SpaceX Falcon 9/Dragon CRS SpX-1 MISSION GENERAL DISCUSSION

[jimvela]

Looks too violent to me to be anything but a RUD on engine #1.  The dark flow looks like it was spewing kerosene for a couple of seconds.

What if the faring came off and smacked the engine nozzle?  It's cooled, right?  That could take off part of the nozzle, cause a huge leak, and thus lead the computer to shut it down fuel-rich.

Does that SPECULATION make sense to the experts here?

Any large chunks of FOD into the airstream could do serious damage.  Faring hitting a part of an engine would be plausible.

I've replayed that video section a number of times.  I "Think" I see things being blown outward in all directions before the chunks start to fall, and I'm not sure a separated fairing would account for that.

[Lars_J]

I have made a slow motion video of the anomaly. Please tell me if I this is not fair use and I will remove it immediately.


Of course we will have to wait for an official assessment but I would say that something has definitely happened and it is not just some clouds.

Thanks for posting the video! That slow-motion is very detailed... It certainly *appears* that the corner engine in question was shut down - note the dark trail which *appears* to be kerosene and/or oxygen that is eventually shut off. (after 2 seconds)

Speculation: It would certainly seem that either the engine was damaged by debris and shut down, or failed in some manner.

Fortunately the F9 appears to be robust! A great launch otherwise!

[Kabloona]

Zephyrus just posted a link to a slo-mo YouTube video of the event, and it clearly shows an engine plume brightening and changing shape BEFORE the chunks start to fly. In that slo-mo, it looks very much like an engine exploding and blowing out chunks of corner fairing, etc.

[jimvela]

If you study the video, there is a bright spot along the edge of the nozzle in the upper right corner of the #1 engine that moves about for a few seconds, becomes very bright, widens, forms two bright spots and then the destructive event happens.

There are similar bright spots on other engines about the same time, however what is happening on #1 is out of character with the others.

At the time of the destructive event, there are at least two items thrown outward at different angles from the rough position of the #1 engine.

[Robotbeat]

I have made a slow motion video of the anomaly. Please tell me if I this is not fair use and I will remove it immediately.


Of course we will have to wait for an official assessment but I would say that something has definitely happened and it is not just some clouds.


Sorry for the slowed down audio, I could not find the exact mencoder option to kill it.

(P.S. Moved from the other thread due to moderator indications).

definitely is something! Wow. Engine-out seems to work pretty well! Engine-out capability converts Russian Roulette into five-finger fillet. A much better trade, IMHO.

[spectre9]

The Merlin 1C nozzle is quite robust.

How many have flown? 40?

One nozzle popped isn't too bad. Happened right at Max-Q so my speculation is it cracked and just couldn't handle the load no longer.

[mr. mark]

What's important is the fact that both Dragon and the Orbcomm satellite were delivered successfully. Let's hope both have success. SpaceX will learn from the engine anomaly.

[Kabloona]

If you study the video, there is a bright spot along the edge of the nozzle in the upper right corner of the #1 engine that moves about for a few seconds, becomes very bright, widens, forms two bright spots and then the destructive event happens.

There are similar bright spots on other engines about the same time, however what is happening on #1 is out of character with the others.

At the time of the destructive event, there are at least two items thrown outward at different angles from the rough position of the #1 engine.

I'm thinking the bright "spot" is the flame near the nozzle throat, and because of the camera angle it appears that the throat "spot" is aligned with the very edge of the nozzle. A sudden change in chamber pressure or mixture ratio due to imminent turbopump failure would likely cause that flame "spot" to change characteristic just before the violent explosion.

So I still think that the failure was upstream of the throat, in the chamber or turbopump, not in the nozzle per se.

[Antares]

"Falcon 9 detected an anomaly on one of the nine engines and shut it down," Musk wrote in an email...

Judging by the video, the engine had already RUD'd and shut itself down de facto by the time it was told to quit.

[Lee Jay]

What's important is the fact that both Dragon and the Orbcomm satellite were delivered successfully. Let's hope both have success. SpaceX will learn from the engine anomaly.

The problem is, they have another CRS flight on this vehicle and this engine, and that vehicle and engine set are already built.

[Jason1701]

What's important is the fact that both Dragon and the Orbcomm satellite were delivered successfully. Let's hope both have success. SpaceX will learn from the engine anomaly.

The problem is, they have another CRS flight on this vehicle and this engine, and that vehicle and engine set are already built.

But we've seen that the corner fairings are not installed until after the vehicle is delivered to the HIF. So if their fragility was the cause of the problem, it might be easier to fix.

[Robotbeat]

"Falcon 9 detected an anomaly on one of the nine engines and shut it down," Musk wrote in an email...

Judging by the video, the engine had already RUD'd and shut itself down de facto by the time it was told to quit.

It looked like there was more unburnt propellant before it actually was shut down. Or, put another way, its exhaust velocity was less than nominal.

[Antares]

The slow-motion makes it look like the engine RUD'd and took out the corner fairing and probably some of the aft skirt.  Nothing to do with a fragile corner fairing.  As scary as it looked and unknown how close it was to fratricide, it's the more amazing that Dragon was dropped off where it was supposed to be.

[Kabloona]

What's important is the fact that both Dragon and the Orbcomm satellite were delivered successfully. Let's hope both have success. SpaceX will learn from the engine anomaly.

The problem is, they have another CRS flight on this vehicle and this engine, and that vehicle and engine set are already built.

Definitely hard to see how this doesn't seriously impact schedule in the short-medium term.

[sdsds]

It looked like there was more unburnt propellant before it actually was shut down.

When Elon asserts F9 shut down the engine, I interpret him to mean it shut down flow of propellant to the engine. Is it fair to assume they do that fuel-rich, i.e. cut the oxidizer flow first?

[Kabloona]

The slow-motion makes it look like the engine RUD'd and took out the corner fairing and probably some of the aft skirt.  Nothing to do with a fragile corner fairing.  As scary as it looked and unknown how close it was to fratricide, it's the more amazing that Dragon was dropped off where it was supposed to be.

Pretty bad and pretty impressive, all at the same time...

[Lee Jay]

The first frame that looks anomalous has expanding "stuff" in at least two directions.  The next frame shows that "stuff" igniting bright orange.  Does that mean it's fuel?  The vehicle was pretty high at the time, so I'm not sure a fuel leak would do that.  Do these engines run fuel-rich?  If so, a LOX plume could ignite in the excess fuel.

[Chandonn]

Official confirmation from Elon is that an anomaly occurred in an engine and it was shut down prematurely by the onboard computer.  Nothing about an explosion in that official statement.

[Kabloona]

The first frame that looks anomalous has expanding "stuff" in at least two directions.  The next frame shows that "stuff" igniting bright orange.  Does that mean it's fuel?  The vehicle was pretty high at the time, so I'm not sure a fuel leak would do that.  Do these engines run fuel-rich?  If so, a LOX plume could ignite in the excess fuel.

Sure looks consistent with a fuel turbopump letting go...

[meekGee]

Zephyrus just posted a link to a slo-mo YouTube video of the event, and it clearly shows an engine plume brightening and changing shape BEFORE the chunks start to fly. In that slo-mo, it looks very much like an engine exploding and blowing out chunks of corner fairing, etc.

Still consistent with a fairing failure.  If the fairing hits the nozzle, the effect on the plume propagates backwards at several km/sec, whereas the fairing itself is only accelerating from "rest" due to the force of the flow and the acceleration of the rocket, so is not anywhere near as fast.

So you'll see the plume deform before you see the fairing cross in front of the engine.