Going with the Flow

At NASA Langley Research Center in Hampton, wind tunnels are at the forefront of aerospace innovation, research and commerce

by Justice Menzel

For decades, Hampton-based NASA Langley has been redefining aerospace testing on every frontier for the benefit of scientific discovery and to reduce the potential for catastrophic failures in spacecraft and aircraft.

However, a flat budget coupled with inflationary pressures has prompted these NASA-first resources to see greater use from high-paying defense and civil sector clients.

Ranging from defense contractors like Lockheed Martin to university researchers, to ground-piloted drone companies, these clients provide the NASA research facilities with welcome revenue, thus offsetting the costs of crucial testing for future NASA missions.

In a wind tunnel, painstakingly crafted scale models, often forged of aluminum alloy, are mounted to a rigid surface so they cannot move. Then, powerful fans or compressed air mechanisms generate air flows around the model, sometimes at wind speeds that break the sound barrier, initiating a sonic boom. Wind tunnel testing helps researchers better understand how a potential craft design will respond “in flight.”

Flight Dynamics Research Facility which is set to open at NASA Langley in late 2024.

Flight Dynamics Research Facility which is set to open at NASA Langley in late 2024.

Jeremy Pinier, an aerodynamicist on the Artemis Lunar Mission, says that with wind tunnels, “you can let nature give you the answer,” as opposed to computer analysis attempting to make sense of impossibly chaotic aerodynamics.

Despite comprehensive testing, all wind tunnels provide imperfect reflections of a typical journey through the atmosphere. However, when used in conjunction with similarly limited supercomputer calculations, tunnels can bridge gaps in data. Between the two, NASA can predict with near-flawless accuracy how any flight might go.

The Space Agency possesses “a suite of wind tunnels to cover the entire speed range of any type of vehicle that flies in the atmosphere,” says Pinier. Several speeds are tested within Langley’s cohort of tunnels, including hypersonic, transonic, subsonic, and Mach-10.

Adding to the suite of wind tunnels is the Flight Dynamics Research Facility which is set to open at NASA Langley in late 2024. It’s the Agency’s first new tunnel in more than 40 years, replacing two 80-year-old tunnels. It promises what NASA says will be a highly versatile and cost-effective option for consumers and a boon to NASA’s budget. With bleeding-edge technology, the tunnel can effectively simulate fiery entry and descent conditions for spacecraft set to visit Mars, Venus, or the Moon, and can test spin and stall techniques now common within high-performance aircraft.

In a select few tunnels, conditions are transformed with “trick of math” cryogenics referred to in the aerodynamics community as a Reynolds Number. According to Pinier’s definition, a Reynolds Number is a mathematical ratio where, at cold temperatures, “the relative particle size of air reduces. So all of a sudden the airflow thinks that a model is way bigger than it is in reality.”

The Transonic Wind Tunnel at Langley’s National Transonic Facility (NTF) is one such species. It’s the largest at 8.2 feet in diameter, and it has the distinction of being the first, and only one of two pressurized cryogenic tunnels in the world, capably operating at the highest range of Reynolds Number testing. To meet sub-zero conditions, the tunnel can inject “up to a ton of liquid nitrogen every second and a half,” says NTF facility manager, Kevin Harrell.

Flight Dynamics Research Facility which is set to open at NASA Langley in late 2024.

Flight Dynamics Research Facility which is set to open at NASA Langley in late 2024.

The Transonic Wind Tunnel has tested several examples of iconic industrial aerospace, including the Boeing 767, Boeing 777, and the Northrop Grumman B2 Bomber.

Approximately four tests have been designated as classified, and at least one submarine has been tested there.

According to Harrell, the use of the NTF has always been one of collaboration between NASA and its industrial partners, although not without substantial costs for its civil sector clients, which range from Boeing to drone companies. One test at the facility could fetch from $500,000 to $5 million depending on the width of a test’s data set.

“We are one of the most expensive facilities that NASA has,” he says. “But if I can get a reimbursable test, our industrial clients are paying for the facility and that’s more revenue being generated by the NTF and NASA as a whole.”

If one fin, one girder or one instrument is out of place or sync with any testing data minutiae during a launch or flight, explosive, costly, and incredibly dangerous consequences can ensue—for those piloting the craft and on the ground. “It’s expected that NASA is always going to succeed,” says Pinier. “But the spacecraft and aircraft we test are going to experience the most extreme conditions known to man; so there’s always going to be an element of risk.”

In testing new materials, finishes, and varying aircraft and spacecraft prototypes to predict how they’ll behave in real life scenarios, wind tunnel testing saves lives and advances aviation. The revenue from commercial and defense clients provides the financial flexibility NASA can use to continue to develop innovative and revolutionary technologies for space exploration.

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