Starship SN8

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Spacex installed a nose cone on a backup Starship SN8, thus completing the assembly of a second full-size prototype. The aerospace company is leaving no stones unturned ahead of Starship’s much-anticipated high-altitude flight test next week.

Extensive Starship Preparations

After the successful launch of the Crew Dragon Demo-2 mission, CEO Elon Musk stated that the company’s primary focus going forward will be developing the Starship launch vehicle. 

Since then, SpaceX has been working extensively on Starship’s development program. The company performed successful 150-meter hop tests for both the SN5 and SN6 prototypes last August.

SpaceX then rolled out its Starship SN8 prototype during the month of September. Over the last two months, the company has effectively put the SN8 through an extended series of tests.  

The prototype underwent four cryogenic proof tests and three triple-engine static fire tests. The SN8 differs from previous iterations, since it was the first prototype that has gone through multi-Raptor static fires. 

The first static fire test was completed on October 20, at 4:21 a.m. EDT. All three Raptor engines produced a thrust almost equivalent to 90% of the nine Merlin engines that power Falcon 9 rockets.

The second static fire conducted on November 12, however, was a different matter. SpaceX lost control of Starship’s hydraulic systems that are needed to operate most of the launch vehicle’s valves.

Musk also stated that the prototype had several burst disks installed in case of an anomaly. A burst disk, or rupture disk, is a pressure relief safety device. With the absence of burst disks, pressure could build and cause equipment failure. 

In Starship’s case, after the rupture disk burst, thus creating an auxiliary outlet to relieve the pressure that was building inside the rocket. This prevented the liquid oxygen header tank from exploding. 

Following the botched static fire, SpaceX made extensive repairs. The SN32 Raptor engine that melted during the test was replaced with an SN42 engine. The burst header tank was also swapped with another, and the launching pad received a fresh coating.

What Are the Odds of A Successful 15-Kilometer Hop Test?

According to Elon Musk, the probability of success is rather low. Musk explicitly stated on Twitter that there is “maybe a ⅓ chance” and many “things need to go right.”

SpaceX’s approach towards technology development has always been a rather conservative one. Modern aerospace companies do not opt to take huge risks. They prefer to adopt a waterfall model.

This model is a breakdown of project activities into linear sequential phases. Each development phase depends on the deliverables of the previous one. Thus, the model develops systematically from one phase to another.

To give a practical example, SpaceX does not proceed with a static fire test for a Starship prototype without undergoing a cryogenic proof test first. Additionally, no hop test is conducted before performing at least two static fires.  

By adopting that model, SpaceX wants to ensure as much as possible a success on the first try of each test.

Despite the conservative, borderline pessimistic outlook, the high-altitude flight could end up being successful. This would be in large part due to SpaceX’s project management’s style, and to establishing contingency plans at every turn.

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