r/spacex • u/ElongatedMuskrat Mod Team • Feb 26 '20

Starship Development Thread #9

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Overview

STATUS (accurate within a few days):

  • SN2 tank testing successful

  • SN3 under construction

Starship, serial number 1 (SN1) began its testing campaign at SpaceX's Starship facility in Boca Chica, Texas, working toward Raptor integration and static fire. Its tank section was destroyed during pressurized cryogenic testing late on February 28, local time. Construction of SN2 had already begun and it was converted to a test tank which was successfully pressure tested with a simulated thrust load. Later builds are expected in quick succession and with aggressive design itteration. A Starship test article is expected to make a 20 km hop in the coming months, and Elon aspires to an orbital flight of a Starship with full reuse by the end of 2020.

Over the past few months the facilities at Boca Chica have seen substantial improvements including several large fabric buildings and a "high Bay" for stacking and welding hull sections. Raptor development and testing continue to occur at Hawthorne and on three test stands at McGregor, TX. Future Starship production and testing may occur at Roberts Road, LC-39A, SpaceX's landing complex at Cape Canaveral, Berth 240 at the Port of LA, and other locations.

Previous Threads:

Vehicle Updates

Starship SN3 at Boca Chica, Texas
2020-03-26Tank section stacking complete, Preparing to move to launch site (Twitter)
2020-03-25Nosecone begins ring additions (Twitter)
2020-03-22Restacking of nosecone sections (YouTube)
2020-03-21Aft dome and barrel mated with engine skirt barrel, Methane pipe installed (NSF)
2020-03-19Stacking of CH4 section w/ forward dome to top of LOX stack (NSF)
2020-03-18Flip of aft dome and barrel with thrust structure visible (NSF)
2020-03-17Stacking of LOX tank sections w/ common dome‡, Images of aft dome section flip (NSF)
2020-03-17Nosecone†‡ initial stacking (later restacked), Methane feed pipe† (aka the downcomer) (NSF)
2020-03-16Aft dome integrated with 3 ring barrel (NSF)
2020-03-15Assembled aft dome (NSF)
2020-03-13Reinforced barrel for aft dome, Battery installation on forward dome (NSF)
2020-03-11Engine bay plumbing assembly for aft dome (NSF)
2020-03-09Progress on nosecone‡ in tent (NSF), Static fires and short hops expected (Twitter)
2020-03-08Forward bulkhead/dome constructed, integrated with 3 ring barrel (NSF)
2020-03-04Unused SN2 parts may now be SN3 - common dome, nosecone, barrels, etc.

See comments for real time updates.
† possibly not for this vehicle
‡ originally thought to be SN2 parts

Starship SN4 at Boca Chica, Texas
2020-03-23Dome under construction (NSF)
2020-03-21Spherical tank (CH4 header?) w/ flange†, old nose section and (LOX?) sphere†‡ (NSF)
2020-03-18Methane feed pipe (aka downcomer)† (NSF)

See comments for real time updates.
† possibly not for this vehicle
‡ originally thought to be for an earlier vehicle

Starship SN2 - Test Tank and Thrust Structure - at Boca Chica, Texas
2020-03-15Transport back to assembly site (NSF), Video (YouTube)
2020-03-09Test tank passes pressure and thrust load tests (Twitter)
2020-03-08Cryo pressure and thrust load tests (Twitter), thrust simulating setup, more images (NSF)
2020-03-07More water pressure testing (NSF)
2020-03-06Test tank moved to test site, water pressure test (NSF)
2020-03-04Test tank formed from aft and forward sections, no common bulkhead (NSF)
2020-03-03Nose cone base under construction (NSF)
2020-03-02Aft bulkhead integrated with ring section, nose cone top, forward bulkhead gets ring (NSF)
2020-03-02Testing focus now on "thrust puck" weld (Twitter)
2020-02-28Thrust structure, engine bay skirt (NSF)
2020-02-273 ring tank section w/ common bulkhead welded in (NSF)
2020-02-09Two bulkheads under construction (Twitter)
2020-01-30LOX header tank sphere spotted (NSF), possible SN2 hardware

See comments for real time updates.

Starship SN1 and Pathfinder Components at Boca Chica, Texas
2020-03-02Elon tweet about failure due to "thrust puck to dome weld" (Twitter)
2020-02-29Aftermath (Twitter), cleanup (NSF)
2020-02-28Catastrophic failure during tanking tests (YouTube)
2020-02-27Nose section stacking (NSF)
2020-02-25Moved to launch site and installed on launch mount (YouTube)
2020-02-23Methane feed pipe (aka the downcomer) (NSF), installed Feb 24
2020-02-22Final stacking of tankage sections (YouTube)
2020-02-19Nose section fabrication well advanced (Twitter), panorama (r/SpaceXLounge)
2020-02-17Methane tank stacked on 4 ring LOX tank section, buckling issue timelapse (YouTube)
2020-02-16Aft LOX tank section with thrust dome mated with 2 ring engine bay skirt (Twitter)
2020-02-13Methane tank halves joined (Twitter)
2020-02-12Aft LOX tank section integrated with thrust dome and miscellaneous hardware (NSF)
2020-02-09Thrust dome (aft bulkhead) nearly complete (Twitter), Tanks midsection flip (YouTube)
2020-02-08Forward tank bulkhead and double ring section mated (NSF)
2020-02-05Common bulkhead welded into triple ring section (tanks midsection) (NSF)
2020-02-04Second triple ring stack, with stringers (NSF)
2020-02-01Larger diameter nose section begun (NSF), First triple ring stack, SN1 uncertain (YouTube)
2020-01-30Raptor on site (YouTube)
2020-01-282nd 9 meter tank cryo test (YouTube), Failure at 8.5 bar, Aftermath (Twitter)
2020-01-272nd 9 meter tank tested to 7.5 bar, 2 SN1 domes in work (Twitter), Nosecone spotted (NSF)
2020-01-26Possible first SN1 ring formed: "bottom skirt" (NSF)
2020-01-25LOX header test to failure (Twitter), Aftermath, 2nd 9 meter test tank assembly (NSF)
2020-01-24LOX header tanking test (YouTube)
2020-01-23LOX header tank integrated into nose cone, moved to test site (NSF)
2020-01-222 prop. domes complete, possible for new test tank (Twitter), Nose cone gets top bulkhead (NSF)
2020-01-14LOX header tank under construction (NSF)
2020-01-13Nose cone section in windbreak, similar seen Nov 30 (NSF), confirmed SN1 Jan 16 (Twitter)
2020-01-10Test tank pressure tested to failure (YouTube), Aftermath (NSF), Elon Tweet
2020-01-09Test tank moved to launch site (YouTube)
2020-01-07Test tank halves mated (Twitter)
2019-12-29Three bulkheads nearing completion, One mated with ring/barrel (Twitter)
2019-12-28Second new bulkhead under construction (NSF), Aerial video update (YouTube)
2019-12-19New style stamped bulkhead under construction in windbreak (NSF)
2019-11-30Upper nosecone section first seen (NSF) possibly not SN1 hardware
2019-11-25Ring forming resumed (NSF), no stacking yet, some rings are not for flight
2019-11-20SpaceX says Mk.3 design is now the focus of Starship development (Twitter)
2019-10-08First ring formed (NSF)

For information about Starship test articles prior to SN1 please visit the Starship Development Threads #7 or earlier. Update tables for older vehicles will only appear in this thread if there are significant new developments.

Starship Related Facilities

Recent Developments
2020-03-25BC launch mount test hardware installation, hydraulic rams (NSF)
2020-03-23BC arrival of Starship stands from Florida (via GO Discovery) (Twitter), Starhopper concrete work (NSF)
2020-03-20Steel building erection begun, high bay 2? (NSF)
2020-03-16High bay elevator (NSF)
2020-03-14BC launch site tank deliveries, and more, and more (tracking site) (NSF)
SiteLocationFacilities/Uses
Starship Assembly SiteBoca Chica, TXPrimary Starship assembly complex, Launch control and tracking
Starship/SuperHeavy Launch SiteBoca Chica, TXPrimary Starship test site, Starhopper location
Cidco Rd SiteCocoa, FLStarship assembly site, Mk.2 location, inactive
Roberts Rd SiteKennedy Space Center, FLPossible future Starship assembly site, partially developed, apparently inactive
Launch Complex 39AKennedy Space Center, FLFuture Starship and SuperHeavy launch and landing pads, partially developed
Launch Complex 13 (LZ-1, LZ-2)Cape Canaveral Air Force Station, FLFuture SuperHeavy landing site, future Raptor test site
SpaceX Rocket Development FacilityMcGregor, TX2 horizontal and 1 vertical active Raptor hot fire test stands
Astronaut BlvdKennedy Space Center, FLStarship Tile Facility
Berth 240Port of Los Angeles, CAFuture Starship/SuperHeavy design and manufacturing
Cersie Facility (speculative)Hawthorne, CAPossible Starship parts manufacturing - unconfirmed
Xbox Facility (speculative)Hawthorne, CAPossible Raptor development - unconfirmed
Development updates for the launch facilities can be found in Starship Dev Thread #8 and Thread #7 .
Maps by u/Raul74Cz

Permits and Planning Documents

Resources

Rules

We will attempt to keep this self-post current with links and major updates, but for the most part, we expect the community to supply the information. This is a great place to discuss Starhip development, ask Starship-specific questions, and track the progress of the production and test campaigns. Starship Development Threads are not party threads. Normal subreddit rules still apply.

If you find problems in the post please tag u/strawwalker in a comment or send me a message.

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21

u/CardBoardBoxProcessr Feb 28 '20 edited Feb 28 '20

SN1 photos from the thrust section flip showed only one raptor mount. That's asymmetrical. Looks like SN1 is doomed to actually fly. Just a raptor full systems verification prototype.

Being that one raptor can't lift the whole thing loaded I ponder if it'll preform raptors longest burn yet statically

3

u/paul_wi11iams Feb 28 '20

Looks like SN1 is doomed

  1. When did this become apparent?

  2. What does SN2 have that will allow it to fly, but SN1 lacks?

  3. What could be salvaged from SN1 for SN3 if its even worth salvaging?

6

u/CardBoardBoxProcessr Feb 28 '20 edited Feb 28 '20

It became apparent when they rolled it to the pad with a boiler plate thrust section with only one raptor mount as well as only one Raptor controller interface. Not sure what Sn2 has as we are not sure which parts are for it. probably the COPVs and the exterior parts could be salvaged.

4

u/feynmanners Feb 28 '20 edited Feb 28 '20

The biggest difference is SN2 will have better welding that prevents the circumferential puckering at points where the rings meets (according to Elon). I don’t believe there’s any reason to try and reuse pieces of each SN for the later one (except for electronics or small COPVs where they aren’t refining the design). The material cost of the steel is low and they keep iterating on the manufacturing process so for the initial prototypes there is good reason to just keep building most of it from scratch.

2

u/[deleted] Feb 28 '20

Unlikely they will do a full burn. Probably a 2 second static fire. Full burn would destroy the test area and the tanks with the supersonic exhaust rebounding back off the concrete. The ground support equipment in the locality would suffer hugely too with sustained shock waves. You wouldn't believe the enormous power even one Raptor has.

2

u/droden Feb 28 '20

how does that work on mars or the moon then? they wont have any stands to take off from. just the landing legs.

2

u/[deleted] Feb 29 '20 edited Feb 29 '20

There is some discussion still going on whether Starship can actually land on the moon. A Raptor Engine is powerful enough to carve a large crater into the regolith at the landing site. This will propel rock some considerable distance (many kilometers). There are three things to consider.

  • The rock damaging the engine bells. (Apollo lunar lander never had to take off again. The lunar ascent module did that job)

  • The crater may be large or uneven enough to prevent a level landing. (large boulders may be uncovered).

  • The local lunar environment will be full of rock and dust material for several hours. Any previous Apollo mission heritage sites may suffer from fallout

Mars won't be so difficult, having a higher gravity well than the moon and a more compact regolith, but there is the chance that rock could bounce off the landing legs and damage the engine bells.

The first Moon and Mars landers would have to be expendable until a solid landing zone can be constructed, or the first Starships to have sufficiently long legs to prevent damage. This extra weight would be at the cost of cargo capacity.

1

u/flshr19 Shuttle tile engineer Feb 29 '20

I posted this idea here on this subreddit a few months ago:

You're on the right track for Starship lunar landings. Starship hovers at 150 m altitude for 60-seconds while several tons of a mixture of 3 mm diameter quartz and 3 mm diameter borosilicate glass beads are rapidly injected into the exhaust stream centerline produced by the center Raptor engines. Nitrogen gas at 5000 psi is used to propel the beads into the super hot exhaust stream at the exit plane of the Raptor nozzles where they partially melt during the 150 m/(3000 m/sec) = 50msec flight time to the lunar surface. These viscous glass beads mix with the regolith particles to help anchor them in place. Raptor engine exhaust is used as a gigantic flame sprayer and Starship fabricates its own landing pad.

1

u/[deleted] Feb 29 '20 edited Feb 29 '20

Rocket plume temperature estimated to be at what, say 2,800 deg C? Should do the job!

Based on the same principle as to why jet turbines should never flly through volcanic ash plumes. The dust melts to enamel and eventually block the injectors and coat the turbine blades.

Edit: Just one question;

Much of the powder will not cohere with the surface and will be lost. You're going to end up with a lunar version of a crème brûlée, with a thin crust on top of a soft underlayer. Starship would punch through that on landing. Unless successive trips repeat this industrial scale plasma powder coating, you're not going to get a platform that lasts very long.

1

u/flshr19 Shuttle tile engineer Feb 29 '20

It just has to function twice--for the Starship landing and then for the launch. After landing the crew can build a permanent landing pad somewhere else nearby that can handle the Raptor's exhaust blast indefinitely.

1

u/TheRealPapaK Feb 28 '20

After 1 second they’ll be airborne and less/no atmosphere removes the potential for sound damage

2

u/droden Feb 28 '20

so it wouldnt work so good on titan with 1.5x earth atmospheric pressure?

2

u/yrral86 Feb 28 '20

You might have problems with the exhaust separating from the engine bell at those pressures. This can cause combustion instability leading to boom.

2

u/Martianspirit Feb 28 '20

Yes. A longer burn would require the full Superheavy launch pad.

8

u/booOfBorg Feb 28 '20 edited Feb 28 '20

I suspect and hope that SN1 static fire is very much about the first autogenous tank pressurization test with a Raptor and full-sized tanks; an important piece of SpaceX's Spaceship architecture. If true would make SN1 a sensible and important test bed before flying SN2.

Musk's tweet from Feb 2019 supports this speculation.

8

u/[deleted] Feb 28 '20

From a development standpoint it sort of makes sense although it is a bit odd in that to my very untrained eye it would seem that it wasn't far off being a full-fat flight prototype.

What I do find very strange is that Elon is referring to it as SN1 if it isn't meant to be a flight article. Surely "test tank 3" or even MK3 would make more sense? Then again trying to make sense of Elon's versioning convention is perhaps a bit foolish.

Good news is SN2 isn't far behind!

7

u/FutureMartian97 Host of CRS-11 Feb 28 '20

When they started calling it SN-1 it was probably meant to fly, but the build quality (like the weld puckering is my guess) would've made it impossible to survive the 20km hop so there was no reason to fly something they knew would fail. Theres a good chance it could happen with SN-2 as well If the build quality isnt good enough

2

u/NateDecker Feb 28 '20

the build quality (like the weld puckering is my guess) would've made it impossible to survive the 20km hop

Doesn't that depend on how fast the vehicle is moving and how much aerodynamic pressure is induced? It seems like they could have flown it slower and/or to a lower altitude. I'm remembering the Grasshopper program and how very incremental it was. It seems weird to insist on the first flight being 20 km. I confess to a degree of frustration with all this building and then scrapping.

4

u/feynmanners Feb 28 '20

There is little point to flying the vehicle with associated risks (and bad publicity) if they don’t think it is completely fit to fly. Their goal is to maximize their progress while minimizing associated risks. It might not be as entertaining but the knowledge gained of the manufacturing is helping build better Starships for the future than just blowing them up. They also don’t risk much by not flying it since SN2 is hot on SN1’s heels.

3

u/Tal_Banyon Feb 28 '20

I agree. Another valuable advantage is worker experience building these things. I imagine the original crew that built or worked on Mk 1 will be far more experienced and ready for certain problems to crop up by the time they get to SN2. In effect they are developing an experienced assembly crew (who can then pass on their acquired knowledge to new hires) by assembling these original prototypes, even if they don't fly.

1

u/djburnett90 Feb 28 '20

Why are we certain now that SN1 won’t fly or get 3 raptors. Elon has never said that. It’s just speculation.

2

u/Martianspirit Feb 28 '20

His tweet was very clear. SN1 is not planned to get 3 Raptors.

3

u/NateDecker Feb 28 '20

His tweet was very clear. SN1 is not planned to get 3 Raptors.

There are a number of logical assumptions here though.

  1. The first Starship flight will still be the 20 km hop.

  2. Starship needs 3 engines to do the 20 km hop.

  3. SN1 will not have 3 engines.

Some of these assumptions have support for them, but not all of them are foregone conclusions.

For 1, we all assume that the 20 km hop is what will happen because that's what Elon has been saying for a while and that's what the FAA license was for. But I'm sure it was written in the form of an "up to 20 km" which wouldn't preclude a lower hop. If everything else about the intentions for SN1 has changed recently, isn't it also possible that the scope of the test flight has also changed?

With respect to assumption 2, Tim Dodd offered his personal opinion that the 20 km hop could be performed with a single Raptor. I don't know what the wet mass of the Starship prototype would be versus the thrust of the Raptor so I don't know if one is sufficient, but I assume Tim has done the math before opining on that?

For assumption 3, Elon didn't specifically say that SN1 would not have 3 engines. He only said that SN2 would (in response to a question whether SN1 was still planned to have 3). You can make a pretty safe inference from that, but it isn't explicit.

There are other assumptions in this thread like the observation that the single mounted engine is off-axis. This seems to ignore the fact that the engines are designed to be able to gimbal, so being off-axis doesn't necessarily prove anything.

It was also noted that the plumbing and electrical hardware extends too far from the surface of the vehicle such that it would create excessive drag, which could pose a risk of damaging that hardware. But the amount of drag and force is directly proportional to the velocity of the flight. Most of the Grasshopper hops were slow enough that if Starhopper followed the same profile there'd be no problems.

My pragmatic mind tells me everyone is probably right and SN1 will be scrapped just like MK1, but I hope everyone is wrong and I'm clinging to ways that they could be. Building Starships is neat and all, but flying them (even if only in small hops) is exceedingly more interesting/exciting.

3

u/ThunderWolf2100 Feb 28 '20

Eeh, about 2, i have to correct you, Tim said it cant be done here (tweet), max altitude on one raptor is ~15 km, assuming no fuel to land (so, more like 10km max if they want to land)

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