Author Topic: Fairing reuse  (Read 371848 times)

Offline Jim

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Re: Fairing reuse
« Reply #600 on: 02/26/2017 01:27 AM »

Though the principle of "performance loss for reusability" still applies.

The current fairing existed before thoughts of such

Offline Jim

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Re: Fairing reuse
« Reply #601 on: 02/26/2017 01:28 AM »
Any idea when this will be flying? Only on Heavy or on F9 also?

there isn't going to be a different fairing for the heavy

Online Lar

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Re: Fairing reuse
« Reply #602 on: 02/26/2017 01:31 AM »
I like the idea that they built a cheap but heavy fairing ....

What makes you think it's cheap?  Elon said it was "millions of dollars", which is quite a lot for a structure this size.

two things....

1) it's an idea which I like but it's not necessarily my idea, I just like it. So ask the originator.
2) cheap is a relative term. If they aren't using buckyballs in it, or unobtanium or whatever, it's cheaper than if they were.

Any idea when this will be flying? Only on Heavy or on F9 also?

there isn't going to be a different fairing for the heavy

Which I guess means that FH will be volume limited in many cases before it is mass limited?
« Last Edit: 02/26/2017 01:33 AM by Lar »
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Online cppetrie

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Re: Fairing reuse
« Reply #603 on: 02/26/2017 02:03 AM »
In that case, the loading seems to me very similar to what a fairing normally experiences, or even more benign.


It is nowhere near the same. On most other vehicles, the fairing never sees any loads from the payload. They could not be used in the same

Just a matter of distributing the loads.  SpaceX clearly designed for this, but it shouldn't double the mass of the fairing.  Worst case they'd have added a ribbed structure from the support point to the payload ring, which would not weight multiple tons.  (And I don't think they needed to do that either).

What makes the SpaceX fairing twice as heavy as other fairings has to be a fairing-wide issue, and the only thing that fits the bill is either incompetence (they don't know how to build a lightweight fairing) or some unique aerodynamic requirements - and the second option is staring us right in the face, since we know they're trying recovery.
Or a structural requirement. The pictures clearly show the fairing with enclosed payload being lifted by the middle of the fairing. From other's comments here, such an operation never happens with fairings for other rockets. SpaceX probably does this for some reason based on their processing flow (maybe not having to have special equipment to deal with the torque on the payload adapter before the adapter gets attached to the rocket.)

Aerodynamic concerns for recovery don't make sense, because information relating to fairing recovery has indicated that the current fairings were not designed for recovery. The current fairings were designed long before they would have been ready to seriously consider fairing recovery.

Also, you are really, really oversimplifying structural analysis in some of your posts.

Of course I am...   I also don't have the details of their structure necessary to even start a more complex analysis....   But neither do the other posters...

All I'm saying is that the extra weight of the fairing (twice what a normal fairing would weigh) seems excessive for  the support outlined, since IMO at the worse case it would have been a small penalty, or more likely, none at all.

OTOH, those fairings are doing something else very differently from regular fairings.... trying to perform controlled re-entry...  so that should be the likely suspect.

As for when did SpaceX start thinking about fairing recovery - I don't know, and neither do you.  It's clearly not the final design, but whether they were built more robustly to enable even initial experimentation - we simply can't tell.  But probably earlier than a year ago...

First post to NSF so forgive the likely uninformed intrusion on a long-running discussion, but what if the reasoning for the heavier fairing design was as follows: by integrating structural support for the payload during launch and MaxQ into the fairing rather than the payload adapter it allows them to jettison the weight of said support when fairing separation occurs meaning less weight is riding on stage 2 afterwards. If all the support is in the payload adapter, then you haul that and it's extra weight all the way out to your destination. Does the SpaceX fairing design allow a lighter payload adapter that is consequently lighter. I've not seen anything in the discussions I've visited thus far indicating one way or the other. Anyone with some insight that can chime in on the hypothesis I put forward?


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Offline woods170

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Re: Fairing reuse
« Reply #604 on: 02/26/2017 10:22 AM »
First post to NSF so forgive the likely uninformed intrusion on a long-running discussion, but what if the reasoning for the heavier fairing design was as follows: by integrating structural support for the payload during launch and MaxQ into the fairing rather than the payload adapter it allows them to jettison the weight of said support when fairing separation occurs meaning less weight is riding on stage 2 afterwards. If all the support is in the payload adapter, then you haul that and it's extra weight all the way out to your destination. Does the SpaceX fairing design allow a lighter payload adapter that is consequently lighter. I've not seen anything in the discussions I've visited thus far indicating one way or the other. Anyone with some insight that can chime in on the hypothesis I put forward?


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Welcome to the forum.
The fairing only supports the payload, via the PAF, during ground handling: rotation from vertical to horizontal, any horizontal handling and horizontal integration onto the rocket. Payload mass throughout launch and MaxQ is supported by the upper stage, via the PAF.
« Last Edit: 02/26/2017 11:54 AM by woods170 »

Offline DOCinCT

Re: Fairing reuse
« Reply #605 on: 02/26/2017 02:59 PM »
...Does the SpaceX fairing design allow a lighter payload adapter that is consequently lighter. I've not seen anything in the discussions I've visited thus far indicating one way or the other. Anyone with some insight that can chime in on the hypothesis I put forward?
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The Payload Adapter Fitting (PAF) comes in two standard versions: the light PAF payloads weighing up to 3,453 kg (7,612 lb), and  the heavy PAF up to 10,886 kg (24,000 lb). 

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Re: Fairing reuse
« Reply #606 on: 02/26/2017 05:09 PM »
...Does the SpaceX fairing design allow a lighter payload adapter that is consequently lighter. I've not seen anything in the discussions I've visited thus far indicating one way or the other. Anyone with some insight that can chime in on the hypothesis I put forward?
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The Payload Adapter Fitting (PAF) comes in two standard versions: the light PAF payloads weighing up to 3,453 kg (7,612 lb), and  the heavy PAF up to 10,886 kg (24,000 lb).

Those are the weight limits for PAFs, but how do the weights of the PAFs themselves compare to PAFs of other launch vehicles with similar weight capacities?


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Re: Fairing reuse
« Reply #607 on: 02/26/2017 05:14 PM »
First post to NSF so forgive the likely uninformed intrusion on a long-running discussion, but what if the reasoning for the heavier fairing design was as follows: by integrating structural support for the payload during launch and MaxQ into the fairing rather than the payload adapter it allows them to jettison the weight of said support when fairing separation occurs meaning less weight is riding on stage 2 afterwards. If all the support is in the payload adapter, then you haul that and it's extra weight all the way out to your destination. Does the SpaceX fairing design allow a lighter payload adapter that is consequently lighter. I've not seen anything in the discussions I've visited thus far indicating one way or the other. Anyone with some insight that can chime in on the hypothesis I put forward?


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Welcome to the forum.
The fairing only supports the payload, via the PAF, during ground handling: rotation from vertical to horizontal, any horizontal handling and horizontal integration onto the rocket. Payload mass throughout launch and MaxQ is supported by the upper stage, via the PAF.

That would seems to disprove my hypothesis. Are other launch vehicles with lighter fairings only vertically integrated? Could SpaceX have made a compromise on fairing weight in order to permit horizontal integration rather than vertical? Is there an advantage in terms of rocket design or launch prep to be able to integrate horizontally?


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Online envy887

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Re: Fairing reuse
« Reply #608 on: 02/26/2017 07:38 PM »
Any idea when this will be flying? Only on Heavy or on F9 also?

there isn't going to be a different fairing for the heavy

Is it related to one of the upcoming F9 blocks?

Offline RoboGoofers

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Re: Fairing reuse
« Reply #609 on: 03/15/2017 03:50 PM »
[...]
And this news article shows a rare image of an encapsulated payload going horizontal: https://www.noozhawk.com/noozhawk/print/falcon_9_rocket_moving_toward_nasa_launch_at_vandenberg_afb

You will notice that the payload and fairing are not held via the PAF (Payload Attachment Fitting), but via the fairing halves. Consequently, the load of the payload goes thru the fairing, not the PAF. This requires a strong fairing. Much stronger than those from RUAG et al.
The fairing doesn't carry the payload since it doesn't touch it.  At worst, during horizontal integration, the fairing half carries its own weight.

There was never a good explanation of why they are heavy, except perhaps the desire for them to survive reentry.
This photo posted above by @woods170 is pretty definitive. The fairing is carrying the weight of the payload.

Are the payloads designed to be positioned with a specific CG inside the fairing? The picture shows it perfectly balanced, but the lift points don't look repositionable, so it's not clear how they deal with different payload sizes and masses. Maybe they add ballast to 'even out the scales'?

Offline Jim

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Re: Fairing reuse
« Reply #610 on: 03/15/2017 03:54 PM »

Are the payloads designed to be positioned with a specific CG inside the fairing? The picture shows it perfectly balanced, but the lift points don't look repositionable, so it's not clear how they deal with different payload sizes and masses. Maybe they add ballast to 'even out the scales'?

There are two cranes in use.  One is attached to the aft of the fairing.

Offline RoboGoofers

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Re: Fairing reuse
« Reply #611 on: 03/15/2017 05:00 PM »

Are the payloads designed to be positioned with a specific CG inside the fairing? The picture shows it perfectly balanced, but the lift points don't look repositionable, so it's not clear how they deal with different payload sizes and masses. Maybe they add ballast to 'even out the scales'?

There are two cranes in use.  One is attached to the aft of the fairing.

Ok I see it now. I guess it's those spiderweb-y looking lines, and maybe that blue square.

Regarding mid-air capture; has anything as large as a F9 fairing been caught mid-air before? I'd imagine its shape would make it whip around a lot behind a plane or below a helicopter.
« Last Edit: 03/15/2017 06:20 PM by RoboGoofers »

Offline Alastor

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Re: Fairing reuse
« Reply #612 on: 03/15/2017 09:05 PM »
Some helicopter pilots on the forum have estimated that it would be a delicate operation, but possible.
Their main concern is actually the range of the helicopters.

As for slowing down the fairing, it's a matter of flying in formation with it, grab it and then slowly enough decelerate it. As for the weight itself, there are some pretty heavy lift helicopters around. That shouldn't be a problem in itself.

Offline IanThePineapple

Re: Fairing reuse
« Reply #613 on: 03/15/2017 09:12 PM »
The fact that CCAFS is an air force base should fare well for helicopters catching fairings
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Offline leetdan

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Re: Fairing reuse
« Reply #614 on: 03/15/2017 09:21 PM »
The fact that CCAFS is an air force base should fare well for helicopters catching fairings

Specifically, CCAFS and the 920th Rescue Wing (HC-130P, HH-60G) are both headquartered at nearby Patrick AFB.

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Re: Fairing reuse
« Reply #615 on: 03/15/2017 09:41 PM »
The fact that CCAFS is an air force base should fare well for helicopters catching fairings

Specifically, CCAFS and the 920th Rescue Wing (HC-130P, HH-60G) are both headquartered at nearby Patrick AFB.
Yeah, but it's not like SpaceX is going to use military assets to recover fairings.
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Offline Kaputnik

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Re: Fairing reuse
« Reply #616 on: 03/15/2017 09:58 PM »
Range does seem to be the killer for helicopter recovery.
I guess you could snag the fairing halves using a fixed wing, then tow them back home, release and catch with a chopper. A bit Rube Goldberg though...
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Offline manoweb

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Re: Fairing reuse
« Reply #617 on: 03/15/2017 10:38 PM »
Honestly I would be very surprised if SpaceX wants to recover the fairings, for the sole purpose of saving money, by catching them on the fly with (military) helicopters. In my opinion they will come out with something much less expensive, even if it will take some time to develop the technology to do so

Offline Jim

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Re: Fairing reuse
« Reply #618 on: 03/16/2017 02:15 AM »
The fact that CCAFS is an air force base should fare well for helicopters catching fairings

It has no bearing on the matter.

Offline Hobbes-22

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Re: Fairing reuse
« Reply #619 on: 03/16/2017 08:33 AM »
Honestly I would be very surprised if SpaceX wants to recover the fairings, for the sole purpose of saving money, by catching them on the fly with (military) helicopters. In my opinion they will come out with something much less expensive, even if it will take some time to develop the technology to do so

A helicopter capable of lifting the fairing can be rented for a few thousand/hour. Not cheap, but not prohibitively expensive either if the potential savings is $2M.

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