Author Topic: Using Carbon Composite tanks for F9/FH Impacts on payload capability  (Read 17546 times)

Online docmordrid

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Propane cannons etc. have been used around airports and other installations for years. So long as you don't mount one on the pad....

example news story...
« Last Edit: 08/18/2017 07:49 PM by docmordrid »
DM

Offline john smith 19

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Hmm.

Perhaps a poll of people who think it would be a good idea to go to a composite F9 booster, a full composite F9 or stay as it is?

I think I can guess the outcome but I don't want to say to avoid prejudicing it one way or the other, so I could be wrong.
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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The fact a material as well characterized as the foam on the ET was,

There is no such fact.  Just another case where anonymous posters choose items to make as fact to support their claims.

Offline 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?

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

Their acoustic energy would be far < that of the engines and they would be mounted such that none could point directly @ the LV, prop storage tanks, lines, etc.

Offline tdperk

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The fact a material as well characterized as the foam on the ET was,

There is no such fact.  Just another case where anonymous posters choose items to make as fact to support their claims.

And as a different poster mentioned, it was well characterized until changed.

A poster no more anonymous than you are, Jack.

Offline TomH

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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.

This IS the kind of thinking that led to both STS disasters. Wanting something to be true doesn't make it true.

No VISIBLE change in the foam?.........From a distant poor quality video? The strike could easily have induced fractures in the foam that caused it to tear apart during MaxQ or Max drag. Even a dent could cause an eddy in the airflow that would eat the foam away.

You BELIEVE the CC tank is more resistant? This is Rocket SCIENCE, not Rocket Faith. Belief ignores facts. In science, belief can be invoked no farther than hypothesis. Rocket science involves rigorous scientific testing and verification. Belief is what got 17 astronauts killed.

Look, I've disagreed with Jim before, too. But you better have some scientific and mathematical justification to do so. This is NOT the forum in which to argue things based on belief.

« Last Edit: 08/21/2017 12:51 AM by TomH »

Offline TomH

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The fact a material as well characterized as the foam on the ET was,

There is no such fact.  Just another case where anonymous posters choose items to make as fact to support their claims.

And as a different poster mentioned, it was well characterized until changed.

A poster no more anonymous than you are, Jack.

Ummmm. He's NOT anonymous. Most people here know that he has a PhD in Aeronautical Engineering/Rocket Science and has worked for NASA for decades.
« Last Edit: 08/21/2017 12:35 AM by TomH »

Offline john smith 19

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This IS the kind of thinking that led to both STS disasters. Wanting something to be true doesn't make it true.

No VISIBLE change in the foam?.........From a distant poor quality video? The strike could easily have induced fractures in the foam that caused it to tear apart during MaxQ or Max drag. Even a dent could cause an eddy in the airflow that would eat the foam away.

You BELIEVE the CC tank is more resistant? This is Rocket SCIENCE, not Rocket Faith. Belief ignores facts. In science, belief can be invoked no farther than hypothesis. Rocket science involves rigorous scientific testing and verification. Belief is what got 17 astronauts killed.

Look, I've disagreed with Jim before, too. But you better have some scientific and mathematical justification to do so. This is NOT the forum in which to argue things based on belief.
I've mentioned before that NASA has tested impact damage to COPV's and found a 30% loss in strength with no visible damage. This was a deliberate test and historically COPV's operate at much higher pressure s than LV main tanks and have much higher safety factors (IIRC more like 6x the standard operating pressure) while human rated LV's have an SF of 1.4.

Unfortunately that 30% on an LV tank (SF = 1.4) would put it to 98% of full standard operating pressure.:(

Caveat Main LV tank <> COPV but this does suggest that impact damage can be an issue with coposite structures in a way they wouldn't with Aluminum alloy.

The reverse argument is that the F9 interstages are both composites and AFAIK there have been no issues with damage. OTOH they are not pressurized structures. OT I had not realized (till I'd seen it happen) that birds will fly into window glass without realizing it's there, breaking their necks in the process. Why they would fly straight into the side of a LV tank is another matter, as the contrast with the sky seems quite clear.   :(

I will note that the tanks supplying supercritical H2 and O2 on all the Shuttles were (AFAIK) original equipment, installed when they were built. So they survived the whole life of the Shuttles they were on.

These are the only data points I have. It would depend on how big an impact you'd need to hit an LV sized composite main tank. Something which on a small tank would cause a 30% loss in strength would not have the same event (you can't say "It wouldn't leave a dent,"  because neither would, which is the problem   :( )

That said acoustic monitoring, with multiple sensors to triangulate sources feeding modern processors, should be able to match any damage signatures with images from monitoring cameras on the pad.

But I wouldn't like to be a passenger on a composite main tanked LV if that was the first flight of such a vehicle.  :( 
« Last Edit: 08/21/2017 07:39 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 livingjw

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... I will note that the tanks supplying supercritical H2 and O2 on all the Shuttles were (AFAIK) original equipment, installed when they were built. So they survived the whole life of the Shuttles they were on....



??? What tanks are we talking about?
« Last Edit: 08/21/2017 06:52 PM by livingjw »

Offline tdperk

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The fact a material as well characterized as the foam on the ET was,

There is no such fact.  Just another case where anonymous posters choose items to make as fact to support their claims.

And as a different poster mentioned, it was well characterized until changed.

A poster no more anonymous than you are, Jack.

Ummmm. He's NOT anonymous. Most people here know that he has a PhD in Aeronautical Engineering/Rocket Science and has worked for NASA for decades.

The several who have met him, yes.  I suspect they cannot verify his identity here for the rest of us.

Offline TomH

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... I will note that the tanks supplying supercritical H2 and O2 on all the Shuttles were (AFAIK) original equipment, installed when they were built. So they survived the whole life of the Shuttles they were on....



??? What tanks are we talking about?

You have copied and redacted incorrectly. I did not write that. Please go back, edit, and correct your mistakes.

Offline livingjw

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Sorry about the improper redaction. What tanks are we talking about?

John

Offline john smith 19

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Sorry about the improper redaction. What tanks are we talking about?

John
The reactant tanks that stored reactants for the Fuel Cell electrical system.
« Last Edit: 08/21/2017 08:34 PM 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 Jim

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Sorry about the improper redaction. What tanks are we talking about?

John
The reactant tanks that sored reactants for the Fuel Cell electrical system.

They were not COPVs

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