https://www.nasaspaceflight.com/2021...aptor-testing/
Starship SN15 prepares to rollout as Raptor testing ups a gear
Just days after Starship SN11 conducted a fog-cloaked test flight that ended in an explosive finale, SN15 is already in final preparations for a rollout down Highway 4 at SpaceX Starbase (Boca Chica). SN15 will sport numerous modifications that SpaceX hopes will result in improved performance ahead of shooting for orbit along with smoother touchdowns for its prototype rocket.
One of the mostly unspecified modifications involves the engines, which are being aided by an increased test cadence at SpaceX’s McGregor test site. The center is currently constructing two additional vertical Raptor test stands to increase throughput.
SN11 was the most dramatic ending to a Starship prototype flight to date, albeit without any cameras catching the explosion due to thick fog in the region.
When SpaceX’s onboard feed froze, SN11 was moving toward the flip and landing burn of its three Raptors. NASASpaceflight.com’s Livestream audio caught the sound engine relight, quickly followed by the explosive boom and pieces of SN11 raining down on the launch site.
Every other stage of flight, including the ascent and the bellyflop return, matched the successes of
SN8 through
SN10. While it was later noted that one engine struggled during the ascent, the vehicle achieved its test objectives heading toward the landing burn.
While online rumors have ranged from issues relating to the Flight Termination System’s triggering (FTS) through to the CH4 (Liquid Methane) Header Tank exploding, it was understood the likely cause was an explosive engine failure during the re-light process that destroyed the vehicle.
Nothing could be confirmed until Elon Musk or SpaceX release the official cause of the vehicle returning to the launch site in pieces, conclusions that were expected per Elon’s surprising and refreshing transparency with the test program.
That came on Monday when Elon tweeted: “Ascent phase, transition to horizontal & control during free fall were good. A (relatively) small CH4 leak led to fire on engine 2 & fried part of avionics, causing hard start attempting landing burn in CH4 turbopump. This is getting fixed 6 ways to Sunday.”......
SN15
SN15 rolled from the Mid Bay to the High Bay during the week, ahead of receiving its Nosecone, which has since been mated to the stack. It will make the trip down Highway 4 as early as Monday, once the impressive Liebherr LR1600/2 Crawler Crane (dubbed “Tankzilla”) has made the trip for the task of raising SN15 on the launch mount.
This vehicle marks the second phase of testing for the full-stack Starship prototypes ahead of pushing on to the orbital vehicles, which is expected to open with the SN20 vehicle –
as previously reported by NASASpaceFlight.com.
“Next major technology rev is at SN20. Those ships will be orbit-capable with heat shield & stage separation system. Ascent success probability is high. However, SN20+ vehicles will probably need many flight attempts to survive Mach 25 entry heating & land intact.”......
BN1-3
Although Elon confirmed the orbital attempt would be as reported, with SN20 and Super Heavy BN3, the claimed target date of “by July” was always highly ambitious. The likelihood BN3 will be the Super Heavy to conduct the flight is also subject to change.
This ever-evolving plan was confirmed when Elon noted
BN1 won’t even undergo testing at the suborbital site and will be scrapped.
Currently stacked in the High Bay, BN1 was never going to hop. However, it was expected to be proof tested – and at one point was potentially Static Fired with a couple of Raptors. While SpaceX may take the opportunity to test how to roll such a tall booster down Highway 4, it appears likely the pathfinder will likely be scrapped at the Production Site.
“BN1 is a manufacturing pathfinder, so will be scrapped. We learned a lot, but have already changed design to BN2,” Elon noted, with the design change likely to be related to the position of the LOX and CH4 tanks in the stack.
Amazingly, Elon added that SpaceX aims to complete the stacking of
the BN2 Super Heavy booster – which is currently in sections outside the High Bay, in time to rollout and lifted on to the yet-to-be-completed Orbital Launch Site mount in a matter of weeks.
“Goal is to get BN2 with engines on orbital pad before end of April. It might even be orbit-capable if we are lucky,” Elon added, with “orbit-capable” a highly surprising statement given his initial note about the first test of a Super Heavy originally being a 150-meter hop.
However, whenever there is doubt in ambitious Starship schedule goals, the Production Site is on hand to add some realism via its incredible cadence. Even BN3 sections have already been spotted by
Mary (@bocachicagal).....