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

[alexterrell]

Heh nice doom and gloom scenario you have here. The most likely reason for no information is that they want to be able to present all the facts.

I wasn't saying the mission was a total failure, just that it could turn out to be a total failure. I'm really relieved the GNC door rumour was wrong, and I hope the Orbcomm one is too. The mission could still turn out to be a total success, though one with a very worrying anomaly. However, even now for all we know it could still end in total failure. Let's not count our Dragons before they hatch.

Do we know now that the GNC door rumour is wrong?

Agree the mission could be a total success, with both a worrying anaomoly and a "good learning experience".

If it is just a case of single engine failure, then the 1 in 40 engine failure rate compares well with most launchers. The arguments over the  benefits of multiple engines have been discussed a lot here and are about to be settled.

Within about 2 years SpaceX should have launched more engines than the shuttle program launched SRBs. That should allow a proven track record.

[Lars_J]

"the fairing ruptured...due to the engine pressure release..." so they already know it wasn't aero loads that broke the fairing loose, it was "engine pressure release," which I'm not sure how to interpret...a turbopump self-destructing, or

"engine pressure release" sounds synonymous to "explosion" to me. Maybe it wasn't a catastrophic explosion, but it definitely went out with a bang.

Don't jump to conclusions. Besides, the term "explosion" is not precise and can mean a lot of things to us not in the business. For example, see the lengthy arguments that have been made re: Challenger exploding or conflagrating.

[Kabloona]

I don't understand the talk about the Orbicom satellite being in the wrong orbit. Wasn't it in Dragon's trunk? If Dragon reached the correct orbit, then so must have Orbicom.

I remember seen an animation that showed the satellite in the trunk and not on the second stage. Does anybody know?

Orbcomm stayed on stage 2, which was supposed to have a second burn to reach a higher orbit after dropping off Dragon.

[SF Doug]

Should we start a new thread full of apologies for those who guaranteed there was an explosion? Or just sweep that under the rug?

How about a "luck" thread?

[mmeijeri]

Do we know now that the GNC door rumour is wrong?

SpaceX have confirmed the door has opened.

If it is just a case of single engine failure, then the 1 in 40 engine failure rate compares well with most launchers. The arguments over the  benefits of multiple engines have been discussed a lot here and are about to be settled.

Well, they do have 10 of those engines on each vehicle, so they need higher reliability.

[Arceus12345]

So was the satellite deployment a failure? I heard it was miles off of the orbit its supposed to be on!

[asmi]

Whatever happened to the engine, ultimately it's a good thing for SpaceX. Most LVs in a history had much worse luck, and their failures had occured later in their lifecycle, and that overconfidence was paid by the blood of humans.
As an engineer I know that if your system goes live without a hitch, it's a sign that troubles are ahead. And that's always been like that. So SpaceX has got a chance to refine system well before anyone is onboard, and that is indeed a very good thing.

[Pelorat]

"the fairing ruptured...due to the engine pressure release..." so they already know it wasn't aero loads that broke the fairing loose, it was "engine pressure release," which I'm not sure how to interpret...a turbopump self-destructing, or

"engine pressure release" sounds synonymous to "explosion" to me. Maybe it wasn't a catastrophic explosion, but it definitely went out with a bang.

Think about it, if you were SpaceX, would you want to say that one of your engines "exploded"?

It's just a way to spin the words I guess. Technically the engine didn't explode. Instead something ruptured, possibly between the turbo pump and the engine thrust chamber, causing a pressure release that had the strength of a small explosion. This pressure release caused a pressure increase in the engine housing which ultimately resulted in the faring being blown to bits. Where you draw the line between a pressure release capable of causing structural damage and an explosion is a matter of semantics I guess

[SpacexULA]

So was the satellite deployment a failure? I heard it was miles off of the orbit its supposed to be on!

This has not been confirmed.  It's also not been confirmed whether they hit Santa Clause on the way up, or if the North Koreans shot engine 1 out .

Just wait, everything will be updated, NASA nor Aerospace companies run at the Space Forum Tempo.  I am sure we will have official confirmation by SpaceX or Orbcomm by Tuesday.

[rcoppola]

"the fairing ruptured...due to the engine pressure release..." so they already know it wasn't aero loads that broke the fairing loose, it was "engine pressure release," which I'm not sure how to interpret...a turbopump self-destructing, or

"engine pressure release" sounds synonymous to "explosion" to me. Maybe it wasn't a catastrophic explosion, but it definitely went out with a bang.

Think about it, if you were SpaceX, would you want to say that one of your engines "exploded"?

It's just a way to spin the words I guess. Technically the engine didn't explode. Instead something ruptured, possibly between the turbo pump and the engine thrust chamber, causing a pressure release that had the strength of a small explosion. This pressure release caused a pressure increase in the engine housing which ultimately resulted in the faring being blown to bits. Where you draw the line between a pressure release capable of causing structural damage and an explosion is a matter of semantics I guess

I'm not so sure about semantics.

A Gas Line "Rupture" is when gas flows out of it's containment vessel. A Gas Line "Explosion" is when the gas is ignited...and well...much more kinetic energy is released and much more damage is done.

[kevin-rf]

The fact that the vehicle continued to orbit is indeed a good thing.  The appearance of a possible engine explosion is not a good thing and I concur with Jim they got "lucky".

I'm not sure just yet what I think I'm seeing in the video.  It might just be an engine shutdown, which if you go back and look at the older Merlin 1C static test videos has a certain violence of its own.  This happened at altitude, which can enhance plume effects, etc.  On the other hand, fragments of something are visible after the shutdown.  These might be structural, but are just as likely to be ice or insulation.

Hopefully SpaceX will be able to fill in the blanks.

 - Ed Kyle

What we need is a time line of events compared to the video.

At what time was the anomaly detected?
At what time did shut down occur?
Was this before, after, or during the observed debris?

Since the vehicle was at near max-Q I am still not convinced what we are seeing is not the aero forces ripping the engine (or nozzle) off as it shut down.

A Nozzle is to a degree pressurized stabilized, just as the Atlas Balloon tank was. You shutdown the engine and you loose that stabilization and the aero forces could collapse then rip it off.

Also, the structure is designed to have the engine pushing on it. The mount might not be strong enough at max-Q to support the drag from an engine that has shutdown.

Have not seen anyone note that they extended the first stage burn, this means they managed to shutoff the propellant flow to the engine. If the valves had left with the engine best case they would have run out of propellants at the nominal time. So what ever happened, happened down stream of the valves. That is good.

[SF Doug]

Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release

Could it mean that the loss of the thrust plume from engine 1 changed the flow/pressure gradient over the fairing?

[JBF]

The fact that the vehicle continued to orbit is indeed a good thing.  The appearance of a possible engine explosion is not a good thing and I concur with Jim they got "lucky".

I'm not sure just yet what I think I'm seeing in the video.  It might just be an engine shutdown, which if you go back and look at the older Merlin 1C static test videos has a certain violence of its own.  This happened at altitude, which can enhance plume effects, etc.  On the other hand, fragments of something are visible after the shutdown.  These might be structural, but are just as likely to be ice or insulation.

Hopefully SpaceX will be able to fill in the blanks.

 - Ed Kyle

What we need is a time line of events compared to the video.

At what time was the anomaly detected?
At what time did shut down occur?
Was this before, after, or during the observed debris?

Since the vehicle was at near max-Q I am still not convinced what we are seeing is not the aero forces ripping the engine (or nozzle) off as it shut down.

A Nozzle is to a degree pressurized stabilized, just as the Atlas Balloon tank was. You shutdown the engine and you loose that stabilization and the aero forces could collapse then rip it off.

Also, the structure is designed to have the engine pushing on it. The mount might not be strong enough at max-Q to support the drag from an engine that has shutdown.

Have not seen anyone note that they extended the first stage burn, this means they managed to shutoff the propellant flow to the engine. If the valves had left with the engine best case they would have run out of propellants at the nominal time. So what ever happened, happened down stream of the valves. That is good.

They mentioned last night that they had an extra 30sec of thrust due to the loss of #1.

[Kabloona]

Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release

Could it mean that the loss of the thrust plume from engine 1 changed the flow/pressure gradient over the fairing?

No. Their wording is PR-speak for a catastrophic engine failure that blew the fairing off.

[Pelorat]

I'm not so sure about semantics.

A Gas Line "Rupture" is when gas flows out of it's containment vessel. A Gas Line "Explosion" is when the gas is ignited...and well...much more kinetic energy is released and much more damage is done.

I stand corrected

On topic. Glad to hear that the engine didn't disassemble itself completely. The fact that they continued to receive telemetry should make it easier to locate the point of failure.

[jcm]

So was the satellite deployment a failure? I heard it was miles off of the orbit its supposed to be on!

This has not been confirmed.  It's also not been confirmed whether they hit Santa Clause on the way up, or if the North Koreans shot engine 1 out .

Just wait, everything will be updated, NASA nor Aerospace companies run at the Space Forum Tempo.  I am sure we will have official confirmation by SpaceX or Orbcomm by Tuesday.

Nevertheless, USSTRATCOM tracking on SpaceTrack shows the objects that are probably Orbcomm and Stage 2 in a low orbit. I agree it's not confirmed that one of these objects is Orbcomm, but the lack of any tracked objects in the correct orbit and the number of objects tracked in the low orbit is strongly suggestive. In contrast, I see no evidence in the orbital data for a polar sleigh intercept propelled by antisatellite ballistic reindeer

[oldAtlas_Eguy]

Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release

Could it mean that the loss of the thrust plume from engine 1 changed the flow/pressure gradient over the fairing?

Yes, a very high probability of what happened. The vehicle was still in atmosphere and there would have been a positive back pressure in the engine 1 compartment area. When engine 1 shuts down the back pressure from the plume would drop suddenly causing a rapid pressure drop, an almost explosive pressure event (here I mean a very rapid and large pressure change not an explosion) occurring on the outside of the faring as related to the pressure on the inside of the faring. All it would take is enough flexing in a a near max Q environment and the engine faring would shred.

As far as engine pressure loss it only means that a pressure sensor backed by a simultaneous reading from the backup pressure sensor detected a lower pressure than the limits allowed for the engine operation. Merlin engines are highly instrumented like the Shuttle's RS-25s because they were meant to be a man rated system. The engine controllers and system responses are also designed with that end goal in mind.

[Hooperball]

For those who don't approve the use of the term "explosion" we may have a new acronym: EPR - Engine Pressure Release.

S

[ugordan]

For those who don't approve the use of the term "explosion" we may have a new acronym: EPR - Engine Pressure Release.

Not to be confused with this.

[rcoppola]

To what degree would this event be mitigated, or not, with the new engine configuration of F9 V1.1?  (at least with what we know thus far)