SCRUB: SpaceX Falcon 9/Dragon COTS Demo (C2+) LAUNCH ATTEMPT 1 UPDATES

[krytek]

is it possible they will choose to perform another static fire to confirm they've fixed the issue?

[ugordan]

You mean like the previous static fire showed the engine #5's fine?

[rickl]

Once integrated, has spaceX ever swapped a falcon 9 engine?

I once read a *rumor* on another site that they did do it once before. Take that with a grain of salt.

Given the company's overall philosophy, I would assume that they have factored that in as a possibility and the vehicle and engines are designed to make that procedure fairly easy.

(Yes, I'm aware of the problem of ass-u-me-ing.)   

[MP99]

They did so well to have such a smooth count. This situation is 100 times better than failing on the way uphill.

There is one minor upside to tonight's scrub - they've had the experience of another full run-through of the countdown, all the way to T-0.5s including pressure of "this is not a drill".

Better than if they'd had to scrub very early in the cycle.

cheers, Martin

[psloss]

45th Weather Squadron issued a forecast for T-0 time on Tuesday after today's attempt:
http://www.patrick.af.mil/shared/media/document/AFD-070716-028.pdf

Still forecasting a 40% chance of weather violation.

[spectre9]

I reckon this hold down and fire process might take SpaceX a while to streamline but it will be worth it in the long run to prevent lifting off with potential problems.

Thanks for the great coverage from those posting screenshots and updates 

[rdale]

Still forecasting a 40% chance of weather violation.

And a 50/50 chance of that

Seriously I don't see any issues at that point in the morning, as I recall those showers don't get going until later (shoot, I don't even consider 345am to be morning in the first place...)

20% chance of weather violation.

[Mike_1179]

I reckon this hold down and fire process might take SpaceX a while to streamline but it will be worth it in the long run to prevent lifting off with potential problems.

Aren't most LV held down until the engines are firing without a problem?  I don't think SpaceX is the only one that does this

[MP99]

I reckon this hold down and fire process might take SpaceX a while to streamline but it will be worth it in the long run to prevent lifting off with potential problems.

Aren't most LV held down until the engines are firing without a problem?  I don't think SpaceX is the only one that does this

I understand yes for liquid-fueled engines, but not for solid motors.

cheers, Martin

[ugordan]

Aren't most LV held down until the engines are firing without a problem? 

Yes. IIRC, Delta II might be different in that the core engine cannot lift it off the pad anyway.

[ugordan]

Post scrub briefing is now on youtube:

[brihath]

So a borescope is similar to an endoscope used by a doctor to check your insides?

http://en.wikipedia.org/wiki/Borescope

So this is a non-destructive means of examination, which will enable them to look at the feed channels for the chamber of Engine 5?

"trending" for "low fuel" could possibly point to a leak in the fuel feed line, perhaps?

It is too early to tell, but it also could involve how quickly the turbopump came up to speed, or whether a valve was open all the way.  Lots of possibilities at this point in time.

[MKremer]

It is too early to tell, but it also could involve how quickly the turbopump came up to speed, or whether a valve was open all the way.  Lots of possibilities at this point in time.

Already stated that valves weren't a problem.
Turbopump speed would have been flagged and noted quickly if deficient.

Let's see what more detailed engine data and borescope inspections lead to, for a possible cause.

[Avron]

Was wondering if the density altitude from time of day, and location of the engine for this mix would cause a startup trend that is out of character ..

[Chris Bergin]

It is too early to tell, but it also could involve how quickly the turbopump came up to speed, or whether a valve was open all the way.  Lots of possibilities at this point in time.

On the vavle:

Next T-0s:

03:44 - 22nd.
About 03:22 - 23rd.

Normal ignition for all nine engines. 5 started fine then started trending high.

Vehicle was held down at all times.

High pressure could be high temps/low fuel in combustion. Prevalve was fully open (nominal). Need to look at the data.

Visual inspection of the chamber, borescope the pump.

Flight 1 the engine wasn't trending like this one.

Traj of the ISS has allowed the possible May 24th opportunity.

Should be able to roll back to the hanger and back out by the 22nd if required.

And that's over.

[Norm38]

Engine 5 was trending high from the start, but hit the abort limit at 0.5 seconds. Compared to static fire, was out of family. Static fire it was rock solid.

Does not look like a sensor failure. Never seen it before on the pad.

Need all nine engines for lift off. Two engines can fail later for nominal mission.

Not a software issue.

PC Pressure on Engine 5 (high pressure) was the abort on the first flight, but they had a window that time.

Ms Shotwell distancing herself from Elon's tweet. Need to look at the engine.

This is not a failure, this is aborted with purpose, it would have been a failure if we lifted off with this issue.

Engine change would be a couple of days. May swap engine 5 from the other F9 at Cape. If required.

Wait, from the quote in bold, are they saying that they're certain the engine would have failed if they lifted off, or that it would have been a failure of their launch criteria to allow a liftoff with an engine out of spec?
Are there any indications the engine was in serious mechanical danger?

Given that the 2nd stage engine is the same, and can have the same issue, obviously they can't abort the 2nd stage ignition.  So does the second stage have vastly reduced limits, or no limits at all?

If this anomaly had been on the 2nd stage, what then?  Just press for orbit and hope the engine holds together?

[edkyle99]

High pressure could be high temps/low fuel in combustion. Prevalve was fully open (nominal). Need to look at the data.

Prevalve, yes, but aren't there are other valves, like the main valves, bleed valves, etc.?

 - Ed Kyle

[aero]

Next T-0s:

03:44 - 22nd.
About 03:22 - 23rd.

Normal ignition for all nine engines. 5 started fine then started trending high.

Vehicle was held down at all times.

High pressure could be high temps/low fuel in combustion. Prevalve was fully open (nominal). Need to look at the data.

Visual inspection of the chamber, borescope the pump.

Flight 1 the engine wasn't trending like this one.

Traj of the ISS has allowed the possible May 24th opportunity.

Should be able to roll back to the hanger and back out by the 22nd if required.

And that's over.

Repeating:

Flight 1 the engine wasn't trending like this one.

I understood Ms. Shotwell to say that Flight 1 engine 5 was trending high, just not as dramatically or as much as this one because the abort limit was much tighter.

The point though, is that it was trending. That makes twice that engine 5 has shown a high pressure trending problem on start-up, that we know of. How many times have all nine engines been integrated with the fuel tanks and fuel feeds then all nine fired simultaneously?

Fool me once, shame on you, fool me twice, shame on me.

[ugordan]

Repeating:

Flight 1 the engine wasn't trending like this one.

Fool me once, shame on you, fool me twice, shame on me.

You're assuming too much. "wasn't trending like this one" and "wasn't trending, [comma] like this one" are two different things.

I understood her to mean the F9-01 was more of a pressure spike (noisy ducer data, etc) than a pressure rise trend. That's IIRC the context the Pc bound was talked about back then and why they went with a simple redline tweak.

Anyway, abort from a remote pad camera:

[Avron]

Next T-0s:

03:44 - 22nd.
About 03:22 - 23rd.

Normal ignition for all nine engines. 5 started fine then started trending high.

Vehicle was held down at all times.

High pressure could be high temps/low fuel in combustion. Prevalve was fully open (nominal). Need to look at the data.

Visual inspection of the chamber, borescope the pump.

Flight 1 the engine wasn't trending like this one.

Traj of the ISS has allowed the possible May 24th opportunity.

Should be able to roll back to the hanger and back out by the 22nd if required.

And that's over.

Repeating:

Flight 1 the engine wasn't trending like this one.

I understood Ms. Shotwell to say that Flight 1 engine 5 was trending high, just not as dramatically or as much as this one because the abort limit was much tighter.

The point though, is that it was trending. That makes twice that engine 5 has shown a high pressure trending problem on start-up, that we know of. How many times have all nine engines been integrated with the fuel tank feeds and fired simultaneously?

Fool me once, shame on you, fool me twice, shame on me.

I understand it was a trend that was out of character ...  she also indicated that it was compared to current knowledge of the engine, and trended outside, and thus  was shutdown..