Rocket general questions 1

[rb1957]

From today's launch (nice launch, not so nice flight) of SpaceX ...
1) what gas are they venting ? can't think they've venting methane
2) how do they control pressure in the tanks ? do they have a bladder/balloon where they can add/remove gas/liquid (N2 ?)
3) they made a point of filling the header tanks (which would not be used) ... so they intended to dump a tank (small though it may be) full of methane into the Pacific ??
4) when they chill the plumbing and such before loading fuel, I assume they're only passing N2 through the system, and it doesn't hang around long (as it did when they did the cryo testing)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[rb1957]

be fair ... he's played along with FAA licensing his launch, he's had accident investigations in the past. This is "just" another investigation ... which is something he'd do himself, to fix the problem.


"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[WKTaylor]

Falcon 9, Falcon-Heavy flight mishap investigations from launch pads designed for safety, re-usability and no-where-near local populations. In these cases, launch/flight analysis investigation anomalies involve ONLY the launch vehicle/payload.

In Musk's case... it might be wise to remember the following...

"Success is a lousy teacher. It seduces smart people into thinking they can't lose." --Bill Gates, Microsoft Corp. co-founder, philanthropist



Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[rb1957]

is that an example of "the blind leading the blind" ?

why would anyone (particularly an engineer) like that Musk's reaction to the first launch would be "damnit, let's do it again (without any investigation)"

He wants to get the rocket to complete the launch (more than most people). He knows and has demonstrated that his team knows and that he understands his team that the reason for the "unscheduled rapid disassembly" was not the desired outcome and will learn as much as they (and NASA and FAA) can about what caused it (as in any aviation accident) and how to stop it happening again.

But, please, ... venting gases anyone ??

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[WKTaylor]

RB... I surrender... This is my last posting here...

The Military and NACA/NASA did early test-learn-test-learn-test-learn- on the first IRBM/ICBM missiles... and wound-up with protocol and insight to design Saturn V... which never had a true failure.

OK... so WHY would SpaceX launch Starship from a fixed platform over concrete... without a suitable flame trench and water suppression [water scarce?]... so close to a populated area? OH yes... and lets skip the static full duration firing tests... and just learn-from-tests about the launch pad/area in 'real-time'.

I'm pretty sure that Musk wishes that the surrounding homes/community would just be condemned by Texas... and the land turned-over to SpaceX... That'll take care of the problem!!!

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[GregLocock]

"so WHY would SpaceX launch Starship from a fixed platform over concrete... without a suitable flame trench and water suppression"

I have seen a Musk fanboi claiming that it was because any launch from another planet would be from an unprepared site. Hmm.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[rb1957]

will, "and wound-up with protocol and insight to design Saturn V... which never had a true failure" ... really ? except for the first one, eh ? but yes, NASA were laerning things, just as SpaceX is learning things, because they're choosing to do things differently ... prioritising other aspects of the design. I'm no "Musk fanboi", as I've previously posted I thought landing a rocket was farcical ... and the first couple of attempts supported this. But he persevered and now 1) has a system with a launch cadence NASA can't dream of, and 2) is the trailblaser for all the "johnny-come-lately"s who are also landing rockets.

I'm not supporting his decision about the landing pad etc (always wondered about the fuel farm being so close to the launch site). I have no doubt that he'll repair the launch site and we'll be seeing SpaceX rockets launching there in the future.

As for the surrounding houses ... I wonder how Cape Canaveral was set up ... maybe by the US Government buying out property owners ?? and yes, I'm sure he wishes that that PITA would just go away ... but he's no different to anyone else.

but, please, anyone ... venting gases ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[rb1957]

final word (I hope but doubt) about the launch pad concrete ... some engineer decided what they had was at least "adequate" given some modelling of the launch pressures.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[WKTaylor]

"There is a name for those who suppose that doing the same thing will produce different results. That name is ‘Idiot’.” -Albert Einstein

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[3DDave]

Becker traced the original back to Rita Mae Brown, the mystery novelist. In her 1983 book "Sudden Death," she attributes the quote to a fictional "Jane Fulton," writing, "Unfortunately, Susan didn’t remember what Jane Fulton once said. 'Insanity is doing the same thing over and over again, but expecting different results.'"

 

[rb1957]

ok, now it's my turn to surrender ...

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[WKTaylor]

RB... question to You...?


I went thru all Saturn V launches I'm aware of... and there were NO launch failures... a few serious problems, heck-Yes... catastrophic failures, NO.

I cannot count the Apollo 1 CSM interior fire... during dress rehearsal... a launch failure.

Of course, The Space Shuttle program was a completely different 'hot mess'...

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[rb1957]

without intending to be callous about it ... NASA has killed more people than SpaceX. Rocketry is a hard business and lessons are learnt painfully.

Should we only use the design formulae that NASA learnt ? Is it wrong for SpaceX to try and develop new solutions, that allow us to do amazing new things.

I'm not saying SpaceX is perfect, but they are trying to do new things and they have succeeded (c'mon, even the most grudging critic must see that).
Have they made some bad decisions ? sure, the pad design is being revisited. Sure, some people will say "told you so", and they'd be right.
But some engineer and SpaceX management thought what they were doing had at least a chance of working, or of working with an acceptable amount of rework.
Ok, they've learnt and are doing a redesign. Ok, you can say "it was obvious (given the power of the rocket)" ... I contend that others thought it had a shot, based on some analysis and not on Elon saying "make it so" (or at least I hope not).

But seriously guys, does no one know what gases are venting ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[WKTaylor]

Up-to now, SpaceX has Launched from NASA/DoD launch-sites where superior launch services were established... Duhhh... including flame trenches and water suppression, widely spaced support facilities, etc.

I don't think SpaceX even launched any of the Falcon series from Boca Chica TX... to establish lessons-learned.

Also... let us not forget that NASA accepted SpaceX's moon lander bid 16 April 2021... after the long/short bidding process during the Trump administration. Hmmmmmm.

Also... On the aspect of man-rated launchers.
NASA/DoD has learned hard/painful lesson from all all aspects of space flight. The 'race to the moon' in the 1960s had really smart seasoned staff pressing forward at the speed-of-heat to meet 1969-man-on-the-moon challenges... and HAD to take steps backward after catastrophes.

For SpaceX... NASA/FAA MANDATED a significant level of safety during launch-fight-stay-duration and re-entry... systems and testing... to ensure highest probability of human survival to-from-earth orbit. SpaceX met that challenge and... also... the 'hat-trick' technology of landing boosters for re-use. I wonder how this program would have 'worked-out' if feet hadn't been put to the fire for safety?

Going back to Boca Chica... Every element of that launch site... and the Starship Program... looks like a throw-back to the 1950's... NOT a smart/savvy extension of the Falcon 1/9/heavy... lessons learned.

Like I said prior... in the interests of progress, expect Texas to condemn/buy-out [at ~10-Cents on the dollar] the surrounding 10-to-20-+ miles-radius... homes and villages/communities... possibly to the Mexican Border. That will solve the problem of locals whining about launch damage and eco-system destruction and all the other disruptions that SpaceX has brought to this area. Besides "it will mostly affect Hispanics who could move anywhere and live just as cheaply". YES I just said that.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[btrueblood]

"Should we only use the design formulae that NASA learnt ? Is it wrong for SpaceX to try and develop new solutions, that allow us to do amazing new things."

Of course not...but one should proceed with caution when exploring new territory, especially with regard to passerby and surrounding communities. And not ignore the results from your own prior tests - engine out failures in static firings being ignored is a problem with management hubris, much like NASA launching the shuttle boosters in low temperatures.

What gases are venting? Well, it's either oxygen or methane...there would be little to no liquid nitrogen left aboard after launch, no need for it once the rockets are lit. There may be some helium tanks aboard for pressurizing attitude control thrusters, but that is unlikely to create huge visible condensation clouds if it was venting. My guess is it's LOX venting, since the plume(s) does/did not catch fire. Whatever was venting was doing so in fairly voluminous quantities for a long period of time, and led to the engines getting starved of propellant (low velocity and altitude) well before the expected separation point, Manley points it out in his video (I thought)? Seems like the same debris impacts that knocked out engines at launch may also have poked some holes in the tank(s)? Or possibly the engine out failures resulted in enough torque on the missile to strain and rupture the tank walls at some point (unlikely, they should have been stressed for that). I assume the FAA will be conducting a failure investigation, and more details may become available as time goes by.

I have to agree with Wil, and I expect the decisions made for Boca Chica were as much about cost cutting and schedule acceleration as they were about anything else. The idea of using the booster (not the starship, though even that vehicle's weight and size make it iffy) for landings and ascents from the moon or Mars is a bit crazy, why drag all that dead weight along. Maybe it is possible, but will need to be proven. The Mars and lunar lander engines had a lot of design work in plume analysis to reduce scour of the (then unknown but presumed very soft) lunar/Martian soils.

 

[rb1957]

ok, back to the topic.

For some YT discussion I've had, I think they vent O2 (still a small flame risk ?) but the fuel vent is recovered (and not vent to atmosphere).

Still interested in how they pressurise the tanks (well, control the pressure in the tanks) and how do they separate the N2 used to chill the tank and plumbing) from the O2 (or fuel) ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[btrueblood]

Somewhere I read a post or video (more Scott Manley?) that claims the venting seen around the time the vehicle goes into its death spiral, and continues for some 40-50 seconds until it explodes...WAS the rupturing of the fuel and oxidizer tanks by the flight safety abort system. The claim is that the tank pressurization took that long to decay until the tanks lost enough structural rigidity to fully collapse.

 

[rb1957]

yeah, I wasn't meaning about the specific SpaceX launch but rockets in general.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[btrueblood]

Fuel venting is an issue only for cryogenics; they vented the shuttle (H2) prior to launch to a flare tower near the pad, then afterwards yes the fuel "vents" to the turbopump inlet. I would assume similar happens for methane...but SpaceX does not publish a lot of stuff. Shuttle and SLS tanks get helium pressurization, again dunno SpaceX. Filling lox tanks is done by chilling with LN2 first. LN2 eventually boils off, as it boils at lower temp than LOX it leaves the lox behind. Pressure is controlled by venting regulator spilling overboard, I think we see that on SLS, Shuttle, and possibly starship launches - essentially residual LN2 boiling off?

 

[rb1957]

yes, thx ! yes RT liquid fuels don't need a vent (though there probably is some off-gassing). And yes, the clouds of vented gas are not fuel vapour (as obviously not !). So fuel vapours (like on SpaceX) are AIUI recycled through the quick disconnect.

ok, but what happens to the LN2 (I assume) used to chill the tank and plumbing or do they chill with LO2 ? But you wouldn't chill the fuel tank with LO2 !!

And how do they control the pressure in the tanks ? I mean, I see them filling these vast tanks (I imagine they fill from the bottom ?) Is the tank prefilled with LN2 ? Is there no mixing ?? (because the fuel is heavier than the LN2 ?)

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[Compositepro]

Rb1957 it is unclear what venting that you are referring to. The Raptor engines have a second combustion chamber to drive the turbo pumps for the main engine. The exhaust from this may be what you are referring to.

https://youtu.be/LbH1ZDImaI8