Author Topic: Fairing reuse  (Read 226467 times)

Offline deruch

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Re: Fairing reuse
« Reply #20 on: 06/02/2015 01:47 PM »
Full res posted to dropbox:  https://www.dropbox.com/sh/vzvobzwhwdz6mdd/AADl7VIEFMrPaGMS2r3rR-XAa

Images rehosted at:
https://imgur.com/a/SyfRN

Galleries from previous finds of SpaceX fairing pieces-
Found in Hawaii:  https://imgur.com/a/g06A2

Found in Cape Hatteras, NC: https://imgur.com/a/0bo6s


edit: updated original gallery to include the full set of pictures from the dropbox posting and added the previous galleries for comparison.
« Last Edit: 06/02/2015 03:02 PM by deruch »
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline Comga

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Re: Fairing reuse
« Reply #21 on: 06/02/2015 02:05 PM »

1.  What about the access port,
2.  the hose, those wavy metal straps,
3.  the ball tipped long arm,
4.   and the short rounded arm?

1.  For spacecraft access
2.  AC ducts
3.  Push rod for fairing sep
4.  fairing sep system

Thanks. Can you be more descriptive or point to a reference?
The "push rod" is clear
Is the "fairing step system" something that was held to a matching piece on the other half with an explosive bolt?
Do AC ducts attach to payloads or just direct the purge flow at specific points?  My assumption was that clean dry gas just flowed into the fairing and out some small port.
Any description of how the access port is opened or held closed in those images?
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Jim

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Re: Fairing reuse
« Reply #22 on: 06/02/2015 02:15 PM »

1.  Is the "fairing step system" something that was held to a matching piece on the other half with an explosive bolt?
2.  Do AC ducts attach to payloads or just direct the purge flow at specific points?  My assumption was that clean dry gas just flowed into the fairing and out some small port.
3.  Any description of how the access port is opened or held closed in those images?


1.  Yes, but the release mechanism is not explosive.  (Spacex has an aversion to them)
2.  The ducts lead to the top of the fairing where the air "showers" over the payload.
3.  Just standard fasteners (screws)

Offline Donosauro

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Re: Fairing reuse
« Reply #23 on: 06/02/2015 04:05 PM »
I don't know how conventional China Great Wall's payload fairings are, but this chapter of one of their user manuals shows both the input port for conditioned air and a number of exhaust ports:

http://www.cgwic.com/LaunchServices/Download/manual/Chapter%204%20Payload%20Fairing.pdf

Offline Kabloona

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Re: Fairing reuse
« Reply #24 on: 06/02/2015 04:35 PM »
Info from the GoPro camera/data logger housing photos:

For the top level assembly:

P/N 00195412-501 Rev A
"Assy, GoPro Housing, Data Logger, Fair" (ie fairing)
Serial numbers 1 and 15 on the two housings shown in the photos

Quick Response code on the label for inventory control/build logs: SPXGUY4

For the cover plate:

P/N 00195412-002 Rev A
PO 387118 (probably a purchase order number, indicating outsourced, not made in-house)

Assembled with NAS6703 bolts, standard aerospace grade made of A286 CRES.

Nothing surprising, but a few interesting tidbits, like the use of GoPro cameras.
« Last Edit: 06/02/2015 04:44 PM by Kabloona »

Online starsilk

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Re: Fairing reuse
« Reply #25 on: 06/02/2015 04:38 PM »
Still can't get my head around that it's worth the effort to re-use fairings!

This is circumstantial evidence that cost/launch is headed way down.

I know they're expending the second stage which is more expensive than a fairing, but still somehow they decided this is important enough to bother.  odd.

we need to think of the long game. it may not be terribly economic to reuse them on the F9 (or perhaps even a loss), but they are learning how to do it for the MCT when the fairing is going to be MUCH bigger and more valuable.

MCT is presumably going to be big enough and expensive enough that it simply has to be fully reused, otherwise it's not economic - except for a rare government launch perhaps where they can afford to throw away hundreds of millions of dollars of hardware.

Offline speedevil

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Re: Fairing reuse
« Reply #26 on: 06/02/2015 07:59 PM »
<snip of why fairing is jetisoned after staging, not at>
Yes there is something.  There is a requirement for the free molecular heating to be below a certain level. The level is determined by spacecraft requirements.

In principle, a very, very light structure - perhaps even inflated could be added inside for a shield in the minute or so afterwards.
A quick calculation indicates Q at this point is well under 1Pa.
(I uses ~M6 and 100km as ballpark staging point).

That doesn't of course answer the awkward point of how you'd get the fairing down to the first stage, and attach it. (swelling dramatically the fairing doesn't seem sane)

If there was an easy way to join the fairing halves again, they'd be a lot more structurally robust, and in principle would have quite a low terminal velocity and weight allowing catch by copter.

Offline Elmar Moelzer

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Re: Fairing reuse
« Reply #27 on: 06/02/2015 08:30 PM »

You mean heating from the air (as minimal as it may be at that altitude)?
Is there an ballpark altitude for that? Just curious.

It is a function of vehicle velocity also well as air density.  So, there isn't a specific altitude.
Thanks, makes sense! So how does that fit in with the suggestion by some to make the fairing part of the first stage (I think someone said that Atlas does that) which would mean fairing separation about a minute earlier?
Does Atlas do the staging later in the flight envelope?

Offline RanulfC

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Re: Fairing reuse
« Reply #28 on: 06/02/2015 09:37 PM »
Check me on this,

It looks like the thing broke up on impact with the ocean so it would seem "reuse" would be on the order of making that event survivable. That however does nothing for the range restrictions issues.

Probably a "bad" idea but what about having the fairing separate along one side and then eject side-ways so that it could close up for reentry?

(And what's this about a "fairing" for the MCT?)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline dcporter

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Re: Fairing reuse
« Reply #29 on: 06/03/2015 05:23 AM »
Check me on this,

It looks like the thing broke up on impact with the ocean so it would seem "reuse" would be on the order of making that event survivable. That however does nothing for the range restrictions issues.

Probably a "bad" idea but what about having the fairing separate along one side and then eject side-ways so that it could close up for reentry?

(And what's this about a "fairing" for the MCT?)

Randy

If the problem is landing rather than falling, how would clamming back up help? I'd think that would reduce drag, increasing the speed left at impact.

Offline Jim

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Re: Fairing reuse
« Reply #30 on: 06/03/2015 01:44 PM »

Thanks, makes sense! So how does that fit in with the suggestion by some to make the fairing part of the first stage (I think someone said that Atlas does that) which would mean fairing separation about a minute earlier?
Does Atlas do the staging later in the flight envelope?

For the 5m, the fairing comes off before 2nd stage sep.
For the 4m, it comes off after 2nd stage start.
Most fairings on other vehicles come off after 2nd stage start.

Offline Jim

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Re: Fairing reuse
« Reply #31 on: 06/03/2015 01:45 PM »

In principle, a very, very light structure - perhaps even inflated could be added inside for a shield in the minute or so afterwards.


Why?  That is the main purpose of the fairing, so why duplicate it and make the system more complex?

Offline Elmar Moelzer

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Re: Fairing reuse
« Reply #32 on: 06/03/2015 02:50 PM »
For the 5m, the fairing comes off before 2nd stage sep.
For the 4m, it comes off after 2nd stage start.
Most fairings on other vehicles come off after 2nd stage start.
Thanks, Jim!
So what speaks against an F9 fairing that always comes off at or shortly before second stage separation? It is obviously possible to do it, since Atlas is doing it with the 5m fairing.

Offline RanulfC

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Re: Fairing reuse
« Reply #33 on: 06/03/2015 03:08 PM »
If the problem is landing rather than falling, how would clamming back up help? I'd think that would reduce drag, increasing the speed left at impact.

Drag should be about the same with both halves being rejoined you have only a single "piece" rather than two to track/control to landing. The halves should also be more supporting together than when separated.
I'm just throwing an idea out but frankly I don't see "fairing-reuse" as being serious.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Jim

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Re: Fairing reuse
« Reply #34 on: 06/03/2015 04:30 PM »

So what speaks against an F9 fairing that always comes off at or shortly before second stage separation? It is obviously possible to do it, since Atlas is doing it with the 5m fairing.

Spacecraft requirements for the environment. 

There is a "blackout" period around stage separation that fairing separation is usually not performed.  The vehicle goes into attitude hold in preparation for booster shutdown.  After shutdown, the vehicle is not accelerating and so fairing sep can't really be done.  There are transients and attitude excursions associated with second stage coast and ignition, so fairing sep is set off few seconds (5 or so after the engine is steady state)

Atlas V first stage burn out is around 240 seconds. 
Fairing come off at 270 seconds for 4 meter (during 2nd stage burn)
Fairing come off at 200 seconds for 5 meter (during 1st stage burn)

Velocity has a role in determining environments, a 5m mission is going to be slower for a given movement is the timeline vs a 4m.

F9 first stage burn out is around 150 seconds.
Falcon 9 fairing comes off at 210 seconds

So, the fairing on F9 isn't going to come off earlier. 
« Last Edit: 06/03/2015 05:00 PM by Jim »

Offline guckyfan

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Re: Fairing reuse
« Reply #35 on: 06/03/2015 04:34 PM »
So what speaks against an F9 fairing that always comes off at or shortly before second stage separation? It is obviously possible to do it, since Atlas is doing it with the 5m fairing.

Falcon 9R stages very early. So the payload still needs some protection, I would assume.

Offline meekGee

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Re: Fairing reuse
« Reply #36 on: 06/03/2015 09:40 PM »
So what speaks against an F9 fairing that always comes off at or shortly before second stage separation? It is obviously possible to do it, since Atlas is doing it with the 5m fairing.

Falcon 9R stages very early. So the payload still needs some protection, I would assume.

I think F9R also flies a more lofted trajectory, which should in principle help to drop the fairing earlier.
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Online douglas100

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Re: Fairing reuse
« Reply #37 on: 06/03/2015 10:01 PM »
I think a re-usable fairing only makes economic and technical sense as part of a re-usable upper stage, maybe like  the Kistler K-1. Bottom line, a re-usable fairing is a non-starter for current vehicles. The extra complexity for little economic return makes it not worth it IMHO.

Since a fairing carried to orbit is going to cause a large payload hit, it only makes sense for a much larger re-usable vehicle.

Douglas Clark

Offline nadreck

Re: Fairing reuse
« Reply #38 on: 06/03/2015 10:04 PM »
I think a re-usable fairing only makes economic and technical sense as part of a re-usable upper stage, maybe like  the Kistler K-1. Bottom line, a re-usable fairing is a non-starter for current vehicles. The extra complexity for little economic return makes it not worth it IMHO.

Since a fairing carried to orbit is going to cause a large payload hit, it only makes sense for a much larger re-usable vehicle.

And if the initial investment in each fairing is $1M and the cost to recover and recommission is $500,000 you wouldn't do it?
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Online douglas100

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Re: Fairing reuse
« Reply #39 on: 06/03/2015 10:11 PM »
I think a re-usable fairing only makes economic and technical sense as part of a re-usable upper stage, maybe like  the Kistler K-1. Bottom line, a re-usable fairing is a non-starter for current vehicles. The extra complexity for little economic return makes it not worth it IMHO.

Since a fairing carried to orbit is going to cause a large payload hit, it only makes sense for a much larger re-usable vehicle.

And if the initial investment in each fairing is $1M and the cost to recover and recommission is $500,000 you wouldn't do it?

Not unless you could demonstrate these numbers are real.
Douglas Clark

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