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

[garidan]

I don't stand nor understand this way of arguing.
What does it mean "I suspect ...." with no number to support this ?
What does this add ? 

If Spacex adfirm something and someone says "I don't believe" without saying why, discussions stops here.

It's not mandatory to write everything one has in his mind or heart ....

[mrmandias]

This is exactly what we're asking.

The only data the stage needs is  A: "Did I successfully deliver Dragon", and B: "can I execute burn 2 plan-A".

If the answers are YES and NO, then the stage can execute the fallback burn 2 plan-B, which is raise the perigee.   Raising the perigee to a circular orbit is a well defined maneuver and is something the GNC should be able to do - I don't see the problem with unknown initial conditions. 

Again, LV's only have one trajectory.  It follows one path and stops either when it completes all the correct delta V's or fails.  It does not go on if it fails.  There are no branches.

No, raising the perigee to a circular orbit is not a well defined maneuver, if you don't know where you are going to start from.  LV's don't move on to the next maneuver unless the first one is complete and successful.  Otherwise, there are too many variations to analyze.

Edited and edited again.
 

Jim,
thanks for being a little more patient than usual and thoroughly explaining this.  I get what you're saying and now understand exactly why the Orbcomm mission had to proceed the way it did, once the first-stage engine failed.

[mrmandias]

SpaceX wasn't lucky. Those redundant systems didn't just appear by luck. It was engineered to work in case of engine failure and it did.

So, let's say the engine gave up not 80 seconds but 10 seconds after liftoff and F9 US had to spend all of its propellant while still not managing to raise the perigee above the atmosphere.

If you're saying the SpaceX was lucky because if the failure had happened differently, their margins might now have worked, then you are saying that *any* mission, by SpaceX or anyone else, is due to luck.  Because you can always come up with a scenario where if something had gone wrong in a way that it didn't in real life, the mission would have failed.  That's a useless definition of luck.

SpaceX would have been lucky if something they didn't foresee prevented the problem from being as bad as it could have been.  There is no evidence of that.  Its still too early to say for sure, but from here it looks like what happened was that planned safety measures worked in the way they were planned to work.

[meekGee]

It is perfectly ok for SpaceX to say that they a certain performance based on Falcon 1.1 and Merlin 1D.

Any talk about engine-out capability assumes at least a 1D, since that's what they are selling to customers right now.  And when Elon discusses performance numbers for booster flyback, he's probably not even using the 1D, but whatever they have on the drawing boards for it.

I am sure the 1.0 and the 1C are being viewed internally as an interim versions.

[yg1968]

SpaceX claims F9 is capable of single engine-out at any stage of launch and still deliver.

It can't during any part of second stage flight.

Yes, obviously they are talking about the core stage burn.  I love that idea of a 'reasonable man interpretation'.

Not applicable to the general public or many on this site.  Also, not including the time from launch (10, 20 or 30 seconds or so) to the engine out capability is viable, the amount time of the ascent that is engine out capability is usable is less than 33%.

Is this also true for version 1.1?

Also, would Max Q be the time that you need engine out the most (in the sense that the engine is mostly likely to fail at that time because of the stress)?

[JBF]

Is that the freezer in the middle of Dragon?

[corrodedNut]

Is that the freezer in the middle of Dragon?

AIUI, powered cargo is located near the side hatch, to make late-load easier.

[Mader Levap]

missed the part about "will be capable" when picking which sections to bold.

It can't during any part of second stage flight.

Oooh, good points. They could word it better. A lot.

Some people realize the fact that just about the only numerical value that has any relation to the current F9 v1.0 on that page is the vehicle diameter.

If that is so, then SpaceX should write clearly that their marketing spiel here is for F9 v1.1.

[StephenB]

If that is so, then SpaceX should write clearly that their marketing spiel here is for F9 v1.1.

If you were really in the market for a Falcon, you'd know. F9 V1.1 is what's for sale now, not V1.0.

[ugordan]

If that is so, then SpaceX should write clearly that their marketing spiel here is for F9 v1.1.

It would be better if that was so, however since the only version they ever meant to "sell" is the old Block 2 and now v1.1, laying out specs for the initial, interim vehicle didn't make much sense.

The problem, however, is people reading those specs and assuming they're valid for v1.0 and SpaceX PR saying nothing to correct that notion. Why would they, saying nothing allows the general impression that the current vehicle is better than it is, a PR win for them.

[Garrett]

SpaceX claims F9 is capable of single engine-out at any stage of launch and still deliver.

It can't during any part of second stage flight.

Yes, obviously they are talking about the core stage burn.  I love that idea of a 'reasonable man interpretation'.

Not applicable to the general public or many on this site.  Also, not including the time from launch (10, 20 or 30 seconds or so) to the engine out capability is viable, the amount time of the ascent that is engine out capability is usable is less than 33%.

The F9 Payload User's guide states:
Importantly, by employing nine first stage engines, SpaceX debuts the world’s first Evolved Expendable Launch Vehicle (EELV)‐class launch vehicle with engine‐out capability through much of first stage flight. 

That seems like a reasonable statement to me. Where did it say that "F9 is capable of single engine-out at any stage of launch"? If they did say that once, it appears to be no longer a current PR statement.

Also, on the F9 webpage (http://www.spacex.com/falcon9.php), the only reference to engine-out capability is this:

NASA CITED SPACEX'S SIGNIFICANT STRENGTHS AS FOLLOWS:
> First stage engine-out capability
> ...

EDIT: I found the offending quote on the F9 webpage:
Falcon 9 has nine Merlin engines clustered together. This vehicle will be capable of sustaining an engine failure at any point in flight and still successfully completing its mission.

[kniklas]

That's all there is to it, really.  Now the focus should be looking for the root cause of the engine failure - and I don't think there's a post related to that in the last 20 pages of comments....

Indeed! I posted my question about possible root cause more than 20 pages ago:

(..)
If I remember correctly previous F9 launch attempt had problem with pressure drop caused by faulty check valve (?). Launch was aborted. I'm not sure if recent and previous pressure drop events in engine chamber share the same root cause.

I was wondering shouldn't we start separate thread on possible root cause. As starting point it would be good to collect posts which explained the anomaly (I'm afraid they may be lost in heaps of other posts).

Regards,
Kamil

[meekGee]

I was wondering shouldn't we start separate thread on possible root cause. As starting point it would be good to collect posts which explained the anomaly (I'm afraid they may be lost in heaps of other posts).

Regards,
Kamil

I was thinking the same thing, so go ahead...   

Should cover the scope of the engine anomaly - root cause and progression of failure.

[cordor]

iss can go as low as 330km, right now orbcomm apogee is at 320km, you make a circle there, it's kinda pretty close.

Not that it matters, but the ISS will never be kept that low again, now that the Shuttle is retired.  It probably won't go below 400 km, at least until the next Sun cycle minimum, IIRC.

Edit: Jim has a point (again!) about not knowing where the circularizing burn would start, and the rocket not being able to calculate a burn on the fly.  It seems possible to have a conditional branch IF there is insufficient fuel to do the planned maneuvers, and IF there is enough for cirularizing and deorbiting and IF the orbit parameters are as planned, but that's a low probability corner case anyways, even if SpaceX hit it.

just because ISS don't go that low anymore doesn't mean policy have changed. nor they like satellite drifting around below ISS.  ISS and orbcomm share the same inclination(?), orbit that close when they are in sync, that satellite will block route to ISS for awhile?

orbcomm is 6.5M + launch(maybe 2~3M)? if it couldn't get to orbit, it's better let it die.

[kniklas]

I was wondering shouldn't we start separate thread on possible root cause. As starting point it would be good to collect posts which explained the anomaly (I'm afraid they may be lost in heaps of other posts).

Regards,
Kamil

I was thinking the same thing, so go ahead...   

Should cover the scope of the engine anomaly - root cause and progression of failure.

New topic posted here on possible root causes:
http://forum.nasaspaceflight.com/index.php?topic=30069.0

[Moe Grills]

Downix, on another section/thread, posted the most informative and poignant editorial to what has occurred with this launch.

SpaceX has not been around as long as say Boeing, Lockheed, OSC,
but as a newer company they have show that they have learned and are learning important lessons that will pay and are paying proverbial dividends
now and in the future.
  Imagine if Falcon 9 had only ONE first-stage engine.
Engine shutdowns are hardly new to the business of rocketry.
Cavitation, sensor-activated shutdowns, etc., have been experienced
in the business for?...decades.
   I'm still thinking of that scene in Apollo 13. You know the one i'm thinking of.

[system9]

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.

[Jim]

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

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

[R.Simko]

3.  My thought is, would it be financially smart to increase the fuel capacity and fuel load of the secondary satellite, so that if it gets dropped off in too low an orbit, it can then raise itself to a functional orbit, thereby saving itself and the secondary mission?

then it would be too heavy to be added to a mission

Thanks Jim and MP99 for answering my question. 

[system9]

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...