SpaceX has made many design changes to its Starship rockets since the April test flight. In this respect informs Ars Technica cites Elon Musk’s statements.
One of the most important changes will be changing the algorithm to separate the stages and turn the motors on them on and off. Many rockets, including the Soviet Soyuz, turned off their first stage engines seconds before they left. Musk said that under the new plan, most of the Super Heavy (first stage) engines will be shut down at the same time as the Starship upper stage engines are firing. This will increase the rocket’s payload, but will require the addition of protection on top of the first stage before it can be reused. Additionally, vents will be added to the Super Heavy to allow gas from the second stage engines to escape.
SpaceX also modified the Raptor engine manifolds, which direct the hot methane-rich (reducing) gas into the combustion chamber to mix with the oxidizing gas. The previous design was prone to leaks and hot gas could leak through the holes used to connect the manifold to the engine. In addition, the hydraulic thrust vector control system will be replaced with an electric one, and additional armor will be placed between the engines to protect the engines from the explosion of their neighbors.
Finally, two multi-ton steel gas deflector plates will be attached to the launch pad to prevent damage from a powerful engine jet. There are over 1000 other minor changes.
Details on Starship’s design can be found at: material “socialbites.ca”.