NASA’s RAMPT (Rapid Analysis and Manufacturing Propulsion Technology) team has been awarded the space agency’s 2024 Invention of The Year award for its contributions to NASA and the commercial industry’s deep space exploration goals.
The team was recognized for its thrust chamber liner and fabrication method, which eliminates complex, bolted joints by using 3D printing and large-scale additive manufacturing (AM) to fabricate a one-piece thrust chamber assembly (TCA). A novel composite overwrap provides support, with an overall mass reduction of over 40%.
The TCA is the heaviest component on the rocket engine, so every pound eliminated allows for additional payload. The benefits include significantly better performance of launch vehicles, consolidation of parts and a simplified fabrication that reduces cost and lead time.
The TCA must withstand a wide range of challenges, including extreme temperatures (from cryogenic temperatures below -290 °F and up to +6,000°F), high pressures (up to 6,000 psi), demanding duty cycles that impact fatigue life, engine dynamics and the reactive thrust loads. In addition, the walls can be as thin as 0.02 inches, increasing the complexity of the technological challenge.
All of this necessitates the use of a variety of materials and involves intricate manufacturing and joining processes while maintaining exceptionally tight tolerances.
The design and construction of the combined combustion chamber and nozzle has numerous novel features:
- A NASA-developed alloy, Copper-Chrome-Niobium (GRCop-42) was matured for the combustion chamber resulting in a 45% increase in wall temperatures.
- The integral channel design supports effective cooling, manifolds, and a range of features that facilitate an integrated coupled nozzle and composite overwrap.
- The chamber and its internal structures are produced using laser powder bed fusion (L-PBF), which uses minimal exterior material, allowing the composite overwrap to effectively contain the high pressure and various engine loads.
- Stock material and integral features build the chamber nozzle onto the aft end using a different alloy, optimizing the overall strength-to-weight ratio.
- While AM typically requires a build plate onto which parts are fabricated, this innovation can use the chamber itself as the build plate.
- The team developed a laser powder directed energy deposition (LP-DED) process with a new NASA alloy for hydrogen environments, called NASA HR-1 (HR = hydrogen resistant). The AM employed to integrate the chamber and nozzle involves the use of two distinct AM processes and alloys, using GRCop-42 for the chamber and NASA HR-1 for the nozzle.
According to NASA, using a composite overwrap significantly reduces weight while providing adequate strength to sustain required pressures and loads. Various filament winding techniques and fiber orientations, guided by modeling simulations, effectively counteract the (barrel) static pressure, startup, and shutdown loads, thrust and gimbal loads. Unique locking features designed into the chamber include turn-around regions (referred to as “humps”) to eliminate complex tooling.
“NASA, through public-private partnerships, is making these breakthroughs accessible to the commercial space industry to help them rapidly advance new flight technologies of their own,” said Paul Gradl, the RAMPT project’s co-principal investigator in an article on the agency’s website. “We’re solving technical challenges, creating new supply chains for parts and materials, and increasing the industry’s capacity to rapidly deliver reliable hardware that draws a busy commercial space infrastructure ever closer.”
“Ten years from now, we may be building rocket engines – or rockets themselves – out of entirely new materials, employing all-new processing and fabrication techniques. NASA is central to all of that,” said John Fikes, RAMPT project manager.
Filed Under: 3D printing • additive • stereolithography, Make Parts Fast