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In the second half of the 20th Century, the commercial jet linked the world in ways that were previously unimaginable. Suddenly, it became possible for many to afford trips to distant countries. People-to-people exchanges surged, laying the foundations for peace and global interconnectedness. But the design of commercial jets has remained relatively fixed in that time. That may soon change. Boeing and NASA have teamed up to test a radical new approach to wing design that promises greatly reduced fuel consumption and lower emissions.
The TTBW
The new wing, called the Transonic Truss-Braced Wing (TTBW), is thinner and about 50 percent longer than comparable cantilever wings, greatly reducing atmospheric drag. Because the longer and thinner wing is subject to greater “fluttering” effects, it needs to be supported by a truss for additional bracing, hence its name. This truss, however, also provides additional lift, serving as a mini wing in itself, and harking (almost) back to the days of the biplane.
To be fair, TTBWs are not exactly new, but they traditionally had been limited in speed and flight altitude, making them commercially unviable for passenger jets. But Boeing has proposed tweaking the wing’s sweep angle and using new modern materials, allowing for higher and faster flights than prior truss-based designs. Thus, they will now be able to keep up with modern commercial airliners.
The TTBW will improve fuel efficiency by up to 10 percent on its own, quite a significant margin for modern jets where fuel is the primary limitation on cost and range. NASA has signed a Space Act Agreement with Boeing, with both parties contributing $425 million and $725 million respectively to additional research. The aim is to test and validate TTBWs on full-sized prototype jetliners by 2028.
Notably, because the wing rests on top of the fuselage and not at the bottom, there is more space for underwing engines, which have been trending larger in recent decades. Indeed, to prevent larger new engines from “drooping” onto the runway, the 737 Max relocated the engines closer to the fuselage. But this change altered the plane’s flight characteristics, creating the instability problem that cause two crashes, killing everyone on board.
Indeed, one has to wonder if the TTBWs could breathe new life into old jetliners like the 737, by enabling them to carry newer, more efficient engines, while simultaneously reducing drag on the same fuselage. More likely though, as indeed suggested by the partnership with NASA, the TTBWs are being evaluated for possible introduction onto a future single-aisle airliner after 2035. Likely the replacement design for the 737.
Progress
NASA’s partnership with Boeing continues a long and storied history of public/private partnerships in the aerospace industry, where there is a symbiotic relationship between the state and the private sector. Especially for new technologies where the ROI is unclear, these partnerships have proven crucial to mitigating risk and bringing about groundbreaking innovations.
More fuel-efficient airliners promise to reduce emissions and costs for consumers, enabling an even greater share of humanity the luxury of travel. Should they work in practice, TTBWs offer a relatively simple means of advancing the commercial airline industry on a more sustainable path and demonstrates how accelerated innovation is key to solving global climate challenges. An example of progress at its best.