Author Topic: Fairing reuse  (Read 561333 times)

Offline docmordrid

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Re: Fairing reuse
« Reply #1720 on: 07/13/2018 08:05 PM »
https://twitter.com/SpaceX/status/1017807493311811584?s=19

SpaceX ✔ @SpaceX
 Mr. Steven now with more net. SpaceXs fairing recovery vessel has been fitted with a 4x larger net ahead of its next recovery attempt targeted for later this month. http://instagram.com/p/BlLYeNnFZNA/
12:26 PM - Jul 13, 2018
|
https://twitter.com/ShorealoneFilms/status/1017807808169795584?s=19

Matt Hartman @ShorealoneFilms
yup. i was there

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Offline john smith 19

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Re: Fairing reuse
« Reply #1721 on: 07/15/2018 07:37 AM »
The pictures of the new net deployed are incredible.  Can't wait.

It will be very interesting to see if and when we see 2 ships and fairings being reflown.

End of this year is coming quick but maybe there is an outside shot at that.
Launch cadence suggests they will have plenty of chances to get it right. There are at least 2 FH launches scheduled before 1st of Jan 2019
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Offline Comga

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Re: Fairing reuse
« Reply #1722 on: 07/16/2018 05:48 AM »
The pictures of the new net deployed are incredible.  Can't wait.

It will be very interesting to see if and when we see 2 ships and fairings being reflown.

End of this year is coming quick but maybe there is an outside shot at that.

Launch cadence suggests they will have plenty of chances to get it right. There are at least 2 FH launches scheduled before 1st of Jan 2019

I think you missed the point.
FH is not what he is talking about.
I think wannamoonbase means two fairing halves from any Falcon launch being recovered, which takes 2 ships, and then be reflown on a single flight.
edit: But you are right that they will have plenty of chances
« Last Edit: 07/16/2018 05:49 AM by Comga »
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Offline aero

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Re: Fairing reuse
« Reply #1723 on: 07/16/2018 04:15 PM »
If one half of the fairing loitered at altitude for as long as possible while the other half descended as quickly as practical, then after catching the quickly descending fairing half, would there be enough time to lower the net, stow the first half fairing and raise the net to catch the second half fairing?
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Offline wannamoonbase

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Re: Fairing reuse
« Reply #1724 on: 07/16/2018 07:24 PM »
If one half of the fairing loitered at altitude for as long as possible while the other half descended as quickly as practical, then after catching the quickly descending fairing half, would there be enough time to lower the net, stow the first half fairing and raise the net to catch the second half fairing?

Have to disagree, that's a gamble and wrestling something as large a fairing on a fast schedule would be ripe with safety problems.

Buy a second boat and install a second net.
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Offline wannamoonbase

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Re: Fairing reuse
« Reply #1725 on: 07/16/2018 07:26 PM »
The pictures of the new net deployed are incredible.  Can't wait.

It will be very interesting to see if and when we see 2 ships and fairings being reflown.

End of this year is coming quick but maybe there is an outside shot at that.

Launch cadence suggests they will have plenty of chances to get it right. There are at least 2 FH launches scheduled before 1st of Jan 2019

I think you missed the point.
FH is not what he is talking about.
I think wannamoonbase means two fairing halves from any Falcon launch being recovered, which takes 2 ships, and then be reflown on a single flight.
edit: But you are right that they will have plenty of chances

Correct, I meant recovering a full fairing and reflying it.

I agree they have plenty of opportunities to try.  But they'll need to add a second west coast and 2 east coast vessels.
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Offline JamesH65

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Re: Fairing reuse
« Reply #1726 on: 07/17/2018 11:06 AM »
Just have two nets. First fairing lands, drop the net towards the deck (big pads on deck, could go all the way down), 'roll' a new net over the top. As long as the first net can drop enough to give clearance for the second, it's then just a matter of unloading at your leisure.

Offline woods170

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Re: Fairing reuse
« Reply #1727 on: 07/17/2018 11:18 AM »
Just have two nets. First fairing lands, drop the net towards the deck (big pads on deck, could go all the way down), 'roll' a new net over the top. As long as the first net can drop enough to give clearance for the second, it's then just a matter of unloading at your leisure.


I think you seriously underestimate the amount of time to hoist a second net in place.

Once catching a fairing is proven you will find that a second fairing-catcher ship will be commissioned real soon.
Each fairing-catcher ship will, per mission, catch one fairing half, at best.

Online Robotbeat

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Re: Fairing reuse
« Reply #1728 on: 07/17/2018 12:30 PM »
They could also put a high tension rope in the middle of the current net once they get really good at catching to separate the net into two halves.

But it is possible to hoist a new net in a few minutes if designed properly with pulleys. That's enough time separation.
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Offline JamesH65

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Re: Fairing reuse
« Reply #1729 on: 07/17/2018 01:12 PM »
Just have two nets. First fairing lands, drop the net towards the deck (big pads on deck, could go all the way down), 'roll' a new net over the top. As long as the first net can drop enough to give clearance for the second, it's then just a matter of unloading at your leisure.


I think you seriously underestimate the amount of time to hoist a second net in place.

Once catching a fairing is proven you will find that a second fairing-catcher ship will be commissioned real soon.
Each fairing-catcher ship will, per mission, catch one fairing half, at best.

They will need 4, two on each coast. As long as flight rate is OK that might be cost effective, but remember, they cannot really do anything else between flights with all that hardware bolted on, so once modified that's all they are good for.

With the right deploying equipment, I see no reason why pulling a new net over couldn't be done in a couple of minutes. All down to how fast you can do it.

Edit: Although at 'only' $10-12M each, plus lets say $1M for the arms, plus whatever running costs are incurred, probably not too much of a hit to have 4.
« Last Edit: 07/17/2018 01:17 PM by JamesH65 »

Offline speedevil

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Re: Fairing reuse
« Reply #1730 on: 07/17/2018 01:27 PM »
They will need 4, two on each coast. As long as flight rate is OK that might be cost effective, but remember, they cannot really do anything else between flights with all that hardware bolted on, so once modified that's all they are good for.
Mr Steven is one of a class of quite fast vessels, they can in principle be repositioned from one coast to the other in a little over a week.
Which is at least another option.

Offline wannamoonbase

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Re: Fairing reuse
« Reply #1731 on: 07/17/2018 01:29 PM »
Edit: Although at 'only' $10-12M each, plus lets say $1M for the arms, plus whatever running costs are incurred, probably not too much of a hit to have 4.

Is that the price of the ship new?  Elon likes buying used equipment and re-purposing.

The benefits of fairing recovery likely wouldn't work at a low flight rate, but at 24+ flights a year it seems to make sense.

If, Starlink becomes a real thing and they need to launch a few hundred F9's to LEO then it really adds up. 

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Online niwax

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Re: Fairing reuse
« Reply #1732 on: 07/17/2018 02:13 PM »
Edit: Although at 'only' $10-12M each, plus lets say $1M for the arms, plus whatever running costs are incurred, probably not too much of a hit to have 4.

Is that the price of the ship new?  Elon likes buying used equipment and re-purposing.

I don't think ships depreciate that much, it's likely more about quick availability.

Would a ship on the west coast be that necessary? They have only had a handful of flights from there, and since they own a large number of their launches with Starlink they could schedule to launch from the west coast in bulk and reposition the ships.

Offline JamesH65

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Re: Fairing reuse
« Reply #1733 on: 07/17/2018 07:41 PM »
Edit: Although at 'only' $10-12M each, plus lets say $1M for the arms, plus whatever running costs are incurred, probably not too much of a hit to have 4.

Is that the price of the ship new?  Elon likes buying used equipment and re-purposing.

The benefits of fairing recovery likely wouldn't work at a low flight rate, but at 24+ flights a year it seems to make sense.

If, Starlink becomes a real thing and they need to launch a few hundred F9's to LEO then it really adds up.

Closest price I could find to a similar vessel (albeit a slower one, seems like Mr Steven is quite an unusual craft), not sure if it was new or not. I think the construction cost was $12M.

Online RobLynn

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Re: Fairing reuse
« Reply #1734 on: 07/17/2018 10:23 PM »
Ships are cheap to build, and a stripped down ship with minimal accommodation that has no other function than to go fast will be even cheaper.

Given the tiny variation in mass that the ship will have in use a small water-line area twin hull (SWATH, effectively submersed pontoons with thin struts extending up through water surface) would likely be best - fast, very stable, insensitive to waves.
https://en.wikipedia.org/wiki/Small-waterplane-area_twin_hull

Being able to tilt the net over by raising or lowering the arms would also seem like a really useful design feature to have to increase the effective target area.
 
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Offline woods170

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Re: Fairing reuse
« Reply #1735 on: 07/18/2018 08:13 AM »
They could also put a high tension rope in the middle of the current net once they get really good at catching to separate the net into two halves.

But it is possible to hoist a new net in a few minutes if designed properly with pulleys. That's enough time separation.

No, it isn't. Both fairing halves are coming down in the same flight profile. They are hitting the water less than half a minute apart. And the lateral separation upon splash-down is larger than Mr. Steven can cover in that time, due to anti-collision considerations.

Offline JamesH65

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Re: Fairing reuse
« Reply #1736 on: 07/18/2018 09:31 AM »
They could also put a high tension rope in the middle of the current net once they get really good at catching to separate the net into two halves.

But it is possible to hoist a new net in a few minutes if designed properly with pulleys. That's enough time separation.

No, it isn't. Both fairing halves are coming down in the same flight profile. They are hitting the water less than half a minute apart. And the lateral separation upon splash-down is larger than Mr. Steven can cover in that time, due to anti-collision considerations.

Are they? I didnt think we had that information? Surely it depnds on when you open the chute, and how big it is? Open later, with a smaller chute, you could increase the time separation. By how much? Who knows?

But anyway, since I reckon the costs of new ships to chase is only about two fairings sets, it probably easier and fairly cheap just to run multiple ships. Or maybe one really big one.

Offline deruch

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Re: Fairing reuse
« Reply #1737 on: 07/18/2018 12:29 PM »
IMO, if SpaceX was able to get multi-minute delays on fairing touchdowns by just adjusting the parachutes and timings, then they would have caught a fairing already.  The ability to fly a "delayed drop" fairing so that it splashes down close enough to the original to allow catching it with the same vessel requires the same tech to be able to drop one in a very small dropzone.  If they could control them so precisely, they would have already caught one or at least not needed the arm/net expansion.

Remember that positioning the ship is about more than just getting to spot X by a certain time.  To have the best chance of catching the fairing they will need to be moving as well.  So, they'll do catch attempts like flying a bombing run.  Get the ship to a staging point by the time the fairing is at a certain altitude and flying a set direction (likely into the wind).  Then motor forward underneath, slipping sideways as needed, to eventually catch it.  To lower the net and manhandle the fairing into a safe stowage position on deck while also traveling at high speed to preposition the ship for the second run in the short amount of time potentially available is a lot to ask.  Personally, I'm convinced they'll need a second ship in order to catch both fairings from a single launch.
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Offline JamesH65

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Re: Fairing reuse
« Reply #1738 on: 07/18/2018 01:14 PM »
IMO, if SpaceX was able to get multi-minute delays on fairing touchdowns by just adjusting the parachutes and timings, then they would have caught a fairing already.  The ability to fly a "delayed drop" fairing so that it splashes down close enough to the original to allow catching it with the same vessel requires the same tech to be able to drop one in a very small dropzone.  If they could control them so precisely, they would have already caught one or at least not needed the arm/net expansion.

Not sure that makes sense. Landing point is irrelevent to the height of deploy (excluding change in cross range whicih is irrelevent). Chute size might make a difference, in that going larger means a lower vertical descent speed. However, these sort of chutes you can trim - trading forward speed with descent rate.

Remember that positioning the ship is about more than just getting to spot X by a certain time.  To have the best chance of catching the fairing they will need to be moving as well.  So, they'll do catch attempts like flying a bombing run.  Get the ship to a staging point by the time the fairing is at a certain altitude and flying a set direction (likely into the wind).  Then motor forward underneath, slipping sideways as needed, to eventually catch it.  To lower the net and manhandle the fairing into a safe stowage position on deck while also traveling at high speed to preposition the ship for the second run in the short amount of time potentially available is a lot to ask.  Personally, I'm convinced they'll need a second ship in order to catch both fairings from a single launch.

Not likely in to the wind. Definitely in to the wind. I don't think the actual process of catching is doubt.

So I think it would be possible to catch both with the same boat, but having looked at the costings of boats vs fairings, it's probably not worth it. Just buy another boat.

Offline Dave G

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Re: Fairing reuse
« Reply #1739 on: 07/22/2018 12:29 PM »
Any news on the fairing recovery for today's Telesat launch?

According to this article:
https://www.nasaspaceflight.com/2018/07/spacex-falcon-9-telstar-19v-launch/
Quote
While SpaceX does not have a dedicated East Coast recovery ship, and therefore cannot catch the fairing before it hits the water, the company should be able to guide the fairing halves to a soft splashdown and then fish them out of the water.

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