This Week in Engineering explores the latest in engineering from academia, government and industry.
Episode Summary:
In the aerospace industry, airframe programs can last for decades. The 747, for example, has sustained a fifty-year production run, but maintaining legacy airframes presents a significant engineering problem: aircraft designed on paper blueprints and early CAD systems are still in service, and replacement parts and modifications are still needed.
Translating old renderings into forms that can be used by modern aviation companies and operators is expensive and ad hoc. To address this problem, a USAF sponsored program by the Wichita State University’s National Institute for Aviation Research has created a digital twin of an entire B-1 Lancer airframe, a large and complex strategic bomber. The results so far demonstrate enhanced, lower cost maintenance, suggesting that digital engineering may be the way forward for the many global operators of older aircraft.
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Transcript of this week’s show:
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Traditionally, the roles of engineering design and manufacturing were clear-cut. Design engineers developed and rendered the parts, and manufacturing engineers used those drawings to make them. Large, complex products such as automobiles and aircraft also required multiple supporting documents and renderings of subassemblies and assemblies leading up to the finished product.
The number of design documents can be immense, and with design changes over the span of a multi-year aerospace program, large air framers tend to hold the IP generated by aircraft design closely. This works well for active programs, but what about legacy aircraft there are no longer in production?
Wichita State University’s National Institute for Aviation Research (NIAR) began a program in early 2020 to create a digital twin of a very large and complex airframe: the Rockwell B-1 bomber. The B-1 B Lancer is a large, supersonic strategic bomber currently in service with the U.S. Air Force, alongside the stealth B-2 Spirit and the venerable B-52 Stratofortress—but the airframes are old. The original design dates to 1974, but changes in the mission profile and the escalating cost of the program deferred procurement until 1981, when the Reagan administration ordered 100 advanced B-1B versions.
The first production aircraft rolled out in 1984 with the final unit delivered in 1988. With the youngest airframes now 34 years old, support for the B-1 system is understandably expensive. The aircraft is complex, is used for high-speed, low altitude operations and must maintain minimal downtime due to technical issues. The manufacturer, Rockwell International, was purchased by Boeing in 1996, and like all highly complex, limited production designs that require extensive end-user support, costs are high.
The NIAR digital twin program was designed to address this issue, focusing on B1 airframe structures. B-1 airframes were ideal for several reasons. The aircraft have remained in service longer than expected, and have been used extensively in the Middle East, accelerating wear.
A digital twin improves aircraft maintenance in several ways. It limits the problem of old, legacy Air Force and OEM drawings which must be translated into modern CAD platforms when onboarding new suppliers, and it allows simulation of new repair procedures and new-build production tooling. NIAR digital engineering files have also been used at depot level maintenance facilities for the design and manufacture of support fixtures, reducing aircraft downtime.
The program is comprehensive. Starting with a structural digital twin of one wing, the model-based systems engineering effort has expanded to include the entire airframe structure and has added a PLM too, and system modeling language representations of multiple mechanical systems. The data is also proving useful for simulation of aerodynamic performance and weapons integration.
The Air Force is pleased, and the B-1 System Program Office has awarded the Institute a six-year, $100 million follow-on contract to continue the digitalization of the B-1 platform. The Lancer is a strategic weapon system with a limited number of airframes in service, but the NIAR has set its sights on a much bigger program: the F-16. That airframe also dates to the 1970s, but is still in production, and the roughly 5,000 airframes built have served in the air forces of 25 nations.
Digitalization of that legacy product could open the door for multinational maintenance support without the need for the OEM, Lockheed Martin, to maintain engineering resources for the two dozen variants of F-16 aircraft—with more on the way.
With proven success in military aircraft, the path appears clear to digitization of legacy airframes in civilian service, as well, and the timing is perfect. With the proliferation of global airlines plus a heavy demand for converted legacy passenger aircraft for freight service, digital engineering offers faster, lower cost maintenance operations just when airlines need it most.
