20 novembre 2019 | International, Aérospatial
B-21 Program Hits Schedule Pressure Even On ‘Conventional Trajectory’
Steve Trimble As the first B-21 enters final assembly in Palmdale, California, the Northrop Grumman-led program is on track to hit a first-flight target in two years, although the first signs of schedule pressure have appeared. Most of the details of the U.S. Air Force's newest stealth bomber remain a tightly guarded secret, but those facts released show the program is following a conventional trajectory despite being managed by an organization with the word “rapid” in its title. The Air Force announced completion of the critical design review in December 2018 in the standard three years after Northrop Grumman won the engineering and manufacturing development contract. The target for the first flight milestone stayed secret until July , when Gen. Stephen Wilson, the Air Force's vice chief of staff, stated publicly—and with remarkable specificity—that the milestone was 863 days away. Wilson offered that timetable on July 25, suggesting the targeted date is around Dec. 3, 2021. SCO leader says earliest flight would be in December 2021 Public rollout event expected in Palmdale, California The final piece of the publicly acknowledged schedule is that the first B-21 entered the early stages of final assembly around September in Palmdale, presumably within Northrop's Site 4 manufacturing complex and perhaps inside Building 401 in the same assembly bay that once housed the B-2. To hit Wilson's first-flight target, Northrop's staff must complete assembly of the first aircraft, stage a public rollout event and perform necessary ground testing within about two years. But Wilson's first-flight target may already be under pressure. His description made the December 2021 date seem like a fixed schedule milestone typical of most major defense acquisition programs. Randall Walden, who leads the Rapid Capabilities Office assigned to lead the B-21 program, describes Wilson's timing as closer to a schedule goal than a deadline. Walden recast the target as the “earliest possible” date for first flight, which he has little confidence the program will achieve. “I would not bet on that date,” Walden told an audience at a Capitol Hill Club breakfast on Oct. 24 organized by the Air Force Association. The comment is a rare cautionary note among otherwise glowing descriptions of the B-21 program by officials cleared to know the status of the development program. In March 2018, Rep. Rob Wittman (R-Va.) reported concerns about the design of the engine inlet, citing an internal dispute between Northrop and engine supplier Pratt & Whitney's engineers. Twelve months later, Wittman confirmed that the inlet design problem had been resolved. The program has since received only glowing assessments by Air Force leaders, including a statement in October by Chief of Staff Gen. David Goldfein that the B-21 ranks at the top of his list of successful acquisition projects. Despite those assurances, transitioning a new aircraft from a paper design into manufactured hardware is a challenging phase for any program. Large pieces of the first aircraft are now in assembly. “We're working a production line, literally, today,” Walden says. An official artist's rendering shows the B-21 shares the all-wing profile of the B-2, minus the latter's distinctive sawtooth trailing edge. The Air Force's acquisition strategy also focused on minimizing risk by relying as much as possible on available technology. But a modern bomber with the B-21's mission to penetrate into highly contested airspace is still anything but a simple project. “It is a complex airplane. I'll leave it at that,” Walden says. Walden expects the Air Force to stage a public rollout event in Palmdale when the aircraft is ready. For the B-2, the rollout was staged seven months before the first flight. If the B-21 stays to the same schedule, the unveiling could come as early as May 2020. But Walden adds that includes several big “ifs.” “Like anything, building a complex system could add those schedule pressures,” Walden says. “We've got to bring parts together, got to assemble it and get it stuffed with the right avionics, get the landing gear on it, all the things that go along with an airplane.” Any schedule pressure facing the B-21 would not surprise Frank Kendall, the former undersecretary of defense for acquisition, technology and logistics. Kendall led the shaping of the acquisition strategy for the B-21. In a recent interview, he recalled pushing back against attempts by the Air Force to award a firm, fixed-price contract instead of a more flexible cost-plus arrangement, which is generally applied to acquisition projects with a higher risk. “When I looked at . . . the actual content of the program, I [was] so glad I told [the Air Force to use cost-plus],” Kendall says. “It's not risk-free. I'll be amazed if they get this thing in on schedule and on cost. But it was designed to have a reasonable chance of success.” An independent estimate by the Defense Department assessed the cost of the engineering and manufacturing development phase at $21.4 billion, with follow-on production of at least 80-100 bombers worth up to $60 billion more. The Air Force has budgeted $5.9 billion over the next five years to pay for the first operational aircraft, with low-rate initial production possibly beginning in fiscal 2023. “There are a lot of things that have to happen between now and a couple of years,” Walden says. https://aviationweek.com/defense/b-21-program-hits-schedule-pressure-even-conventional-trajectory