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SpaceX tests all engines of its superheavy rocket; 31 out of 33 worked

Updated: Feb 11, 2023

'Booster B7' created the new power record

The static test lasted 6 seconds, with the activation of 31 of the 33 motors (one of them was turned off beforehand and the other stopped shortly after being turned on) - Carlos Nunez / Space Intelligence

SpaceX's SuperHeavy rocket booster ignited its engines on Feb. 9, 2023, at around 4:14 pm ET (19:14 GMT), in the first full static test of the superheavy payload rocket.

The operation took place at the company's Starbase test center in Boca Chica, Texas. Thirty-three Raptor 2 engines were fired, but the controllers shut one of them down shortly before full production of expected thrust, and another was shut down by the automatic management system; the remaining 31 engines ran for nearly 6 seconds, with the rocket and launch infrastructure "remaining intact" after the test. SpaceX said the "full intended duration" for the test had run.

The B7 stage is 70 meters long and has a basic diameter of 9 meters. - Homem Do Espaco

The stage is mainly constructed of steel, is 70 meters long, with a liquid oxygen tank volume of 2,251 m³ and the liquefied methane reservoir with 1,700 m³

Super Heavy Booster 7 completed a full duration static fire test of 31 Raptor engines, producing 7.9 million lbf of thrust (~3,600 metric tons) – less than half of the booster’s capability

Even so, this value would be the highest ever achieved in a static test, making the SuperHeavy the most powerful first stage rocket ever tested. Yesterday's test was another step towards the development of the Starship/SuperHeavy system , whose first test flight is scheduled to take place later this year, and during which the first stage rocket will be used to accelerate the spacecraft to orbital speed up to a controlled drop into the Pacific Ocean.

The second engine that did not run was shut down by the automatic system to cancel the effect of shutting down the first engine before starting. In rockets it is common to shut down the engine opposite a defective one in order to maintain power balance. Engines that continue to run can be set to a slightly higher thrust to compensate for the fault caused by the inoperative engine.

Since its unveiling in 2016, SpaceX's next-generation space transportation system has gone through numerous names as well as design changes, but some key design features have remained constant: full reuse, full-flow stage combustion engines, and LOX/LCH4 deeply subcooled as propellants. Other features have changed: while the initial Interplanetary Transport System (ITS) was supposed to weigh over 10,000 tons, the current design is expected to weigh about half that. The main frame material was also changed from carbon fiber composites to stainless steel.

The aerodynamic settings have also been adapted and refined over the six years since the initial public presentation. The current status, dubbed Starship and Super Heavy, is the first in which significant progress towards integrating material from entire stages has been achieved. While it is virtually certain that the design will be further adapted and refined based on the first orbital tests, the current model is set to be the first fully integrated version that will attempt to reach orbit.

Raptor 2 No.200

In parallel with work carried out on the vehicle's systems, engine development progressed rapidly, and was initially planned to be completed by the end of 2019, and indeed the first flights of the 'Starhopper' test vehicle that year used functional Raptor engines, making This engine is the first full flow stage combustion (FFSC) cycle to be flight tested. However, development continued and the design was further refined, culminating in the current Raptor 2, with better cost, sturdiness, less mass, as well as a higher level of thrust. Each Raptor 2 was set to produce 213,200 kgf in today's test.

The Raptor, which has already performed several flight tests in atmospheric conditions, operates in a full flow similar to the RS-25 of the American space shuttle and SLS. The initial sea level or first stage version had a nozzle expansion ratio of 35 and a chamber pressure of at least 250 bar, but in later tests it reached 300 bar or more.

Since 2022, the new Raptor 2 version has been in production, for which the nominal chamber pressure has been increased to 30 MPa, while the expansion ratio has been slightly reduced. The key objective for this design choice was to significantly increase the thrust available on the stage while still being able to house the 33 engines in the available Super Heavy bore. Since almost no space is available between the engines for this reason, outer ring Raptors have no tipping capability, or TVC [*] .

Engines arranged in a crown in the first stage engine bay

[*] TVC = thrust vector control , where an entire engine is tilted about an axis, usually by two hydraulic actuators, to give the rocket direction. This eliminates the need for specific motors to control pitch, yaw and pitch, as well as their brackets, actuators, piping and control units

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