Primed for Protection

This rover may not be destined for Mars, but it’s helping build the ride that’s designed to send astronauts around the moon.

At NASA’s Michoud Assembly Facility near New Orleans, Boeing teammates have developed a better way to prime the Space Launch System (SLS) fuel tank, known as the core stage, for its signature thermal protection system (TPS) coating.

That iconic orange spray foam is designed to regulate the temperature of the rocket’s 733,000 gallons (2.8 million liters) of liquid hydrogen and liquid oxygen (LOX) propellants, which are stored at minus 423 F and minus 297 F (minus 253 C and minus 183 C) during preparation and launch.

The TPS spray foam may not adhere to the tank’s surface if the primer isn’t first applied consistently and in compliance with engineering requirements.

Yellow before orange

Before production teams can apply the vibrant orange protective foam to the rocket, they must coat the bare aluminum surfaces of the tank with a primer. An automated spray system primes most of the cryotank’s surface, which is 149 feet (45.4 meters) long, but technicians must spray the domes manually.

As the tank rotates, technicians use handheld spraying devices to coat the dome’s surface. Due to the size and shape of the dome, this manual spraying is challenging, both technically and ergonomically. This is where the rover comes into play.

Spray it forward

After discussing alternatives with industry partners, Boeing technicians and engineers designed the rover to help reduce inconsistencies in manual spraying and improve operator ergonomics.

“Kicking off this project was a bit overwhelming as well as exciting,” said Boeing engineer Nick McEvoy. “It’s a challenge to collaborate across different functional groups, using everyone’s unique strengths and perspectives, but rewarding.

“We had team members familiar with chemical processing, engineering design and requirements, and practical knowledge of applying these concepts for manufacturability. I’m proud of how our Boeing teammates worked together to create a simple yet effective solution to solve such a complicated problem.”

Rover results

Using the rover enabled the team to cut the time it takes to apply the primer by about 25%. The thickness of the primer is consistent, the application process is repeatable, and the technicians appreciate the improved ergonomics.

“Seeing the CS3 LOX tank roll out of the spray cell was a proud moment for our team,” said Boeing engineer Natalie Weber. “It meant the many months of hard work, learning and collaboration we’d dedicated to this process were a success.”

The unique collaboration gave technicians an opportunity to gain additional training and certification to perform large-scale primer applications. By stepping in to work with production teammates, the engineers gained a better understanding of the work requirements in the primer spray cell.  

Working together to design the tooling and optimize the spray process, the team delivered consistent results. In one month of development, technicians completed 12 fuel tank dome sprays — enough to supply three rockets — helping to ensure the rover’s readiness to prime the next core stage fuel tank.

“We all contributed, and we all learned something,” said Boeing engineer Jared Bates. “We share the pride for what we achieved.

“No matter how minor it seems, every process improvement is critical to building a rocket that is safe for the astronauts. And every tank that rolls out of the cell is a picture of a job well done.”  IQ

By Casey Cappa, Boeing writer