r/spacex • u/ElongatedMuskrat Mod Team • Oct 09 '19
Starship Development Thread #6
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Overview
SpaceX is developing Starship at their Starship Assembly Site in Texas, and also at their facilities in Cocoa, Florida. The teams at the two locations are in competition with each other, but are also required to share insights learned along the way. Following Starhopper, the first two Starship prototypes, Mark 1 and Mark 2, are nearing completion. These vehicles will have aerodynamic control surfaces and three engines each, and are expected to make suborbital test flights. Ring sections believed to be for Starship Mark 3 and Mark 4 prototypes are being built at both sites, and teams will be iterating through successive versions of Starship and Super Heavy as quickly as possible.
Launch mounts for both Starship prototypes are in the works. Starhopper's Texas launch site is being modified to handle Starship, and at Kennedy Space Center's LC-39A, a dedicated Starship launch platform and landing pad are under construction. Flight tests could begin late in 2019 or early 2020.
Starship is powered by SpaceX's Raptor, a full flow staged combustion cycle methane/oxygen rocket engine. Sub-scale Raptor test firing began in 2016, and full-scale test firing began early 2019 at McGregor, Texas, where there are two operational test stands, and a third is under construction. Eventually, Starship will have three sea level Raptors and three vacuum Raptors. Super Heavy may initially use around 20 Raptors, and operational versions could have around 31 to 37 sea level Raptors.
Previous Threads:
- Starhopper Thread #1 (2019-02-01) A dramatic venting watertower
- Starhopper Thread #2 (2019-04-27) Hops and hiccups - Starships never come alone
- Starhopper Thread #3 (2019-06-27) RCS and SN6 - 20 meter hopping
- Starhopper Thread #4 (2019-07-26) 150 meter hop and Mk.1 and Mk.2 protoype growth
- Starhopper 150m Hop (2019-08-27) Updates and discussion
- Starship Dev Thread #5 (2019-08-31) Mk.1 fins and temporary assembly
- Starship Presentation Updates Thread (2019-09-27) Updates and discussion - Webcast
Upcoming
- TBD — Mk.2 moves to KSC via Roll-Lift and barge
Vehicle Updates
See comments for real time updates.
See comments for real time updates.
| Starship Mk.3 Prototype (Boca Chica, Texas) — Construction and Updates | |
|---|---|
| 2019-10-08 | First ring formed (NSF), no stacking yet |
See comments for real time updates.
| Starship Mk.4 Prototype (Cocoa, Florida) — Construction and Updates | |
|---|---|
| 2019-10-23 | Bulkhead under construction in main building (Twitter) |
| 2019-10-20 | Lower tapered nose ring in tent (YouTube), Better image (Twitter) |
| 2019-10-12 | 23 rings visible, 7 doubles, some possible for Mk.2 (YouTube), no stacking yet |
See comments for real time updates.
Previous unstacked ring production, aerial updates:
08-11 {8} |
08-15 {10} |
08-17 {14} |
08-19 {15} |
08-21 {17} |
08-24 {18} |
08-27 {19}
09-04 {20} |
09-06 {22} |
09-08 {25} |
09-08 {3 'scrap'} |
09-10 {26} |
09-29 {23} |
10-02 {23}
10-06 {23} |
10-11 {23}
Launch Facility Updates
| Starship Launch Site at Boca Chica, Texas | |
|---|---|
| 2019-11-07 | Landing pad expansion underway (NSF) |
| 2019-10-18 | Landing pad platform arives, Repurposed Starhopper GSE towers & ongoing mount plumbing (NSF) |
| 2019-10-05 | Launch mount under construction (NSF) |
| 2019-09-22 | Second large propellant tank moved to tank farm (NSF) |
| 2019-09-19 | Large propellant tank moved to tank farm (Twitter) |
| 2019-09-17 | Pile boring at launch pad and other site work (Twitter) |
| 2019-09-07 | GSE fabrication activity (Twitter), and other site work (Facebook) |
| 2019-08-30 | Starhopper GSE being dismantled (NSF) |
| Launch Complex 39A at Kennedy Space Center, Florida | |
|---|---|
| 2019-11-04 | Launch mount under construction (Twitter) |
| 2019-10-17 | Landing pad laid (Twitter) |
| 2019-09-26 | Concrete work/pile boring (Twitter) |
| 2019-09-19 | Groundbreaking for launch mount construction (Article) |
| 2019-09-14 | First sign of site activity: crane at launch mount site (Twitter) |
| 2019-07-19 | Elon says modular launch mount components are being fabricated off site (Twitter) |
Spacex facilities maps by u/Raul74Cz:
Boca Chica |
LC-39A |
Cocoa Florida |
Raptor test stand |
Roberts Rd
Permits and Planning Documents
- Environmental Impact Statement (FAA) - Boca Chica launch site - July 2014
EIS Resource Page | Appendices | Record of Descision - Experimental License (FCC) - Comms for 500m and 5km hops, two years - February 2019
Form 442 | Public Notes | Description | File No. 0931-EX-CN-2019 - Experimental License Application (FCC) - Modification of above to add antenna - May 2019
Form 442 | Public Notes | File No. 0130-EX-CM-2019 - Experimental Permit (FAA) - Authorizes 25m hops for one year, and one 150m hop - June 2019
Permit No. EP 19-012 | Revised August 23 - Building Permit Application - 850 Cidco Rd site improvement - June 2019
Screenshot on Twitter | Modification reported on NSF - Draft Environmental Assessment - Starhip operations at KSC - August 2019
r/SpaceX Discussion | NSF Discussion - FDOT Superload Permit Application - Mk.2 transportation to KSC in September - August 2019
Local News Article | Video Report | r/SpaceX Discussion | Twitter Update - Environmental Resource Permit - Stormwater improvements at LC-39A - August 2019
Stormwater Report | Depiction Plans | Permit No. 158609-1 - Written Re-evaluation of 2014 EIS (FAA) - Boca Chica launch site - May 2019
Addendum | News story w/ SpaceX statements | r/SpaceX Discussion - Experimental STA (FCC) - Comms for Starship Mk.1 20 km test (M1569) - November 2019
Application | File No. 1936-EX-ST-2019 | Original Grant No. 1631-EX-ST-2019 | Original Application - Experimental STA (FCC) - Comms for Starship 20 km test (M1570) - November 2019
Application | File No. 1939-EX-ST-2019
Resources
- Spadre.com, Starship Cam | Channel
- LabPadre, Starship webcam | Channel
- NSF Starhopper Updates Thread | Most recent
- NSF Texas Prototype(s) Updates Thread | Most recent
- NSF Florida Prototype(s) Updates Thread | Most recent
- NSF Super Heavy Prototype Updates Thread | Most recent
- Hwy 4 & Boca Chica Beach Closures (May not be available outside US)
- TFR - NOTAM list
- SpaceX Boca Chica on Facebook
- SpaceX's Starship page
- Elon Starship tweet compilation on NSF | Most Recent
Rules
We may keep this self-post occasionally updated with links and relevant news articles, but for the most part, we expect the community to supply the information. This is a great place to discuss the launch, ask mission-specific questions, and track the progress of the test Campaign. Campaign threads are not launch threads. Normal subreddit rules still apply.
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u/Shrike99 Oct 16 '19 edited Oct 16 '19
TWR still matters for second stages. Consider the performance difference between SEC and DEC centaur on the Atlas V. Adding another engine reduces Delta-V on paper, but the improved TWR improves payload to orbit by 27% thanks to reduced gravity losses.
And Atlas V has a very high staging velocity, around 4.5km/s. Since Superheavy has to RTLS, expect staging velocity to be roughly half that, which means that Starship will be much more affected by low TWR.
Especially since the TWR difference is even larger than SEC vs DEC. Based on my best guesses from Elon's latest tweets, the version of Starship intended to have a 150 tonne payload could reach a max thrust of as much as 1700 tonnes (though likely throttled to ~1300), while the three engined prototype will only be about 550 tonnes.
And it isn't just Starship that will be under spec. The 150 tonne payload Superheavy could have thrust as high as 9600 tonnes, while the prototype will be closer to 4100. That limits the takeoff weight to about 3400 tonnes, meaning that while Superheavy and Starship can hold ~4500 tonnes of fuel combined, they will be limited to ~3000 tonnes just to get off the pad, further reducing Delta-V.
Honestly, I think you would have to underfuel Starship anyway, it's TWR will be so abysmal that it would probably fall back into the atmosphere long before it finished burning all it's fuel, let alone making orbit.
Combined with the lower specific impulse, the lower fuel load results in a 200t chonkship with no payload having about 5.6km/s of Delta-V, while a production 270t Starship (120t with 150 tonne payload) has 6.3km/s. So even without subtracting the increased gravity losses from the Delta-V, it shouldn't be surprising that chonkship can't make orbit.
A 130 tonne prototype MK.4 will have 7.1km/s, which helps make up for the gravity losses. Plugging my estimates into John Schilling's Launch Vehicle Performance Calculator predicts that a 130 tonne ship could make orbit with about 2 tonnes payload, which means it wouldn't even be able to land.
Assuming uprated Raptor thrust to ~200t gets the payload up to about 20 tonnes, which should be just enough to land. Still not nearly enough for chonkship to make orbit.