SpaceX COTS Demo 1 Updates

[ugordan]

A static fire gets you a lot of information (way more than nothing) about the stack you are about to fly very cheaply.

How different is that firing from the two extended burns on the VTS in Texas and where do you think is the point of diminishing returns on finding out anything useful with the pad static firings?

They already have two data points on SLC-40, one static firing and an actual launch. Another static test cannot add *that* much to the table.

[simonbp]

They already have two data points on SLC-40, one static firing and an actual launch. Another static test cannot add *that* much to the table.

Ah, but you're assuming that there have been no changes since the first flight. However, the software in Falcon 9 has almost certainly been updated since the first flight, and I wouldn't be surprised if there were also numerous mechanical tweaks. So, tanking tests and static fires allow them to test the tweaks, to make sure they don't break something else.

In other words it's a reminder that Falcon 9 is not a finished, full-operational rocket, and so is not following what others may define as a Standard Operational Procedure.

[ugordan]

However, the software in Falcon 9 has almost certainly been updated since the first flight, and I wouldn't be surprised if there were also numerous mechanical tweaks.

Which of the two couldn't have been tested in integrated stage tests in Texas? Why would engine roll bias software tweaks need a static firing?

[cheesybagel]

the static fire should be deleted.  WDR's are SOP for most vehicles

Falcon 9 has nine first stage engines. The first stage is substantially more complex than your average first stage. Anything that can test the first stage before a full flight reduces risk. What you are proposing is the same course of action used by the Russians for N1.

If the rocket blew up on the launch pad how much would you have saved by skimping on testing?

What you are proposing is the US auto manufacturer standard operating procedure. Saving money by reducing testing of subcomponents. The same policy which has lead GM to near bankruptcy. The truth is the earlier in the production chain you find an issue, the cheaper it is to solve it, plus you get more reliable hardware with more customer value.

The way to reduce costs for SpaceX will be to judiciously reduce the number of parts and manufacturing steps, or reusing their rockets, not skimping on testing.

[ugordan]

What you are proposing is the same course of action used by the Russians for N1.

Uh, no. You are aware this flight stage accumulated 40 + 90 seconds of test stand firing + probably another 20 s of individual engine acceptance test firings? Much more than EELV engines go through, not to mention the fact there are no integrated stage firings there.

A far cry from N1 which couldn't afford a single ground test.

[ngilmore]

The same policy which has lead GM to near bankruptcy.

Check your calendar. Both GM and Chrysler went through bankruptcy in 2009. Unless you are predicting another bankruptcy...
 

[cheesybagel]

What you are proposing is the same course of action used by the Russians for N1.

Uh, no. You are aware this flight stage accumulated 40 + 90 seconds of test stand firing + probably another 20 s of individual engine acceptance test firings? Much more than EELV engines go through, not to mention the fact there are no integrated stage firings there.

A far cry from N1 which couldn't afford a single ground test.

It does not take a lot of thinking to realize the stage could be damaged during transport from Texas to Florida. All it takes is a loose bolt or corroded nut.

Delta IV has one single first stage engine. Atlas V has a single first stage engine with two nozzles. Falcon 9 has nine first stage engines. Plus the associated tanks, plumbing, and control systems.

Another thing that can happen is different launch environments in Texas and Florida. Just because something works in the Texas test stand, it does not mean it will work in the Florida launch site. There were plenty of occurrences of issues like this during the static test firing campaign for the first Falcon 9.

[marsavian]

Inside SpaceX: Dragon Debut

http://www.spaceref.com/news/viewnews.html?id=1438

[Lars_J]

Inside SpaceX: Dragon Debut

http://www.spaceref.com/news/viewnews.html?id=1438

Sweet, the first COTS demo 1 Dragon image from the article: http://images.spaceref.com/news/2010/IMG_8390_KenKremer.jpg
(Interesting Draco covers, perhaps temporary until launch)

Some quotes from the article, regarding earlier speculation in this thread:

SpaceX engineers told me that the next step is to remove the Dragon from the Falcon 9 and place it on a processing cradle. At some point in early October, the spacecraft will be fueled with hypergolics - monomethyl hydrazine and nitrogen tetroxide - retested and then reattached to the Falcon 9 booster. Fueling will only be done after confirming the launch date due to the toxic nature of the propellants.

In mid-October, a static test firing of all 9 Merlin first stage engines will be conducted with an expected duration of three to five seconds - similarly to tests run by SpaceX prior to the first Falcon 9 launch. The test firing is planned for roughly a week prior to the actual launch, SpaceX engineers said to me.

The goal of the static firing is to test launch pad propellant and pneumatic systems as well as the ground and flight control software that controls pad and launch vehicle configurations and assure that all systems are "GO" in expectation of a launch.

SpaceX hopes to establish a Falcon 9 launch rate at pad 40 that supports approximately 12 liftoffs per year or one per month.

[Ronsmytheiii]

They already have two data points on SLC-40, one static firing and an actual launch. Another static test cannot add *that* much to the table.

Ah, but you're assuming that there have been no changes since the first flight. However, the software in Falcon 9 has almost certainly been updated since the first flight, and I wouldn't be surprised if there were also numerous mechanical tweaks. So, tanking tests and static fires allow them to test the tweaks, to make sure they don't break something else.

In other words it's a reminder that Falcon 9 is not a finished, full-operational rocket, and so is not following what others may define as a Standard Operational Procedure.

Yes, but what is so different between the testing environment in Texas? All these changes can be tried on the test stand, all WDR does is look good for the cameras.

[corrodedNut]

You guys are forgetting about the first F9 hot-fire abort back on March 9th:

"We tested everything on the vehicle side exhaustively in Texas, but didn't have this iso valve on our test stand there"

Even small things can make a big difference.

[Antares]

1) A static fire gets you a lot of information (way more than nothing) about the stack you are about to fly very cheaply.

2) Nobody else does it ... because they can't.

1) There are far better, safer and cheaper ways to do it.  If something got damaged in transport, then they have bad transportation practices.

If they're testing the rocket, they should have done that at the test stand.  If they're testing the pad, they don't need the rocket to do that.  If they're testing the integrated system... oh wait, Falcon 1 1-3 proved they need to work on that.

2) That's completely inaccurate.  Please post true facts.

[Lars_J]

Geez, I guess NASA are/were idiots for running pad hotfire tests too, then?





The more progress SpaceX makes, the more bizarre and/or irrational the detractors become.

[Jim]

\

I think *you* have an inaccurate view of vehicle processing. A static fire gets you a lot of information (way more than nothing) about the stack you are about to fly very cheaply. Nobody else does it ... because they can't.

Wrong on all accounts.
a.  Antares knows what he is talking about
b.  Static fires are not cheap and are more risky to hardware
c.  Others can do static fires but chose not to
d.  Static fires are unnecessary with good system engineering, good workmanship and good design.
e.  Static fires are development tests and not operational tests

[Jim]

They already have two data points on SLC-40, one static firing and an actual launch. Another static test cannot add *that* much to the table.

Ah, but you're assuming that there have been no changes since the first flight. However, the software in Falcon 9 has almost certainly been updated since the first flight, and I wouldn't be surprised if there were also numerous mechanical tweaks. So, tanking tests and static fires allow them to test the tweaks, to make sure they don't break something else.

In other words it's a reminder that Falcon 9 is not a finished, full-operational rocket, and so is not following what others may define as a Standard Operational Procedure.

Static fires are not for software testing.  They are only for propulsion system testing

[Jim]

Geez, I guess NASA are/were idiots for running pad hotfire tests too, then?

The more progress SpaceX makes, the more bizarre and/or irrational the detractors become.

Bad examples.  All new orbiters did a FRF and there was one for RTF


Who are the detractors?

Static fires for ELV are unnecessary especially if the stage has be hot fired

[Jim]

the static fire should be deleted.  WDR's are SOP for most vehicles

Falcon 9 has nine first stage engines. The first stage is substantially more complex than your average first stage. Anything that can test the first stage before a full flight reduces risk. What you are proposing is the same course of action used by the Russians for N1.

If the rocket blew up on the launch pad how much would you have saved by skimping on testing?

What you are proposing is the US auto manufacturer standard operating procedure. Saving money by reducing testing of subcomponents. The same policy which has lead GM to near bankruptcy. The truth is the earlier in the production chain you find an issue, the cheaper it is to solve it, plus you get more reliable hardware with more customer value.

The way to reduce costs for SpaceX will be to judiciously reduce the number of parts and manufacturing steps, or reusing their rockets, not skimping on testing.

Wrong, the N1 did no development testing.  This is past that stage.

The stage was already hot fired.

[spacetraveler]

Bad examples.  All new orbiters did a FRF and there was one for RTF

Well I think the point is, NASA determined the orbiters needed that. This is a new vehicle and SpaceX determined they needed that. I think they know their vehicle best, and a static fire while maybe not standard on other similar class vehicles is hardly an abnormal type of test.

Static fires for ELV are unnecessary especially if the stage has be hot fired

1. They don't want it to be expendable, they want to recover the first stage.

2. And even if it has been hot fired, there were tweaks to their system to eliminate roll off the pad. Perhaps they want to test pad loads or something. Also they had a problem previously with their test stand not having the exact same configuration as the pad. What's wrong with being extra careful knowing there is precedent for issues there?

[Jim]

Another thing that can happen is different launch environments in Texas and Florida. Just because something works in the Texas test stand, it does not mean it will work in the Florida launch site. There were plenty of occurrences of issues like this during the static test firing campaign for the first Falcon 9.

wrong, that is bad logic and would mean that spacex has bad engineering.

Because something works in the Texas test stand, it does mean it will work in the Florida launch site.
That is the reason for the test stand in TX, otherwise eliminate the stand in TX and use FL for everything.

+19 EELVs with only 1 pad test firings
+100 Delta II's with none

WDR's with off pad testing does everything necessary

[spacetraveler]

wrong, that is bad logic and would mean that spacex has bad engineering.

It doesn't necessarily mean their entire system is faulty, it could just mean they made a minor mistake, such as they uncovered in the previous flight.

Because something works in the Texas test stand, it does mean it will work in the Florida launch site.
That is the reason for the test stand in TX

Of course it is. But what your logic is saying is that if they didn't get it 100% right the first time (which they found out they didn't on the last flight) then they should just scrap the whole thing, which is absurd.

They had a minor mistake last time, hopefully they've corrected it now so the environments are identical. Doing a static firing as an extra verification that that is the case is a perfectly reasonable procedure.