Boeing to build braced-wing airliner, shooting for 30% efficiency gain

If you burn as much fuel as an airline, even an order of magnitude reduction in fuel efficiency can result in significant savings. Take a look at the drag-reducing Aeroshark film that Swissair has applied to his 12 Boeing 777s. The film delivers an efficiency gain of 1%, and as a result, with just 12 aircraft, Switzerland expects to save almost 4,800 tonnes of jet fuel each year. At today’s prices, $500,000 per aircraft per year. For an operator like American Airlines, a 1% improvement in efficiency translates to nearly $500 million a year for American Airlines, which has 1,000 aircraft.

So you can see how a passenger plane that is 30% more efficient than today’s best single-aisle aircraft would be a big deal. We first came across Boeing’s “truss braced wing” design concept in 2010 as part of the “Subsonic Ultra Green Aircraft Research” (SUGAR) Volt concept designed as part of NASA’s research program.

The idea takes advantage of the higher lift and lower drag available in longer, slimmer, higher aspect ratio wings found in non-powered gliders. For example, a concept Boeing was testing in his 2016 had a wing about 50% wider than a comparable standard aircraft.

Structurally, things like that don’t work without reinforcement. Therefore, Boeing’s design suspends the wings from the top of the fuselage and supports them on long trusses extending from the fuselage of the aircraft. These too are carefully shaped airfoils that add strength and stability as well as lift.

boeing

As a subsonic concept cruising at Mach 0.70 to 0.75 (519 to 556 miles per hour, 835 to 895 km/h), Boeing estimates that these fixed-wing airliners can consume 50% less fuel than conventional planes. bottom. In 2019 the concept was redesigned to cruise at the transonic edge around Mach 0.8 (593 mph, 955 km/h). Whether it’s increased speed or simply a better understanding of aerodynamics, the Boeing is back in efficiency.

“Combined with anticipated advances in propulsion systems, materials, and system architecture, single-aisle aircraft in TTBW configurations can reduce fuel consumption and emissions by up to 30% compared to today’s most efficient single-aisle aircraft. We can reduce the number of planes depending on the mission.”

Digital modeling and sub-scale wind tunnel testing has taken a long time, but NASA has now provided Boeing with $425 million in funding through the SFD Space Act Agreement, with funding from Boeing and various other business partners. We plan to invest approximately $725 million. It’s about actually building things at full scale and properly flight testing them.

NASA says it expects to complete testing of its Transonic Truss-Braced Wing demonstrator aircraft by the late 2020s. 2030s. “

NASA

There will certainly be challenges. First of all, these very long wings may not fit in existing airport terminals or hangars. Boeing hasn’t said anything about the demonstrator plane, but the 2019 concept did talk about using folding wings to sidestep this problem on the ground.

And then there’s the fact that the huge, thick, low-aspect-ratio wings of standard airliners create the perfect hollow space for fuel tanks. By keeping the wing fuel free, more weight is closer to the center of lift, reducing engineering stress where the wing meets the body. It can contribute to some degree of safety in a crash and keep fuel away from passengers. And in terms of pure brass tacks, it frees up space in the cabin for extra money-making seats. It has been.

Boeing, on the other hand, says the high-mounted, braced wing “will ultimately be able to accommodate advanced propulsion systems that are limited by the lack of underwing space in today’s low-wing aircraft configurations.” This demonstrator isn’t testing fancy new motors right away.

Needless to say, anything that allows a plane to fly further for a given amount of energy is highly relevant to decarbonization efforts. Battery-electric, hydrogen-electric, hydrogen-combusted, ammonia, and other clean powertrain technologies are all constrained by shorter range than traditional jet fuel power, and designs like these will undoubtedly make a big contribution. There is likely to be.

CFD (Computational Fluid Dynamics) The video below shows the wind tunnel work incorporated into this design.

Source: NASA, Boeing