Starship SN8 is expected to complete the second run of Static Fire tests over the coming week ahead of test flight later this month. While SN8 will be aiming for a touchdown on the launch pad, Elon Musk provided clarity on the primary goals of SN8’s flight – with a stable, controlled descent via its aero surfaces a major objective.
Starship SN8 is currently waiting for the second set of testing, which will involve cryogenic proof testing of the nosecone’s LOX header tank, followed by ever-evolving Static Fire tests with one, then two engines – both via the Header Tank system.
A full, three-engine, Static Fire will then be conducted, mirroring the first-ever triple Raptor test, although this time with one of the engines swapped out. Raptor SN36 has taken the place of the since-removed SN39, likely requiring a second full Static Fire.
The Header Tank tests are related to the landing burn, with the propellant supplied via these small tanks, of which the LOX tank is located at the tip of the since-installed nosecone.
However, to get to that point – where SN8 will initiate a Raptor relight, pushing the aft to face the ground before a smooth touchdown on the landing legs – will require many things to go right during the flight.
Lifting off under the power of the three Raptors, SN8 will be aiming for an altitude of 50,000 feet. Then, for the first time during Starship testing, the aero surfaces will come into play, as SN8 glides/descends – or, as many like to word it, bellyflops back toward terra firma.
This phase of the test will be a major data point for SpaceX, allowing them to recreate what they’ve already evaluated in a wind tunnel in the more challenging regime of real life.
Stable, controlled descent with body flaps would be great. Transferring propellant feed from main to header tanks & relight would be a major win.
— Elon Musk (@elonmusk) October 31, 2020
The “big win” of engine relight will involve using the Header Tank system’s ability to supply the Raptors.
Based on the Static Fire test plan, it is likely the single, and then dual-engine, tests’ aim to provide ground testing for what is expected to be a single Raptor ignition during the flip, followed by a two engine landing burn.
Any subsequent “wobbly landing” would be something that could be refined via the data gathered during SN8’s attempt.
“Understanding exactly how the body flaps control pitch, yaw & roll during descent, such that the ship is positioned well to relight, flip & land, would be a big win,” added Elon in subsequent Twitter replies.
Of course, Elon also provided the hopefully-unlikely scenario of SN8 failing as she leaves the pad. Although the most likely failure point is expected to be during the attempt to return to the landing pad, the ability to drop SN8 into the sea – should the return trip not go to plan – is also available.
“Although, if it fails right at the end, some landing pad repair will be needed to fill in the crater,” Elon added.
Should SN8 fail to make it back in one piece, Elon also cited the production cadence of SpaceX Boca Chica, which is self-evident via Mary’s (@bocachicagal)‘s daily videos.
While SN8 is tested at the Launch Site, the Production Facility saw SN9 moved to the High Bay for aero surface installation.
While the 150 meters Hop-Twins SN5 and SN6 had taken up temporary residence inside the High Bay during recent stormy weather, this is the first time a future Starship had entered the new facility for pre-flight processing.
The High Bay’s primary role – once its gantry crane is installed – will enable stacking operations for the tall Super Heavy booster.
The move of SN9 into the High Bay provided relief to the Mid Bay, which – once SN10 is fully stacked – will allow SN11 to begin stacking operations.
This production cadence emphasizes SpaceX’s ability to rapidly return from any potential test flight failure with a new vehicle ready to take a trip to the launch site within days of losing the previous vehicle. Or, in the event of successes, the ability to tag-team prototype vehicles on numerous test flights to gain additional data.
Refinements are already taking place, with “minor” – as Elon stated on Twitter – changes already implemented on SN9. It is known that SN9 will be the first prototype Starship to sport structure made entirely from 304L steel, whereas SN8 still has some parts made from the 301 alloy.
Although Super Heavy sections remain staged outside one of the Production Facility tents, the collection of vehicle-specific Starship sections is impressive.
The current status of SpaceX's Starship & Superheavy prototypes. 01/11 pic.twitter.com/ymrjUyembc
— Brendan (@_brendan_lewis) October 31, 2020
Fully identified parts for vehicles up to SN12 are on site, with specific hardware – observed via Mary via labels – up to SN14, such as a downcomer that arrived several weeks ago.
One element of Starship hardware that has seen a reduction of late has been the nosecones, with several test articles scrapped over recent days, allowing for the focus to be placed on the flight nosecones that will be mated with upcoming Starships.
The HLS nosecone in view – via Mary (@bocachicagal)
However, one spare nosecone has been repurposed, albeit with a lick of white paint and likely internal work yet to take place.
This nosecone will be used as a mock-up for Starship’s Human Landing System (HLS) bid.
Most photos via Mary (@bocachicagal)
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