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SpaceX currently tries to land their fairing halves on a boat with a net attached to it. So far they had no success but landed nearby, although quadrupling the net area.

They first tried with this sized net.

Mr Steven with first generation net

After they got close, but not close enough they decided to increase the size to increase their chances.

Mr Steven with second generation net

To get a feel for the size differences, consider this comparison picture.

Comparing before and after

What makes it so difficult to precisely land a fairing with steerable parachutes?

geoffc
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DaGroove
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    The answer, my friend, is blowing in the wind; the answer is blowing in the wind –  Jul 30 '18 at 17:34
  • See also how this question is fairing: https://space.stackexchange.com/questions/25649/falcon-9-fairings-stability-on-reentry/25656#25656 – Rob Jul 31 '18 at 07:19

1 Answers1

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The fairing itself is large, (a pair can enclose a school bus sized payload) and is very light, and not very aerodynamic when split into two halves.

When joined together it is very aerodynamic, when split apart, dramatically less so.

Thus the parachute has to overcome a very oddly shaped, unoptimized for gliding shape.

Paz Fairing on the water

It is fairly large, ungainly, and hard to control so that it does not twist nor interfere with the parachute.

In the question about Fairing Separation Altitudes the questioner compiles a table of how high the fairings get released. They all release above 100km altitude and about 7000-9000 km/h. Re-entering from such heights and speeds is very difficult.

That SpaceX has been able to get them down to the surface, to land on the water, visibly intact (Obviously wet with salt water and not reusable, but more intact than they have any right to be), is pretty dang impressive. Now they are trying to hit a net, that is large for humans, but tiny when you compare the height/speed numbers.

They have gotten within 50m on one attempt, and on the Iridium-7 crew reported they could see the fairing, but they failed to catch it. That is pretty darn close.

Expanding the size of the net is one way to make it more likely to succeed. They seem close enough at this point that minor tweaks should make it happen soon enough.

geoffc
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  • If it floats, why not attach an outboard motor to the thing and have it ferry itself back home?! (Jokes aside, it does look like the spitting image of a boat in that picture). – Magic Octopus Urn Jul 31 '18 at 12:57
  • Do you have pictures of the fairing chutes in action? – Magic Octopus Urn Jul 31 '18 at 13:05
  • @MagicOctopusUrn Sure does look like a boat. Though apparently once waves kick up and water gets inside, it quickly starts to sink. As for pics of a fairing in flight, I have yet to see an official one. Someone did a CGI one, but that is not helpful. Best I have is a drop test at the dock of a fairing in the net. – geoffc Jul 31 '18 at 13:33
  • You also made an interesting point about the fairing being less aerodynamic when split. Maybe reconnecting the halves after separating would be an idea to remove the odd flight pattern, though I'm not even sure if that's possible (unless maybe a tether, or never fully separating the two halves). It also seems more likely you'd catch one thing rather than two. – Magic Octopus Urn Jul 31 '18 at 18:48
  • If you somehow reconnected the fairings in the few minutes while still outside the atmosphere, then the aerodynamics of the fairings return to their original design: Flying like a bullet. While this would greatly increase their accuracy, it also greatly increases their speed, requiring larger and stronger chutes, reducing max payload weight and increasing the amount of fuel needed to get the same payloads to orbit. – Ghedipunk Jul 31 '18 at 23:31