Author Topic: Fairing reuse  (Read 231122 times)

Offline dcporter

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Fairing reuse
« on: 06/01/2015 08:41 PM »
An interesting hint at fairing reusability in a tweetback from Elon:

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

Offline meekGee

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Re: Fairing reuse
« Reply #1 on: 06/01/2015 08:56 PM »
I didn't believe this when the first hints showed up, but I guess it's for real...

Well, if anyone can pull this off right now, it's SpaceX.
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Offline ClayJar

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Re: Fairing reuse
« Reply #2 on: 06/01/2015 09:17 PM »
Apparently three of them found the fairing piece:

Kevin (twitter) posted a full set of high-res original images on his dropbox.
Grier (twitter) said they were sending GoPro/card back to SpaceX.
Nate (twitter) posted another high-res shot on ow.ly.

(Should someone attach the photos for posterity?)

Offline Comga

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Re: Fairing reuse
« Reply #3 on: 06/01/2015 09:30 PM »
Can anyone explain the details seen in the images?
That's a GoPro camera in an aerospace grade housing?
Whatt about the access port, the hose, those wavy metal straps, the ball tipped long arm, and the short rounded arm?
I am not sure this is really OT for reuseable farings.  This one is definitely not reuseable, although the camera might be.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Elmar Moelzer

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Re: Fairing reuse
« Reply #4 on: 06/01/2015 09:35 PM »
I am not sure this is really OT for reuseable farings.  This one is definitely not reuseable, although the camera might be.
IMHO it is on topic, because Musk wants to use the information gathered from it for their future reusable fairings.

Offline ClayJar

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Re: Fairing reuse
« Reply #5 on: 06/01/2015 09:53 PM »
Can anyone explain the details seen in the images?
That's a GoPro camera in an aerospace grade housing?
Whatt about the access port, the hose, those wavy metal straps, the ball tipped long arm, and the short rounded arm?
I am not sure this is really OT for reuseable farings.  This one is definitely not reuseable, although the camera might be.
The big hoses must be for environmental control (air conditioning the insides of the fairing before launch), as I can't think of anything else that would make sense.  The wavy metal straps are brackets for the large hoses, which were attached with zip ties.  (The remaining longer hose piece is still attached to some of them with the same zip ties that are present in some of the now empty brackets.)

The long arm with a ball joint at one end has a hinge at the remaining attachment, and the short round heavy-duty eye appears to contain a bearing.  Obviously related to moving parts (for fairing sep?).

And it's two GoPro camera/data logger housings, actually.  One is clearly visible, and the second is by the two big hoses near the side (the ball-tipped arm nearly hits it).  We've only seen occasional glimpses inside the fairing during launch video, but they apparently are kitted out for more than we see (which is, of course, a gross understatement).  I can only imagine that if the GoPro cameras continued rolling after fairing sep, having them back with full-resolution imagery and so on could provide some quite handy information.

Online FutureSpaceTourist

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Re: Fairing reuse
« Reply #6 on: 06/01/2015 10:09 PM »
(Should someone attach the photos for posterity?)

I inadvertently created a duplicate thread. Here are the initial photo's I uploaded.

Still can't get my head around that it's worth the effort to re-use fairings!

Offline Arcas

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Re: Fairing reuse
« Reply #7 on: 06/01/2015 10:28 PM »
Why not just attach the fairings to hinges, and snap them shut after releasing payload instead of blowing them off.
The risk I took was calculated, but boy am I bad at math.

Offline DMeader

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Re: Fairing reuse
« Reply #8 on: 06/01/2015 10:33 PM »
Why not just attach the fairings to hinges, and snap them shut after releasing payload instead of blowing them off.

They separate to reduce weight. At that point in the ascent they are no longer needed to protect the payload. However, the vehicle is still under power, significantly before the payload is released.
« Last Edit: 06/01/2015 10:37 PM by DMeader »

Offline meekGee

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Re: Fairing reuse
« Reply #9 on: 06/01/2015 10:37 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.
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Online Robotbeat

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Re: Fairing reuse
« Reply #10 on: 06/01/2015 11:34 PM »
Why not just attach the fairings to hinges, and snap them shut after releasing payload instead of blowing them off.
Because fairings are attached to the upper stage and so you'd have to bring it all away up to orbit. You could attach the fairing to the first stage like an atlas V (an idea I like and toyed with once when designing an RLV) but then the fairing would have to be at least twice as big.
« Last Edit: 06/01/2015 11:35 PM by Robotbeat »
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Offline sojourner

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Re: Fairing reuse
« Reply #11 on: 06/02/2015 01:29 AM »
Maybe the "reuse" part of the tweet was just Elon being Flippant?

Offline Jim

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Re: Fairing reuse
« Reply #12 on: 06/02/2015 01:47 AM »

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

Offline Elmar Moelzer

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Re: Fairing reuse
« Reply #13 on: 06/02/2015 01:48 AM »
I have always wondered why they wait a full minute after the separation of the second stage for the separation of the fairing. Is there anything preventing them from doing that event earlier? If not, how early could it theoretically happen? Given the heavy SpaceX fairing, an earlier fairing separation could IMHO mean a bit of extra performance (and for reuse getting it down closer to the launch site might be beneficial too).

Offline Jim

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Re: Fairing reuse
« Reply #14 on: 06/02/2015 01:53 AM »
I have always wondered why they wait a full minute after the separation of the second stage for the separation of the fairing. Is there anything preventing them from doing that event earlier? If not, how early could it theoretically happen? Given the heavy SpaceX fairing, an earlier fairing separation could IMHO mean a bit of extra performance (and for reuse getting it down closer to the launch site might be beneficial too).

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.

Offline bstrong

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Re: Fairing reuse
« Reply #15 on: 06/02/2015 03:29 AM »
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.

I wonder if they've come to the conclusion that maintaining hazard zones like they do today is going to prevent them from achieving super-high launch rates

Assuming they can someday convince the FAA/USAF that the risk of dropping first stages on unsuspecting boaters is comparable to the risk of planes falling out of the sky on them, uncontrolled fairing descent could be the only reason for keeping the hazard zones around.

Offline Elmar Moelzer

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Re: Fairing reuse
« Reply #16 on: 06/02/2015 04:23 AM »
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.
You mean heating from the air (as minimal as it may be at that altitude)?
Is there an ballpark altitude for that? Just curious.

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Re: Fairing reuse
« Reply #17 on: 06/02/2015 05:16 AM »
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.
You mean heating from the air (as minimal as it may be at that altitude)?
Is there an ballpark altitude for that? Just curious.

More than 100 km high in most cases - usually closer to 110-130 km.
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Offline Jim

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Re: Fairing reuse
« Reply #18 on: 06/02/2015 10:54 AM »

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.

Offline MattMason

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Re: Fairing reuse
« Reply #19 on: 06/02/2015 12:42 PM »
Why not just attach the fairings to hinges, and snap them shut after releasing payload instead of blowing them off.

Looks like, historically, full separation of fairings is the safer plan, too. Apollo 7's S-IVB adapter panels simply opened like flower petals. But they opened asymmetrically and concerned mission planners that future LM extractions or the CSM would be jeopardized. So fairing jettison was the way to go to avoid collisions or obstructions.

I don't think a recloseable fairing system would work. First, how would it safely move off the vehicle? That would require it to open up like a clamshell to provide payload clearance and then be propelled upward like a launch escape system tower, and then commanded to close again.

Even if the fairing was jettisoned whole, like the pulling the cover to the tip of a pen, it would need to be larger in diameter to add a little extra space to avoid brushing the payload as it exits. In either case, the fairing is heavier with the jettison jets and separation must be perfect or the payload or LV is in jeopardy.

None of my fanciful speculations will stop a company from figuring out an idea to make that work, however.
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