Author Topic: SpaceX Falcon 9 (F9-S1-0024) Reuse Testing Coverage  (Read 63299 times)

Offline The Roadie

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #40 on: 07/29/2016 11:25 PM »
Another 145 second test tomorrow and I think we'll be able to discern their plans. :-)
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Offline enzo

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #41 on: 07/29/2016 11:39 PM »
From an engineering perspective, how well would the upper stage mass simulator be expected to simulate flight stresses? After all, it's no surprise the engines continue to fire well, but what concerns me more is the whole structure. The number of times it's fired doesn't necessarily correlate with flight readiness...
Yes I am aware most failures are engine related.

Offline rpapo

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #42 on: 07/30/2016 12:00 AM »
Yes I am aware most failures are engine related.
Traditionally, but SpaceX has been very untraditional in that sense.  I am sure that SpaceX has noted many, many minor failures in their 27+ flights, but what the public knows about so far are (ignoring the landing attempts): one engine failed in CRS-1, the Dragon RCS thrusters were temporarily out of commission in CRS-2 (?), and there was a structural failure in the second stage while still under first stage power in CRS-7.  Only that last failure was fatal.  AFAIK, their record for commercial customers with the Falcon 9 has been blemished only by launch scrubs.

That said, and especially now that they have five intact recovered booster stages to look at, I am quite sure that the SpaceX engineers have their hands full fixing newly discovered failures, both major and minor.  They are in what some would call "a target rich environment", with a lot of things to work on all of a sudden.
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Online meekGee

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #43 on: 07/30/2016 03:13 AM »
From an engineering perspective, how well would the upper stage mass simulator be expected to simulate flight stresses? After all, it's no surprise the engines continue to fire well, but what concerns me more is the whole structure. The number of times it's fired doesn't necessarily correlate with flight readiness...
Yes I am aware most failures are engine related.

It's a common problem that you can't replicate the real environment in testing.  Best example - fluid pressure on the bottom of the tank.

What you always do is characterize the test environment, make predictions on what effects IT will have on the system, and compare. 

The trick is to get the test environment into the same regimes as the real life environment (one way or the other).

So you do test firing, you do hydrostatic tests, you do external compression tests, vibe tests...  and for each you predict the response...

Remember that "test how you fly" or any of its variants is only an aspirational statement.  The longer version was "whenever practical, get as close to flight conditions, procedures, and practices as possible"...  But it wouldn't fit on the sign over the bathroom sink, so they had to shorten it.
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Online Melanchthon

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #44 on: 07/30/2016 06:49 AM »
Facebook group member Keith Wallace reported ANOTHER full duration test just now. Another $200,000 worth of propellant consumed for our amusement!

Quite a bit more, actually.

https://spaceflightnow.com/2016/03/31/spacex-hopes-to-sell-used-falcon-9-boosters-for-40-million/

“My CFO (chief financial officer) would kill me, but the cost of the fuel is $1 million, or maybe even under $1 million. It would be great if the first stage was maybe just 2x or 3x (2 to 3 times the cost) of that.” — Shotwell

So roughly $800,000.

Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #45 on: 07/30/2016 08:06 AM »
From an engineering perspective, how well would the upper stage mass simulator be expected to simulate flight stresses? After all, it's no surprise the engines continue to fire well, but what concerns me more is the whole structure. The number of times it's fired doesn't necessarily correlate with flight readiness...
Yes I am aware most failures are engine related.

It's a common problem that you can't replicate the real environment in testing.  Best example - fluid pressure on the bottom of the tank.

What you always do is characterize the test environment, make predictions on what effects IT will have on the system, and compare. 

The trick is to get the test environment into the same regimes as the real life environment (one way or the other).

So you do test firing, you do hydrostatic tests, you do external compression tests, vibe tests...  and for each you predict the response...

Remember that "test how you fly" or any of its variants is only an aspirational statement.  The longer version was "whenever practical, get as close to flight conditions, procedures, and practices as possible"...  But it wouldn't fit on the sign over the bathroom sink, so they had to shorten it.

Very good summary of the concepts utilized in ground testing for rocketry. It is my understanding that the main issue with ground testing is the inability to combine the numerous variables that come together during actual launch conditions. As such, the best SpaceX can do is simulate and combine as many as possible at once, or test each individual variable significantly beyond the predicted (or measured) stresses each component experiences.

Furthermore, I suspect that SpaceX has a mind-boggling array of sensors that collect data for each location on the rocket and likely each major component. This would allow them to very effectively characterize the environment each component experiences throughout launch and thus quite effectively test each component individually, on the ground.

Offline geza

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #46 on: 07/30/2016 10:18 AM »
Great explanations, thanks! I am just curious: Does a stage test fire include testing the TVC system? Whether is it still operational in that thermal environment?

Online AncientU

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #47 on: 07/30/2016 12:06 PM »
From an engineering perspective, how well would the upper stage mass simulator be expected to simulate flight stresses? After all, it's no surprise the engines continue to fire well, but what concerns me more is the whole structure. The number of times it's fired doesn't necessarily correlate with flight readiness...
Yes I am aware most failures are engine related.

One thing the static loading can simulate is full axial load on the first stage when it is at cryogenic temperatures and pressurized for firing.  Not sure if this is peak loading, but is a case that can be tested statically during hot fire.

On reviewing the firing video, looks like the interstage has no grid fins(not completely clear, but that is what I see), so just a structural test article.
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Offline Jim

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #48 on: 07/30/2016 12:17 PM »


Furthermore, I suspect that SpaceX has a mind-boggling array of sensors that collect data for each location on the rocket and likely each major component. This would allow them to very effectively characterize the environment each component experiences throughout launch and thus quite effectively test each component individually, on the ground.

They don't.  See CRS-5

Online AncientU

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #49 on: 07/30/2016 12:18 PM »
Wow. Whatever the refurbishment between recovering the stage and yesterday's test, I think we can be pretty confident there was little change since yesterday!

IIRC Elon has suggested SpaceX is aiming for something like 10 flights per engine with minimal work required. Not expecting them to get to 10 with this stage, as they may hit an unexpected limiting factor, but my guess is that's the number they're working towards. I'd guess at least a couple more tests with this stage, which would suggest at least a couple of re-uses per stage is well within bounds. That feels to me like minimum confidence needed for a customer to commit to a first re-use.

This also argues for the engines being the original set.  The structural test should be one and done... engine reusability is now being tested IMO.
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Offline inonepiece

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #50 on: 07/30/2016 03:48 PM »
Facebook group member Keith Wallace reported ANOTHER full duration test just now. Another $200,000 worth of propellant consumed for our amusement!

Quite a bit more, actually.

https://spaceflightnow.com/2016/03/31/spacex-hopes-to-sell-used-falcon-9-boosters-for-40-million/

“My CFO (chief financial officer) would kill me, but the cost of the fuel is $1 million, or maybe even under $1 million. It would be great if the first stage was maybe just 2x or 3x (2 to 3 times the cost) of that.” — Shotwell

So roughly $800,000.

I don't know what she's including in that figure, but from the raw materials figures I have jotted down for the first stage from past googlings (apologies for lack of citations):

276,600 kg LOX
119,100 kg RP-1

at $60 per tonne of LOX and $3.60 per gallon RP-1, that's about:

LOX $17000
RP-1 $140000

i.e. about $160,000 total for the first stage.  I think Musk has mentioned a figure of $200,000, so that tallies.

Obviously there are all kinds of other fixed and one off costs associated with a test.  Shotwell explicitly said in the report you quote that she was being guarded about costs.  Also, she was talking about the possibility of achieving (per flight) first stage costs comparable to propellant costs.  That may have prompted her pick assumptions for accounting for fuel costs that give a low multiple of first stage build cost to refueling cost, in order to present reusability in its best light.  Perhaps she was choosing to quote just the order of magnitude.

Exciting to think there's a chance we'll see a lot more of these tests soon on this rocket!

Offline DOCinCT

Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #51 on: 07/30/2016 04:36 PM »
Considering that the 2nd stage is not reusable, launch costs can never be just propellant costs.  With several reuses, maybe 50% less?

Offline LastStarFighter

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #52 on: 07/30/2016 04:52 PM »
Considering that the 2nd stage is not reusable, launch costs can never be just propellant costs.  With several reuses, maybe 50% less?

I thought they stated first stage reuse could only lower costs by 30%

Online AncientU

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #53 on: 07/30/2016 05:30 PM »
Considering that the 2nd stage is not reusable, launch costs can never be just propellant costs.  With several reuses, maybe 50% less?

I thought they stated first stage reuse could only lower costs by 30%

Price, not cost.
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Offline Nomadd

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #54 on: 07/30/2016 05:48 PM »
Considering that the 2nd stage is not reusable, launch costs can never be just propellant costs.  With several reuses, maybe 50% less?
Reusing 90% of the engines, which are the most expensive things, the interstage and main thrust structure might save more than 50%.

Offline rpapo

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #55 on: 07/30/2016 06:13 PM »
Considering that the 2nd stage is not reusable, launch costs can never be just propellant costs.  With several reuses, maybe 50% less?
Reusing 90% of the engines, which are the most expensive things, the interstage and main thrust structure might save more than 50%.
That may be true, but AncientU has a good point: price <> cost.  In fact, to stay in business, product price must be greater than product cost when averaged out over all product sold.  And for SpaceX, the product is launches for payloads.  SpaceX needs enough profit to fund it's development program, and eventually trips to Mars.  They're not a charity.

Pardon me if I'm being too obvious, but it seems some people lose sight of the obvious.
« Last Edit: 07/30/2016 06:24 PM by rpapo »
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Offline meberbs

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #56 on: 07/30/2016 06:28 PM »
Considering that the 2nd stage is not reusable, launch costs can never be just propellant costs.  With several reuses, maybe 50% less?
Reusing 90% of the engines, which are the most expensive things, the interstage and main thrust structure might save more than 50%.
Don't forget that there is more to launch costs than hardware and fuel. Integration, range time and other support, pre-launch testing, etc. all contribute to cost as well. These are a bigger slice of the pie than most people realize. Remember that the GPS launch contract is $82 million. That is a full $20 M more than a standard F9 launch, and the DoD was surprised it was that cheap even though they knew the standard price.

I don't know how much of the standard price is related to non-hardware costs, but I would guess > $10M. This is something SpaceX is probably working in the background to bring down.

Online AncientU

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #57 on: 07/30/2016 06:59 PM »
Considering that the 2nd stage is not reusable, launch costs can never be just propellant costs.  With several reuses, maybe 50% less?
Reusing 90% of the engines, which are the most expensive things, the interstage and main thrust structure might save more than 50%.

First stage was quoted by EM as 75% of the vehicle cost.  As discussed a while back, if all the cost savings are passed on to the customer in that 30% price break (about $20M), and assuming zero refurbishment cost, that makes the total hardware cost around $26.7M.  If a nominal refurbishment cost is $3-5M, then the hardware total cost would be around $32M (again assuming that all of the savings were passed on to the customer). 

Bottom line from my perspective is that hardware cost is about half of the standard launch price of $62M -- if a 50% price reduction is going to happen (without second stage reuse), a chunk of it has to come from more efficient ground ops.
« Last Edit: 07/30/2016 07:00 PM by AncientU »
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Online Chris Bergin

Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #58 on: 07/30/2016 08:21 PM »
Oh, just another full duration test - see:
https://www.facebook.com/groups/spacexgroup/

https://www.facebook.com/groups/spacexgroup/permalink/10154437920066318/

That's three for those keeping count.

Six if you consider:

McGregor.
Static Fire SLC-40.
Launch.
McGregor R1
McGregor R2
McGregor R3

(Heck, there were also the entry and landing burns!)

Offline rpapo

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Re: SpaceX Falcon 9 (F9-0024-S1) Reuse Testing Coverage
« Reply #59 on: 07/30/2016 08:24 PM »
(Heck, there were also the entry and landing burns!)
Yes, but those were by The One and The Three, as opposed to The Nine.
« Last Edit: 07/30/2016 08:25 PM by rpapo »
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