SpaceX: Starship Hot-Stage Ring Was a Big Mistake! Can Cause Failure - IFT 3 & IFT 4SpaceX Community
SpaceX: Starship Hot-Stage RIng Ejection Is a CRITICAL FIX. Can Cause Failure - IFT 3 & IFT 4
In SpaceX’s latest blog post on the Flight 3 report and upcoming changes for Flight 4, they mentioned: "Upgrades derived from the flight test will debut on the next launch from Starbase on Flight 4, as we turn our focus from achieving orbit to demonstrating the ability to return and reuse Starship and Super Heavy. The team incorporated numerous hardware and software improvements in addition to operational changes, including the jettison of the Super Heavy’s hot-stage adapter following boost back to reduce booster mass for the final phase of flight."
So, what is meant by hot-stage adapter jettison? Before directly addressing that, let’s go back to Flight 2. After Flight 1, SpaceX introduced the concept of hot-stage separation for the Starship Super Heavy to increase the efficiency and payload capacity of the spacecraft. In this method, most of the 33 Raptor engines on the Super Heavy booster are turned off, but a few remain firing when the engines on the Starship upper stage are ignited. This avoids the loss of thrust during traditional stage separation, where the lower stage shuts down first.
The hot-stage separation involves the Starship firing up its own six engines to push itself away from the Super Heavy booster. To make this method safe for the booster, an additional ring section was installed on Starship's interstage to direct the blow of the engines. This method could potentially increase Starship's payload-to-orbit capacity by 10%.
Now, why do they want to jettison this additional ring section? I think this change is part of a broader effort to reduce the mass of the Super Heavy booster. A fully fueled booster has a mass of up to 3,500 tons. After liftoff, the mass reduces as the propellant is used up. During its return phase, it would barely have the fuel for the boost-back burn and landing. As you know, for the Falcon 9, SpaceX mentioned that they only keep the fuel necessary for the same process. This is done to reduce the mass of the rocket as much as possible. This same principle applies to the Super Heavy booster too, but additionally, if they could remove some more mass that significantly doesn’t contribute to the landing process, isn’t it good to remove that? Of course, it is. That’s the reason why they are jettisoning the hot-stage adapter. By jettisoning, SpaceX aims to minimize the risk of potential difficulties during landing and maximize the chances of successful recovery and reuse with improved control over the booster. The HSR ejection will occur shortly after the boost-back burn shutdown process.
https://www.youtube.com/watch?v=JcNeU9MSC8w
