Author Topic: Fairing reuse  (Read 511204 times)

Online Robotbeat

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Re: Fairing reuse
« Reply #480 on: 08/12/2016 11:21 PM »
I was recently at a tour of SpaceX Hawthorne and my guide offered information on fairing recovery.

He cautioned that it was still early, but one method of interest for recovery would be to use a large semi-inflated bag to cushion the landing.  He described it like a larger version of "bounce bags" that you might find at a summer camp.
They cost about $1000 online for a 3m by 7m one, so you could buy a thousand of them for a million dollars and place them in a 100m by 200m grid. Should be able to hit that with a guided parasail.
This is not elegant.
I take that as a compliment. :)

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Offline Nomadd

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Re: Fairing reuse
« Reply #481 on: 08/13/2016 01:57 AM »
 You need to stop posting these ideas in a public forum before Boeing or BO patents them all.
 (I'm for the giant ball pit landing zone myself)

Offline CuddlyRocket

Re: Fairing reuse
« Reply #482 on: 08/13/2016 06:13 PM »
I was recently at a tour of SpaceX Hawthorne and my guide offered information on fairing recovery.

He cautioned that it was still early, but one method of interest for recovery would be to use a large semi-inflated bag to cushion the landing.  He described it like a larger version of "bounce bags" that you might find at a summer camp.
They cost about $1000 online for a 3m by 7m one, so you could buy a thousand of them for a million dollars and place them in a 100m by 200m grid. Should be able to hit that with a guided parasail.

Air bags not carried by the fairings?  There's a concept...

Like that skydiver that jumped into a net instead of using a parachute...   That'd be funny.

So who knows, giant autonomous station-keeping air bags... ASDB! 

Why not a net? What's the terminal velocity of a fairing compared to a human?

Online envy887

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Re: Fairing reuse
« Reply #483 on: 08/13/2016 07:32 PM »
Why not a net? What's the terminal velocity of a fairing compared to a human?

Musk said they were planning to try steerable chutes, so terminal velocity is probably only a few m/s. The only question is whether they are willing to splash them, use a built-in inflatables, or land them on something.

Stretching a net between two ships seems a lot harder than floating a bunch of airbags though...

Online docmordrid

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Re: Fairing reuse
« Reply #484 on: 08/13/2016 09:04 PM »
I'm thinking the collapsed air bag(s) will be conformal to the inside of the fairing, expanded by an N2 cylinder or chemical gas generator. Access cutouts or uncovered  positions as needed per fairing design.

Basically, large Turtle-Pacs

Perhaps the parafoil will be externally mounted and conformal under a blister fairing?
« Last Edit: 08/13/2016 09:19 PM by docmordrid »
DM

Offline meekGee

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Re: Fairing reuse
« Reply #485 on: 08/14/2016 06:44 AM »
I'm thinking the collapsed air bag(s) will be conformal to the inside of the fairing, expanded by an N2 cylinder or chemical gas generator. Access cutouts or uncovered  positions as needed per fairing design.

Basically, large Turtle-Pacs

Perhaps the parafoil will be externally mounted and conformal under a blister fairing?

Yeah, but bouncing around in the waves, this is a large structure, and it's in two pieces that are much weaker than the whole thing.

I'm honestly baffled by all of this.  Heli recovery sounds odd because the range is so long.   Airplane recovery I can believe, but landing it is tricky. 

Hey, if the fairing is going to see salt water anyway, maybe have it sink, and hang underwater using a buoy. 

Then pick it up with a boat and a crane.
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Offline gregpet

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Re: Fairing reuse
« Reply #486 on: 08/15/2016 03:24 AM »
It would make sense that SpaceX would want the fairings to end up as close to a recovery vessel as possible.  Given the success using GPS and steering/landing 1st stage, why wouldn't SpaceX not bring fairings back to OCISLO (using steerable chutes and GPS to steer).  Maybe even try to land them on the barge somehow (after the first stage lands so timing would obviously have to work).

Given the height of release, do you have enough altitude to cove the ground (water) back to the SpaceX flotilla?   

Offline Comga

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Re: Fairing reuse
« Reply #487 on: 08/15/2016 03:56 AM »
From over in the Missions section

(snip)


 I happened to watch the launch this morning standing next to some of the crew who work the Go Quest and Go Searcher and among other things they mentioned that they secure the rockets where they land as soon as possible and don't try to move them on deck for fear of toppling. They said the last successful one was a real handful with the bent leg.

They also said they are routinely within 5 miles of the splashdown point of the fairings and they can see them "tumbling like a leaf" before hitting the water, where they then break up. Pieces are recovered.


If they are whole and tumbling within sight one would think some moderate amount of parachute deployed at low altitude might be enough to get them into the water without breaking up.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline meekGee

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Re: Fairing reuse
« Reply #488 on: 08/15/2016 05:30 AM »
It would make sense that SpaceX would want the fairings to end up as close to a recovery vessel as possible.  Given the success using GPS and steering/landing 1st stage, why wouldn't SpaceX not bring fairings back to OCISLO (using steerable chutes and GPS to steer).  Maybe even try to land them on the barge somehow (after the first stage lands so timing would obviously have to work).

Given the height of release, do you have enough altitude to cove the ground (water) back to the SpaceX flotilla?   

I'm surprised at that.  The second stage is burning for a while there before the fairings are jettisoned.  Covering more distance, and increasing velocity...

And without a lot of aerodynamics, and only, what, 10 miles of somewhat useful atmosphere - I can't see them flying back.  I'd think they need to back track 100s of miles.
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Online Robotbeat

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Re: Fairing reuse
« Reply #489 on: 08/15/2016 05:43 AM »
There's a little more than 10 miles, but yeah. I think you could glide for about 100 miles maybe. More like 50 miles reliably.
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Online envy887

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Re: Fairing reuse
« Reply #490 on: 08/15/2016 02:00 PM »
For JCSAT-16, S1 sep happened at 2265 m/s velocity and ~1000 m/s change in altitude, so ~2050 m/s downrange velocity. Fairing sep happened 59 seconds later at 2500 m/s velocity and ~400 m/s change in altitude, so ~2460 m/s downrange velocity.

It shouldn't be too hard to figure the downrange distance between the fairings and the S1 as they each coast uphill after sep, but things get a lot tougher after that. To start with, the downrange distance between them at fairing sep is the average velocity of the fairing relative to the S1, multiplied by the time that it is accelerating: d_sep = (v_S1 - v_f)/2 * 59 = 12,100 m.

The S1 is coasting up for ~100 seconds to bleed off the 1,000 m/s vertical velocity at MECO. MECO is at ~65 km, so it coasts up to ~116 km at about T+253 sec. Fairing sep is at 113 km altitude with enough velocity up to coast to ~120 km about 40 seconds after sep (T+252 sec). Additional distance between the two while going uphill is 410 m/s for 40 seconds, or 16.5 km.

So the S1 and fairing end up at nearly the same apogee at almost exactly the same time, separated by about 28.5 km, but with the fairing still going downrange somewhat faster. Depending on how much faster aero drag slows the relatively light and large fairing, the S1 might actually land farther downrange than the fairings.
« Last Edit: 08/15/2016 03:38 PM by envy887 »

Offline Comga

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Re: Fairing reuse
« Reply #491 on: 08/15/2016 03:59 PM »
For JCSAT-16, S1 sep happened at 2265 m/s velocity and ~1000 m/s change in altitude, so ~2050 m/s downrange velocity. Fairing sep happened 59 seconds later at 2500 m/s velocity and ~400 m/s change in altitude, so ~2460 m/s downrange velocity.

It shouldn't be too hard to figure the downrange distance between the fairings and the S1 as they each coast uphill after sep, but things get a lot tougher after that. To start with, the downrange distance between them at fairing sep is the average velocity of the fairing relative to the S1, multiplied by the time that it is accelerating: d_sep = (v_S1 - v_f)/2 * 59 = 12,100 m.

The S1 is coasting up for ~100 seconds to bleed off the 1,000 m/s vertical velocity at MECO. MECO is at ~65 km, so it coasts up to ~116 km at about T+253 sec. Fairing sep is at 113 km altitude with enough velocity up to coast to ~120 km about 40 seconds after sep (T+252 sec). Additional distance between the two while going uphill is 410 m/s for 40 seconds, or 16.5 km.

So the S1 and fairing end up at nearly the same apogee at almost exactly the same time, separated by about 28.5 km, but with the fairing still going downrange somewhat faster. Depending on how much faster aero drag slows the relatively light and large fairing, the S1 might actually land farther downrange than the fairings.

All well and good, but it doesn't matter.
Quote
[The recovery crew] said they are routinely within 5 miles of the splashdown point of the fairings and they can see them "tumbling like a leaf" before hitting the water, where they then break up.

I am as surprised as anyone that the fairings don't come down a hundred kilometers downrange, but they don't.
There is no need for said "50 miles" of fairing glide range, or even any controlled landing (yet). 
It seems to be not a large step to get the fairings into the water without being destroyed, so that they can be fetched whole by the recovery crew just like the "Pieces are recovered".
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Kaputnik

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Re: Fairing reuse
« Reply #492 on: 08/15/2016 04:22 PM »
Is that quote from the ASDS/Elsbeth etc crew, or from the Go Searcher crew who are/were specifically looking for the fairings?
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Online Hobbes-22

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Re: Fairing reuse
« Reply #493 on: 08/15/2016 05:13 PM »

All well and good, but it doesn't matter.
Quote
[The recovery crew] said they are routinely within 5 miles of the splashdown point of the fairings and they can see them "tumbling like a leaf" before hitting the water, where they then break up.

I am as surprised as anyone that the fairings don't come down a hundred kilometers downrange, but they don't.
There is no need for said "50 miles" of fairing glide range, or even any controlled landing (yet). 
It seems to be not a large step to get the fairings into the water without being destroyed, so that they can be fetched whole by the recovery crew just like the "Pieces are recovered".

The first stage (when in the proper orientation for recovery) has a much higher ratio of mass vs. surface area than the fairings so it experiences much less deceleration due to drag.

Offline Jcc

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Re: Fairing reuse
« Reply #494 on: 08/15/2016 06:03 PM »

All well and good, but it doesn't matter.
Quote
[The recovery crew] said they are routinely within 5 miles of the splashdown point of the fairings and they can see them "tumbling like a leaf" before hitting the water, where they then break up.

I am as surprised as anyone that the fairings don't come down a hundred kilometers downrange, but they don't.
There is no need for said "50 miles" of fairing glide range, or even any controlled landing (yet). 
It seems to be not a large step to get the fairings into the water without being destroyed, so that they can be fetched whole by the recovery crew just like the "Pieces are recovered".

The first stage (when in the proper orientation for recovery) has a much higher ratio of mass vs. surface area than the fairings so it experiences much less deceleration due to drag.

It's a pity SpaceX cut off the "falling back" video before it hit the atmosphere, but you can bet they know what happens to it:


Apparently, it remains intact until it hits the water at terminal velocity, so a parachute would allow it to splash down intact, but I would think it much better if it never falls n saltwater.

So, my thought is to put 2 helicopters on a barge or ship with helipads, and take off at launch time, snag the fairings in mid-air, and set them back on the barge and land again on the helipads. Solves the helicopter endurance problem.

Offline rickyramjet

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Re: Fairing reuse
« Reply #495 on: 08/15/2016 08:38 PM »

Apparently, it remains intact until it hits the water at terminal velocity, so a parachute would allow it to splash down intact, but I would think it much better if it never falls n saltwater.

So, my thought is to put 2 helicopters on a barge or ship with helipads, and take off at launch time, snag the fairings in mid-air, and set them back on the barge and land again on the helipads. Solves the helicopter endurance problem.
I think the cost of two ships, two helicopters, crew, fuel, and always on call for whenever a launch is planned would soon negate the advantage of fairing recovery.  I would also imagine trying to snag a fairing on a chute at night would be super difficult and dangerous.  Now that S1 recovery kinks are getting ironed out I think we'll soon see fairings with chutes of some kind, and a soft landing in the ocean.  Being composite it may be that salt water is not as terrible as many think. 

Online abaddon

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Re: Fairing reuse
« Reply #496 on: 08/15/2016 09:09 PM »
Is that quote from the ASDS/Elsbeth etc crew, or from the Go Searcher crew who are/were specifically looking for the fairings?
From the original quote up above:
Quote
next to some of the crew who work the Go Quest and Go Searcher

Online abaddon

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Re: Fairing reuse
« Reply #497 on: 08/15/2016 09:10 PM »
I think the cost of two ships, two helicopters, crew, fuel, and always on call for whenever a launch is planned would soon negate the advantage of fairing recovery.
The fairing costs in the "millions", I've seen the estimate of 3-5 million thrown around.  You can do a lot for that, assuming the results are worth it.

Not saying it would be easy or cheap.

Offline Jcc

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Re: Fairing reuse
« Reply #498 on: 08/15/2016 09:44 PM »

Apparently, it remains intact until it hits the water at terminal velocity, so a parachute would allow it to splash down intact, but I would think it much better if it never falls n saltwater.

So, my thought is to put 2 helicopters on a barge or ship with helipads, and take off at launch time, snag the fairings in mid-air, and set them back on the barge and land again on the helipads. Solves the helicopter endurance problem.
I think the cost of two ships, two helicopters, crew, fuel, and always on call for whenever a launch is planned would soon negate the advantage of fairing recovery.  I would also imagine trying to snag a fairing on a chute at night would be super difficult and dangerous.  Now that S1 recovery kinks are getting ironed out I think we'll soon see fairings with chutes of some kind, and a soft landing in the ocean.  Being composite it may be that salt water is not as terrible as many think.

You may be right, we will find out. They can have gps and a radio transmitter to report their location in real time, and lights to help see them at night. That would be useful for a splashdown recovery also.

Offline Comga

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Re: Fairing reuse
« Reply #499 on: 08/17/2016 04:18 AM »
All well and good, but it doesn't matter.
Quote
[The recovery crew] said they are routinely within 5 miles of the splashdown point of the fairings and they can see them "tumbling like a leaf" before hitting the water, where they then break up.

I am as surprised as anyone that the fairings don't come down a hundred kilometers downrange, but they don't.
There is no need for said "50 miles" of fairing glide range, or even any controlled landing (yet). 
It seems to be not a large step to get the fairings into the water without being destroyed, so that they can be fetched whole by the recovery crew just like the "Pieces are recovered".

(snip)
Apparently, it remains intact until it hits the water at terminal velocity, so a parachute would allow it to splash down intact, but I would think it much better if it never falls n saltwater.

So, my thought is to put 2 helicopters on a barge or ship with helipads, and take off at launch time, snag the fairings in mid-air, and set them back on the barge and land again on the helipads. Solves the helicopter endurance problem.

Define "better" and remember that "Better is the enemy of good enough".

We generally agreed to NOT propose mechanical solutions and wait for SpaceX to tell us what they are actually doing.

I didn't say how SpaceX could do that.  Risking violating this agreement, parachutes are a solution SpaceX has tried to use, back on Falcon 1 and the original Falcon 9.  Those boosters didn't survive reentering the atmosphere, so they never got to the point they could deploy their parachutes.  However we have reliable information from participants that this is not the case for fairings.

It still seems that the fairing halves' flight could be changed from "falling leaf" to something stable. With the right angle and reduced velocity, they could land without breaking up.  Then SpaceX can see if salt water immersion is fatal or tolerable, if it is "good enough" or if they need something "better".
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

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