The first thing that caught my attention here is the exhaust itself: a narrow blue and purple plume with clearly defined shock diamonds, held steady across a 25 second burn. A clean, stable pattern like that is not something you see every day from a printed engine, and it made me sit up right away.
The engine, named the E1-LOXCOOL725, is a liquid design printed in copper alloy on an EOS M290 machine. The assembly combines a metallic bell nozzle with the combustion chamber, and it runs liquid oxygen through the walls for regen cooling. On the plumbing side there is insulated piping plus flexible braided metal feed lines, which strikes me as a tidy way to route propellant on a stand.
The firing was horizontal, with the engine mounted on a test stand inside a corrugated metal shipping container. The maker ran it at 588 psi with an O/F mix ratio of 2.4, and the measured C* efficiency came out at 98 percent. For a printed copper chamber, that efficiency figure is genuinely impressive in my view.
After the burn, the injector and combustion chamber were inspected, and there was no melting or damage anywhere. Launcher clearly got the cooling path right. One thing still open is the color question: whether the blue comes from the copper engine or simply from burning very clean has not been settled, and I would enjoy seeing that pinned down.
Project by Launcher. Watch it on their YouTube channel: