Author Topic: SpaceX: Falcon 9 Hotfire Attempt 2 Updates (Read 138684 times)

zeke01 · « **Reply #60 on:** 03/11/2010 09:15 pm »

Elon Musk, SpaceX's founder and CEO, has provided the following update on the cause of Tuesday's aborted launch pad engine test:

"The valve that didn't actuate is the ground side isolation valve to release ground supplied high pressure helium to start the first stage engine turbopumps spinning at several thousand rpm. Once that happens it generates enough pressure to start the gas generator, which is a small rocket engine that powers the turbopump. There are no vehicle side valves actuated for spin start (just check valves), so it is an all engines or none situation.

The problem was pretty simple: our autostart sequence didn't issue the command to the normally closed ground side isolation valve. We had tested everything on the vehicle side exhaustively in Texas, but didn't have this iso valve on our test stand there. Definitely a lesson learned to make sure that *everything* is the same between test stand and launch pad on the ground side, not just on the vehicle side.

Ignition fluid (TEA-TAB) flowed nominally to all engines creating the green flame and the main valves opened, but no engines actually started and the system automatically aborted on lack of spin. The fire generated was from flushing the system of fuel and LOX from the open mains. No damage to the vehicle or ground systems and no other anomalies that need to be addressed. If all goes well, we will try the static fire again in the next few days. Right now, we are holding due to extreme weather. It is raining sideways at 46 mph and tornados have been spotted just north of the Cape.

It is important for readers to appreciate that what we are going through right now is the equivalent of "beta testing." Problems are expected to occur, as they have throughout the development phase. The beta phase only ends when a rocket has done at least one, but arguably two or three consecutive flights to orbit."

Chris Bergin · « **Reply #61 on:** 03/11/2010 09:17 pm »

SpaceX Presser:

FYI--explanation on the exact cause of Tuesday’s abort at SpaceX’s launch pad in Cape Canaveral below, this is a statement from Elon:

“The valve that didn't actuate is the ground side isolation valve to release ground supplied high pressure helium to start the first stage engine turbopumps spinning at several thousand rpm. Once that happens it generates enough pressure to start the gas generator, which is a small rocket engine that powers the turbopump. There are no vehicle side valves actuated for spin start (just check valves), so it is an all engines or none situation.

The problem was pretty simple: our autostart sequence didn't issue the command to the normally closed ground side isolation valve. We had tested everything on the vehicle side exhaustively in Texas, but didn't have this iso valve on our test stand there. Definitely a lesson learned to make sure that *everything* is the same between test stand and launch pad on the ground side, not just on the vehicle side.

Ignition fluid (TEA-TAB) flowed nominally to all engines creating the green flame and the main valves opened, but no engines actually started and the system automatically aborted on lack of spin. The fire generated was from flushing the system of fuel and LOX from the open mains. No damage to the vehicle or ground systems and no other anomalies that need to be addressed. If all goes well, we will try the static fire again in the next few days. Right now, we are holding due to extreme weather. It is raining sideways at 46 mph and tornados have been spotted just north of the Cape.

It is important for readers/viewers to appreciate that what we are going through right now is the equivalent of “beta testing”. Problems are expected to occur, as they have throughout the development phase. The beta phase only ends when a rocket has done at least one, but arguably two or three consecutive flights to orbit.

Lee Jay · « **Reply #62 on:** 03/11/2010 09:22 pm »

Nice statement. That's why we do end-to-end tests wherever possible. You never know what you might find that you didn't think of.

SpacexULA · « **Reply #63 on:** 03/11/2010 10:18 pm »

Quote from: ugordan on 03/11/2010 07:23 pm

Quote from: Kabloona on 03/11/2010 06:58 pm
Anyone know what the wind limits might be for the static firing?

I'm trying to think of a reason why wind would be an issue for a vehicle anchored to the pad. Are they playing this out as a real launch down to ground wind constraints, even though this time the vehicle isn't leaving the pad?

Also, any idea why they'd even attempt the hotfire today when the weather was clearly abysmal? They can't rush for the launch without getting range safety approvals anyway. Could it be a sign those are being finished up?

40mph+ wind gusts & rain at the cape today. Let' let the poor 1st year employees stay inside today.

Ronsmytheiii · « **Reply #64 on:** 03/11/2010 11:22 pm »

Quote from: SpacexULA on 03/11/2010 10:18 pm

40mph+ wind gusts & rain at the cape today. Let' let the poor 1st year employees stay inside today.

Not to mention the level 2 lightning advisory, oh and I was on the Cape then and now tour today...weather was terrible!

Ronsmytheiii · « **Reply #65 on:** 03/11/2010 11:26 pm »

From Tuesday: zoom in to see full details:

Jim · « **Reply #66 on:** 03/12/2010 02:57 am »

Quote from: Avron on 03/11/2010 03:20 pm

Ok, question, what is the minimum acceptable weather for a Static test fire..

This is a spacex call.

Jim · « **Reply #67 on:** 03/12/2010 02:58 am »

Quote from: Kabloona on 03/11/2010 06:58 pm

Saturday forecast is clear but windy (gusts to 25 mph). Anyone know what the wind limits might be for the static firing?

same for this (spacex call)

kevin-rf · « **Reply #68 on:** 03/12/2010 12:25 pm »

What, no one today is clamoring for them to be able to launch into 40mph+ wind gusts through a lightening storm

stockman · « **Reply #69 on:** 03/12/2010 01:03 pm »

Quote from: kevin-rf on 03/12/2010 12:25 pm

What, no one today is clamoring for them to be able to launch into 40mph+ wind gusts through a lightening storm

That would just be showing off... I am sure SpaceX is more reserved than that..

stockman · « **Reply #70 on:** 03/12/2010 01:08 pm »

No Official word one way or the other yet today but it looks highly unlikely anything will happen today...

ugordan · « **Reply #71 on:** 03/12/2010 01:12 pm »

Based on some online forecasts for the Cape, there *might* be a slight break in the weather around 1-2 PM, i.e. fewer showers as opposed to heavy thunderstorms. Winds also don't appear to be as big an issue as yesterday.

Avron · « **Reply #72 on:** 03/12/2010 01:26 pm »

Quote from: ugordan on 03/12/2010 01:12 pm

Based on some online forecasts for the Cape, there *might* be a slight break in the weather around 1-2 PM, i.e. fewer showers as opposed to heavy thunderstorms. Winds also don't appear to be as big an issue as yesterday.

I would be impressed if they go for a test today.. it looks bad.. even if there is a small gap in the weather, its pushing things... maybe they can dry run the sequence with the valve connected.. or is that a waste of a cycle?

rdale · « **Reply #73 on:** 03/12/2010 01:37 pm »

Actually there are no storms in the area now - they are all on the west coast and moving east, so it'll get worse over the next few hours.

Kim Keller · « **Reply #74 on:** 03/12/2010 02:25 pm »

The rumblings I'm hearing say the next try will be tomorrow.

rdale · « **Reply #75 on:** 03/12/2010 02:32 pm »

Still pretty windy tomorrow (15-30mph) but dry.

mwfair · « **Reply #76 on:** 03/12/2010 02:45 pm »

I appreciate the 'beta' test nature of what they are doing, and it is no skin of my nose if they test/fail/test/fail for many months. Its all internal to SpaceX, at least up until launch day.

But the realization of a missing command in the integrated vehicleChassis / vehicleElectronics / groundEquipment is the sort of thing that is more suited to 'unit' test than to beta testing. In other words, this glitch is the sort of thing that is (I think) most economically caught by a systems engineering discipline within the organization of by an oversight group. In many cases this sort of disconnect would be discovered automatically by systems engineering and requirements management software tools. Anyone know if SpaceX is using DOORS? The second level of testing ought to be unit tests, which are designed to check for the existence and accuracy of the outputs of every software component. Oops for the guy who wrote the unit test for this part of the command sequencer.

So I think Elon's general point is valid, that they are testing. But beta testing is not really the right analogy. If Word 'forgot' to put the text on the screen during beta testing, then we would say they never should've released a beta.

Robotbeat · « **Reply #77 on:** 03/12/2010 02:51 pm »

Quote from: mwfair on 03/12/2010 02:45 pm

I appreciate the 'beta' test nature of what they are doing, and it is no skin of my nose if they test/fail/test/fail for many months. Its all internal to SpaceX, at least up until launch day.

But the realization of a missing command in the integrated vehicleChassis / vehicleElectronics / groundEquipment is the sort of thing that is more suited to 'unit' test than to beta testing. In other words, this glitch is the sort of thing that is (I think) most economically caught by a systems engineering discipline within the organization of by an oversight group. In many cases this sort of disconnect would be discovered automatically by systems engineering and requirements management software tools. Anyone know if SpaceX is using DOORS? The second level of testing ought to be unit tests, which are designed to check for the existence and accuracy of the outputs of every software component. Oops for the guy who wrote the unit test for this part of the command sequencer.

So I think Elon's general point is valid, that they are testing. But beta testing is not really the right analogy. If Word 'forgot' to put the text on the screen during beta testing, then we would say they never should've released a beta.

? That sort of thing happens often in software beta testing. Of course, Google has sort of twisted everyone's definition of "beta testing." But yeah, I agree that Falcon 9 shouldn't be considered fully operational until 2 or 3 consecutive flights to orbit. Of course by aircraft standards, every launch vehicle is in beta testing still (with the possible exception of the R-7 family of rockets).

mmeijeri · « **Reply #78 on:** 03/12/2010 02:53 pm »

Illustrates the old saying: end to end is further than you think. Also illustrates that bugs show up beyond the point where you've stopped testing.

RedLineTrain · « **Reply #79 on:** 03/12/2010 03:00 pm »

Quote from: kevin-rf on 03/12/2010 12:25 pm

What, no one today is clamoring for them to be able to launch into 40mph+ wind gusts through a lightening storm

I realize that this was said in jest, but I'm sure that SpaceX has robust ground wind design specs for the Falcon 9. SpaceX has stated the design spec on the Falcon 1 is 50 mph+ and "all weather."

The wind on Kwajalein Atoll is rather extreme and SpaceX wanted almost total availability despite those conditions. For instance, for the next week, there's not a day where winds are forecasted below 20 mph on Kwaj.