A sounding rocket flight test at Sandia National Laboratories' Kauai Test Facility has delivered measured reentry vibration and aerodynamic load data that engineers will use to validate models and drive nonnuclear component designs for the W93 — the first new U.S. nuclear weapon under development in nearly 30 years.

The Atrax test, funded and flown within roughly 18 months, closes data gaps about two years before the first scheduled flight test for the W93 warhead. Sandia is the design agency for the W93's nonnuclear components and lead warhead systems integrator for U.S. nuclear weapons programs.

"The Atrax sounding rocket flight test is helping us improve credibility and confidence in our modeling and simulation tools in preparation for the W93 warhead," said Ross Wagnild, an aerospace engineer at Sandia. "Getting confidence in our toolset earlier allows more time to inform the design of components."

What did the test actually measure?

The target was reentry — an environment where aerodynamic forces and structural response interact in complex ways that ground testing cannot fully replicate. "Vibration during reentry is a mechanical environment challenging to some of our components," said Peter Coffin, a Sandia engineer who analyzes structural dynamics. "This test helps us understand our models so that we can better predict those environments as we move forward on new vehicles."

Unlike typical tests that field only internal vibration sensors, the team outfitted the reentry vehicle with sensors characterizing external aerodynamic loads — the drivers of internal mechanical vibration. The instrumentation worked as intended.

"It demonstrated that it worked," Coffin said. "It gave us good data without damaging the reentry vehicle."

The test also introduced a new reentry vehicle, a three-stage sounding rocket and a new separation system — additions that carried technical risk for both flight success and data capture.

Where do the modeling tools come from?

The flight environment characterization drew on two NNSA-funded capability streams:

• Modeling and simulation tools developed within NNSA's Advanced Simulation and Computing program.
• Ground test and diagnostics capabilities funded by NNSA's Engineering and Technology Maturation program.

With flight data now in hand, engineers no longer need to rely on estimates as model inputs. They can decompose the dataset to check how thermal, fluid and structural codes perform and identify where improvements are needed.

"The goal is to help us better evaluate the survivability of nonnuclear components of our weapon systems," Wagnild said.

Why does earlier data change design economics?

The core portfolio argument is scheduling: informed design decisions made earlier in development are easier and cheaper to implement. "If you understand what your environments are earlier, you can more precisely design your components," said Kelsey Forsberg, who works in nuclear deterrence at Sandia. "You can design components to the right environment."

Kauai data also arrives before system architecture development, reducing overall program risk. Forsberg credited prior NNSA investments — the High Operational Tempo Shot program and the Enzo demonstrator — with paving the way. "Those programs are enabling transformative improvements and reducing risk to the W93 program," she said.

How did the test move so fast?

The 18-month turnaround from funding to flight rested on one design decision: the test article did not need to replicate the fielded system. "The system we flew for this test didn't have to look like the system we're intending to field," Forsberg said. "We focused on relevant reentry vehicle characteristics to cut down the timeline to get the test done."

That distinguishes a sounding rocket test from a program flight test: the goal is environmental data collection, not reentry precision or accuracy.

What is the reach beyond W93?

Wagnild said the Atrax dataset extends to the broader hypersonics community, where it could improve hypersonic modeling and build confidence in modern sensor suites for other hypersonic vehicles.

For R&D managers, the case is straightforward: an 18-month, non-representative flight article bought validated environmental inputs two years ahead of the first W93 flight test, front-loading model credibility where design changes remain cheapest.