Detailed explanation of the second flight of the starship to win high scores: successfully overcome the most difficult hurdles, flying up to 148 kilometers
After 7 months of waiting, the tallest and strongest giant arrow in history soared into the sky again, and finally staged the second flight of the starship. Although it still didn't fly the whole flight for 90 minutes, it was far better than the Starship's first flight on April 20 - flying higher, farther and more beautiful!
After a hundred turns and thousands of turns, finally waited for the second flight of the starship. There is only a 20-minute launch window, and SpaceX finally locks in: at 7:02 a.m. on Saturday, November 18 (21:02 p.m. Beijing time on November 18), located at the orbital launch pad of the Starship Base in Boca Chica, Texas, the second test flight of the Starship System is majestic, earth-shattering, breathtaking, mighty, and more shocking and exciting than the first flight of the Starship.
A large number of on-site witnesses in the safety zone 8 kilometers away from the launch site experienced the earth-shattering and thrilling experience as if they were hit by the gravitational waves, the strongest energy source in the universe, including the surrounding space, as if they were distorted, and at the same time, accompanied by a huge tail flame noise that tore through the air, with a shocking force that penetrated everything, it was deafening and heartbreaking. It seems that what you are watching is not a giant rocket soaring into the sky, but a nuclear bomb explosion that splits the world...
After the dragon soared into the sky, the 146-meter-high integrated launch tower still stood out with its steel body, and it seemed that it had not been excessively ablated by the high-temperature tail flame, and the capture arm, QD arm, and launch pad were still there... Of particular note is that the new launch pad, which has been revamped and upgraded, has indeed withstood the rigors of the test, without the massive damage caused by the Starship on its maiden flight, which appears to have been hit by a Hellfire missile. In fact, the Starship Launch Pad has become an impregnable fortress thanks to many enhancements such as the reinforcement of the launch pad base, the addition of a water-cooled steel plate system, and the addition of a flame deflector. Even if it is a high-frequency launch once a month in the future, it seems that it will be invincible.
What levels did Starship Fly Second through?
On the eve of the launch, SpaceX's official website announced the established operation process for the second flight of Starship, which took 3.5 hours as planned, from the approval of the launch director to the completion of the Starship spacecraft flying over most of the world and finally completing the controlled sea splash. From the launch of the starship to the splashing of the starship on the sea, the whole process lasted 1.5 hours (90 minutes) as planned, and it was interlocking and progressive. Of course, this is the ideal launch state. If you compare the actual flight conditions with the ideal state one by one, you will know: The second flight of the starship has gone through layers of levels, and which step will it finally rush to?▼
The live broadcast after takeoff shows that all 33 Raptor engines of the super-heavy rocket continue to exert force until T+2 minutes and 40 seconds, when just a few seconds before the separation of the first and second stages, the first stage shuts down 27 Raptor engines, leaving only 3 central engines, and burning at 50% thrust.
At about T+2 minutes and 46 seconds, the Starship spacecraft started three vacuum engines, and the primary and secondary thermal separation was successfully achieved. This is quite an achievement!
Musk had previously judged: Which level is the most difficult to break through in the second flight of Starship? It is the redesigned primary and secondary separation system, that is, the newly added hot separation stage, the probability of successfully passing this level is only 60%, but this first test was successful in one fell swoop!
You must know that the second-stage Starship spacecraft began to start the ignition of the three Vacuum Raptors before they separated from the first-stage super-heavy rocket, instead of igniting after the separation of the first and second stages as previously designed, which is undoubtedly the most dangerous during the second flight of the Starship. It is very important to test the thermal protection ability, structural stress and shock wave bearing capacity of the thermal separation ring. After all, this new change has never been verified in real flights.
Where's the break?
After breaking through the first and second stage separation, the first stage of super heavy B9 turned on to enter the return home mode, just at T+3 minutes and 20 seconds, when the super heavy started the return ignition, it suddenly exploded in the air. At this moment, the B9 has an altitude of about 90 km and a speed of 3,818 km/h. As the second-stage Starship spacecraft S25, the firepower of 6 Raptors is turned on at full power, and the flight altitude has reached 95 kilometers and the flight speed is 6342 kilometers / h.
Until 8 minutes after liftoff, at T+8 minutes 04 seconds, the S25 signal suddenly lost contact, and the telemetry data displayed on the live broadcast screen was fixed: flight altitude of 148 km, flight speed of 24124 km / h, and 6 Raptor suddenly flashed back. T+8 minutes and 10 seconds, the screen suddenly shows signs of an explosion in the air.
Then there was a picture of Musk discussing with the Starship team, apparently they were talking about a scene that had just happened: Starship S25 activated the self-destruct detonation of the automatic flight termination system. In the end, he died heroically in a low orbit of 148 kilometers. It is much higher than the Starship's first flight in the air at 39 kilometers.
Shortly after the livestream, SpaceX officials declared: "The Super Heavy exploded and disintegrated shortly after thermal separation, and the Starship spacecraft engine continued to ignite for several minutes during the flight into space. 」
Why the new thermal separation stage?
The reason why the B9 adopts the newly designed Hot Staging mode, that is, a new interstage ring is added to the top of the super-heavy rocket to ignite the engine of the second-stage starship spacecraft before the separation of the first and second stages, and the main purpose is to improve the efficiency of the starship.
When only 3 central engines of the first stage are retained to burn at 50% thrust a few seconds before the separation of the first and second stages, the 3 vacuum engines of the second stage will be started at the right time, and the superimposed thrust formed in this way will accelerate the propulsion of the starship spacecraft, thereby reducing the gravitational loss, thereby improving the efficiency of the starship in orbit. According to Musk, adopting this thermal separation mode is expected to increase Starship capacity by 10%. Although this separation mode is not the first of its kind to SpaceX, it was designed and used by Soviet and Russian rockets at the earliest, but the Starship system, as the largest and most avant-garde space vehicle experiment, SpaceX will undoubtedly do everything to try it, dare to try, and continue to optimize.
Thermal separation is also used for another purpose: to accelerate the Starship spacecraft to quickly push away from the Super Heavy rocket, thereby reducing the risk posed by the Super Heavy rocket. Therefore, this thermal separation ring is designed as a primary consumable hollow structure to quickly dissipate the tail gas flow emitted by the spacecraft engine and to provide thermal protection by adding a layer of thermal insulation on top of the super heavy rocket.
What is the value of a second flight of a starship?
The B9+S25, the tallest and most powerful starship system in history (1.8 meters taller than the B7+S24 and with greater thrust), finally completed the pioneer mission with a heroic attitude, providing the most valuable first-hand data and information for subsequent tests. In order to evolve into a full-fledged starship as soon as possible, these sacrifices are a price to pay. Just like the starship martyrs who were buried in the sea of fire before, such as SN8, SN9, SN10, SN11, B7+S24, all lined up in the glorious starship hall to welcome the final winner.
This is the rapid iterative development model of SpaceX leading the aerospace industry, and the spiritual core behind it is the concept of "fast failure and rapid iteration" that Musk has always adhered to: willing to take risks, not afraid of failure, blow up, reflect and correct, and invest in the next test, so that you can quickly mature and approach success. In Musk's words: "We don't want to eliminate all risk in the design, otherwise we won't achieve anything." 」
On the other hand, other launchers, especially the national teams and established aerospace giants such as Boeing, Norger, and ULA, all follow the principle of more secure/more conservative linear development, first spending years designing each link, then years building hardware components, and then years testing and modifying... Progressively being safe in exchanging time and money for gradual stability is essentially risk-averse and fearful of failure. After all, any subject where bureaucracy prevails is afraid of failure, of making a fool of oneself, of suffering from gains and losses.
This rapid iterative development approach is the foundation of all of SpaceX's major innovations, including the Falcon series of rockets, the Dragon spacecraft, Starlink, and more, especially the creation of an epoch-making fully reusable super space transportation system, Starship, where recursive improvements are crucial.
The first and second flights of the starship were both pioneers, and the successors were already eager to try. The third flight is expected to be staged as early as February next year. After all, time is pressing, and there are still a series of technical difficulties to overcome: precise orbit entry, re-entry capability, vertical landing, in-orbit refueling, orbit transfer capability, manned capability, lunar landing capability... All of this has to rely on multiple actual battles, continuous trial and error, and progressive experience, in order to quickly polish and iterate the starship system, and get closer and closer to the mature version of the starship. In my optimistic prediction, SpaceX may achieve this goal after about 10~20 test flights. From now on, a new era of starships is bound to rewrite human civilization and usher in a new era of real space odyssey.
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