SpaceX (general discussion)

Something to keep in mind is that if I've read discussions correctly, this Big F____ Grasshopper is not going to be testing aerodynamics or re-entry; just in-flight Raptor engine and landing control performance. A full scale Starship is likely to be what tests re-entry, etc.
 
Dragon029 said:
just in-flight Raptor engine and landing control performance.

Sure, but it still looks *flimsy.* Just sitting on the pad and running up its engines the nosecone will be subjected to some fair turbulence, and these sheets of foil look like they'll fly off like corrugated tin roofing in a TV weathermans hurricane broadcast.
 
Some more updates from Mr Musk. Sounds like he’s building a vehicle straight out of fifties sci-fi to me. Also that I believe the original Atlas rocket was pretty flimsy too, and he has drawn a general comparison with it.

Starship will look like liquid silver

https://twitter.com/elonmusk/status/1077346382359322625

https://twitter.com/elonmusk/status/1077353613997920257

Leeward side needs nothing, windward side will be activity cooled with residual (cryo) liquid methane, so will appear liquid silver even on hot side
 
Musk teases new details about redesigned next-generation launch system

SpaceX Chief Executive Elon Musk says a redesigned test vehicle for the company’s next-generation reusable launch system could be ready for initial flights early next year.

In a tweet early Dec. 24, Musk posted a photo of two parts of that initial test article, a conical section next to a cylindrical unit with landing legs. “Stainless Steel Starship,” he wrote.
 
Orionblamblam said:
Sure, but it still looks *flimsy.* Just sitting on the pad and running up its engines the nosecone will be subjected to some fair turbulence, and these sheets of foil look like they'll fly off like corrugated tin roofing in a TV weathermans hurricane broadcast.

I'm just left wondering about production facilities and methods used here. Doesn't seem to conform to any kinds of best practices of spacecraft construction I've inferred from seeing other stuff built even at SpaceX (clean rooms, exacting tolerances, bespoke tooling, bunch of people with checklists watching over everyone's shoulder). A shoestring space elevator next ... not that I'm intent on picking on Mr Musk based on a few pictures alone but this sure does seem extra weird. Got my attention, tho.
 
UpForce said:
I'm just left wondering about production facilities and methods used here. Doesn't seem to conform to any kinds of best practices of spacecraft construction I've inferred from seeing other stuff built even at SpaceX (clean rooms, exacting tolerances, bespoke tooling, bunch of people with checklists watching over everyone's shoulder). A shoestring space elevator next ... not that I'm intent on picking on Mr Musk based on a few pictures alone but this sure does seem extra weird. Got my attention, tho.
Well it's not as if they're building a spacecraft; it's essentially just an engine test stand (albeit one that flies at low airspeeds and low atmospheric altitudes).

I think we can safely assume that SpaceX know how to build rockets.
 
Dragon029 said:
UpForce said:
I'm just left wondering about production facilities and methods used here. Doesn't seem to conform to any kinds of best practices of spacecraft construction I've inferred from seeing other stuff built even at SpaceX (clean rooms, exacting tolerances, bespoke tooling, bunch of people with checklists watching over everyone's shoulder). A shoestring space elevator next ... not that I'm intent on picking on Mr Musk based on a few pictures alone but this sure does seem extra weird. Got my attention, tho.
Well it's not as if they're building a spacecraft; it's essentially just an engine test stand (albeit one that flies at low airspeeds and low atmospheric altitudes).

I think we can safely assume that SpaceX know how to build rockets.
Hmm.... Looks like a very agile design method with a dedicated test article. That's why they move fast. For some reason, they need to test something basic and critical to he overall architecture, now matter what. These lessons, once learnt, will feed and iterate the entire engineering. Teamwork is also part of the challenge. And learning by doing on such huge scales helps refine the forthcoming systems. So in a way, yes it is odd-looking, but it is not the primary intent.

A.
 
Given that th ere-entry system is totally new, it would make sense to have a representative prototype built and tested using well known technologies (1960/70's tech). That will feed their model with reference point while still validating/testing the new re-entry/aero/dyn balance etc...
 
UpForce said:
Orionblamblam said:
Sure, but it still looks *flimsy.* Just sitting on the pad and running up its engines the nosecone will be subjected to some fair turbulence, and these sheets of foil look like they'll fly off like corrugated tin roofing in a TV weathermans hurricane broadcast.

I'm just left wondering about production facilities and methods used here. Doesn't seem to conform to any kinds of best practices of spacecraft construction I've inferred from seeing other stuff built even at SpaceX (clean rooms, exacting tolerances, bespoke tooling, bunch of people with checklists watching over everyone's shoulder). A shoestring space elevator next ... not that I'm intent on picking on Mr Musk based on a few pictures alone but this sure does seem extra weird. Got my attention, tho.

You don't need clean room standards if you're just building aerodynamic, minimal load-carrying, fairings for a grasshopper-type vehicle. Plus it's not composite so the need for clean-room standards is reduced (if not eliminated).
 
[quote author=lots of forum members]Subject wonderfully clarified[/quote]

Hey, thanks for the explanations ... and a belated (and thread-wise misplaced) "Happy Holidays"!
 
More Mr Musk.

Eric Ralph said:
How about the chances that Starship reaches orbit in 2020?
Elon Musk said:
Probability at 60% & rising rapidly due to new architecture
https://twitter.com/13ericralph31/status/1078177567532707840
https://twitter.com/elonmusk/status/1078180361346068480

K10 said:
Any chance of new superior alloys? (Exciting)
Elon Musk said:
https://twitter.com/Kristennetten/status/1078182659052863488
https://twitter.com/elonmusk/status/1078182922643861504

Walter MacVane said:
What was the trigger for the latest redesign?
Elon Musk said:
Time. Although it also turned out to be dramatically better.
https://twitter.com/EcoHeliGuy/status/1078185404077985792
https://twitter.com/elonmusk/status/1078185691475922944

Sean Bragg said:
How did switching the design so late lead to a quicker production?
Elon Musk said:
I will provide a detailed explanation in March/April
https://twitter.com/SeanABragg/status/1078186988182822913
https://twitter.com/elonmusk/status/1078187280563560448
 
SpaceX’s Elon Musk: odds of Starship reaching orbit by 2020 are “rising rapidly”

Let there be little doubt – I am still immensely skeptical of this radical redesign and the implausible logistics of conducting said redesign at the last second while somehow maintaining the test schedule, let alone expediting it by 6-9 months. Despite the fact that Musk does seem to have a compellingly rational answer to every question thus far asked, he was no less convincing in mid-2016 when he stated with contagious conviction that Tesla’s Fremont factory would be an almost 100%-automated “alien dreadnought” as early as 2018. There is, of course, nothing wrong per se with being wrong, although taking 24 months and several hundred million dollars to realize as much can be downright fatal or at least a major health risk for any given company that faces such a challenge, as was the case with Tesla.
 
Local law enforcement cracking down on gawkers it seems.

https://twitter.com/austinbarnard45/status/1078794581733502977?s=21
 
This thing is being constructed at a phenomenal rate.

New pictures from the Boca Chica Facegroup page:

https://www.facebook.com/groups/1541938906124567/permalink/2210876259230825/
 
Photoshop preview of whats to come using pics from; https://twitter.com/austinbarnard45/status/1078794581733502977
 

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It seems that Rocket building is new Goldrush

special for town of Boca Chica
since SpaceX building there Launch complex and start build this Testmodel
the Village is overrun by Tourist who bring Money

North of Boca Chica lies a bay with good overview for future launches
guess what, yes there building now Hotels and Viewpoints for Tourist...

Rocket Summer is coming

source
http://forum.nasaspaceflight.com/index.php?topic=47001.0
 
Base is now standing on its own legs off the concrete structure.

Now what looks like a shiny ‘middle’ section is being constructed on the concrete base.

The nosecone was looking like it was having its gaps filled in & now the lower parts look shiny.

All info via NSF.
 
ICYMI in Boca Chica Texas: #GrasshopperII was lifted off her weld stand last night. Replaced this morning with a fresh mystery. #FlyBocaChica #SpaceTeX : BocaChicaGal

https://twitter.com/cowboydanpaasch/status/1079769953488777221

Three of these sections have now been stacked one on top of the other.

Base now has three possible engine place holders in a line.
 
The next Falcon Heavy's core booster has arrived at McGregor: https://www.instagram.com/p/BsCLo14nCdy/

Engines appear to be attached:
 

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New picture of the hopper from Maria Pointer at SpaceX Boca Chica Texas Facebook page.
Here's a link:
https://www.facebook.com/photo.php?fbid=2054020257997902&set=pcb.2214103015574816&type=3&theater&ifg=1
 
Flyaway said:
New picture of the hopper from Maria Pointer at SpaceX Boca Chica Texas Facebook page.
Here's a link:
https://www.facebook.com/photo.php?fbid=2054020257997902&set=pcb.2214103015574816&type=3&theater&ifg=1

From that page:

https://www.youtube.com/watch?v=Vgd5uQM6SSg
 
SpaceX’s Starship hopper spotted with trio of dual-bell Raptor engines

Known as deep throttling in rocketry, ensuring stable combustion and thrust at 20% (let alone 40%) throttle is an extraordinarily challenging feat, often subjecting engines to forces that can literally tear non-optimized hardware apart. To achieve such a deep throttle capability without excessively disrupting the engine’s design, SpaceX appears to have potentially sided with less efficient but extremely simple alternative, known as a dual-bell (or dual-expansion) rocket nozzle. A 1999 Rocketdyne paper concisely explained the primary draws of such a nozzle:
 
It appears that the Hopper's legs are also being being covered with panels to turn them into fins as well:

https://twitter.com/austinbarnard45/status/1080971599908691970?s=19

DwBh5S1UcAA0o_i.jpg
 
It's interesting to see SpaceX's approach. It's an iron bird, testing propulsion and software, so it doesn't need to be pretty. I can't imagine one of the traditional suppliers daring to "risk" the perception of not building such a thing in a clean room, in a billion dollar facility, and painting it up all nice and pretty. Or of daring to use something as "radical/risky" as a dual-bell nozzle.
 
From user bocachicagal at the Nasa Space Flight forum; it also appears that the mid-section where the flag is will also sport some holes; there's currently no real idea as to what the holes are for; some say in-flight ventilation (but then why so many and so large?), some say they're just for ventilation during construction (why cut holes in an airframe when you can blow air in through the bottom or top?), some say they're refueling ports (but for a test platform do you need fuel lines that large, and is it not possible to run fuel through the bottom as planned for the final design?), some say they're RCS ports (but there seems to only be 4 ports on one side), some say they're blow-out ports or inspection ports (but again, why do you need 4 of them?), etc.

13zq198.jpg
 
The hopper’s top and middle sections have been fitted together as you can see on the link below.

https://twitter.com/CowboyDanPaasch/status/1081291936777060352

Vertical at
@NASAKennedy
, a #Falcon9 rocket with the
@SpaceX
Crew Dragon capsule. Notice the new crew access arm added to pad 39a #SpaceX
@news6wkmg

Picture on the link below.

https://twitter.com/News6James/status/1081282248773697536
 
https://twitter.com/elonmusk/status/1081573955591258113

https://twitter.com/elonmusk/status/1081576707365064704

https://twitter.com/elonmusk/status/1081572521105707009

https://twitter.com/elonmusk/status/1081575156990894082

https://twitter.com/NASASpaceflight/status/1081578399724916739

https://twitter.com/Mulymule/status/1081586947397697542

https://twitter.com/enn_nafnlaus/status/1081617473462521856

https://twitter.com/Yaru_Sasaki/status/1081662015339417601

https://twitter.com/elonmusk/status/1081662202124296192

More Hopper info plus rendering.
 
Summary:

1: The thing at Boca Chica is 100% confirmed as a flight test vehicle.
2: This is what the hopper will roughly look like when completed:
DwKIR5EWkAAqDuW.jpg

3: The engines currently on the hopper are a blend of Raptor developmental & operational parts. The first hopper engine that'll actually be fired is almost finished assembly in California and will probably fire on a test stand for the first time in February.
4: They plan to perform the first Hopper flight test in 4 weeks (ie right after the engines are fired on a test stand [perhaps the Hopper will be the test stand], although Elon admits that it'll probably be more like 8 weeks due to unforeseen issues that'll inevitably rear their head.
5-9: The hopper most likely won't be as shiny as shown in the above picture, but Starship most probably will.
 
On a minor scale, interesting also that this is what we came around when the first pictures appeared (see post on the 23rd of Dec.)
 
What Scott Manley has to say about it

https://youtu.be/XVgEKBwE2RM

About that Altitude compensating Nozzle
it's a dual-bell nozzle design that allow optimal operation in atmosphere and Vacuum of space
SpaceX is again ahead of competition they manage to intergrade dual-bell nozzle on Raptor combustion chamber

Some technical paper about it
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160008031.pdf
http://psrcentre.org/images/extraimages/1%20214303.pdf
 
Michel Van said:
About that Altitude compensating Nozzle
it's a dual-bell nozzle design that allow optimal operation in atmosphere and Vacuum of space
SpaceX is again ahead of competition they manage to intergrade dual-bell nozzle on Raptor combustion chamber

Looking at the size, having the outer bell vacuum optimized is very unlikely. I think it's a lot more likely that the outer bell is ~50:1 and the inner bell is ~20-15:1. This would mean that at full throttle, the outer bell is fully in use right from sealevel.

Why have the inner bell then?

Because raptor needs to do something that most other rocket engines don't need to do -- throttle down to <20% for multi-engine redundant landing. So the outer bell is designed for operation at full throttle at sea level, while the inner bell is used when landing, at low throttle and at sealevel.
 
Looking at what happen a SpaceX launch site Boca Chica
it remind me of this...
DwKECeBX4AA-5JG.jpg
 

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