totm nov 2023 SpaceX Discussion Thread

[NSEP]

23 minutes ago, DAL59 said:

Woah!  Apparently SpaceX is planning to test the BFR in Texas by next year:

https://www.teslarati.com/spacex-mars-rocket-test-texas-late-2018/

He said earlier on Reddit that the test will be using an empty bfr as an ssto!  Looks like an ssto race between arca and spacex.  

All we can do now is hope it doesn't get pushed back 5 years.

[cubinator]

22 minutes ago, DAL59 said:

Woah!  Apparently SpaceX is planning to test the BFR in Texas by next year:

https://www.teslarati.com/spacex-mars-rocket-test-texas-late-2018/

 

That article says that the facility will be ready for vehicle tests in that timeframe, not that BFR will be ready to be tested. Personally I'm skeptical that the first BFR can be built that quickly. Could someone who knows a bit more than me about how long it takes to build a rocket chime in?

[KSK]

I think the last paragraph of that article is important to bear in mind - and props to them for adding it:

"Full disclosure: As Shotwell did not specify which vehicle or vehicles could be expected to begin testing in 2018/2019, it is possible that Falcon 9, not BFR, was the statement’s target. This article should be taken with a grain of salt, as it is educated speculation based upon public information from SpaceX executives and Texas contractors. Teslarati reached out to SpaceX for additional information, but the company was unable to comment further on Shotwell’s presentation at the moment."

Good to see that SpaceX has accumulated enough Funds to upgrade the Tracking Station though.  And, despite the slightly speculative article, it is exciting to see development of the Boca Chica site ramping up! I wouldn't expect 'vehicle tests' to be orbital flights though, whether or not they happen at the end of 2018 (*checks magic 8-ball. Hmmm magic 8-ball says 'check Elon time') - more likely to be Grasshopper style tests in my opinion, although that's pure navel gazing.

And with all due respect to Arca, I'll take them a bit more seriously if and when they release some progress updates beyond their 'it's coming soon - honest' articles. Some pictures of actual vehicle components would be nice, maybe even footage of an engine test? I'm thinking Blue Origin levels of news rather than SpaceX but something would be nice. Besides SSTO is easy - plenty of booster stages have been able to make orbit, at least in principle. SSTO with any sort of payload fraction is the hard part.

[IncongruousGoat]

Apparently the reason for the static fire having been delayed is a glitch with one of the hold-down clamps at LC-39A.

https://www.teslarati.com/spacex-falcon-heavy-first-static-fire-test-cape-canaveral-scrubbed/

[KSK]

15 minutes ago, IncongruousGoat said:

Apparently the reason for the static fire having been delayed is a glitch with one of the hold-down clamps at LC-39A.

https://www.teslarati.com/spacex-falcon-heavy-first-static-fire-test-cape-canaveral-scrubbed/

Ahhh, that would explain it. My previous jests notwithstanding, they don't want any problems trying to hold down 5 million pounds of thrust. I rather liked the comment on BFR by 2018 being a 'truly Muskian deadline' too.  

[sevenperforce]

17 minutes ago, IncongruousGoat said:

Apparently the reason for the static fire having been delayed is a glitch with one of the hold-down clamps at LC-39A.

https://www.teslarati.com/spacex-falcon-heavy-first-static-fire-test-cape-canaveral-scrubbed/

And as Elon pointed out, the hold-down clamps are a touch important for the static fire. Otherwise you end up launching early.

Re BFR: I see no indication at all of SSTO tests. The only reason for BFR speculation was the size of one of the new cranes there.

[PB666]

2 minutes ago, KSK said:

Ahhh, that would explain it. My previous jests notwithstanding, they don't want any problems trying to hold down 5 million pounds of thrust. I rather liked the comment on BFR by 2018 being a 'truly Muskian deadline' too.  

Yes but at what stage, a shell with some standard rocket components. I guess the appearance of progress at times is just as important as progress. He also wants to earn some money this year I suspect so he will need to devote resources to tending contracts.

[sevenperforce]

Even single-Raptor Grasshopper-style cradle landing tests would qualify as progress toward BFR. 

[sevenperforce]

In order to perform cradle landings (which I think are a Musk design element which may in fact survive, given the enormity of strain on landing legs for a SHLV first stage), the BFR test prototype will need better translation authority in the final moments of landing. You cannot use gimbal for reliable translational control on landing, not when required accuracy is a matter of inches. This means RCS thruster banks on both the top and bottom of a test vehicle, so the main engines will likely be gimbal-locked during final landing approach and use only thrusters for attitude control and translation. You don't want a repeat of the Bulgariasat incident.

The thrusters are intended to be hot methane+gox engines fed from the main ullage tanks, so that integrated design will need to be completed before full-up testing can commence. I anticipate the same fixed-leg approach as the Grasshopper, but with translation tests to maneuver those legs themselves into a cradle. 

[DAL59]

18 minutes ago, sevenperforce said:

Even single-Raptor Grasshopper-style cradle landing tests would qualify as progress toward BFR. 

He said he would do that on reddit.  

Also, page 200!

[CatastrophicFailure]

36 minutes ago, sevenperforce said:

And as Elon pointed out, the hold-down clamps are a touch important for the static fire. Otherwise you end up launching early.

Thermal Curtain Failure narrowly averted, they’d Best check the building for a mishevious spherical robot...  someone please get that.... 

 

In regards to testing in less than a year, do they even have the facilities anywhere to actually build the thing? The Big F Rocket is, well, big... can their Falcon factory handle it?

[DAL59]

4 minutes ago, CatastrophicFailure said:

Thermal Curtain Failure narrowly averted, they’d Best check the building for a mishevious spherical robot...  someone please get that.... 

 

In regards to testing in less than a year, do they even have the facilities anywhere to actually build the thing? The Big F Rocket is, well, big... can their Falcon factory handle it?

Yes.  The size of the ITS was reduced to the current BFR so it could fit in the existing factory.  

[sevenperforce]

12 minutes ago, CatastrophicFailure said:

Thermal Curtain Failure narrowly averted, they’d Best check the building for a mishevious spherical robot...  someone please get that.... 

 

In regards to testing in less than a year, do they even have the facilities anywhere to actually build the thing? The Big F Rocket is, well, big... can their Falcon factory handle it?

SPACE CAAAAAMP

I believe Elon stated their existing facilities can narrowly handle 9m tooling.

[magnemoe]

57 minutes ago, sevenperforce said:

And as Elon pointed out, the hold-down clamps are a touch important for the static fire. Otherwise you end up launching early.

Re BFR: I see no indication at all of SSTO tests. The only reason for BFR speculation was the size of one of the new cranes there.

Or you launch one booster or core + one booster, anybody who have played KSP know this does not end well. 

41 minutes ago, sevenperforce said:

In order to perform cradle landings (which I think are a Musk design element which may in fact survive, given the enormity of strain on landing legs for a SHLV first stage), the BFR test prototype will need better translation authority in the final moments of landing. You cannot use gimbal for reliable translational control on landing, not when required accuracy is a matter of inches. This means RCS thruster banks on both the top and bottom of a test vehicle, so the main engines will likely be gimbal-locked during final landing approach and use only thrusters for attitude control and translation. You don't want a repeat of the Bulgariasat incident.

The thrusters are intended to be hot methane+gox engines fed from the main ullage tanks, so that integrated design will need to be completed before full-up testing can commence. I anticipate the same fixed-leg approach as the Grasshopper, but with translation tests to maneuver those legs themselves into a cradle. 

Or an virtual cradle as in gps and painted target grind on pad. 
Note that any fail here will cost an launch pad. 
Crashing an BFR will be as bad as the static fire test fail a bit dependent on fail mode, worst case is bird go dead during final braking and would be way worse. 
Yes you can build against it but it would increase cost. 

[PB666]

37 minutes ago, CatastrophicFailure said:

Thermal Curtain Failure narrowly averted, they’d Best check the building for a mishevious spherical robot...  someone please get that.... 

 

In regards to testing in less than a year, do they even have the facilities anywhere to actually build the thing? The Big F Rocket is, well, big... can their Falcon factory handle it?

Boca chica is not being used, if you don't mind sea-gull excrement and sand crabs.

18 minutes ago, magnemoe said:

Crashing an BFR will be as bad as the static fire test fail a bit dependent on fail mode, worst case is bird go dead during final braking and would be way worse. Yes you can build against it but it would increase cost. 

Just make a cheapo landing site that is made say of soft sand. (Boca chica for instance) you could theoretically just land in the surf at say 4 feet of water. The way I see it is that these types of failures are built into the system. So for instance the break burn is at a slight angle, so that if it doesn't ignite then it crashes in simple terrain. Aside from that completely, they expect failure so the cost is built into the system. Musk if anything is very tolerant of errors, as long as they launch improvements.

Having said that, I don't see full model testing this year.

[PakledHostage]

1 hour ago, KSK said:

Ahhh, that would explain it. My previous jests notwithstanding, they don't want any problems trying to hold down 5 million pounds of thrust.

So about 15% less than that crappy little Space Shuttle that everyone hates so much... Just sayin'.

[GoSlash27]

Wow, thread- jack much?

 This thread is about SpaceX, not the shuttle.

Best,
-Slashy

[PakledHostage]

1 hour ago, GoSlash27 said:

Wow, thread- jack much?

 This thread is about SpaceX, not the shuttle.

Not "thread-jacking" (if that's a thing). Just keeping Falcon Heavy's size in perspective. And if you look back through this thread's 200 odd pages, you'll see plenty of other mentions of the Shuttle in here.

But thanks for starting a new thread specifically about the shuttle...

[GoSlash27]

5 minutes ago, PakledHostage said:

Not "thread-jacking" (if that's a thing). Just keeping Falcon Heavy's size in perspective. And if you look back through this thread's 200 odd pages, you'll see plenty of other mentions of the Shuttle in here.

 Well, the Shuttle's thrust was in line with the Falcon Heavy. It's payload , OTOH, is not.

8 minutes ago, PakledHostage said:

But thanks for starting a new thread specifically about the shuttle...

 You're welcome I look forward to hearing your thoughts on the subject over there.

Best,
-Slashy

[sevenperforce]

Was Energia ever test-fired?

[_Augustus_]

42 minutes ago, sevenperforce said:

Was Energia ever test-fired?

Energia flew twice.

[sevenperforce]

6 minutes ago, _Augustus_ said:

Energia flew twice.

But was it test-fired before flying? That was the question.

Because a test-fire is far more energetic, from a pad standpoint, than a launch.

If Energia was never test-fired, tomorrow's test may be the most energetic intentional rocket event in history.

[tater]

 

[Nefrums]

12 hours ago, KSK said:

Ahhh, that would explain it. My previous jests notwithstanding, they don't want any problems trying to hold down 5 million pounds of thrust.

If the launch clamps are able to hold the rocket up before the engins start, they should have no problem holding it down after ignition.

With a twr of 1,5 the force the launch clamps have to hold down is only half of what the have to hold up before ignition. 

[KSK]

2 minutes ago, Nefrums said:

If the launch clamps are able to hold the rocket up before the engins start, they should have no problem holding it down after ignition.

With a twr of 1,5 the force the launch clamps have to hold down is only half of what the have to hold up before ignition. 

Well I would think they'd also have to cope with a pretty big dynamic load at engine start, so I wouldn't think it's a case of simply scaling up by 1.5. But yeah, as @PakledHostage pointed out, FH is hardly the most powerful launch vehicle ever built, so its not like sufficiently strong hold-downs are a new thing. They're still not something you want to take any chances with though.