Author Topic: Using Carbon Composite tanks for F9/FH Impacts on payload capability  (Read 18144 times)

Offline john smith 19

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Regarding high temp auto-pressurization: 
How thick does a layer of epoxy have to be to prevent reaction to LOx?  Is a linerless tank simply lined with extra epoxy from the molding process?
I think it's a bit more subtle than that.

You've got competing processes between the "hot" GO2 (400F, 205c in the case of the Aerojet Orbital tug dual expander drive concept of 1994) and the mixing with the existing tank ullage contents before hitting the walls. Assuming the GO2 is still hot enough to react it then depends how much thermal mass is in the polymer layer and how cold it is wheather it can quench the GO2 faster than the GO2 can start it burning, either across the surface or at hotspots caused by a rough surface layer before the heat of the reaction diffuses into the rest of the layer and shuts it down.

This is clearly a job for CFD. Fortunately what's available for a given price has improved a lot in 25 years.

So thick enough, smooth enough and cold enough (and not placing the tank inlets too near the walls) and the gas could be pretty warm without an issue.

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Offline john smith 19

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My gut tells me that as a grotesque over-reaction to the foam strike on an RCC leading edge loss of a Shuttle, that NASA has baked into their requirements some quite unrealistic assumptions.  Are the engineering justifications for that requirement as written available?
Possible.  :(

It depends if they date from the Shuttle days or if they go back much further.

I'd never heard of bird strike as an issue. That said didn't Mercury and Gemini ride inside fairings?
 Apollo had the "eyelid" due to concerns about exhaust from the emergency escape system motors cutting visibility after they fired on separation and covered the windows?
Quote from: tdperk
Are there any recorded birdstrikes in launch vehicle history?
It does sound like it would the sort of thing that would stick in your mind but I can't recall one.
Quote from: tdperk
How many launches have there been?
Globally since 1956 10 000+? 20 000?

However some of them may have failed without a final root cause being established, so a bird strike could be lurking in the data somewhere (y'know, absence of evidence <> evidence of absence  :( )
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Jim

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Are there any recorded birdstrikes in launch vehicle history?



Offline Jim

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That said didn't Mercury and Gemini ride inside fairings.

No


 Apollo had the "eyelid" due to concerns about exhaust from the emergency escape system motors cutting visibility after they fired on separation and covered the windows?

No, Apollo had a Boost Protective Cover that was jettison with the LES

http://www.collectspace.com/resources/reviews/model/saturn_v_04.jpg

Offline Jim

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or detecting if the birds are flying above the launch pad and only launching if there is a clear path.  One of the three has to be possible.  I could see drones chasing birds away as one solution.

https://www.nasa.gov/mission_pages/shuttle/behindscenes/avian_radar.html

Offline Lars-J

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Are there any recorded birdstrikes in launch vehicle history?




Wow, I had not seen that before. I imagine the sound basically disabled them (full on panic), but they were dead anyway... The radiant heat of the SRB's would have fried them even if they tried to fly away at full speed.

Offline tdperk

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Are there any recorded birdstrikes in launch vehicle history?

[ duplicative video deleted ]

Wow, I had not seen that before. I imagine the sound basically disabled them (full on panic), but they were dead anyway... The radiant heat of the SRB's would have fried them even if they tried to fly away at full speed.

Gotta tell you, if I'd seen that I wouldn't be worried about the bird.

Still about, what, two seconds from launch it was doing 30mph?  No visible change in the foam.

I have to believe a CC tank would be far more resistant to damage.

I cannot find any engineering justification for the problematic birdstrike resistance requirement, or even yet what that requirement is.
« Last Edit: 08/17/2017 07:15 PM by tdperk »

Offline Jim

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Still about, what, two seconds from launch it was doing 30mph?  No visible change in the foam.

That is Columbia type thinking.

Offline tdperk

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Still about, what, two seconds from launch it was doing 30mph?  No visible change in the foam.

That is Columbia type thinking.

No, the Columbia type thinking is seeing damage and imagining it is not relevant, because it has not been yet.

Observing that birdstrikes at that speed cause no damage is the beginning of an engineering assessment as to what is a hazard, putting a lower bound to the issue with respect to a structure which is no longer in use.

Burdening Commercial Crew with excuseless requirements which NASA itself does not intend to meet with it's own vehicles is politics. 

I cannot find any engineering justification for the problematic birdstrike resistance requirement, or even yet what that requirement is.
« Last Edit: 08/17/2017 07:20 PM by tdperk »

Offline Jim

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Still about, what, two seconds from launch it was doing 30mph?  No visible change in the foam.

That is Columbia type thinking.

No, the Columbia type thinking is seeing damage and imagining it is not relevant, because it has not been yet.

Observing that birdstrikes at that speed cause no damage is the beginning of an engineering assessment as to what is a hazard, putting a lower bound to the issue with respect to a structure which is no longer in use.


Just wrong.  Columbia type thinking is seeing an impact and  hand waving it away just as you did.
« Last Edit: 08/17/2017 07:35 PM by Jim »

Offline tdperk

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Still about, what, two seconds from launch it was doing 30mph?  No visible change in the foam.

That is Columbia type thinking.

No, the Columbia type thinking is seeing damage and imagining it is not relevant, because it has not been yet.

Observing that birdstrikes at that speed cause no damage is the beginning of an engineering assessment as to what is a hazard, putting a lower bound to the issue with respect to a structure which is no longer in use.


Just wrong.  Columbia type thinking is seeing an impact and  hand waving it away just as you did.

No, you are just wrong.  The history of NASA's mismanagement of it's human spaceflight program is of seeing actual damage and ignoring it.  Observing no damage is a very different thing.

For O-rings to ice to presumably damage to tiles caused by shed foam, NASA ignored actual damage caused by it's piss poor engineering, and carried on as before in spite of that observed damage and the plausibility that the damage could be far worse later.

Observing no damage /= observing damage.

But imagining "no damage" = "damage"...that is the sort of paralysis by meaningless and endless analysis (and I mean that two ways, endless by being indefinite and endless by way of having no point) which will prevent NASA from getting anything done worthwhile if it is allowed to continue even if it is given twice it's current budget.  You can always spend all the money and time you have making something metriclessly "more safe".

And it may be "safe" for a government bureaucrat pretending to be an engineer to do just that, the Iron Laws of Bureaucracy being what they are.

The fact a material as well characterized as the foam on the ET was, sustains no damage from a birdstrike at about 30mph provides good info as to what kind of hazard a birdstrike poses to a CF structure. Where is the evidence the birdstrike requirement spoken of in this thread is driven by engineering? What is that requirement, exactly?

When arriving at it, did they remember to thaw the bird?
« Last Edit: 08/17/2017 08:45 PM by tdperk »

Online Ictogan

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No, you are just wrong.  The history of NASA's mismanagement of it's human spaceflight program is of seeing actual damage and ignoring it.  Observing no damage is a very different thing.

For O-rings to ice to presumably damage to tiles caused by shed foam, NASA ignored actual damage caused by it's piss poor engineering, and carried on as before in spite of that observed damage and the plausibility that the damage could be far worse later.

Observing no damage /= observing damage.

But imagining "no damage" = "damage"...that is the sort of paralysis by meaningless and endless analysis (and I mean that two ways, endless by being indefinite and endless by way of having no point) which will prevent NASA from getting anything done worthwhile if it is allowed to continue even if it is given twice it's current budget.  You can always spend all the money and time you have making something metriclessly "more safe".

And it may be "safe" for a government bureaucrat pretending to be an engineer to do just that, the Iron Laws of Bureaucracy being what they are.

The fact a material as well characterized as the foam on the ET was, sustains no damage from a birdstrike at about 30mph provides good info as to what kind of hazard a birdstrike poses to a CF structure. Where is the evidence the birdstrike requirement spoken of in this thread is driven by engineering? What is that requirement, exactly?

When arriving at it, did they remember to thaw the bird?
So you are concluding that bird strikes are safe for all vehicles from a single video where a bird strike did not do visually obvious damage to one vehicle. Right.

Columbia type thinking is seeing potential issues, but just handwaving them away because they happened before without any actual failure.

Offline tdperk

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No, you are just wrong.  The history of NASA's mismanagement of it's human spaceflight program is of seeing actual damage and ignoring it.  Observing no damage is a very different thing.

For O-rings to ice to presumably damage to tiles caused by shed foam, NASA ignored actual damage caused by it's piss poor engineering, and carried on as before in spite of that observed damage and the plausibility that the damage could be far worse later.

Observing no damage /= observing damage.

But imagining "no damage" = "damage"...that is the sort of paralysis by meaningless and endless analysis (and I mean that two ways, endless by being indefinite and endless by way of having no point) which will prevent NASA from getting anything done worthwhile if it is allowed to continue even if it is given twice it's current budget.  You can always spend all the money and time you have making something metriclessly "more safe".

And it may be "safe" for a government bureaucrat pretending to be an engineer to do just that, the Iron Laws of Bureaucracy being what they are.

The fact a material as well characterized as the foam on the ET was, sustains no damage from a birdstrike at about 30mph provides good info as to what kind of hazard a birdstrike poses to a CF structure. Where is the evidence the birdstrike requirement spoken of in this thread is driven by engineering? What is that requirement, exactly?

When arriving at it, did they remember to thaw the bird?
So you are concluding that bird strikes are safe for all vehicles from a single video where a bird strike did not do visually obvious damage to one vehicle. Right.

No, I've said nothing like that.  That is a data point however.

Columbia type thinking is seeing potential issues, but just handwaving them away because they happened before without any actual failure.

And the issues seen were actual damage which was waived away.  Not hypothetical damage for which there was not merely no evidence, but in fact evidence there was no damage.

Obviously Jim disagrees but I do not think the point is one without distinction.

Now if a train of thought descending from this imagery had resulted in examination of what would happen with hits higher and faster, and the "shotgun" effect of a bird hitting the foamed ET had been extrapolated to the worst case of a single foam piece, maybe with adhered ice, hitting a stressed RCC leading edge in conjunction with the fact foam pieces were regularly falling off throughout the flight in the regular launch profile...then that could have been productive.

But it is still true that the knowledge that foam was regularly falling off throughout the flight in the regular launch profile was generally known and not followed up, even though damage to tiles was seen.  Was all the damage to tiles always traced to a definite cause?  No way to know now how much was from foam strikes, and probably no point either.  The Shuttle can no longer be improved.

But the birdstrike requirement giving delay to Commercial crew can be looked at for pertinency.
« Last Edit: 08/17/2017 09:46 PM by tdperk »

Offline Eric Hedman

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or detecting if the birds are flying above the launch pad and only launching if there is a clear path.  One of the three has to be possible.  I could see drones chasing birds away as one solution.

https://www.nasa.gov/mission_pages/shuttle/behindscenes/avian_radar.html
Interesting line from this link: "If the test proves successful, the unit's location will allow it to monitor either of the launch pads at Launch Complex 39 during future space shuttle launches, providing a new margin of safety for astronaut crews."
Does anyone know how well this worked?

Offline oldAtlas_Eguy

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This has wandered away from the point of the tread. Which is how a carbon composite tank affects the payload and operations such as recovery of boosters. Bird strikes is not any more of a concern by a carbon composite tank than for other LV designs.

Offline woods170

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<snip>
The fact a material as well characterized as the foam on the ET was, <snip>
This is a flaw in your thinking.

The foam on the ET was NOT well characterized, nor was it well understood. It kept surprising the engineers (both NASA and non-NASA) and NASA management until the very last shuttle flight.
One of the prime lessons from the shuttle program is that you do NOT expose your vehicle's TPS to ill-characterized, ill-understood, debris-shedding, elements of the launch vehicle. Or haven't you noticed how NASA has made a very big deal of hardening Orion's backshell and completely encasing Orion's primary TPS in the CMA? Not to mention putting the spacecraft on top of the launch vehicle in stead of side-mounting it.

Most notable surprise-moments from shuttle:
- When a seemingly "harmless" suitcase-sized piece of ET foam managed to put an 16" by 16" hole in an RCC panel during one of the CAIB tests. That result quite literally dropped the jaws on a boatload of engineers and management and proved to be the "smoking-gun" evidence for what happened to Columbia.
- When the supposedly "fixed" foam-loss problem turned out to be very much NOT fixed on STS-114 (the first Return To Flight mission after Columbia). It initiated a "Take 2" on fixing the ET foam loss problem and yet another stand-down for the space shuttle.
- Every monitored shuttle mission since STS-114 observed multiple instances of ET foam loss, despite the problem now supposedly having been fixed... Twice... Fortunately, most of those pieces were very small.
« Last Edit: 08/18/2017 12:20 PM by woods170 »

Online TomH

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Do I infer correctly that if the radar spots the vultures just before launch that it is scrubbed? Or can the same radar target a focused sonic weapon, shotgun, etc? Do the environmental protections in place prohibit those?

Offline john smith 19

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This has wandered away from the point of the tread. Which is how a carbon composite tank affects the payload and operations such as recovery of boosters. Bird strikes is not any more of a concern by a carbon composite tank than for other LV designs.
I can think of a couple of points.
1) It depends on the "exchange rate" between stage mass and payload to orbit. IIRC this is quite high for a first stage (13 to 1?). This is good news for recovery hardware as you can put 13 (lbs, Kgs, bananas) of hardware on the booster and loose 1 in payload to orbit.

But this leverage is not so good for mass reduction. You have to lose a lot of stage mass to make it worthwhile to (this was a key discovery of Arthur Schnitlers design to cost studies, which lead to the "Sea Dragon" chain of thinking).  :(

Then you've got composite structure reuse. NDE for flight damage and failure modes which are different from metal tanks. Yes H2 COPVs flew dozens of times on the Shuttle so we know it's possible, but is it desirable??

Composite tanks are like 3D printing. You can duplicate existing structures with it but that does not play to the strengths of the technology.

That suggests you're looking at clean sheet design for the stage, and once you've done that you're looking at doing the US as well. You're also looking at scrapping the FSW technology they've used so far for a completely different materials and mfg approach. That has serious cost implications.

Given SX seems more focused on costs than other LV mfgs. This does not seem worth the gain for the massive stand down. F9 is not broke, why fix it?
« Last Edit: 08/18/2017 08:18 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline john smith 19

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Most notable surprise-moments from shuttle:
- When a seemingly "harmless" suitcase-sized piece of ET foam managed to put an 18" by 18" hole in an RCC panel during one of the CAIB tests. That result quite literally dropped the jaws on a boatload of engineers and management and proved to be the "smoking-gun" evidence for what happened to Columbia.
- When the supposedly "fixed" foam-loss problem turned out to be very much NOT fixed on STS-114 (the first Return To Flight mission after Columbia). It initiated a "Take 2" on fixing the ET foam loss problem and yet another stand-down for the space shuttle.
- Every monitored shuttle mission since STS-114 observed multiple instances of ET foam loss, despite the problem now supposedly having been fixed... Twice... Fortunately, most of those pieces were very small.
Note however that AFAIK this occurred after H&S concerns about some of chemicals used to make and spray the foam lead to a change in the mixture.  I think this was ruled a "minor" change, so did not require the full battery of tests the original formulation had passed acceptably.

However this was compounded by programme officials who did not believe that something with the consistency of a ceiling tile could do any damage to something as strong and rigid as RCC.

Except things change when what you're being hit by is traveling at Mach 2.  :( I guess they'd never heard the UL about the wood splinter found embedded in the side of an armored car after a hurricane (which is odd given how many hurricanes blow through Florida  :( )

I'll note that in conventional aviation they'd settle this by using a "bird gun" to fire a standard sized (defrosted) bird into the rocket, or capsule, at whatever angle or bird weight they were concerned about, as they do with jet engine ingestion tests.

The real problem would be what to do if the orbiter failed the test (or rather how to fund what to do about it  :(  )

I think it's time to close this discussion and re-focus on the title of this thread.
« Last Edit: 08/19/2017 07:10 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline RoboGoofers

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Do I infer correctly that if the radar spots the vultures just before launch that it is scrubbed? Or can the same radar target a focused sonic weapon, shotgun, etc? Do the environmental protections in place prohibit those?

I'm not sure those are great options around a rocket prepped for flight.

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