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SpaceX Reusable Rockets Section / Re: BFS Design Requirements
« Last post by livingjw on Today at 03:08 PM »
But they have 38 engines per BFR/BFS, all of which will be tested. During development, testing will probably include individual engine FOD and RUD containment tests as well. I think it will be done similar to turbine engine development.

John

Do you expect that they will do tests analogous to the blade-out test that is done on commercial turbofans, i.e. intentionally cause a turbopump failure to test the engine controller shutdown response and the containment system? I seem to recall hearing that spacex has already done a "nut ingestion" test.

Yes. They already have shown a containment cover for the engine. Most likely Kevlar or similar. Safe containment and shutdown will probably be part of development. Probability of a malfunctioning engine goes up with the number of engines, and they have a lot of them.

John
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SpaceX is playing their Starlink cards very close. 

Even considering the EM unrealistic schedule factor the Starlink launches should be starting to show up.  But which vehicle, which site, altitude, payload mass etc.

Not much to work with right now, the 100 flights is interesting. 

There commercial launch rate win percentage would be interesting to know.  Hard to see how anyone competes with them on a $ basis.
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I'd also like to know who is the NSF pony-granter.)
QuantumG.

As for grog. this is a grog free zone.

It's all for me Grog, me jolly jolly grog. Its all for me mixed NTO.... cause ai spent my Hydrazine, fighting torque induced spin, so across them stationed orbits I must wander...
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SpaceX Mars / Re: BFR/ITS risk due to composites
« Last post by envy887 on Today at 03:03 PM »
Right now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELV

This is incorrect. COPVs are composite tanks subjected to cryocycles and structural loads and carried through the entire flight. They are used in many vehicles and SpaceX has plenty of experience with them.

Those are aluminum wrapped tanks, they would not scale to BFS propellant tank dimensions. Not applicable.

They are not Al-wrapped, they are Al-lined. The LOX-facing side is CRFP, not Al. SpaceX also said they would line the BFR tanks with invar if necessary, but they don't expect it to be needed.

The construction method for COPVs would not scale, but the COPV experience shows that the material itself is capable of cryocycles, structural loads, and flight with suitable tank construction.

Right now the only vehicle that's taken composite tankage through the whole flight regime to orbit is Rocket Labs Electron ELV

This is incorrect. COPVs are composite tanks subjected to cryocycles and structural loads and carried through the entire flight. They are used in many vehicles and SpaceX has plenty of experience with them.

Irrelevant. COPVs are lined with aluminum. COPVs are orders of magnitude smaller. COPVs are not subject to widely varying environment, since they are immersed in the LOX tank. One major problem with unlined LOX tanks is the energy given off when fibers break under stress. Special matrix material has been used to address this problem. The CH4 tanks are not as much of a problem.

John


The COPV CRFP is unlined on the LOX side.

What do you mean by "widely varying environment"? They go from STP to cryo temps and flight pressures at negative and positive g loads (they float in LOX but sink in GHe). That's the same environments that the main tanks will see, except for entry (which is demonstrated by the interstage, legs and fairings).
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Mods edited my translation, but it is posted in full here:
https://www.facebook.com/groups/spacexgroup/permalink/10156321346131318/
I've posted for educational purposes only and am not selling or paid anything, so I think the translation is fair use.  The Russians can have all the money I make from the translation.
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Advanced Concepts / Re: electric pumped rocket cycle
« Last post by msat on Today at 02:58 PM »
I suspect their ISP figures are quite accurate. Remember, there's not propellant being burned to power the turbine and dumped overboard bypassing the CC. Similarly, practically full pump pressure is being supplied to the CC unlike staged combustion, expander, etc. cycles.

I also vaguely recall reading about thrust chamber pressure. Though that may have been an estimation performed by someone on this forum.
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Bringing this thread back into the current ASDS reality... The reddit user llama_llover posted a picture of JRTI today berthed along the outer harbor berth 46 (just south of the normal SpaceX berth). It is clear JRTI is missing some necessary things... discuss.

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Space Policy Discussion / Re: FY19 NASA Budget Request
« Last post by yg1968 on Today at 02:51 PM »
Seems to me I have heard this song before... or a similar tune, in 2009-10... I panicked then, but I won't panic now... The ebb and flow of support for Science / Exploration will swing with the pendulum of time, and we will see a return to science... Keep Calm and Carry On :D This is just a bit of Scotch Mist...
as for WFIRST, wasn't it a mothballed program to begin with... so worst comes to worst, it will be put back into storage, waiting for better days..
Science, well, there will be some science that will have to be done regardless, so perhaps the private sector can step up to the plate.... just as Cities did after America abandoned the Paris Climate Accord
American / World's capacity for ingenuity is quite large.. Now where is "Radar" O'Reilly when you need him???

Science isn't being cut. There is less priority on climate change but that is about it. The Trump administration tried to cut the same climate change missions last year but it didn't work. Appropriation bills need Democratic support in the Senate (60 votes are required). So Earth science ends up not being cut at all. 
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ISS Section / Re: Expedition 54 Thread
« Last post by centaurinasa on Today at 02:50 PM »
A relatively rare view of the Russian segment...
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Where are the major cost savings coming from on Vulcan?
My guess is that most savings come from the elimination of three launch vehicle families to be replaced by one.  That eliminates three launch pads and a long string of subcontractors.  ULA will need fewer employees (labor is the real cost of these things), but even more importantly the number of subcontractor employees will also plummet.   The company will also probably shed some facilities, such as the sites that currently build legacy Atlas and Delta IV fairings, etc.

 - Ed Kyle
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