NASA's eco-friendly aircraft passes key wind tunnel tests

NASA has finished a round of wind tunnel tests for its X-66 airliner, a design with long, thin wings that should cut fuel use. 

If the design performs as planned, single aisle jets could burn up to 30 percent less fuel than today’s models.

Engineers put a scale model of the Boeing built X-66 through high speed tests at NASA‘s Ames Research Center in California. 

That model stood in for a test aircraft in NASA’s Sustainable Flight Demonstrator project (SFD), which aims to prove cleaner designs can meet airline demands.

Testing the X-66

Instead of testing a full airplane, the team used a semi-span, a half airplane model fixed to one wall of the wind tunnel. 

This setup lets them build a larger model with more sensors, so they can track lift, drag, and stability in much greater detail.

The work is led by NASA’s Armstrong Flight Research Center in California (AFRC), which manages the Sustainable Flight Demonstrator project for the agency. 

Its research teams focus on turning experimental aircraft like the X-66 into practical tools for cleaner, more efficient aviation.

Because the model represents only half of the airplane, the support hardware can stay simpler and stiffer, which reduces unwanted vibrations during tests. 

That makes it easier for NASA and Boeing engineers to trust that small changes in force readings come from the wing, not the stand.

Semi span models also cost less to build and modify than full airplane models, letting the team test more design ideas in the tunnel. 

That flexibility matters when every change in wing sweep, thickness, or truss angle could mean big differences in fuel savings later on.

Inside the transonic wind tunnel

The X-66 model was tested in an 11 foot transonic wind tunnel at Ames, where air moves close to the speed of sound. 

Those conditions match what single aisle airliners see as they cruise, so the forces on the model give a realistic picture of future flight.

Tiny holes along the wing fed sensors that tracked surface pressure, the push of the air on each small section of the wing. 

By combining those readings with force measurements, engineers can see how changes to the wing shape or angle affect lift, drag, and stability.

Earlier work at NASA’s Langley Research Center used a smaller airplane model to study how the new wing behaves at different speeds and angles. 

Results from that campaign showed the wing’s shape could cut fuel use by up to 10 percent, according to an image feature. 

X-66 aircraft fuel savings

The X-66 uses a truss braced wing, a long thin wing supported by diagonal struts so it can span farther without becoming too flexible. 

That extra span helps the wing produce the lift an airliner needs with less air resistance and lower thrust at cruise.

NASA and industry researchers have spent years modeling these wings, not just for one plane but for whole families of future airliners. 

One recent assessment found that a transonic truss braced design cut fuel burn per seat by five percent versus a similar conventional jet.

Those findings fit into a bigger plan for cleaner aviation that lines up with national climate goals for 2050. 

NASA sees the truss braced wing as one tool for reaching net zero, a future where remaining emissions are balanced by cuts and removals.

Researchers have also applied multidisciplinary design optimization, a method that tunes many aircraft parts at once using linked computer models, to truss braced concepts. 

In one study, an optimized medium range design showed 20 percent less fuel weight than a comparable jet.

From wind tunnel data to future flights

Data from the Ames tests will feed into the final X-66 wing design, guiding choices on shape and controls before any metal is cut. 

Engineers will use the results to tune computer models and flight simulators, so pilots can practice the handling before the aircraft takes off.

Other teams are exploring how the same thin wings handle bad weather in NASA‘s historic Icing Research Tunnel in Cleveland. 

There, researchers test a section of the transonic truss braced wing and measure ice buildup and needed protection, summarized in a recent article.

NASA leaders see this kind of test program as part of a longer story in everyday aviation, not just in spaceflight. 

“Since the beginning, NASA has been with you when you fly. It is in our DNA,” said NASA Administrator Bill Nelson.

The X-66 will not become a passenger plane, but its lessons are meant for future single aisle airliners that carry most travelers. 

If the new wing performs as hoped, future jets based on this work could help airlines cut costs, trim emissions, and keep tickets affordable.

Image credits: NASA/Brandon Torres Navarrete.

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