Author Topic: Fairing reuse  (Read 560964 times)

Re: Fairing reuse
« Reply #1080 on: 12/21/2017 08:02 PM »
There might be a very obvious answer to this question but since it's not obvious to me I'll ask it.
      Why can't the two halves be caught in the same net despite contact. Would the damage be that great that would render the effort worthless? I don't know enough about the material and speed of landing to be able to discern the impact.
     Also seems to me that the first try is more about catching than using the fairings that were caught.

I am not sure about this at all, but my speculation is that Mr. Steven will be catching exactly one half of the fairing this attempt.  Any of the "multiple catch" scenarios (except maybe the double decker net) or offloading between catches treat these fairings much more robustly than I think they are built.  The cost estimates are currently somewhere between "pallet of cash" and the $6m neighborhood of comparable fairings.  To me, this means that these are complicated, expensive, and therefore fragile, delicate, high grade aerospace carbon composite structures that cannot be "slid" off nets, or moved by hand, or hastily moved by crane.  I think any contact between the halves would be an instant deal-breaker as well.  This is why I suspect that they will catch only one half this attempt.

Supposing that they do in fact catch only one half this time, will it be able to be re-used?  What I mean, is are the fairing halves built to be paired with a specific second half, or are they interchangeable, even in theory?  If they catch one half, or course it is good practice for future efforts and proof of concept, but without the second "matching" (I in no way claim to know that they need to be matched, but it seems possible to me at first thought) fairing half, is it potentially useless for reuse?
Probably not this time.  As of 1:00 PM PST today, December 21, which is less than 29 hours from the launch target, Mr. Steven is still moored in San Pedro.  I assume it should have left port by now if it's going to attempt a fairing recovery. https://www.marinetraffic.com/en/ais/home/shipid:3439091/zoom:14

Offline RDoc

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Re: Fairing reuse
« Reply #1081 on: 12/21/2017 08:12 PM »
I'd not be surprised if jcc was close https://forum.nasaspaceflight.com/index.php?topic=37727.msg1761981#msg1761981. Two large floating air cushions, port and starboard, one per half. One issue I see with nets is t some kind of shock absorbing mechanism the fairing half will decelerate pretty quickly.
Pretty easy to add some shock absorbing to the net. Think trapeze safety net. Some springs at the mount points plus the tensioning cables and netting material will have some inherent stretch and thus shock absorption capacity.
But the arms still need to absorb the force of the landing.

Floating mats on the other hand just need to be secured to the ship. The force is very spread out with the ocean as the support structure. A simple air bag like pressure release release system could be the shock absorber.

Such a system would provide a much larger pair of targets too.
« Last Edit: 12/21/2017 08:17 PM by RDoc »

Offline RocketLover0119

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Re: Fairing reuse
« Reply #1082 on: 12/21/2017 08:24 PM »
As of a few min. ago, Mr. Steven is still docked, however, NRC quest has vanished from the dock

EDIT: just checked and NRC quest is well offshore heading to where the fairings may be.... Mr Steven sitting this one out?
« Last Edit: 12/21/2017 08:27 PM by RocketLover0119 »
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Re: Fairing reuse
« Reply #1083 on: 12/21/2017 08:32 PM »
As of a few min. ago, Mr. Steven is still docked, however, NRC quest has vanished from the dock

EDIT: just checked and NRC quest is well offshore heading to where the fairings may be.... Mr Steven sitting this one out?
NRC Quest is currently (1:31 PM PST) just south of Santa Catalina Island, heading almost due South (185 degrees) at 9.7 knots. https://www.marinetraffic.com/en/ais/home/shipid:447294/zoom:10

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Re: Fairing reuse
« Reply #1084 on: 12/21/2017 08:50 PM »
As of a few min. ago, Mr. Steven is still docked, however, NRC quest has vanished from the dock

EDIT: just checked and NRC quest is well offshore heading to where the fairings may be.... Mr Steven sitting this one out?
NRC Quest is currently (1:31 PM PST) just south of Santa Catalina Island, heading almost due South (185 degrees) at 9.7 knots. https://www.marinetraffic.com/en/ais/home/shipid:447294/zoom:10

Mr Steven is fast enough to wait until morning to get under way.
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Re: Fairing reuse
« Reply #1085 on: 12/21/2017 09:12 PM »
I'd not be surprised if jcc was close https://forum.nasaspaceflight.com/index.php?topic=37727.msg1761981#msg1761981. Two large floating air cushions, port and starboard, one per half. One issue I see with nets is t some kind of shock absorbing mechanism the fairing half will decelerate pretty quickly.
Pretty easy to add some shock absorbing to the net. Think trapeze safety net. Some springs at the mount points plus the tensioning cables and netting material will have some inherent stretch and thus shock absorption capacity.
But the arms still need to absorb the force of the landing.

Floating mats on the other hand just need to be secured to the ship. The force is very spread out with the ocean as the support structure. A simple air bag like pressure release release system could be the shock absorber.

Such a system would provide a much larger pair of targets too.
By the looks of them those arms are more than strong enough to withstand the force of the fairings landing. Big giant air cushions on the waterís surface would require a crane of some sort to move the fairing from the cushions to the deck for the ride home. If caught in a netting strung between the arms then the net is simply lowered and the fairings secured for transport. A cradle on deck is all that would be needed to secure the halves upon lowering.

Offline jabe

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Re: Fairing reuse
« Reply #1086 on: 12/21/2017 09:31 PM »
i may be out of loop.. or missed a comment...there are two halves..how is 2nd half caught? 2nd boat?
jb

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Re: Fairing reuse
« Reply #1087 on: 12/21/2017 09:32 PM »
Cross-posting:

A type of reuse I havenít noticed customers discussing before:

Quote
@IridiumBoss with the move to allow using flight proven cores, would Iridium now be open to being the first company to use reused Fairings?

https://twitter.com/beeberunner/status/943544314096955397

Quote
We're open to anything if it can be proven to improve risk, schedule and cost.  We're about getting our amazing next generation network in space as fast and safely as we can, not creating history for its own sake (though happy to do that this week with our fourth launch)!

https://twitter.com/iridiumboss/status/943547579001987073

Customer views on reuse belong in the original thread, but Iím posting here due to the last comment. Evidence of more significant fairing recovery attempt this time?

Offline nacnud

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Re: Fairing reuse
« Reply #1088 on: 12/21/2017 09:40 PM »
i may be out of loop.. or missed a comment...there are two halves..how is 2nd half caught? 2nd boat?
jb

Probably just catching the one half this time. Much speculation as to how the 2nd half is caught, no answers yet.

Offline RocketLover0119

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Re: Fairing reuse
« Reply #1089 on: 12/21/2017 10:13 PM »
totally speculating, but maybe on Iridium 4 one half will go to Mr. steven and the other NRC Quest ???

i may be out of loop.. or missed a comment...there are two halves..how is 2nd half caught? 2nd boat?
jb

Probably just catching the one half this time. Much speculation as to how the 2nd half is caught, no answers yet.


 
« Last Edit: 12/22/2017 06:42 PM by Lar »
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Re: Fairing reuse
« Reply #1090 on: 12/21/2017 10:22 PM »
Cross-posting:

A type of reuse I havenít noticed customers discussing before:

Quote
@IridiumBoss with the move to allow using flight proven cores, would Iridium now be open to being the first company to use reused Fairings?

https://twitter.com/beeberunner/status/943544314096955397

Quote
We're open to anything if it can be proven to improve risk, schedule and cost.  We're about getting our amazing next generation network in space as fast and safely as we can, not creating history for its own sake (though happy to do that this week with our fourth launch)!

https://twitter.com/iridiumboss/status/943547579001987073

Customer views on reuse belong in the original thread, but Iím posting here due to the last comment. Evidence of more significant fairing recovery attempt this time?

I think he's referring to being the first company to buy two launches on the same booster.

Offline Flying Beaver

Re: Fairing reuse
« Reply #1091 on: 12/22/2017 12:53 AM »
Mr. Steven is currently underway at 15 knots just east of Catalina Island, destination reading as Guadalupe Island, which i'd say is in approximate area for a fairing recovery with extended stage 1 burn (600km downrange).
Watched B1019 land in person 21/12/2015.

Offline llanitedave

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Re: Fairing reuse
« Reply #1092 on: 12/22/2017 03:44 AM »
Ok, super crazy idea (perhaps wine-induced), so bear with me.

How feasible would it be to tether the fairing mid-flight to the boat and parasail the thing down to the cradle/claw basket by winching it down in a controlled fashion? Once tethered, the boat's speed could be used to raise altitude or keep the fairing from falling too fast until it is caught.

Presumably, all the equipment the fairing would need would be a [right type of] parachute system and a long enough tether to hang down so the boat can catch the tether before the fairing hits the water.

It sounds James Bond enough for SpaceX  ;D

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Offline JamesH65

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Re: Fairing reuse
« Reply #1093 on: 12/22/2017 09:54 AM »
I'd not be surprised if jcc was close https://forum.nasaspaceflight.com/index.php?topic=37727.msg1761981#msg1761981. Two large floating air cushions, port and starboard, one per half. One issue I see with nets is t some kind of shock absorbing mechanism the fairing half will decelerate pretty quickly.
Pretty easy to add some shock absorbing to the net. Think trapeze safety net. Some springs at the mount points plus the tensioning cables and netting material will have some inherent stretch and thus shock absorption capacity.
But the arms still need to absorb the force of the landing.

Floating mats on the other hand just need to be secured to the ship. The force is very spread out with the ocean as the support structure. A simple air bag like pressure release release system could be the shock absorber.

Such a system would provide a much larger pair of targets too.

Hitting water with a flexible cover on it is almost like hitting concrete. The water DOES NOT GIVE. As a one time windsurfer, I was flipped and hit the sail lying flat on the surface. Quite quickly. Nearly knocked me out.  So you would need large floating air bags to absorb ALL the impact - the water doesn't help.

So just use a sodding great big net. Much easier, easy to make very shock absorbing (check out people diving down on nets from a long way up - less mass, but easily scalable), and easy to simply lower one net and slide another one over the top for the second half of the fairly. The fairings are not hugely heavy.

Don't over think this - Musk hasn't.


Offline vanoord

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Re: Fairing reuse
« Reply #1094 on: 12/22/2017 01:34 PM »
Floating mats on the other hand just need to be secured to the ship. The force is very spread out with the ocean as the support structure. A simple air bag like pressure release release system could be the shock absorber.

Such a system would provide a much larger pair of targets too.

A potential advantage of putting a big net on top of the ship is the ability to move the net at the last minute / have the net moving to reduce the relative speed during the final approach.

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Re: Fairing reuse
« Reply #1095 on: 12/22/2017 01:45 PM »
A potential advantage of putting a big net on top of the ship is the ability to move the net at the last minute / have the net moving to reduce the relative speed during the final approach.
The net weighs orders of magnitude less than the fairing, so the impact even without any other measures is going to be quite soft.

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Re: Fairing reuse
« Reply #1096 on: 12/22/2017 01:53 PM »
Floating mats on the other hand just need to be secured to the ship. The force is very spread out with the ocean as the support structure. A simple air bag like pressure release release system could be the shock absorber.

Such a system would provide a much larger pair of targets too.

A potential advantage of putting a big net on top of the ship is the ability to move the net at the last minute / have the net moving to reduce the relative speed during the final approach.

I don't think the final approach of the parachute system will intersect the net.

I think the last 1-2 seconds will be in free-fall, to minimize last-second wind effects, and to make the trajectory more vertical (and thus more perpendicular to the net)

I think the parachute system will sweep high, by 10-20', overtaking the ship, but making sure the IIP intersects the ship's path.  Then it's just a matter of timing the release correctly, the fairing drops, and the net catches it.

Meanwhile the parachute, having been released early, falls back and does not add post-landing complications.

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Offline LouScheffer

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Re: Fairing reuse
« Reply #1097 on: 12/22/2017 03:59 PM »
I don't think the final approach of the parachute system will intersect the net.

I think the last 1-2 seconds will be in free-fall, to minimize last-second wind effects, and to make the trajectory more vertical (and thus more perpendicular to the net)

If you watch human parachuters trying to hit a target, then come down steeply but not vertically, and they keep adjusting to the very last second.  Dropping seems worse for last-minute winds.  You still need to hit the drop point exactly, but then you can't adjust any further.

Also, the boat is quite fast.   If it maneuvers under the parachute, and matches the horizontal component of velocity, then the fairing comes down perpendicular to the net with no relative horizontal velocity.  And this way you keep control right up until capture, with the lowest impact speed into the net.  So I expect it to work like an aircraft carrier, with the parachute under positive control and the ship moving into the wind to minimize the relative velocity.

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Re: Fairing reuse
« Reply #1098 on: 12/22/2017 05:25 PM »
I don't think the final approach of the parachute system will intersect the net.

I think the last 1-2 seconds will be in free-fall, to minimize last-second wind effects, and to make the trajectory more vertical (and thus more perpendicular to the net)

If you watch human parachuters trying to hit a target, then come down steeply but not vertically, and they keep adjusting to the very last second.  Dropping seems worse for last-minute winds.  You still need to hit the drop point exactly, but then you can't adjust any further.

Also, the boat is quite fast.   If it maneuvers under the parachute, and matches the horizontal component of velocity, then the fairing comes down perpendicular to the net with no relative horizontal velocity.  And this way you keep control right up until capture, with the lowest impact speed into the net.  So I expect it to work like an aircraft carrier, with the parachute under positive control and the ship moving into the wind to minimize the relative velocity.
Just like with F9 landings, the way humans do it is dictated by how humans process information.

A helicopter pilots hovers and adjusts continuously, and then lands slowly.  A computer hover slams.

A falling fairing, in 1-2 seconds, even in changing wind, is predictable.

A parachutes OTOH has a huge sail area, and not enough authority to combat a gust of wind in real time.

If a human tried to land on a moving ship in open seas, they'd likely miss.  Plus, they typically don't have a net to arrest vertical motion.  (Except for that one guy..)
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Offline RDoc

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Re: Fairing reuse
« Reply #1099 on: 12/22/2017 06:17 PM »
I'd not be surprised if jcc was close https://forum.nasaspaceflight.com/index.php?topic=37727.msg1761981#msg1761981. Two large floating air cushions, port and starboard, one per half. One issue I see with nets is t some kind of shock absorbing mechanism the fairing half will decelerate pretty quickly.
Pretty easy to add some shock absorbing to the net. Think trapeze safety net. Some springs at the mount points plus the tensioning cables and netting material will have some inherent stretch and thus shock absorption capacity.
But the arms still need to absorb the force of the landing.

Floating mats on the other hand just need to be secured to the ship. The force is very spread out with the ocean as the support structure. A simple air bag like pressure release release system could be the shock absorber.

Such a system would provide a much larger pair of targets too.

Hitting water with a flexible cover on it is almost like hitting concrete. The water DOES NOT GIVE. As a one time windsurfer, I was flipped and hit the sail lying flat on the surface. Quite quickly. Nearly knocked me out.  So you would need large floating air bags to absorb ALL the impact - the water doesn't help.

So just use a sodding great big net. Much easier, easy to make very shock absorbing (check out people diving down on nets from a long way up - less mass, but easily scalable), and easy to simply lower one net and slide another one over the top for the second half of the fairly. The fairings are not hugely heavy.

Don't over think this - Musk hasn't.
Nobody's talking about a flexible cover.

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