Starship SN8

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SpaceX is set to conduct a 15-kilometer (approximately 50,000 feet) flight test next week for its Starship SN8 prototype. The aerospace company is ready to initiate the next crucial phase of its Starship launch vehicle development program. 

When Was the Decision Taken by SpaceX?

The company made the decision after completing a second triple-Raptor-engine static fire test two days ago. The static fire was performed at SpaceX’s Boca Chica, Texas test site.

Founder and CEO Elon Musk confirmed the news via Twitter the next day.

According to NASAspaceflight, the SN8 may undergo a test flight as soon as November 30.

A Drawn-Out  Engine Testing Campaign

The Starship SN8 completed its first triple-engine static fire over a month ago, on October 20. All three Raptor engines produced a thrust almost equivalent to 90% of the nine Merlin engines that power Falcon 9 boosters.

The SN8 then underwent a second triple-engine static fire test on November 12, 7:15 pm EDT. About an hour later, Elon Musk stated that SpaceX lost control of the rocket. More specifically, the company lost control of Starship’s pneumatics, or hydraulic systems needed to operate most of the rocket’s valves.

Musk also revealed that the Starship prototype had several burst disks installed as a contingency plan. A burst disk, or rupture disk, is a pressure relief safety device. It is a type of safety valve used to control or limit pressure. 

With the absence of burst disks, pressure might build up and create a process upset, or equipment failure. In worst case scenarios, pressure causes explosions. 

In Starship’s case, a rupture disk effectively burst. This created an auxiliary outlet for the pressure building inside the rocket. It thus prevented its liquid oxygen (LOx) header tank from exploding. 

The SN8’s nose cone contains the LOx header tank. The latter stores the propellants used for landing. It is also placed in the nosecone to assist with weight redistribution. More specifically, it maintains Starship’s stability during atmospheric re-entry.

On the other hand, following the botched static fire, SpaceX made extensive repairs. One of the Raptor engines, the SN32, was removed and replaced by an SN42 engine.

The header tank burst disk was also replaced, and the launching pad surface had a fresh coating.

Reminder: How is Starship SN8 Different From Previous Iterations?

The SN8 prototype is different from prior versions in numerous ways. Unlike previous iterations, it is equipped with a nose cone and body flaps.

The nose cone is the forwardmost section of a rocket. It is the first point that meets the air. It is designed to reduce aerodynamic drag as the spacecraft elevates into orbit. Drag itself is the force that opposes an aircraft’s motion through the air.  

A spacecraft’s stability relies on its ability to keep flying through the air pointing in the right direction without wobbling or tumbling. Body flaps provide that stability and control direction.

A Pessimistic Outlook?

Elon Musk stated that the odds of a successful high-altitude flight test are slim. SpaceX’s CEO estimated that there is “maybe a ⅓ chance”, but also added that SN9 and SN10 iterations are ready for a fast follow-up.

The goal of SpaceX is to build prototypes simultaneously in order to test and iterate quickly. Let us hope that SN8’s flight test is successful before it is retired by the company.

What are your thoughts? Do you think that the Starship SN8 will emerge unscathed from its hop test? Let us know in the comments below!

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