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

[peter-b]

I've been thinking about it, and it sounds like the sort of thing that happens when you have a metallurgical defect (e.g. a streak of impurities in the metal blank that a component was machined from). Any materials engineers want to comment? I understand that these can be very difficult to directly test for...

It's my understanding that SpaceX is using an old Pratt & Whitney Heat Treating Furnace Cisco 80-85. It might be time for them to upgrade. Inconsistent heat treating would cause a failure of this nature.

Perhaps this should be taken to the new thread on root cause...

[Robotbeat]

  Imagine if Falcon 9 had only ONE first-stage engine.

Atlas V and Delta IV are doing fine with 1 first stage engine.

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

[ugordan]

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

Actually there is, Atlas III flew 6 additional RD-180s.

[cordor]

  Imagine if Falcon 9 had only ONE first-stage engine.

Atlas V and Delta IV are doing fine with 1 first stage engine.

Delta IV uses RS-68, it's about 20M a piece now. second stage use completely different engine, so it's not going to be cheaper for 2. No way you can offer 54M launch package using  highly reliable well designed brand name engine.

oh wait, maybe you can use russian's engine like Atlas V, but it isn't cheap neither.

9+1 is a good plan for limited time and budget.

[Jim]

  Imagine if Falcon 9 had only ONE first-stage engine.

Atlas V and Delta IV are doing fine with 1 first stage engine.

Delta IV uses RS-68, it's about 20M a piece now. second stage use completely different engine, so it's not going to be cheaper for 2. No way you can offer 54M launch package using  highly reliable well designed brand name engine.

oh wait, maybe you can use russian's engine like Atlas V, but it isn't cheap neither.

9+1 is a good plan for limited time and budget.

We aren't talking cost.

[Robotbeat]

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

Actually there is, Atlas III flew 6 additional RD-180s.

Still not statistically significant.

[ugordan]

The fact is RD-180 demonstrated reliability is higher than M1C. Not bad for a ruskie engine that's operating on the verge of disaster, a ticking time bomb, etc. etc.

[peter-b]

The fact is RD-180 demonstrated reliability is higher than M1C. Not bad for a ruskie engine that's operating on the verge of disaster, a ticking time bomb, etc. etc.

I'm pretty certain it's not statistically significant. And pretty immaterial, given that the M1C is already obsolete.

[Robotbeat]

The fact is RD-180 demonstrated reliability is higher than M1C. Not bad for a ruskie engine that's operating on the verge of disaster, a ticking time bomb, etc. etc.

Statistical significance matters in this discussion, and you are ignoring it. It is thus not a fact that Merlin 1C is less reliable. If another fails on the next flight (and no rd180s fail), then we have enough statistical significance to make that claim.

[rklaehn]

  Imagine if Falcon 9 had only ONE first-stage engine.

Atlas V and Delta IV are doing fine with 1 first stage engine.

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

What you can say is that both engines have not flown very often, so it is not possible to say whether they are reliable or not. The thing is that spacex is gathering data at a very fast pace, so by the time they do their first manned flights they will have a large database of engine data, provided they settle on one design and don't change everything completely every 5 launches.

[cordor]

  Imagine if Falcon 9 had only ONE first-stage engine.

Atlas V and Delta IV are doing fine with 1 first stage engine.

Delta IV uses RS-68, it's about 20M a piece now. second stage use completely different engine, so it's not going to be cheaper for 2. No way you can offer 54M launch package using  highly reliable well designed brand name engine.

oh wait, maybe you can use russian's engine like Atlas V, but it isn't cheap neither.

9+1 is a good plan for limited time and budget.

We aren't talking cost.

I guess that's my point. being expensive is not doing fine at all, you just not talk about it.

[cordor]

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

Actually there is, Atlas III flew 6 additional RD-180s.

Still not statistically significant.

look at their families.

[IRobot]

The fact is RD-180 demonstrated reliability is higher than M1C. Not bad for a ruskie engine that's operating on the verge of disaster, a ticking time bomb, etc. etc.

Statistical significance matters in this discussion, and you are ignoring it. It is thus not a fact that Merlin 1C is less reliable. If another fails on the next flight (and no rd180s fail), then we have enough statistical significance to make that claim.

"A single death is a tragedy, a million is a statistic".

[Rocket Science]

All sensor and telemetry data aside, it would be interesting if they could salvage the engines and have a look at what occurred directly…

[Robotbeat]

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

Actually there is, Atlas III flew 6 additional RD-180s.

Still not statistically significant.

look at their families.

That would give an unrealistic low reliability to the rd180, given several zenit failures from the rd171 (I expect western procedures to have improved on the reliability of the rd171). If we followed your suggestion, though, the merlin1c and rd180 are still pretty reasonably equivalent, to the limits of statistical uncertainty.

My point is that until another failure occurs for Merlin 1c, it is very difficult to get a statistically significant contrast between the two engines.

[yg1968]

The fact that this hapenned on the 4th flight (and the first non-test flight) of Falcon 9 is also relevant. It's still very early in Falcon 9's history.

[kevin-rf]

This is not the first Merlin 1C anomaly, Though it was not as dramatic there was one other early shutdown of a Merlin 1C due to it going out of bounds. (An article about it was linked several pages back)

That needs to be remembered when doing the statistics.

[Comga]

What if they get me to where I want to go, but they send my luggage somewhere else for a week?

I think you just summed up this launch to the T. +1
The luggage was placed in the wrong orbit.

Bad analogy. The luggage belonged to somebody else.

+1
If an airline gets me home on time but looses someone else's luggage, I still think of the flight as a total success.

The success or failure IS a matter of opinion.  Ed calls it a 100% failure. Jonathan calls it a 95% success.  If someone were to insure a scondary payload, they wouldn't rely on somone's calcualted percentage of successes and failures.  With the scant evidence at hand, they would see that on the fourth flight, after an engine failed, the second stage had a 95% probablility of having sufficient liquid Oxygen to execute an orbit raising burn and a disposal burn.  Without the stringent ISS safety criteria levied by NASA, this would be pretty close to a success.  IMO

If this were a commercial launch with a customer other than NASA, is there any way for NASA to apply similar criteria?

[cordor]

SpaceX has flown 39 Merlin 1C engines, one has had a serious problem. Atlas v has flown only 33 rd180s. There's no a statistical basis for saying the rd180 is more reliable.

Actually there is, Atlas III flew 6 additional RD-180s.

Still not statistically significant.

look at their families.

That would give an unrealistic low reliability to the rd180, given several zenit failures from the rd171 (I expect western procedures to have improved on the reliability of the rd171). If we followed your suggestion, though, the merlin1c and rd180 are still pretty reasonably equivalent, to the limits of statistical uncertainty.

My point is that until another failure occurs for Merlin 1c, it is very difficult to get a statistically significant contrast between the two engines.

rd-171/180 staged combustion engine are more complex, each of those generate lot more thrust than  single 1c, also at much higher isp. zenit 2/3 launched 51 times and only 2~3 failures directly caused by rd-171.

 on the other hand spacex's flight electronic seems doing much better job  taking care their engines than zenit or russian rockets. 1c generate lot less thrust, and gas generator cycle is more simple design.

Comparing rd-171/180 and merlin is like comparing apple and orange. Personal opinion, merlin is still very immature. 1c was rushed out in order to grab NASA's contracts.  i say, gas generator cycle 600kN class RP-1/LOX engine supposed to be lot more reliable than that.

[Jim]

 on the other hand spacex's flight electronic seems doing much better job  taking care their engines than zenit or russian rockets.

It has nothing to do with electronics but an effect of the fuel-oxidizer ratio