing gear, aligning and attaching the tail grouping to the aft fuselage and attaching the rear fuselage to the aft portion of the center wing section.

After four years’ work, the airframe was ready for paint. By that time more than 24,000 man-hours had gone into the project. Over 3,000 nuts and bolts were put into place, along with roughly the same number of rivets.

The bomber’s topside was sprayed with 275 gallons of aluminum acrylic paint, and its underside was given a coat of “anti-flash” white. Marchand compared painting all 28,000 square feet of the B-36 to painting an entire squadron of F-4 Phantom IIs.

Today Pima’s plane is one of only four B-36s in existence. Summing up what it took to transport the big Peacemaker to Tucson and bring it back to life, Marchand recalled countless moments of frustration, bruised knuckles and aching muscles. But in the end, he said, the project had been well worth it: “It is a great addition to our collection.”

 

Originally published in the March 2011 issue of Aviation History. To subscribe, click here.  

, , , , , ,



Sponsored Content: