YouTube dissects how SpaceX mastered engines

A May 16 YouTube video about how SpaceX built its rocket engines lands on terrain the company has documented for years: repeated testing, tight manufacturing control and steady engine redesign. SpaceX says its McGregor, Texas, development site spans 4,000 acres and includes 16 specialized test stands that validate every Merlin engine for flight. SpaceX’s own product pages draw the basic split the video is explaining. Merlin, which powers Falcon rockets, burns RP-1 kerosene and liquid oxygen in a gas-generator cycle. Raptor, which powers Starship, is a reusable methane-oxygen staged-combustion engine that SpaceX says delivers twice the thrust of Falcon 9’s Merlin engine. ### Why does the video spend so much time on test stands and factory floors? McGregor, Texas, is central to the explanation because SpaceX says that is where it tests engines, vehicle structures and systems before flight. (spacex.com) The company says every Merlin engine and every Draco thruster is validated there, tying design work directly to hot-fire results instead of waiting for full mission outcomes. NASA described that same process in a 2021 account of Commercial Crew work. (spacex.com) NASA said Marshall and SpaceX engineers spent months reviewing Merlin test data generated in McGregor before engines were delivered to Kennedy Space Center, and NASA official Steve Gaddis said the testing was “rigorous, integrated, and holistic.” ### What tradeoffs are engine designers actually making? (spacex.com) Merlin and Raptor show that propulsion programs are usually balancing more than raw power. SpaceX describes Merlin as a reusable kerosene-oxygen engine for Falcon 1, Falcon 9 and Falcon Heavy, while Raptor is a reusable methane-oxygen engine for Starship and Super Heavy. Those choices affect performance, plumbing, materials, restart behavior and how a vehicle is meant to fly again. (nasa.gov) Starship’s engine layout also shows how those tradeoffs scale. SpaceX says Starship uses six engines — three sea-level Raptors and three vacuum-optimized RVac engines — while the Super Heavy booster uses 33 Raptors, forcing the company to solve not just combustion questions but startup timing, thermal protection and fluid distribution across a much larger propulsion system. ### Why does vertical integration matter so much in this story? (spacex.com) SpaceX’s public material repeatedly stresses that the company designs, manufactures and launches its own vehicles. In practice, that means engine development is not isolated from structures, avionics, plumbing or launch operations, which is one reason outside explainers often focus on vertical integration when describing SpaceX’s pace. A May 2026 SpaceX update offered a current example. (spacex.com) The company said the Starship fuel transfer tube feeding 33 Raptor engines was completely redesigned, and said propulsion and avionics systems were “tightly integrated” to coordinate fluids, power and networking to those engines. ### How did the company move from Merlin to Raptor? Falcon 9 established SpaceX’s engine-production model with Merlin, a kerosene engine built around recovery and reuse. (youtube.com) SpaceX says Merlin was originally designed for recovery and reuse, and Falcon 9 became the vehicle on which the company demonstrated landing, droneship recovery and orbital-class reflight between 2015 and 2017. Starship pushed the company into a different class of engine. (spacex.com) SpaceX says Raptor is a reusable methane-oxygen staged-combustion engine, and an earlier Starship SN5 test page described it as a full-flow staged-combustion methalox engine, reflecting the higher-performance architecture SpaceX chose for the fully reusable Starship system. ### Why does this resonate with propulsion hiring and engineering culture? (spacex.com) NASA’s Steve Gaddis described engine work as a multidisciplinary review of turbopumps, thrust vector controls, computational fluid dynamics, structural resonance, materials and processes. That matches the hiring theme often attached to propulsion programs: analysis, manufacturing and test operations have to be linked closely enough that problems found in one area can be corrected in hardware quickly. (spacex.com) SpaceX’s current Starship program still reflects that coupling. The company’s latest public updates focus on redesigned engine feed systems, integrated propulsion and avionics, and the challenge of managing 33 Raptor engines together on the booster before the next Starship flight campaign. (spacex.com) (nasa.gov)