Author Topic: SCRUB: SpaceX Falcon 9/Dragon COTS Demo (C2+) LAUNCH ATTEMPT 1 UPDATES  (Read 192571 times)

Online ugordan

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(You watch, they'll find a faulty valve now I've said that! :D)

Engine pressure anomaly traced to turbopump valve.

Hahaha, prophetic words, Chris!  ;D

Offline Space Pete

So it was a valve!

Chris, you should have been a propulsion engineer! :D
« Last Edit: 05/19/2012 09:27 pm by Space Pete »
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Online Chris Bergin

I knew it! ;D

Also funny that the second I said there wasn't an update, Elon tweeted.
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Offline hrissan

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So what does it mean when the valve fails on the engine which was tested many times and performed flawlessly?

Is it a quality control issue? Or the engine shutdown (during tests) is too much a stress itself and can damage various components?

Online Chris Bergin

So what does it mean when the valve fails on the engine which was tested many times and performed flawlessly?

Is it a quality control issue? Or the engine shutdown (during tests) is too much a stress itself and can damage various components?

Welcome to the site's forum and that's a good question. Depends what exactly is wrong with the valve, etc. Probably too early to know as I suspect Elon's tweeted that as a live update to what he's been told. More details are likely to come, then we can work that question better.
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Offline Prober

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So what does it mean when the valve fails on the engine which was tested many times and performed flawlessly?

Is it a quality control issue? Or the engine shutdown (during tests) is too much a stress itself and can damage various components?

maybe the lube coked up after a few tests?
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Offline Archer

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They have only one vital pipe, not 2 parallel pipes and valves?
Wow! Is this the common practice in rocket engines?

We always had all important pipelines doubled in oil/chemical industry.
« Last Edit: 05/19/2012 09:39 pm by Archer »
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Offline dunderwood

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They have only one vital pipe, not 2 parallel pipes and valves?
Wow! Is this the common practice in rocket engines?

We always had all important pipelines doubled in oil/chemical industry.

That's not practical in cases where you have to carry all your infrastructure with you.  Every pound you add to a second stage is a pound less of payload.  Every ~5 pounds or so on the first stage is a pound less payload.

Offline Antares

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Aerospace engineers build munitions.  Everyone else builds targets :)

It's easy when you can use 4x factors of safety.
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Online Chris Bergin

SpaceX statement:

Today’s launch was aborted when the flight computer detected slightly high pressure in the engine 5 combustion chamber. We have discovered root cause and repairs are underway.

During rigorous inspections of the engine, SpaceX engineers discovered a faulty check valve on the Merlin engine.  We are now in the process of replacing the failed valve.  Those repairs should be complete tonight.  We will continue to review data on Sunday.  If things look good, we will be ready to attempt to launch on Tuesday, May 22nd at 3:44 AM Eastern.
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Offline mr. mark

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Good news, hope to see a launch early Tuesday morning.

Offline krytek

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What's really scary is that if this malfunction occurred only a few seconds later the entire mission would have failed.

Offline Vegeta

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So what does it mean when the valve fails on the engine which was tested many times and performed flawlessly?

It does make me curious on how SpaceX tests for lifetime degradation of components. I also hope they don't damage anything unexpectedly during a replace operation.

I've worked in designing electronics for aerospace and it's very easy to fix one thing but then break two others.

Offline Mader Levap

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So this time it wasn't bogus/overly conservative settings? Whoa. As krytek said, it could be very bad. Happy to hear fix is easy.
Only one question left, why this valve was faulty to begin with? Multiple test firings damaging something? Quality issue? Process issue? Something else?
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Offline arkaska

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Thanks Antares for the explanation on margin.  Sadly I expect you (and others) will be answering the exact same question in three days, because that's what's been happening here for months now.  FAQ #1: why the instantaneous / 1sec launch window?  Shuttle, cross range, Soyuz, over and over and over.

Also, can you guys who are arguing about the statistics just agree to disagree and stop cluttering this update thread, especially as many of us are checking this thread (and L2) frequently throughout the weekend to see what SpaceX finds out and decides?

It is important to note that Shuttle only had a 5 minute launch window and even if this mission had had a 5 minute window it wouldn't be enough to recycle from a T-0 abort (in this cause it needed a valve R&R so a recycle wouldn't be possible by hopefully but you get my point anyway).

As a second note, do we have any info if SpaceX got the range for May 22? IIRC in the presser they said SpaceX might be ready for 22nd but they didn't have the range get.
« Last Edit: 05/19/2012 10:45 pm by arkaska »

Offline jongoff

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Aerospace engineers build munitions.  Everyone else builds targets :)

It's easy when you can use 4x factors of safety.

+1

Of course, finding a way to get past the munition model and more towards transportation hardware would be a good thing.

~Jon
« Last Edit: 05/19/2012 10:44 pm by jongoff »

Offline douglas100

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What's really scary is that if this malfunction occurred only a few seconds later the entire mission would have failed.

One of the reasons spaceflight is so expensive: you must get it right first time on launch. Meticulous attention to detail and extensive testing costs.

And even when the vehicle has flown many times things can still go wrong, for example the Sea Launch Zenit. Like they say, it's hard.
Douglas Clark

Offline douglas100

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And one way of potentially reducing costs is what Jon just said. But that's as OT as I should go.
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Offline aero

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A faulty valve. That's a relief and an easy fix, relatively speaking.
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Offline Norm38

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I take it back, the limits are set right to catch a true hardware failure.

But to what degree did the valve fail?  Would 5 have produced no thrust, partial thrust, exploded?  Or could it have sub optimal but stable?

They can't lose an engine at liftoff but can they have a weak one and still get off the pad?  What's the margin?

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