Project Overview
Item | Details |
|---|---|
Industry | Aerospace |
Client | Innovative Propulsion Laboratory (IPL) |
Product | Copper alloy rocket engine combustion chamber |
Project | Redwing Rocket Engine (Race2Space 2026) |
Manufacturing Process | Metal 3D Printing |
Technology | Selective Laser Melting (SLM) |
Material | Copper alloy |
Post-Processing & Inspection | CT inspection, heat treatment, dimensional inspection, surface roughness updates, laser engraving |
Result | Production-ready one-piece chamber with CT-verified internal cooling channels for a 7.7 kN, 50 bar rocket engine program |
Background
Innovative Propulsion Laboratory (IPL) is developing Redwing, a high-pressure rocket engine for Race2Space 2026. The program targets up to 7.7 kN of thrust at 50 bar chamber pressure, placing the engine in a demanding experimental propulsion category.
At the center of the project is a copper alloy combustion chamber with built-in regenerative cooling channels. Before combustion, fuel flows through small passages inside the chamber wall, absorbing heat from the hot inner wall before reaching the injector.
For this reason, the chamber had to do more than hold its external shape. It needed open, clean, and verifiable internal cooling channels, while also withstanding extreme heat, internal pressure, and thermal cycling during engine operation.
Challenges
IPL needed a copper alloy combustion chamber that could withstand high-performance rocket engine conditions while keeping its internal cooling geometry functional, manufacturable, and verifiable.
Key challenges included:
Extreme operating conditions: The combustion chamber had to withstand extreme thermal load, high internal pressure, and thermal cycling during engine operation.
Functional internal cooling channels: The regenerative cooling passages had to remain open, clean, and usable after printing so they could support chamber wall cooling during a full burn.
High-conductivity material requirement: Copper alloy was needed for thermal performance, but its high conductivity and processing behavior made SLM printing and powder removal more demanding.
First-build manufacturability and verification: The chamber was more than a simple prototype. IPL needed a manufacturable path from the first serious build, with internal flow geometry that could be verified before heat treatment.
Solution
Unionfab combined copper alloy SLM printing, DFM-led geometry optimization, targeted validation, and close customer collaboration to make the Redwing chamber manufacturable.
One-Piece SLM Copper Alloy Chamber
Unionfab selected Selective Laser Melting (SLM) to build the chamber wall, regenerative cooling channels, injector interface, and outer mounting geometry as one integrated copper alloy part. This avoided brazed joints along the cooling path and gave the team freedom to form continuous internal passages around the engine's thermal and hydraulic requirements.
DFM-Led Geometry Optimization
Early printing showed blockage risk in the internal cooling channels. Unionfab's DFM review found that the issue was not only channel size, but also channel shape: sharp internal corners could trap powder and reduce depowdering effectiveness. Unionfab recommended chamfered and rounded transitions to smooth the flow path and make the channels easier to print, depowder, and inspect.
Customer Collaboration and CAD Revision
The recommendation worked because IPL was willing to act on it. Instead of treating early blockage as a supplier issue or stopping the project, IPL reviewed the engineering rationale, accepted the geometry updates, revised its CAD files, adjusted dimensions and tolerances, and gave Unionfab time to validate the revised design before the next full chamber build.
Targeted Validation and Post-Processing
Before committing to final production, Unionfab printed a local test section around the highest-risk internal channel area to confirm that the revised geometry could remain open. After the final build, the chamber underwent CT inspection before heat treatment, heat treatment, surface roughness updates, dimensional inspection, injector-chamber fit checking, injector-orifice tolerance clarification, and laser engraving.
Key Design Shift
The most decisive adjustment was the internal channel geometry. The design moved from the original 1 x 1 mm square channels, to enlarged 1 x 2 mm channels, and finally to chamfered and rounded transitions.
This was more than a dimensional update. It changed how the channels could be printed, depowdered, and inspected, giving IPL a manufacturable path toward its 7.7 kN, 50 bar combustion chamber.
Results
After multiple rounds of design review, test printing, and engineering communication, Unionfab successfully produced the Redwing copper alloy combustion chamber. The final build met the key targets that had made the part difficult to print at the beginning of the project.
Verified outcomes:
Internal cooling channels: Confirmed open, fully depowdered, and CT-verified before heat treatment.
Chamber geometry: Manufactured as a single integrated copper alloy component with no brazed joints along the cooling path.
Critical dimensions and tolerances: Confirmed against customer-marked drawings.
Injector interface: Fit-checked with the Redwing injector before shipment, including 0.5 mm, 1.0 mm, and 1.2 mm small injector orifices.
Surface roughness: Produced to the level specified in the updated quality plan.
Part identification: Applied via laser engraving on the side of the chamber.
The result was a verified copper alloy rocket engine chamber that turned hard-to-print internal cooling geometry into production-ready propulsion hardware.
Customer Testimonial
Future Outlook
The Redwing chamber highlights the value of metal additive manufacturing for aerospace and advanced propulsion parts where internal channels, thermal loads, pressure requirements, and development speed push the limits of conventional manufacturing.
The same approach can support regeneratively cooled combustion chambers, injectors, heat exchangers, UAV propulsion components, turbine hardware, and other high-performance metal parts that require integrated geometry and verifiable internal features.
Unionfab looks forward to supporting IPL and other propulsion teams with DFM review, copper alloy SLM printing, CT inspection, post-processing, and engineering collaboration for complex metal components.
Acknowledgement
Unionfab thanks Innovative Propulsion Laboratory (IPL) for its collaboration and openness throughout the Redwing chamber development process. Special thanks also go to our engineering and manufacturing teams for supporting DFM review, test printing, SLM production, post-processing, inspection, and final verification.
