Author Topic: Fairing reuse  (Read 329153 times)

Offline guckyfan

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Re: Fairing reuse
« Reply #500 on: 08/17/2016 07:22 AM »
Then SpaceX can see if salt water immersion is fatal or tolerable, if it is "good enough" or if they need something "better".

That is the one thing I expect them to know already. It is quite easy to dump a piece into the water and get it out after a few hours. They may have a defective fairing half to do that or they produce a sheet using the same production methods.


Offline vaporcobra

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Re: Fairing reuse
« Reply #501 on: 08/18/2016 01:22 AM »
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.

Good to remember that possibly the main motivator behind fairing recovery is the fact that fairings themselves act as a significant roadblock to even relatively minor increases in cadence, and definitely act as a hard ceiling for any serious increases in cadence. Price is very much secondary, though it is significant :)
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Offline vaporcobra

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Re: Fairing reuse
« Reply #502 on: 08/18/2016 01:29 AM »
Quote
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".

Worth noting that fairings already almost certainly have a significant level of control over their course, at least to the extent that they almost certainly already have RCS and some serious onboard avionics. They likely have a surprising amount of control over where they end up!
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Offline joncz

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Re: Fairing reuse
« Reply #503 on: 08/18/2016 11:17 AM »
Worth noting that fairings already almost certainly have a significant level of control over their course, at least to the extent that they almost certainly already have RCS and some serious onboard avionics. They likely have a surprising amount of control over where they end up!

Source for this claim?

Offline The_Ronin

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Re: Fairing reuse
« Reply #504 on: 08/18/2016 06:06 PM »
There was footage a couple launches ago of one of the fairing halves firing RCS thrusters.

Offline Comga

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Re: Fairing reuse
« Reply #505 on: 08/18/2016 10:31 PM »
There was footage a couple launches ago of one of the fairing halves firing RCS thrusters.

While a true statement, that does not say they "have a significant level of control over their course".
At least one fairing had RCS.  Whether that was sufficient to control its attitude and course is not known.

If it was sufficient, they would be stable in the atmosphere.  It's unlikely that SpaceX would have abandoned an effective control system, so the fact that the fairings are seen as falling like leaves means it was probably not sufficient.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Burninate

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Re: Fairing reuse
« Reply #506 on: 08/18/2016 11:50 PM »
There was footage a couple launches ago of one of the fairing halves firing RCS thrusters.

IIRC, there was footage of a gas release.  This is distinct from an RCS in goals and degree of control.  Emptying the pneumatic cylinders would just be a safety measure designed to ensure that anything which lands on the ground doesn't explode on impact with greater than kinetic energy.

Offline Chris_Pi

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Re: Fairing reuse
« Reply #507 on: 08/19/2016 12:25 AM »
There was footage a couple launches ago of one of the fairing halves firing RCS thrusters.

While a true statement, that does not say they "have a significant level of control over their course".
At least one fairing had RCS.  Whether that was sufficient to control its attitude and course is not known.

If it was sufficient, they would be stable in the atmosphere.  It's unlikely that SpaceX would have abandoned an effective control system, so the fact that the fairings are seen as falling like leaves means it was probably not sufficient.

RCS to start, But IMHO it's unlikely to be RCS all the way down* - Earlier in this thread:
https://twitter.com/elonmusk/status/738471747540783104

in response to a question: Are RCS thrusters the sole component for fairing recovery? Are chutes required?

Quote
@mattyteare @karaswisher @waltmossberg @YouTube autosteering chutes will be added soon

So, we'll perhaps see some fairing halves coming back under chutes!

RCS just has to keep it stable until the air is thick enough to deploy a parachute without tangling it. And probably can't do much more - Increasing forces on the fairing will chew through the gas supply pretty quick. Big enough and it could be made to work, But at some point the parachute is probably lighter than the gas bottles.

Since it sounds like they're coming down pretty close to the support ships the impact point must be pretty predictable even if they can't steer them to where they want. Pretty sure they know the ships won't take a hit from a fairing, So the return location is probably known within a couple miles or less. In one piece until impact at least suggests they don't tumble during re-entry.

I think this problem is being solved form separation on down - Control orientation, keep stable until parachutes can be used (Where things appear to be now), Then add expensive/heavy parachutes and prove they work. Soft-splashdown or midair snag last.

*It's turtles, Of course.**
** I couldn't just leave that one sitting there. Had to.


Offline CraigLieb

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Re: Fairing reuse
« Reply #508 on: 08/19/2016 03:38 PM »
Green Goblin Glider?
 Deploy small jet engines from the back curve and steer it down using the curved shape to surf the air.
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Offline Comga

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Re: Fairing reuse
« Reply #509 on: 08/20/2016 03:00 AM »
What Chris-PI said

And it IS turtles all the way down!
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Jet Black

Re: Fairing reuse
« Reply #510 on: 08/22/2016 08:09 AM »
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.

Good to remember that possibly the main motivator behind fairing recovery is the fact that fairings themselves act as a significant roadblock to even relatively minor increases in cadence, and definitely act as a hard ceiling for any serious increases in cadence. Price is very much secondary, though it is significant :)

Given the investment interest that people have in SpaceX, but the relatively closed shop since they aren't going for IPO, I wonder whether it would be worth them starting up a public supplier company to raise the money just for that job.
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Offline Geron

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Re: Fairing reuse
« Reply #511 on: 02/20/2017 06:23 AM »
Gwynne shot well stated the fairings will be recovered this year mid air as submersion in salt water is not allowable.

Offline FutureSpaceTourist

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Re: Fairing reuse
« Reply #512 on: 02/20/2017 08:44 AM »
Gwynne's other key quote from the 39A press conference on Friday was that they'd love to re-use fairings and maybe this year you'll see that.

Must imply some fairing recovery attempts rather sooner?

Offline Jarnis

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Re: Fairing reuse
« Reply #513 on: 02/20/2017 10:45 AM »
Gwynne's other key quote from the 39A press conference on Friday was that they'd love to re-use fairings and maybe this year you'll see that.

Must imply some fairing recovery attempts rather sooner?

Maybe as soon as... 2 weeks  :)

Offline envy887

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Re: Fairing reuse
« Reply #514 on: 02/20/2017 01:33 PM »
Gwynne shot well stated the fairings will be recovered this year mid air as submersion in salt water is not allowable.

Did she specifically say airborne recovery? There are other methods of recovery that can prevent immersion.

Online Robotbeat

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Re: Fairing reuse
« Reply #515 on: 02/20/2017 02:23 PM »
Always important to get exact phrasing.
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Offline rsdavis9

Re: Fairing reuse
« Reply #516 on: 02/20/2017 02:36 PM »
All she said was "we don't want to get it wet".
Never anything about airborne or whatever(barge?).
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Offline dorkmo

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Re: Fairing reuse
« Reply #517 on: 02/20/2017 05:10 PM »
I think there was some speculation that they were outfitting one of the GO vessels for fairing recovery? Wonder if thats still on the table. Hard to imagine they could use a ship for recovery while keeping the fairings dry. Maybe they could deploy some big inflatable rafts?

Offline cscott

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Re: Fairing reuse
« Reply #518 on: 02/20/2017 11:36 PM »
Or RTLS if they have enough cross-range.  I was listening carefully as well and @rsdavis9 has it right. "Not wet" but not specific on how that was to be done.

Offline Kaputnik

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Re: Fairing reuse
« Reply #519 on: 02/21/2017 01:27 PM »
Any merit in a poll? Mid air recovery, support ship deck, RTLS, other?
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