Starhopper successfully conducts debut Boca Chica Hop

by Thomas Burghardt

SpaceX’s Starhopper has successfully undertaken its first real hop into the Texas air on Thursday. The Hop saw the vehicle rise under the power of its Raptor (SN6) engine, around 20 meters in altitude, before translating several meters from where it launched. Elon Musk said the hop was successful and next will be a hop of 200 meters “in a week or two”.

(Lead photo by Jack Beyer for NSF/L2)
Following the arrival and installation of a new Raptor engine on to the Starhopper vehicle at SpaceX’s test facility in Boca Chica, Texas – a Static Fire test was conducted late last Tuesday. This test was required ahead of what is expected to be a 20-meter hop for the vehicle.

The Static Fire appeared to cause some secondary events including the ignition of a discharge of methane. However, the vehicle survived and underwent positive inspections allowing for the vehicle to proceed towards its Hop test.

The Hop was scrubbed after Raptor engine ignition before a recycle was attempted late in the window before it too was scrubbed.

Resuming Starhopper testing is part of facilitating further development of Raptor, the orbital Starship spacecraft, and the Super Heavy booster.

Raptor is SpaceX’s liquid methane and oxygen powered rocket engine, under development for the Starship and Super Heavy vehicles.

The engine that recently arrived in Boca Chica is the sixth full-scale Raptor built, succeeding previous builds that reached various phases of testing.

Raptor Serial Number 1 (SN-1) was disassembled for analysis and spare parts after testing at SpaceX’s rocket development facility in McGregor, Texas. SN-2 was tested in McGregor and shipped to Boca Chica, where it powered two brief, tethered Starhopper flights in April. Both SN-2 and SN-3 were also disassembled for analysis and parts after testing.

SN-4 was, at one point, intended to power the upcoming hop tests. However, after encountering issues in McGregor, the engine was only used for fit checks and Thrust Vector Control (TVC) testing in Boca Chica.

The engine was installed on the Starhopper vehicle, and commanded to gimbal to various directions at various speeds. After these tests, the engine was removed and shipped away, and Starhopper waited for another Raptor.

Raptor SN-5, however, also ran into issues in McGregor. Two seconds into a planned 50-second test firing, the engine was damaged beyond repair. The failure prompted changes for engine SN-6, which would have to pass testing in McGregor before being shipped to Boca Chica.

The first and second test firings of SN-6 went well, lasting 20 and 10 seconds respectively. The third firing lasted 50 seconds before a “soft abort” occurred. The test program continued, though, and the engine was successfully fired a fourth time for 65 seconds. On the fifth and final firing, Raptor roared for 85 seconds, a new record for the Raptor engine.

Having aced its McGregor test program, Raptor SN-6 was shipped to Boca Chica and installed on the Starhopper vehicle.

The engine was first used for further TVC tests. Now, it will be used for the next phase of Starhopper tests, which will incrementally get closer to firing the engine and eventually flying untethered above the launch pad.

The first test saw Starhopper fueled with liquid methane and oxygen and put through Ox spin prime and Fuel spin prime testing – effectively testing how to start up the turbines, as required ahead of testing the preburner.

Once this was completed nominally, Raptor’s preburner itself was tested, but without completely igniting the engine.

Only after successful preburner testing did SpaceX teams move towards the static fire test, which took place late on July 16 at 10:25 pm Central time.

The firing was an expected five-second run for SN6 Raptor which was understood to be nominal, as proven with the allowance to proceed to the Hop test without a second hotfire of the Raptor.

While the test itself fired for its full duration, events relating to this test appeared to cause some issues with Hopper, later seen when a secondary fire rose up to engulf the test vehicle.

With two small fires – one on the vehicle and one on the pad – a discharge of methane resulting from a CH4 vent line coming loose, caused a fireball to rise over the vehicle.

This occurred during the safing of the vehicle, meaning a fire hose was already being directed at the small fires, allowing for the fire to be extinguished before it caused any serious damage to the vehicle.

The post static fire safing – via Jack Beyer for NSF

The successful safing of the vehicle was evident when photos showed it is suffering from no obvious damage from external views. This was backed up by a successful detanking and power down overnight after the test.

Pad safing took some time before crews could check on how much damage was sustained on the vehicle. The results were positive with only minor damage allowing for a hop test to be replanned for the following week after the Static Fire, according to Elon Musk, who tweeted the news last Thursday.

Preparations for the Hop had been ongoing since, with Hopper gaining new “shoes”.

The shiny shoes fit on the one-inch plates that act as the feet – the latter of which are intentionally slightly bent and in that shape, to act as impact absorbers. The test article is a rigid structure and these feet are designed to be the “crunch/crumple zone”.

With Raptor already completing TVC checks per the aft steering of the vehicle, the thrusters on the top end of the Hopper were tested again overnight this week.

Now Starhopper was ready to fly untethered for the first time. With the tethers around her legs removed – which only allowed Hopper to jump a matter of inches during the Static Fire tests – Hopper was free to rise to an altitude of around 20 meters.

The vehicle also “diverted” sideways, similar to early flights of SpaceX’s Grasshopper test vehicle that informed the development of the reusable Falcon 9 booster.

However, the first attempt was scrubbed just after engine ignition, before a lengthy recycle which came close to the final minutes of the countdown before an issue forced the team to scrub the attempt for the night.

Another attempt was conducted on Thursday.

Despite some challenges that delayed the scheduled 7:30pm local time T-0, the teams successfully pressed through to a 10:45pm Hop, which saw the Raptor power into life and send Hopper up and across from where it had launched.

Although the event set off a brush fire, Elon Musk was quick to note the test was successful and that Hopper will next be tasked with a 200 meter hop “in a week or two”.

Looking farther ahead in the Starship development process, progress is continuing on both orbital prototypes, under construction in Texas and Florida. Construction of the Mk. 1 prototype in Boca Chica is continuing with the addition of more rings of stainless steel.

The most recent rings have had a protective covering, removed after the ring is welded to the cylinder.

The Boca Chica team is also building a windbreaker structure, which will be covered in fabric once completed. The purpose of the structure is understood to be protection from coastal winds, which affects the quality of the welding between each steel section.

The plans for these orbital Starship prototypes are fluid. They also may not represent the latest design of the operational Starship vehicle, as SpaceX CEO Elon Musk has stated further design changes have been made to the fins/legs.
An official update by Musk, on both the vehicle’s design and launch plans, is expected after Starhopper’s first untethered test flight.

Although Musk did note the hop will be webcast by SpaceX – which has numerous internal use cameras around the pad that could be fed into a live stream – no official word on this option has yet been provided.

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