Author Topic: Fairing reuse  (Read 438862 times)

Online AncientU

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Re: Fairing reuse
« Reply #1180 on: 12/30/2017 01:01 PM »
My money is on them eventually having 2 boats out there. Just catching 1 fairing half during the test phase then setting up a second ship when they go into normal recovery operations. KISS principle at work

Two boats seems the pragmatic approach.  I'm not sure I'd want to bet $5 million on everything going right without any glitches.  (Or would that be $2.5 million, since you'd only have to wave goodbye to the second half?)

If I were trying to find ways to make things more efficient, the first thing I'd have to wonder is whether I can consolidate something *other* than fairing catching.  Can I, perhaps, get a fairing catcher that can also tow an ASDS into position?  Saves me the same number of boats, but doesn't require perfect timing.  (Not saying a fairing catcher can be a ASDS towing craft, but you get the general idea.)

It may be wrong that both fairing halves are equally valued.  The active half may be worth significantly more.  IMO, the best argument for investing the effort to catch the fairings at all is that it saves the large capital expenditures needed to make a whole lot more fairings, and thereby enables SpaceX's goal of a much higher flight rate.  Catching just 1 could be enough to meet their short term needs and so we won't see anything else until they start getting closer to their limiting rate.

The rig looks heavy enough to catch a second stage... just sayin'
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Online Steve D

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Re: Fairing reuse
« Reply #1181 on: 12/30/2017 02:29 PM »
My money is on them eventually having 2 boats out there. Just catching 1 fairing half during the test phase then setting up a second ship when they go into normal recovery operations. KISS principle at work

Two boats seems the pragmatic approach.  I'm not sure I'd want to bet $5 million on everything going right without any glitches.  (Or would that be $2.5 million, since you'd only have to wave goodbye to the second half?)

If I were trying to find ways to make things more efficient, the first thing I'd have to wonder is whether I can consolidate something *other* than fairing catching.  Can I, perhaps, get a fairing catcher that can also tow an ASDS into position?  Saves me the same number of boats, but doesn't require perfect timing.  (Not saying a fairing catcher can be a ASDS towing craft, but you get the general idea.)


I think the requirements of the fairing catching ship and a tug boat are too different to be able to do both. The catcher need to be fast and maneuverable, the tug needs  to be a high "torque" kind of powerful. Its the difference between a sports car and a bulldozer. You dont pull a trailer with a corvette, you dont run around town in a bulldozer. 

Offline corrodedNut

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Re: Fairing reuse
« Reply #1182 on: 12/30/2017 08:48 PM »
I'm thinking it's something like this:

https://www.youtube.com/watch?v=6qF_fzEI4wU?t=1m

Offline meekGee

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Re: Fairing reuse
« Reply #1183 on: 12/30/2017 09:06 PM »
I'm thinking it's something like this:

https://www.youtube.com/watch?v=6qF_fzEI4wU?t=1m

Yup - that's the "Except one guy" I referred to up thread...   Isn't it the craziest, yet actually most well-controlled stunts there ever was?

I mean - you can argue it was actually safer than a parachute jump since he didn't even have to worry about a parachute malfunction...  It was already open, only he wasn't wearing it yet  :)

Can't watch it without laughing out loud, but that's the kind of thinking of why I think the parachute will cut loose from the fairing before being caught.
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Offline OxCartMark

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Re: Fairing reuse
« Reply #1184 on: 12/31/2017 02:01 AM »
There is another way that a net or other catcher could be rigged on those four masts though not likely.  A smaller net could be suspended by four lines from the posts or from rigging on the perimeter line and controlled by multiple servo winches so that the net would be rapidly moved as needed to catch the fairing half.  Similar to the mobile TV cameras that are suspended above football fields.  Perhaps such a setup could be used without a net to connect with feature(s) on the fairing.  What is the benefit to such a system over a simple large net?  Only one I can think of - the ability to catch a fairing half and quickly manipulate it off to the side and ready itself for a second catch.  Do I think this is what they are doing?  No.  Primarily because those fairing halves are really stinking large (ref. Roadster image) and the area defined by the four masts can't be that much larger.  Secondarily the rigging of the lines on the four masts looks too basic, too low tech for that.

Personally I doubt they would do a high altitude opening (I have a Class A jump certification, but am certainly no authority).

Upper level wind is pretty high and often contrary to lowers. This leads to a loss of precision in the landing zone, even when using a steerable chute. Additionally, high altitudes in turn give low air density which in turn require larger strokes over longer times to effect control authority over the wing. Low density deployment also leads to higher spring recoil where the parachute can momentarily have a higher descent velocity than the payload.

Point being, Id guess a later opening to pick up denser air with less variables re wind speed and direction.
The effects of high altitude wind could be mitigated (mostly) if Mr. Steven threw out a few weather balloons to determine what's up.  Back in the 70s I made a thing of predicting the landing spot of model rockets.  When there was significant wind and we were expecting a high flight I would often put up a kite.  You can look up a kite line and see how the wind bows it at various levels.

Low density deployment also leads to higher spring recoil where the parachute can momentarily have a higher descent velocity than the payload.

OT: That phenomenon is even more pronounced when a paraglider wing opens after being wadded up and falling for a bit - it can shoot forward and down so vigorously that it can end up under its pilot.  The pilot can than fall into and become wrapped up in his own wing which is never really a good thing.

My money is on them eventually having 2 boats out there. Just catching 1 fairing half during the test phase then setting up a second ship when they go into normal recovery operations. KISS principle at work
Unlikely but possible alternate scenario: Fabricate a light weight high speed hull to use as a trailer behind the main high speed ship.  Light enough to maintain speed, same cross section profile, same catch area, unmanned.


I think the parachute will cut loose from the fairing before being caught.
Ya gotta get rid of it as soon as you're in the net there isn't much of a way around that, you're only a few knots below the speed at which the lift of the chute would exceed the weight of the fairing (in which case the fairing would briefly be able to maintain level flight and possibly ascend a bit - until contact with the net were to be broken which would remove the horizontal propelling force.  Even below flying speed there is very little normal force on the net to allow sufficient friction force to keep the fairing from sliding out the back of the net.  Very similar to kiting a paraglider in high winds where you may only have a few single digit pounds of weight on your feet with which to try to maintain an adequate forward force for your weight and L/D.

Offline john smith 19

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Re: Fairing reuse
« Reply #1185 on: 12/31/2017 08:43 AM »
Personally I doubt they would do a high altitude opening (I have a Class A jump certification, but am certainly no authority).

Upper level wind is pretty high and often contrary to lowers. This leads to a loss of precision in the landing zone, even when using a steerable chute. Additionally, high altitudes in turn give low air density which in turn require larger strokes over longer times to effect control authority over the wing. Low density deployment also leads to higher spring recoil where the parachute can momentarily have a higher descent velocity than the payload.

Point being, Id guess a later opening to pick up denser air with less variables re wind speed and direction.
The effects of high altitude wind could be mitigated (mostly) if Mr. Steven threw out a few weather balloons to determine what's up.  Back in the 70s I made a thing of predicting the landing spot of model rockets.  When there was significant wind and we were expecting a high flight I would often put up a kite.  You can look up a kite line and see how the wind bows it at various levels.
IIRC high altitude winds scrubbed a number of Shuttle launches and landings, presumably because they exceeded the pre loaded parameters in the GNC software.

Toward the end of the programme they were starting to use radar "sounders" to do wind profile measurements. They seemed to do this at 30 min intervals up to launch but I was never sure if this was because the processing was so complex or that was just what they were set up for. IIRC they were quite long wave systems, in the 10s, not 100s of MHz.  LIDAR would also be an option. I'd guess they would be most useful in putting the recovery vessel in a more optimal location, reducing motion of it or the parachutes.
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Online Oersted

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Re: Fairing reuse
« Reply #1186 on: 12/31/2017 05:46 PM »
The rig looks heavy enough to catch a second stage... just sayin'

Or a Dragon 2?

Online yokem55

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Re: Fairing reuse
« Reply #1187 on: 12/31/2017 08:08 PM »
The rig looks heavy enough to catch a second stage... just sayin'

Or a Dragon 2?
Or other folks might want to catch an engine compartment from a booster...

Offline brainbit

Re: Fairing reuse
« Reply #1188 on: 01/05/2018 09:42 PM »
I think they are only practicing to catch a dragon 2, since they dropped the Draco power decent they have a problem with re-use if the dragon 2 drops in the sea. If they can catch the dragon 2 before it lands in the water it would be much cheaper to re-use. This is why they only need one catchers mitt. And why they are practicing with the fairings.   

Offline Tomness

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Re: Fairing reuse
« Reply #1189 on: 01/06/2018 12:33 AM »
The rig looks heavy enough to catch a second stage... just sayin'

Or a Dragon 2?
Or other folks might want to catch an engine compartment from a booster...



Can I pull a Jim say No?.... b/c do you know how heavy Dragon is?, apples to oranges of recovery of catching fairings vs catching a dragon... feather vs dumb bell.


« Last Edit: 01/06/2018 04:05 AM by Tomness »

Offline JamesH65

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Re: Fairing reuse
« Reply #1190 on: 01/07/2018 10:03 AM »
The rig looks heavy enough to catch a second stage... just sayin'

Or a Dragon 2?
Or other folks might want to catch an engine compartment from a booster...



Can I pull a Jim say No?.... b/c do you know how heavy Dragon is?, apples to oranges of recovery of catching fairings vs catching a dragon... feather vs dumb bell.

Although the net arms on that boat appear massively engineered to just to catch that feather of a fairing..

Offline Hobbes-22

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Re: Fairing reuse
« Reply #1191 on: 01/07/2018 10:38 AM »
That's a side effect of arm length. Supporting 1 ton at 10 meters out means the base of the arm needs to withstand 10 ton-meter. And you don't want the arms to go TWANGGGG when the fairing hits.

Offline rsdavis9

Re: Fairing reuse
« Reply #1192 on: 01/07/2018 01:08 PM »
So what is the weight of a fairing? 1 ton?
Dragon 2 is 6.4t dry and 2.5t return payload so 9t.
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Offline Alastor

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Re: Fairing reuse
« Reply #1193 on: 01/07/2018 01:24 PM »
SpaceX has been saying for quite a long time that they initially had more issues than expected with salt water ingressing the dragons system, which complicated a lot the refurbisment.
They also have been very public about the fact that they have been working on that problem so that they can continue operations as initially planned without having to essentially wipe out everything but the pressure vessel during refurbishment operations.
SpaceX has also been public about the fact that they DO intend to recover fairings and that they are working on it.

In a nutshell, fairing recovery operations are not a rehearsal or a preparation step for dragon recovery operations and I think we should get back on topic.

Online the_other_Doug

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Re: Fairing reuse
« Reply #1194 on: 01/09/2018 09:55 PM »
Any clues as to whether any attempt was made at recovering one or both of the fairings from Sunday's Zuma launch?
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Offline Tomness

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Re: Fairing reuse
« Reply #1195 on: 01/10/2018 07:13 AM »
Any clues as to whether any attempt was made at recovering one or both of the fairings from Sunday's Zuma launch?
That would be G-14 classified, that mission is so nuts, i wouldn't put it past them to pyro the fairings to make sure every trace has been removed. Better used on more benign campaign.

Offline Alastor

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Re: Fairing reuse
« Reply #1196 on: 01/10/2018 08:37 AM »
Any clues as to whether any attempt was made at recovering one or both of the fairings from Sunday's Zuma launch?

I have seen video evidence of fairing detachment (SpaceLaunchReport video), but I have seen no sign of RCS firing.
Of course this does not mean that the fairing seen in there would be the active one. This does not mean either that RCS firing would necessarily be seen in this video, nor that RCS firing would happen while the fairing is visible (though based on past experience, I expect it would happen).

Another element is that the spaceX ships do not seem to have been on location for recovery ops.

Finally they already had issues with fairing on Zuma and this is a highly classified highly valuable payload, so I expect they might not be very willing to experiment on that one (since something can always go wrong).

All of this leads me to say that there probably wasn't any fairing recovery ops with this launch.

Offline Jarnis

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Re: Fairing reuse
« Reply #1197 on: 01/10/2018 11:42 AM »
Cold Gas RCS firings with the fairings are visible only during dusk/dawn launches or really clear sky day launches.

Late night launch like Zuma, no way to see them. Heck, the fairings themselves were only barely visible in the amateur footage.

Offline Alastor

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Re: Fairing reuse
« Reply #1198 on: 01/10/2018 11:52 AM »
I'm not certain they couldn't be illuminated by plume interaction, when close to the booster. But I agree, they probably wouldn't be seen given the illumination conditions.

Offline Dave G

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Re: Fairing reuse
« Reply #1199 on: 01/13/2018 09:49 AM »
Does anyone know if SpaceX plans to recover the Falcon Heavy fairing ?

Also, what ever happened to the fairing they recovered from SES-10 ?

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