Author Topic: Fairing reuse  (Read 589599 times)

Offline iamlucky13

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Re: Fairing reuse
« Reply #300 on: 04/09/2016 02:58 AM »
Yes, and estimated costs in the $5-6 million range for the similarly sized Ariane 5 fairing, which is also composite, have been documented further up thread. Fairings are more complicated structures than most people realize.

I'm pretty sure this is the first public mention of fairing recovery plans.

Offline leetdan

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Re: Fairing reuse
« Reply #301 on: 04/09/2016 05:34 AM »
Today at the press debriefing Mr. E. Musk mentioned they are pursuing fairing reuse, because it costs several million dollars.
Wouldn't that be first official mention of fairing reuse?

Fairing reuse has been mentioned in response to people posting images of fairing fragments washing up elsewhere.

My questions is, have we officially heard anything about thrusters on the fairing?  I know people 'saw something' in the SES-9 launch videos, but has SpaceX ever confirmed what we were seeing?

Online meekGee

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Re: Fairing reuse
« Reply #302 on: 04/09/2016 06:05 AM »
Today at the press debriefing Mr. E. Musk mentioned they are pursuing fairing reuse, because it costs several million dollars.
Wouldn't that be first official mention of fairing reuse?

Fairing reuse has been mentioned in response to people posting images of fairing fragments washing up elsewhere.

My questions is, have we officially heard anything about thrusters on the fairing?  I know people 'saw something' in the SES-9 launch videos, but has SpaceX ever confirmed what we were seeing?
There was informal but credible info on L2 for a while now.
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Offline mikelepage

Re: Fairing reuse
« Reply #303 on: 04/09/2016 10:25 AM »
Some "fairing blimp" calculations: feel free to skip.

Coming over from the airship thread, and reading upthread about the potential for having some kind of bladder on the inside of the fairing, I just wanted to do a back of the envelope on the possibility of converting each fairing half into a lighter-than-air craft before it reaches the ground.  Could inform potential Venus airship mission too.

Total fairing weight for the 13.1x5.2m ("bus containing") is supposed to be 1750kg.  Dividing that by 2 gives 875kg per half:
Pre-empting the results below, I'm assuming we're adding 225kg per half to take it to 1100kg per half:

1) Amount of Helium required to provide equivalent buoyancy force:
Each mole of Helium is 4 grams, displaces ~29g of atmosphere, and expands to 22.4 L at STP.
1100000g fairing half/ 25g = 44000 moles of helium (176kg).
At STP that would fill a bladder to ~985.6m3 (call it 1000m3)

2) Assuming the bladder expands to a cylinder 13.1m long capped with hemispheres
V = 4/3πr3 + 26.2πr
r ~ 5.2 m

3) Surface area of inflated bladder
5.2π*13.1+ 4π(5.2)2 = 340m2
Standard blimp envelope material seems to be 80-90g per m2
giving us 30.6kg of envelope material.

Not really sure of the weight/size requirements of the helium gas canister you'd need, but it seems to me this could be within the realms of workability, if you can have some kind of drogue chute that would keep the fairing somewhat oriented to protect the bladder material on the way down.

Offline Radical_Ignorant

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Re: Fairing reuse
« Reply #304 on: 04/09/2016 10:54 AM »
Many  here like the idea of keeping both pieces connected and closing them before reentering atmosphere. I find it compelling as connected they create shape which seems to be much more stable. And easier to keep afloat.

And how to keep them connected? Well, I see on the video were they test separation mechanism that both parts are connected, so it seems possible. And in old days there were those rockets controlled by cables, so there are things which can survive and do the job.

But then is it required at all? Pieces found are pretty large, so maybe it's enough to reduce impact speed (with water) by small parachute and no need anything more than orienting it on the start to protect the parachute from burning in initial phase.

But still I'm intrigued if connection as on test video could be used with some minor modifications in real mission.

Offline Jim

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Re: Fairing reuse
« Reply #305 on: 04/09/2016 01:49 PM »

And how to keep them connected? Well, I see on the video were they test separation mechanism that both parts are connected, so it seems possible. And in old days there were those rockets controlled by cables, so there are things which can survive and do the job.


not true on either point.  The cables would put loads on the fairings and there is no way to bring them together in a controlled matter without them slamming together.

Which rockets were controlled by cables?

Online tyrred

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Re: Fairing reuse
« Reply #306 on: 04/09/2016 03:25 PM »
May be a reference to TOW missiles (Tube-launched Optically tracked Wire-guided)?

Offline Radical_Ignorant

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Re: Fairing reuse
« Reply #307 on: 04/09/2016 04:31 PM »

And how to keep them connected? Well, I see on the video were they test separation mechanism that both parts are connected, so it seems possible. And in old days there were those rockets controlled by cables, so there are things which can survive and do the job.


not true on either point.  The cables would put loads on the fairings and there is no way to bring them together in a controlled matter without them slamming together.

Which rockets were controlled by cables?

Of course that they would put loads, and so? This load would be symetric, fairings would be tiny bit heavier.
No way to bring them together? You mean that it's impossible to control  force required to pull the cable? Or you say that using force in only one way it's not possible to gently stop momentum? Like for example on rocket falling from the sky? Or you claim that TOWs (thanks tyrred - I was lazy) weren't working because there is no cable which could easily withstand rocket exhaust?

It's always super easy to claim "no it's impossible". But that's rarely true. That would be too hard, or that would not be cost effective, or that could be dangerous/not reliable because of... that I could believe.

Offline llanitedave

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Re: Fairing reuse
« Reply #308 on: 04/09/2016 04:53 PM »

And how to keep them connected? Well, I see on the video were they test separation mechanism that both parts are connected, so it seems possible. And in old days there were those rockets controlled by cables, so there are things which can survive and do the job.


not true on either point.  The cables would put loads on the fairings and there is no way to bring them together in a controlled matter without them slamming together.

Which rockets were controlled by cables?

Of course that they would put loads, and so? This load would be symetric, fairings would be tiny bit heavier.
No way to bring them together? You mean that it's impossible to control  force required to pull the cable? Or you say that using force in only one way it's not possible to gently stop momentum? Like for example on rocket falling from the sky? Or you claim that TOWs (thanks tyrred - I was lazy) weren't working because there is no cable which could easily withstand rocket exhaust?

It's always super easy to claim "no it's impossible". But that's rarely true. That would be too hard, or that would not be cost effective, or that could be dangerous/not reliable because of... that I could believe.


How about "it's simply unnecessary."
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Offline Stan-1967

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Re: Fairing reuse
« Reply #309 on: 04/09/2016 05:42 PM »

And how to keep them connected? Well, I see on the video were they test separation mechanism that both parts are connected, so it seems possible. And in old days there were those rockets controlled by cables, so there are things which can survive and do the job.


not true on either point.  The cables would put loads on the fairings and there is no way to bring them together in a controlled matter without them slamming together.

Which rockets were controlled by cables?

Of course that they would put loads, and so? This load would be symetric, fairings would be tiny bit heavier.
No way to bring them together? You mean that it's impossible to control  force required to pull the cable? Or you say that using force in only one way it's not possible to gently stop momentum? Like for example on rocket falling from the sky? Or you claim that TOWs (thanks tyrred - I was lazy) weren't working because there is no cable which could easily withstand rocket exhaust?

It's always super easy to claim "no it's impossible". But that's rarely true. That would be too hard, or that would not be cost effective, or that could be dangerous/not reliable because of... that I could believe.

I'll try offer my criticism, and not just dismissal.  Although I would add that "dismissal", when it comes from many veteran sources pretty clued into real world experience with space hardware, is a good hint that an idea may not be great.   I like that this site because it has threads that allow some speculation.  Maybe this thread should be split, as the MOD has indicted he is considering.  I do think a thread based solely on what we "know", would be about 10 posts long, and boring.   Most of us here are probably of a technical/engineering background, and so we have PI's that either like to ruminate endlessly over such speculation, or we don't suffer fools, and dismiss things with little tact or feeling when we are so inclined.

So back to the topic of cables....

I don't think the cables seen in the SpaceX fairing test video from the Plum Brook facility indicate in any way that cables would work like this in a freefall/zero-g environment.   It's nice to imagine in our gravitationally conditioned minds that the fairings will magically come back together and reattach.  That's because our earth environment conditions our minds with lots of dampening and frictional forces.   

It's too easy to think of this problem like a household vacuum cord automatically winding itself back inside the appliance housing, but it just won't work like that.  Each pull of the cord/cable on attached fairing halves will accelerate the halves in the direction of the pull.   Unless the vector of that acceleration exactly moves the halves to a rendezvous, they will impact obliquely, & spin apart from each other from an in-elastic collision, and not rendezvous.   Furthermore, once they are accelerating towards each other, cables cant slow them down.   Ever try making compression forces with a string?  That means RCS and sensors, and you may as well eliminate the cables entirely.   I see a a big tangled mass of cable and fairing resulting after a few collisions together.
« Last Edit: 04/09/2016 05:44 PM by Stan-1967 »

Offline Stan-1967

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Re: Fairing reuse
« Reply #310 on: 04/09/2016 05:49 PM »

And how to keep them connected? Well, I see on the video were they test separation mechanism that both parts are connected, so it seems possible. And in old days there were those rockets controlled by cables, so there are things which can survive and do the job.

It is not the cable that control the rocket, ( i.e TOW's) but electrical signals sent through the cable.  The cable is spooled out behind the rocket in a manner that tries to eliminate or reduce any drag or moments that affect the rockets guided flight path.   

Offline Stan-1967

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Re: Fairing reuse
« Reply #311 on: 04/09/2016 05:57 PM »

Thinking to something like this, very light.
For first part, reentry, managing the shock

http://forum.nasaspaceflight.com/index.php?topic=37727.msg1511754#msg1511754

I'd like it even more if it worked in a passive mode, vs. needing active control.  Something like this seems simple if it can keep the orientation stable.   So assuming this method keeps it stable and gets it into a landing zone, would you still need a parachute for soft landing?
« Last Edit: 04/09/2016 06:01 PM by Stan-1967 »

Offline cambrianera

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Re: Fairing reuse
« Reply #312 on: 04/09/2016 06:08 PM »

Thinking to something like this, very light.
For first part, reentry, managing the shock

http://forum.nasaspaceflight.com/index.php?topic=37727.msg1511754#msg1511754

I'd like it even more if it worked in a passive mode, vs. needing active control.  Something like this seems simple if it can keep the orientation stable.   So assuming this method keeps it stable and gets it into a landing zone, would you still need a parachute for soft landing?

No active control needed to keep it stable, basically  the shuttlecock principle.

Parachute still needed for softer landing.
Reorienting the half fairings concave first, drag increases two-three fold (plus parachute drag).
« Last Edit: 04/09/2016 06:09 PM by cambrianera »
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Offline Stan-1967

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Re: Fairing reuse
« Reply #313 on: 04/09/2016 06:14 PM »
Some "fairing blimp" calculations: feel free to skip.

Coming over from the airship thread, and reading upthread about the potential for having some kind of bladder on the inside of the fairing, I just wanted to do a back of the envelope on the possibility of converting each fairing half into a lighter-than-air craft before it reaches the ground.  Could inform potential Venus airship mission too.

Snip...

Not really sure of the weight/size requirements of the helium gas canister you'd need, but it seems to me this could be within the realms of workability, if you can have some kind of drogue chute that would keep the fairing somewhat oriented to protect the bladder material on the way down.

Thanks for doing those calcs.  I did some BOE that suggested the mass of the HE gas would be much less than the flexible bladder material.  My point in the bladder idea was not to make it "lighter than air" but to give it a shape that would be stable during a ballistic re-entry, and thereby aid in a smaller recovery zone.  Furthermore, if it could be landed with the bladder impacting the ocean as a type of "airbag", it would aid in preservation.

I think the adhesion of the bladder to the composite shell would be tricky, but doable.   Jim and others pointed out that problem.   It didn't seem overly complex to me, certainly not trivial.    It is very likely more simple methods would be tested long before the wilder ideas tossed around here.

1. nothing..just find it floating in the ocean
2. Some sort of controlled impact achieved with deployable control surfaces
3. Impact with drogue chute orienting the impact
4. Drogue chute plus bigger parachute orienting the impact
5. other ideas.
« Last Edit: 04/09/2016 07:27 PM by Stan-1967 »

Offline bstrong

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Re: Fairing reuse
« Reply #314 on: 04/09/2016 06:29 PM »
Today at the press debriefing Mr. E. Musk mentioned they are pursuing fairing reuse, because it costs several million dollars.
Wouldn't that be first official mention of fairing reuse?
Elon mentioned it in a tweet last year:

https://twitter.com/elonmusk/status/605460768516014080

Offline Space Ghost 1962

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Re: Fairing reuse
« Reply #315 on: 04/09/2016 06:44 PM »
Before you design a system, you must appreciate the environment of an existing system, what occurs in the life cycle of use, what qualities / requirements you have for the new system that the old one didn't have. E.g. aclear statement of the problem.

If I understand this wandering thread, what is desired is a jettisonable multipart fairing that largely works as the current one has done, but retains the integrity/registration/tensile qualities/compression/other of the fairing so that after its located/recovered, it can be economically remanufactured/reprocessed and qualified for reuse without refabrication?

The environment of this is to undergo payload/launch integration with US/LV, launch, ascent, staging, jettison ... as before. Then, either passively/actively negotiate the dissipation of extreme frictional heating and dynamic aeroloads in increasing atmospheric densities with decreasing velocities, until near terminal velocity and ocean impact.

And like the original system, you don't wish to greatly increase the mass penalty that robs from payload to orbit.

A lesser cost possibly is the drag of the system, so within the trades might be a larger effective diameter design with a hypothetical "fluffier" construction of some kind.

Also within the trades might be a design where the inside is much like the outside which already handles the ascent environment, with all the other requirements handled by stage or payload adapter or jettisonable (structure only reusable).

Next - prior experience. What allows past fairings to survive intact, and not others? When we compare a best case to an unused one, how has it been affected that makes the best case undesireable for reuse. What now do we have to preserve that we didn't before, and how do we instrument/test/prove such through consecutive flight, such that we converge on a useful solution.

All of this discussions would make this thread more focused and useful to address the topic.

Or is this just more jawing about random things that appeal or not?

add:
Approaches:
a) more durable version of the existing two part design (refinement)
b) reduced ballistic coefficient design with more, smaller components that each more easily survive to surface  (divide and conquer)
c) active structure that reconfigures post jettision to adapt to descent environment for better survival of structure (vehicle/glider?)
« Last Edit: 04/09/2016 07:00 PM by Space Ghost 1962 »

Offline savuporo

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Re: Fairing reuse
« Reply #316 on: 04/09/2016 06:53 PM »
If I understand this wandering thread, what is desired is a jettisonable multipart fairing that largely works as the current one has done, but retains the integrity/registration/tensile qualities/compression/other of the fairing so that after its located/recovered, it can be economically remanufactured/reprocessed and qualified for reuse without refabrication?
Is symmetrical separation a must have ? Or can upper stage RCS deal with asymmetries ?

EDIT: also, what are the reasonable time limits for separation event ? A few seconds ? or tens of seconds ?
« Last Edit: 04/09/2016 06:56 PM by savuporo »
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Offline Space Ghost 1962

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Re: Fairing reuse
« Reply #317 on: 04/09/2016 07:13 PM »
If I understand this wandering thread, what is desired is a jettisonable multipart fairing that largely works as the current one has done, but retains the integrity/registration/tensile qualities/compression/other of the fairing so that after its located/recovered, it can be economically remanufactured/reprocessed and qualified for reuse without refabrication?
Is symmetrical separation a must have ? Or can upper stage RCS deal with asymmetries ?


Symmetrical stress/loading is a must due to dynamic loads on launch. This dictates design and leads to fewer surprises in separation. Fabrication/test/qualification of symmetric parts simplifies proving such a design.

Titan had a triple gore design. There have been some unusual shrouds on certain payload in the past.

If you have any asymmetry/complexity, you risk recontact with the stage/payload. The more components/differences, the greater the risk.

That said, yes, such a design could possibly be made to work. The hard part would be proving that it always would work.

When you jettision, aeroloads are at a minimum by definition. The lower you jettison, the more mass you don't carry. Too low and the delicate payload is at risk.

add:
Quote

EDIT: also, what are the reasonable time limits for separation event ? A few seconds ? or tens of seconds ?
Sorry. Too quick.

We're talking seconds. Otherwise you are coasting, which for the ascent you are planning may not be feasible. And to be fair, coasts of a hundred seconds can occur, although likely not optimal.

Another item with asymmetry. Your payload and vehicle stack have to have at least a well known center of mass that you thrust through. If you partial jettison or asymmetric part jettison , your center of mass will shift, which you may or may not be able to compensate for in various ways - how do you avoid the cosine loss or attitude change?
« Last Edit: 04/09/2016 07:33 PM by Space Ghost 1962 »

Offline savuporo

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Re: Fairing reuse
« Reply #318 on: 04/09/2016 07:30 PM »
Symmetrical stress/loading is a must due to dynamic loads on launch. This dictates design and leads to fewer surprises in separation. Fabrication/test/qualification of symmetric parts simplifies proving such a design.

Titan had a triple gore design. There have been some unusual shrouds on certain payload in the past.

If you have any asymmetry/complexity, you risk recontact with the stage/payload. The more components/differences, the greater the risk.

That said, yes, such a design could possibly be made to work. The hard part would be proving that it always would work.

When you jettision, aeroloads are at a minimum by definition. The lower you jettison, the more mass you don't carry. Too low and the delicate payload is at risk.
Well, any gadget you add beyond current system is always an added risk anyway. Question is, is the risk manageable and worth it.

For example, the two current fairing halves could be joined by servoed hinges on one side that fully opens one side before separation push, and then push it to one side. But thats a huuge asymmetry, not sure if this is remotely feasible.

The point would be to close clamshell again after separation to have the same aerodynamic shape reenter that went up. And then do trailing ballute, streamer or parachute or whatnot to survive the splash
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Offline Space Ghost 1962

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Re: Fairing reuse
« Reply #319 on: 04/09/2016 07:45 PM »
Symmetrical stress/loading is a must due to dynamic loads on launch. This dictates design and leads to fewer surprises in separation. Fabrication/test/qualification of symmetric parts simplifies proving such a design.

Titan had a triple gore design. There have been some unusual shrouds on certain payload in the past.

If you have any asymmetry/complexity, you risk recontact with the stage/payload. The more components/differences, the greater the risk.

That said, yes, such a design could possibly be made to work. The hard part would be proving that it always would work.

When you jettision, aeroloads are at a minimum by definition. The lower you jettison, the more mass you don't carry. Too low and the delicate payload is at risk.
Well, any gadget you add beyond current system is always an added risk anyway. Question is, is the risk manageable and worth it.

Yes. Likely negligible gain just from the start. Have to have significant advantage. Like forming a reentry vehicle w/o much additional cost.

Quote
For example, the two current fairing halves could be joined by servoed hinges on one side that fully opens one side before separation push, and then push it to one side. But thats a huuge asymmetry, not sure if this is remotely feasible.

The point would be to close clamshell again after separation to have the same aerodynamic shape reenter that went up.

The asymmetries also affect the flight of the payload + US.

Here's a rude thought. You jettison with a hinge that opens, and the halves later "bounce" and relatch ;)

Now for the downsides of any of these. You have three vehicles that have to be axis symmetric/stable for flight - the original launch stack, the payload+US, and the reformed fairing/shroud.

And, to avoid recontact, you'd have to guarantee that the separation planes (two, not one)  could never be coincident - e.g. it "sticks" in one or both and the still combined fairing "tilts" into the payload.

Quote
And then do trailing ballute, streamer or parachute or whatnot to survive the splash

Separate issue entirely. Make it into a hypersonic glider.

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