Aethon

Blue Origin Thread (merged)

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3 minutes ago, insert_name said:

the RUD occurred before the test could happen

LOL at myself -- yeah, I should have read a few more posts and looked at that video before I asked my question.

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25 minutes ago, Streetwind said:

I've no idea how it can just go off like that. Wouldn't you need at least two or three concurrent faults? Like a short circuit next to a fuel leak?

Basic answer is that you need an ignition source and the proper fuel/oxygen ratio. Vapors do leak during fueling, so normally the protocol is to eliminate all ignition sources.

Watch an airplane refueling and you will see them always electrically ground the airplane and the fueling truck. When you put gas in your car at the station, the signs always say to turn off your engine and no smoking. Refinery workers use brass tools because they don't spark like steel tools do. Etc.

If you can't be sure of eliminating the ignition sources, then you have to go the other way and try to inert the atmosphere. That's why airplanes now have nitrogen inerting systems for their body fuel tanks.

Looks to me like they knew they had an explosive vapor situation, so they were trying to eliminate all ignition sources. Somehow one got past them.

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The only source of ignition in the second stage that I can think of is electrical. But even then... this makes no sense whatsoever, and I can't think of a failure mode that would cause this on the pad.

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Is it possible to ignite to the oxygen vapors coming off the rocket? Or do they disperse too quickly?

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Just now, Motokid600 said:

Is it possible to ignite to the oxygen vapors coming off the rocket? Or do they disperse too quickly?

Oxygen doesn't ignite. Other things ignite in the presence of oxygen. And what you saw in the video was exactly that.

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6 minutes ago, CptRichardson said:

The only source of ignition in the second stage that I can think of is electrical. But even then... this makes no sense whatsoever, and I can't think of a failure mode that would cause this on the pad.

Could they have over pressurized the LOX or Kerosene tanks? 

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Just now, Robotengineer said:

Could they have over pressurized the LOX or Kerosene tanks? 

You wouldn't have the tank-internal ignition.

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3 minutes ago, mikegarrison said:

Oxygen doesn't ignite. Other things ignite in the presence of oxygen. And what you saw in the video was exactly that.

I see. Had to be a spark of some kind, but I refuse to believe there wasn't proper grounding.

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They really should replace that second stage with something. What if you used a Centaur or a Peacekeeper?

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1 minute ago, _Augustus_ said:

They really should replace that second stage with something. What if you used a Centaur or a Peacekeeper?

 

First one wasn't their fault, and this one is too suspicious to pin on them yet. Otherwise, the second stage has been entirely reliable.

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3 minutes ago, _Augustus_ said:

They really should replace that second stage with something. What if you used a Centaur or a Peacekeeper?

Not likely. Second stage is pretty reliable & efficient. As of yet we don't know if 2nd stage was at fault this time (explosion looks like it comes from where the umbilical meets the rocket; could be a short in the power supply causing ignition)

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3 minutes ago, CptRichardson said:

 

First one wasn't their fault, and this one is too suspicious to pin on them yet. Otherwise, the second stage has been entirely reliable.

Neither ULA, nor anyone else, would sabotage it....

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6 minutes ago, CptRichardson said:

You wouldn't have the tank-internal ignition.

If the tank blew and the contents came into contact with exposed electronics, maybe? 

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Pretty obviously the explosion occurred right about where that upper venting was happening. I'm sure they will quickly focus in on some kind of cause in that location.

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25 minutes ago, _Augustus_ said:

They really should replace that second stage with something. What if you used a Centaur or a Peacekeeper?

Centaur? It'S super low thrust. ~10% of thrust of F9 S2. The second stage is really that overpowered because it needs to overcome more gravity losses due to being released lower into the atmosphere to make S1 recovery even possible. Even a DEC Centaur would cause problems, and payload mass fraction wouldn't be too god if the payload weighs 5t and the Centaur 20t. So great idea for geostationary things, really bad idea for low orbit sats/spacecraft.

Also keep in mind how difficult it would be to manage a rocket with multiple propellants at one pad.. doable, but not really an option for SpaceX.

Edited by Kartoffelkuchen

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36 minutes ago, _Augustus_ said:

They really should replace that second stage with something. What if you used a Centaur or a Peacekeeper?

The F9 second stage has been pretty reliable until now, and although the MVac engine has a lot of differences with the stage 1 Merlins, there are some serious economies of scale. 

Centaur and Minotaur are pretty expensive.

 

34 minutes ago, CptRichardson said:

 

First one wasn't their fault, and this one is too suspicious to pin on them yet. Otherwise, the second stage has been entirely reliable.

Regarding the first failure, material and supplier selection is their fault. Cutting corners by going for the cheaper supplier who sells non-aerospace grade parts has a cost.

As for "suspicious", I don't even want to try to figure out what you meant.

Edited by Nibb31

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2 hours ago, Frida Space said:

Mr Musk has spoken... or tweeted: "Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon."

Three years on this forum and I still don't know how to embed tweets.

EDIT: Oh nevermind, apparently it does it automatically.

What's a tweet, you like grab little birds and put them in bed. 

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Does the second stage use deep cryo O2 like the first? Probably, but I would prefer to have someone confirm it either way.

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11 minutes ago, Nibb31 said:

Regarding the first failure, material and supplier selection is their fault. Cutting corners by going for the cheaper supplier who sells non-aerospace grade parts has a cost.

Should be noted that NASA had misgivings over whether or not SpaceX had really found the root cause in that case. I suppose we'll know in a few months.

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45 minutes ago, mikegarrison said:

Basic answer is that you need an ignition source and the proper fuel/oxygen ratio. Vapors do leak during fueling, so normally the protocol is to eliminate all ignition sources.

Watch an airplane refueling and you will see them always electrically ground the airplane and the fueling truck. When you put gas in your car at the station, the signs always say to turn off your engine and no smoking. Refinery workers use brass tools because they don't spark like steel tools do. Etc.

If you can't be sure of eliminating the ignition sources, then you have to go the other way and try to inert the atmosphere. That's why airplanes now have nitrogen inerting systems for their body fuel tanks.

Looks to me like they knew they had an explosive vapor situation, so they were trying to eliminate all ignition sources. Somehow one got past them.

Hydrazine mearly needs a catalyst, if its leaking. Kerosene is too dense to become volatile at the LO2 degassing temperature, there could have been methane, residue from a glue such as liquid electrical tape that will flame gas.  If you had a kero spill on a heated surface, again thats an if, not an assumption, then you could have a surface fire that progressed to a hydrazine explosion once the hydrazine tank heated. There could be chemicals in the hydrazine that caused a runaway reaction. 

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2 hours ago, KAL 9000 said:

Just want to point out, LC-39 is reserved for history-making missions (Apollo, STS, The flagship probes, SLS, etc.)

That's the point. It's leased to spaceX for the fh. That could make history.

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2 minutes ago, PB666 said:

Hydrazine mearly needs a catalyst, if its leaking. Kerosene is too dense to become volatile at the LO2 degassing temperature, there could have been methane, residue from a glue such as liquid electrical tape that will flame gas.  If you had a kero spill on a heated surface, again thats an if, not an assumption, then you could have a surface fire that progressed to a hydrazine explosion once the hydrazine tank heated. There could be chemicals in the hydrazine that caused a runaway reaction. 

What hydrazine are you talking about? Isn't this rocket kerolox?

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2 minutes ago, Emperor of the Titan Squid said:

There may have been a hydrazine tank on the pad for the attitude control.

It's obvious where the ignition happened, and it wasn't in some tank down on the pad. It was right where that venting was happening at the top of the second stage. If you don't believe your own eyes, Musk just tweeted the same thing.

Edited by mikegarrison

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