Tuesday, August 6, 2019

Starship's helter-skelter progress

From Teslarati:

In the last week alone, SpaceX’s twin orbital Starship prototypes have made some truly jaw-dropping progress. Onlookers have witnessed Florida’s Starship push through a rapid growth spurt, while the company’s Texas team has begun to install propellant tank bulkheads and work on a triple-Raptor thrust structure.

Meanwhile, SpaceX CEO Elon Musk has suggested that one or both of the orbital-class Starship prototypes could be “almost ready to fly” by August 24th, the date of the CEO’s next official update on Starship (formerly BFR and ITS). Although the actual challenge of building a massive, orbital-class launch vehicle is far subtler than the visible steelwork needed to build its primary structure and pressure vessels, the veritable leaps forward made in both Texas and Florida in the last 7-10 days are extremely encouraging signs.

Starting off in Boca Chica, Texas, SpaceX’s team of engineers and technicians have been simultaneously handling Starhopper’s first untethered flight test (completed on July 25th) and building the facility’s orbital-class Starship prototype. Most significantly, after a few days of preparation, what is likely the Texas Starship’s first bulkhead was lowered inside its ~25m-tall (80 ft) barrel section, composed of the spacecraft’s propulsion section and propellant tanks.

Pictured below, technicians carefully craned the first 9m (30ft) diameter dome inside the Texas Starship on July 30th. Based on its orientation and the recent arrival of a similar dome, this particular bulkhead is almost certainly the bottom dome and first of three to be installed. It will thus serve as the bottom of the Texas Starship’s liquid methane propellant tank, as well as a significant structural member of the rocket’s thrust structure, needed to safely transfer the force of 3-6 Raptors to the rest of Starship.



SpaceX Texas also accepted delivery of the first multi-engine Starship thrust structure, featuring three obvious spots for three Raptors, meshing with Musk’s August 3rd statement that “Starship Mk1” would feature three of the engines.

Meanwhile, at SpaceX’s similar Florida Starship facility, the similar-but-not-quite-identical spacecraft has experienced even more rapid growth. Over the course of perhaps 4 or 5 days, technicians installed a full six new rings worth of steel segments on the vehicle’s tank section, separated from the curved nose section just like SpaceX’s Texas Starship. With an individual height of almost exactly six feet (~1.8m), the six new rings combined to add more than 10.5m to the Florida Starship’s relative height in just a few days. Combined, the nose and barrel sections would likely reach a height of 45-50m (145-165 ft), roughly 10-15% shy of full height (55m).

No fewer than 7 additional rings are visible in various stages of work (c. Aug. 4) across the Cocoa campus after the recent growth spurt.

Of note, a bulkhead visible between the Florida Starship’s barrel and nose sections in mid-July disappeared around the third week of the month, a strong indicator that SpaceX’s Florida campus actually beat Texas to their first Starship tank dome installation by as much as ~10 days. The fact that SpaceX is effectively racing itself to build the first flight-ready orbital-class Starship is deeply entertaining, but it also serves as an extremely unique example of the application of A/B testing (commonly used in software dev.) to spacecraft assembly.

[Read more here]



Of course, building a spaceship is far more than just building its hull.  But the rocket engine which will power it to LEO, the Moon and Mars, has been in development for 3 years.   What the incredibly fast progress building Starship Mk1 and 2 shows is that building in steel is far faster than building in carbon-fibre composite.  It's also 100 times cheaper, according to Musk.  Both prototypes could be ready for suborbital flights by September or October, and orbital early next year.  This is an extraordinary rate of progress.   It makes the Mars 2026 timetable plausible.

The next test is whether such a large rocket can be reverse-thrust landed with the new engines after its hops.  Then suborbital flights.  Then re-entry, with the new ceramic shields Musk is suggesting will be used instead of "weeping" steel.  If it doesn't break up, if it can be controlled when it lands (a la Falcon 9), if it requires little refurbishment after each flight, all these have to be tested.  But, wow!  Given the way SpaceX works, there will be constant iterations and tweaks to improve the product.  What eventually goes to Mars might look quite different to the ships they're now building.

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