Undergraduate students from Purdue University's PSP-AC team recently partnered with Elementum 3D for their groundbreaking TADPOLE propulsion system. Elementum 3D printed the aluminium combustion chamber, cooling circuit, and nozzle as a single integrated component through laser powder bed fusion.
The students are harnessing additive manufacturing (AM) to push the boundaries of vertical take-off and vertical landing (VTVL) technology with support from Elementum 3D. Their ongoing project aligns with the goals of the Collegiate Propulsive Lander Challenge (CPLC), where student teams are tasked with designing self-landing rockets. From this challenge emerged PSP-AC's innovative TADPOLE propulsion system.
"We are honored to offer our team's AM knowledge, expertise, and technology to inspire all the students involved in the Purdue Space Program to push the limits of conventional thinking and print the first ever A6061-RAM2 thrust chamber assembly," said Dr. Jacob Nuechterlein, Founder and President of Elementum 3D.
About the TADPOLE propulsion system
The TADPOLE propulsion system is a significant milestone in PSP-AC's development of a bipropellant hopper vehicle. This vehicle demands a propulsion system with extended burn durations, a regenerative cooling system, and the ability to control thrust vector. To meet these exacting requirements for the thrust chamber assembly (TCA), which involves intricate geometries and tight tolerances, PSP-AC partnered with Elementum 3D.
PSP-AC, operating at a chamber pressure of 250 psi and within a thrust class of 550 lbf, recognised the necessity of Elementum 3D's advanced RAM technology to realise their project. Employing the aluminium alloy A6061-RAM2, they found the material's yielding characteristics ideally suited for TADPOLE's operational demands, providing an extended lifespan to the thrust chamber assembly (TCA). This extension enabled the team to incorporate more tests into their campaign, enhancing their learning experience in designing and testing a propulsion system.
Why aluminium
The decision to utilise aluminium for printing the thrust chamber assembly was rooted in its excellent thermal properties, lightweight nature, and cost-effectiveness. PSP-AC was particularly pleased to find that Elementum 3D's aluminium alloy overcame common challenges associated with other AM aluminium powders, such as rough surface finishes. The thrust chambers produced with A6061-RAM2 exhibited remarkably smooth surfaces, conducive to efficient heat transfer, and boasted superior thermal and mechanical properties compared to competing alloys.
Challenges encountered
The PSP-AC team encountered another hurdle in the 3D printing process of the thrust chamber assembly (TCA): the post-processing and depowdering of internal channels. Collaborating closely with engineers from Elementum 3D, they devised effective solutions and optimised dimensions to facilitate proper powder removal.
Furthermore, the PSP-AC team collaborated extensively with Elementum 3D's engineers to access detailed material property information on the alloy. This was a notable achievement, as they had reportedly faced challenges obtaining such data from other suppliers. Armed with this comprehensive understanding of the alloy, they were able to model and predict the performance and functionality of the TCA. Ultimately, this enabled them to compare their predictions with the experimental data gathered during engine testing.
“The whole process is a great engineering challenge and learning experience that was made possible by Elementum 3D’s support. PSP-AC will use these simulations and experimental results to design their next engine,” said Andrew Radulovich, Chief Engineer at PSP-AC.
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