Author Topic: Refurbishment of Used Stages/Vehicles  (Read 149585 times)

Offline gin455res

  • Full Member
  • ***
  • Posts: 315
  • bristol, uk
  • Liked: 7
  • Likes Given: 18
Re: Refurbishment of Used Stages/Vehicles
« Reply #700 on: 08/19/2017 07:15 AM »
Is there any information on which parts of the falcon are predicted to wear out fastest?

e.g.  Might the cooling channels degrade faster than the turbo-pumps?

any thoughts on hypothetical f9 used part economics could be interesting

Online speedevil

  • Full Member
  • **
  • Posts: 252
  • Fife
  • Liked: 123
  • Likes Given: 102
Re: Refurbishment of Used Stages/Vehicles
« Reply #701 on: 09/04/2017 10:59 AM »
Is there any information on which parts of the falcon are predicted to wear out fastest?

Well, for stuff we know wears out - crush cores in the legs, fairing and second stage  are both one-use, as well as payload adaptors.

At least some, perhaps most of the ablative under the engines covering 'stuff' seems likely to at least need monitoring if not replacement every flight.
The grid fins used to wear quite a lot - titanium may wholly fix this.
NASA have expressed concerns about cracking in turbopump rotors, but it's not clear if this is a wear item.

The paint often seems rather torn up.

Offline obi-wan

  • Full Member
  • **
  • Posts: 252
  • Liked: 571
  • Likes Given: 3
Re: Refurbishment of Used Stages/Vehicles
« Reply #702 on: 09/04/2017 04:07 PM »
Is there any information on which parts of the falcon are predicted to wear out fastest?

Well, for stuff we know wears out - crush cores in the legs, fairing and second stage  are both one-use, as well as payload adaptors.

At least some, perhaps most of the ablative under the engines covering 'stuff' seems likely to at least need monitoring if not replacement every flight.
The grid fins used to wear quite a lot - titanium may wholly fix this.
NASA have expressed concerns about cracking in turbopump rotors, but it's not clear if this is a wear item.

The paint often seems rather torn up.
A friend at SpaceX (who is extremely closed-mouthed about everything) said that one thing he could tell me is that you will recognize a Block 5 first stage instantly by the heat shields around the base - it's going to be all Inconel.

Online gongora

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1641
  • US
  • Liked: 1082
  • Likes Given: 862
Re: Refurbishment of Used Stages/Vehicles
« Reply #703 on: 09/04/2017 04:53 PM »
A friend at SpaceX (who is extremely closed-mouthed about everything) said that one thing he could tell me is that you will recognize a Block 5 first stage instantly by the heat shields around the base - it's going to be all Inconel.

It will be interesting to see which of the fancy new bits gets left off of any expendable launches on Block 5.

Online Space Ghost 1962

  • Senior Member
  • *****
  • Posts: 2273
  • Whatcha gonna do when the Ghost zaps you?
  • Liked: 2036
  • Likes Given: 1498
Re: Refurbishment of Used Stages/Vehicles
« Reply #704 on: 09/04/2017 05:05 PM »
Shades of X-15 and X-20 (Dynasour) inconel hot structures. Likely they'll still be smoking after landing.

(Shuttle glass tiles retained heat internally long after - under test "bricks" you could see had still "melted" centers.)

add:

If they don't mind a little mild radioactivity, they could instead use HK31, an alloy of magnesium, thorium, and zirconium which is no longer in use since the three percent that is thorium makes the alloy radioactive.

It's much lighter and reradiates heat faster while still retaining the same thermal capacity.
« Last Edit: 09/04/2017 05:17 PM by Space Ghost 1962 »

Offline theinternetftw

  • Member
  • Posts: 7
    • www.theinternetftw.com
  • Liked: 41
  • Likes Given: 53
Re: Refurbishment of Used Stages/Vehicles
« Reply #705 on: 09/04/2017 08:42 PM »
If they don't mind a little mild radioactivity, they could instead use HK31, an alloy of magnesium, thorium, and zirconium which is no longer in use since the three percent that is thorium makes the alloy radioactive.

It's much lighter and reradiates heat faster while still retaining the same thermal capacity.

For general reference, mild in this case means routine handling of this kind of metal results in about one cranial CT scan worth of radiation every 4 years (note that this is for the amount expected to be used in aircraft).  An extended vacation on the beaches of Guarapari, Brazil can result in a greater dose of radiation in a much shorter period of time, and those beaches are routinely well-populated.

Of course, the opposing argument is, "If you can do the job and not irradiate people, why don'tcha?"

Online Space Ghost 1962

  • Senior Member
  • *****
  • Posts: 2273
  • Whatcha gonna do when the Ghost zaps you?
  • Liked: 2036
  • Likes Given: 1498
Re: Refurbishment of Used Stages/Vehicles
« Reply #706 on: 09/04/2017 09:49 PM »
If you measure the radiation off of brick walls/walkways/hearths/chimneys, you'll have a 1:5 chance of finding more radioactive sources as the clays had a tendency to be rich in various radioactive materials.

Some parts of the US, Russia, Iran, and others have surface radioactive soils too.

In the 1970's we were calibrating a scintillation counter with a source. When the source was withdrawn, there were still counts. Traced it back to the brick walkway and mentioned it to the facilities people after lead shielding the side of the wall so we could get on with the instrument work.

Over the period of years I'd look out the window and see increasing visits of university, city, county, state, federal safety personnel/officials visit/measure the bricks,  then eventually "surgically" remove them (had the "hottest" one properly secured for measurement/analysis which was quite entertaining) and they restored the brickwork carefully - it was a well traveled campus path). Very much in excess of health standards. The brickwork had been done in the 60's.

The biggest problem is expecting reasonable care in an ignorant environment, which seems to be vastly larger than it was then. Imagine a rocket explosion/failed landing and having to find all the pieces and prove there's no radiation hazard present. Our culture isn't mature enough for such, thus the heavier, greater heat retention inconel makes sense over the more performant thorium laced alloy (which has gotten even better since the 70's).

If we can't handle minor radioactive situations, no wonder nuclear rocketry has zero chance, even though we are about to max out chemical propulsion, and its next after EP.

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 5733
  • Everyplaceelse
  • Liked: 713
  • Likes Given: 4129
Re: Refurbishment of Used Stages/Vehicles
« Reply #707 on: 09/06/2017 04:51 PM »
In the 1970's we were calibrating a scintillation counter with a source. When the source was withdrawn, there were still counts. Traced it back to the brick walkway and mentioned it to the facilities people after lead shielding the side of the wall so we could get on with the instrument work.
I'd take a wild guess and suspect it could be  traced back to the debris from some of the 1st generation reactors built for (and disposed of) by the Manhattan project.

IIRC an aerial survey with the right gear showed various highways whose hard core substructure was basically crushed reactor concrete.

The Magnesium Thorium alloy you mentioned rings a bell. Was it also used on the BOMARC missile?

Old NASA and DTIC reports suggested "Thoriated Dispersion" alloys had quite a future back in the early 70's due to their very good high temperature performance, until of course the R word started to be discussed more loudly.  :(

I'd say "If only there was a way to make 'Depleted Thorium' cheaply," but people would probably only worry that "OMG, you've got enriched  Thorium. Are you trying to make a bomb?" :( despite the idea of a Thorium bomb being a plot for a straight-to-download video. IOW a total fantasy.

One option that rarely seems to be looked at in the US are the FeCrAlY (AKA "Fecralloy") alloys developed by the UK AEA and tested extensively for cladding pipe and plates. Highly resistant to oxidation and sulfurization and relatively low density, but not very high mechanical strength. So not a bad choice for facing a thermal shield, with any additional strength provided by the structure behind it.

TBH I've become quite weary of reading test reports on high temperature testing of materials as so little of it seems to apply to rocket engines or space craft heat shields. Their test criteria make no sense in that context.

Say a perfectly good alloy survives 900 hrs of continuous heating but does not survive 1000 hours. It's considered "failed."
So what? It's no good for use in a land gas turbine generator. OTOH an RLV rocket engine runs for maybe 10mins at a time (and most of the test firings won't even be that), then soaks back to ambient before (possibly) starting again for re-entry. A 900 hr operating life would be literally 1000s of missions, or 900 launches and 50 mins of test firing per launch (imagine that. That's a lot of test firing.  :) )

TPS materials seem to have been cyclically tested a bit better but again weren't most lifting re-entries outside Shuttle finished in < 15 minutes? AFAIK Shuttle, Buran or X37b are (or were) down in less than 90 minutes anyway.   
« Last Edit: 09/06/2017 04:55 PM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Online Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 8160
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 4913
  • Likes Given: 3334
Re: Refurbishment of Used Stages/Vehicles
« Reply #708 on: 09/06/2017 06:17 PM »
Thorium alloys and nuclear propulsion might not be on topic.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Online Space Ghost 1962

  • Senior Member
  • *****
  • Posts: 2273
  • Whatcha gonna do when the Ghost zaps you?
  • Liked: 2036
  • Likes Given: 1498
Re: Refurbishment of Used Stages/Vehicles
« Reply #709 on: 09/07/2017 05:55 AM »
One of the costs of refurbishment of the Shuttle's TPS was the need to address the multiple elements of its design and fabrication, for it to function on the next flight. Hot structures don't just function by themselves, you need to have supports and means to isolate / attach them. Even the choice of materials / alloys can become critical to such.

Heat capacity and convection/conduction of materials matters a great deal, as well as the means to support repeatable use, possibly w/o refurbishment.

Earlier use of thoriated alloys allowed for some of these options, which is why it was brought up, as an alternative to much more heavy inconel. An old trade for those that remember it.

Not to mention some of the work the DLR did also on metallic heat shields for X-38.

add:
(Alludes to some of this: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080014278.pdf )
« Last Edit: 09/12/2017 08:52 PM by Space Ghost 1962 »

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 5733
  • Everyplaceelse
  • Liked: 713
  • Likes Given: 4129
Re: Refurbishment of Used Stages/Vehicles
« Reply #710 on: 09/07/2017 09:45 AM »
One of the costs of refurbishment of the Shuttle's TPS was the need to address the multiple elements of its design and fabrication, for it to function on the next flight. Hot structures don't just function by themselves, you need to have supports and means to isolate / attach them. Even the choice of materials / alloys can become critical to such.
Indeed. People seem to forget there's a reason they are called thermal protection systems

Possibly the worst case of that I'm aware of was the Shuttle tiles. Amazing thermal properties but during the whole process no one seemed to ask "What happens when you bond a brittle material to a ductile one which expands 3x as much per degree rise in temperature, and then apply a flight level temperature gradient."

Pity, as NASA patented a mechanical fastener to cope with bolting RCC, or large pieces of tile to a metal substructure in the early 80's.  :( 
Truly one of those "if only" moments. 20 000 tiles reduced to 200? On the upside still available (and long out of patent) for anyone who wants a hot skin/cold structure design. Maybe one day.
Quote from: Space Ghost 1962
Heat capacity and convection/conduction of materials matters a great deal, as well as the means to support repeatable use, possibly w/o refurbishment.
I've just heard the interview Dave Masten recently gave on the "Broadsword" dual expander Methalox engine.
In theory Aluminum is a non starter for a rocket combustion chamber, but people forget that's exactly what Bell Aerospace made the CC for the Agena engine out of.
It's not how hot you can run. It's how fast you can get the heat out of it while you're running it that counts.  :) Something John Carnack also rediscovered.
Unfortunately to really go with this I think you'd have to develop a blanket of flexible heat pipes, as active cooling just seems far too risky for most people (although HMX did some work on it).
Quote from: Space Ghost 1962
Earlier use of thoriated alloys allowed for some of these options, which is why it was brought up, as an alternative to much more heavy inconel. An old trade for those that remember it.
There was a time... <sigh>.
Amazes me there's still a market for parts in Beryllium.
Quote from: Space Ghost 1962
]
Not to mention some of the work the DLR did also on metallic heat shields for X-38.
That is a surprise.
I thought they were very keen on CMC, especially RCC, and the idea of tesselating the surface with flat pieces of RCC to deliver the aerodynamics of sharp edged curves with relatively easy mfg  EG water jet cutting.
« Last Edit: 09/07/2017 08:38 PM by john smith 19 »
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Tags: