https://techcrunch.com/2020/04/27/spacexs-latest-starship-prototype-passes-a-key-test-that-puts-it-on-track-for-a-first-flight/

SpaceX has been developing its next-generation Starship rocket for some time now, but the large-scale prototypes it’s building in Boca Chica, Texas, have thus far always encountered a fatal error during an important part of testing called “cryo” – or filling the fuel tank to full pressure in conditions that simulate the vacuum of space. The latest prototype, called ‘SN4’ for ‘serial number 4,’ has finally passed this test however, and that clears the way for an engine fire test followed by a short flight.

SpaceX’s SN4 prototype resembles what its final rocket will look like, unlike the Starhopper sub-scale demonstrator that the company originally flew just to show off what its new Raptor engine could accomplish. The SN4, like the Starhopper, is equipped with a single Raptor engine, which will make it possible for the vehicle to make short flights for testing purposes. The next version, SN5, will have three raptor engines according to SpaceX CEO and founder Elon Musk, which is still less than the six that the full, functional version of Starship is intended to have, but that will allow it to perform longer test flights in preparation for an orbital launch demonstration.