SpaceX’s giant launch vehicle, the Starship, has been fully assembled on its Starbase launch pad. He stands ready for his test flight which will take place after two important tests. A one-time repeat of the launch procedure and a static ignition of all 33 main stage engines.
On January 9, 2023, SpaceX assembled the two parts of the Starship, its future 120-meter-high giant launcher, on its launch pad! The upper stage, which is the transport vehicle and is called Starship, was installed on the Super Heavy main stage, i.e. the booster needed to launch Starship.
This is the third time since August 2021 that the two parts of the launcher have been joined together and form the Starship launcher. The first two times, they were placed on top of each other. This time, they are assembled (or in the process of being assembled). The two parts of the launcher were mounted using the “chopstick” arms of the huge crane nicknamed Mechazilla and built by SpaceX in two copies: one at Boca Chica in Texas, the other at Cape Canaveral in Florida.
Elon Musk expects the Starship’s maiden flight to take place within weeks, in March. Before that, two main crucial tests must be passed. A launch timeline repeat with padding (wet dress rehearsal, in NASA jargon), which will consist of filling the tanks and carrying out all the stages preceding takeoff but which will stop before the end of the countdown. This will be followed by a static ignition of the 33 Raptor engines on the main stage. This will be the first time that all of the Super Heavy’s engines will be fired at once. A previous test had been carried out with “only” 14 engines.
From Texas to the Hawaiian Islands
This first test flight is scheduled to last more or less 90 minutes. Starship will be put into orbit by the Super Heavy launch vehicle approximately nine minutes after liftoff and will fly to the Hawaiian archipelago, with a passage through space, but without achieving a full orbit around the Earth. If all goes as planned, the main stage of the Super Heavy will return to land on dry land, which will not be the case for the Starship. After an atmospheric reentry, it should sink in the open sea off the coast of Hawaii, after a controlled landing. In early 2021, Elon Musk explained that “ if he did not expect any particular problems during the takeoff of the Super Heavy and the Starship “, he had conceded on the other hand that it will probably take ” many attempts before SpaceX perfected the Starship’s reentry and landing maneuvers from orbit “.
Fly a multi-engine launcher
To understand the difficulty of flying a launcher with several engines, it is necessary to know that, from one engine to another, the level of combustion is never the same and is very difficult to model, hence the importance of ground tests and the experience acquired with the flights of the Falcon 9, whose main stage has nine engines, and of the Falcon Heavy and its 3×9 engines – its main stage and made up of three main stages of the Falcon 9.
The jet of each engine does not mean that together these jets work as if they were separate engines. These jets will interact with each other and this can pose many aerodynamic constraints, in particular lateral, and therefore hinder the ascent of the machine. One of the jets can also turn off the jet of another engine! Another problem is the orientation of the motors. It’s obviously not the same to have three engines rather than just one! With such high flow rates, suction can occur in the skirt and create a vacuum effect.