Boeing Dreamlifter 747 - Large Cargo Aircraft

The Boeing Dreamlifter is a modified 747-400 passenger airplane that can haul more cargo by volume than any airplane in the world. It is the primary means of transporting major assemblies of the Boeing 787 Dreamliner from suppliers around the world to the 787 final assembly site in Everett, Wash. This reduces delivery times to as little as one day from as many as 30 days.

With its big graceful lines and distinctive hump, the Boeing 747 long has been one of the world's most recognizable airplanes. But a modification to the 747-400, currently being developed by a team of Boeing Commercial Airplanes engineers and international engineering design partners, promises to bring even more recognition to the venerable jetliner and the company. The 747-400 Large Cargo Freighter (LCF) with a greatly enlarged fuselage, a swing tail that opens to accommodate major Boeing 787 Dreamliner sections, and a vertical fin that extends 5 feet (152 centimeters) higher than a typical 747-400 - turned heads when it makes its first test flight in mid-2006, leading to certification later that year.

The LCF has one basic mission : efficiently ferry large composite 787 sections, including major fuselage sections, wings and the horizontal tail, from supplier factories in Grottaglie, Italy; Charleston, S.C.; Wichita, Kan.; and Nagoya, Japan, to Boeing's final assembly plant in Everett, Wash. It was a tangible example of Boeing's commitment to new production system methods on the 787 program, marking the first time that Boeing jetliner production will rely primarily on airplanes for delivery of components. Moving major 787 assemblies by air could save 20 to 40 percent in cost compared to traditional shipping methods, and reduce delivery times to as little as one day from as many as 30 days today.

Such savings allowed Boeing to recoup its nonrecurring investment in the LCF engineering modification during the first few years of 787 manufacturing, according to the program. Two LCFs were needed to support initial 787 production. A pair of used 747-400s, purchased by Boeing last year, were the first to be converted to the new LCF configuration.

Work began in 2004 In early 2004, Boeing engineers in the Puget Sound region of Washington state, California and Moscow partnered with Aernnova in Spain (formerly Gamesa Aeronautica) and Stork Fokker of The Netherlands to begin designing the LCF to the exact specifications required by the 787 program. Firm configuration of the airplane’s design was achieved in October 2004, and parts production began at more than 200 suppliers around the world. The team also bought three used passenger jets, one through the Boeing Aircraft Trading organization and two from China Airlines.

Boeing engineers from the Puget Sound region of Washington state, Moscow and Canoga Park, Calif., as well as suppliers in Spain and the Netherlands, are hard at work on the detailed design. The engineering task on this program is substantial and the schedule challenging. The team relied upon existing tools and processes as much as possible. The engineering design on a program involving three modification airplanes was much different than design on a traditional program that may involve hundreds of airplanes going through the factory. Programs with a large production run may emphasize reducing weight or improving performance. But the focus on the LCF is to find optimal solutions very quickly and to greatly limit nonrecurring costs to avoid designs that will require hard tooling, for example.

Major engineering design work was required to modify the freighter's fuselage, which increased the volume of the main cargo deck to 65,000 cubic feet (1,840 cubic meters). That is three times the cargo by volume than the 747-400 Freighter, the largest freighter in regularly scheduled service. The LCF's bulging fuselage is about 18 inches (45.7 centimeters) larger in diameter than the Airbus A380's.

Because of the airplane's mission, its detailed design did not require at least some of the expensive engineering solutions necessary in other airplanes. Cases in point: The use of doublers, or required extra layers of outer skin material, that are being designed for installation on the outside of the airplane rather than on the inside; and the use of button-head fasteners on the outside of the airplane in many places that would not be used in typical production models.

Another challenge in the modification involves maintaining close communication with the team of engineers working on it at Boeing and around the world. Keeping the lines of communication open and working well with engineers in other buildings in Everett, let alone in Amsterdam and Moscow, was really challenging. Eleven time zones away from Everett, engineers at the Boeing Design Center in Moscow helped design the freighter's enlarged upper fuselage and rear fuselage, as well as the main cargo deck floor and transition zone that marries the new structure to the existing airplane structure. About 25 percent of all the engineering work on the LCF fuselage and up to 60 percent of drawing preparation for specific disciplines were done in Moscow.

Much of the LCF fuselage design incorporates a new concept referred to as Monocoque with Integral Shear Ties. The concept involves a new method of transferring stringer (lengthwise reinforcement) load to the frame without separate clips or shear ties and takes advantage of high-speed machining advancements, simplifying the assembly process, requiring fewer fasteners and less tooling.

Engineers at Boeing Rocketdyne in Canoga Park, CA assisted the structural design team in Everett with changes to the LCF's "Section 41" flight deck area, the only part of the airplane that is pressurized. The modifications include work on the upper and lower decks, and relocation of several systems. The team at Rocketdyne also designed stairs, based on stairs used for the 747-400 Special Freighter, for use by the flight crew to enter and exit the LCF flight deck.

In Amsterdam, engineers at Stork Fokker assisted in the design of the pressure bulkhead that separates the pressurized flight deck section of the airplane from the unpressurized cargo area. The bulkhead, which has a waffle design, was manufactured from 75,000 pounds (34,000 kilograms) of raw aluminum stock. Boeing engineers designed a 5-foot extension to the airplane's vertical fin to aid pilot control during flight, but no design changes were necessary to the freighter's wings. In addition, a conical-shaped aft fuselage extension added 10 feet (3 meters) to the airplane's length. One of the more unusual and critical design challenges involved the "swing zone" of the freighter, the part of the aft fuselage that opens to allow loading and unloading of the 787's large composite structures. After landing, the LCF's entire tail section, supported by independent ground support equipment, swings aside to allow easy loading via custom-built cargo loaders. The cargo loaders raise the huge 787 sections to the airplane's floor level and slide them into the unpressurized fuselage.

Two pull-in actuators and numerous latches are involved in the proprietary system that opens, closes and locks the swing tail in place, Whiteman says. The latches, originally designed for a proposed folding wing on the Boeing 777, are activated only by the ground support equipment and are specially designed to assure that the swing tail always is latched and locked when in service.

In February 2005, Gamesa Aeronautica of Spain began providing engineering support and analysis to Boeing on the design of the hinges and other aspects of the freighter's swing zone - essentially the area about 10 feet forward and 10 feet aft of where the airplane swings open for loading. It is an area that required complicated, "dense" structure to handle the airplane's load requirements.

Once the design work was completed, the components and systems were largely provided by current 747 suppliers. Parts were shipped to Taiwan, where the airplanes were modified beginning in the summer of 2005 by Evergreen Aviation Technologies Corporation (EGAT) at a maintenance hangar adjacent to Taipei's Chiang Kai-Shek International Airport.

On 09 September 2006 a mere 375 working days after the modifications began, the first LCF made its first flight.