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Old 04-04-2017, 09:19 PM   #76
Andy44
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Originally Posted by C3PO View Post
 It was more expensive to reuse STS SRBs than to replace them, so reusing fairings would probably make even less sense economically. I'm guessing it depends on how expensive the "re-certification" is.
Maybe. Reusing the SRBs really meant tearing them completely down, sending the segments back to the factor for refueling, and rebuilding and recertifying them, with all the attendant inspections and mating seems and so on. An SRB is actually a very complicated device.

It remains to be seen if fairing reuse is economical or not.

Part of the problem is that making anything reusable that used to be expendable means making it more expensive, so you have to get to that breakeven point. The RS-25 (aka SSME) engine was very expensive because it was built to be reusable, but arguably worth it. STS as a whole was never able to break even though.
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Old 04-04-2017, 09:26 PM   #77
Kyle
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Originally Posted by HarvesteR View Post
 I had the amazing good fortune of actually being there (at Hawthorne) during the launch.... way at the back of the room, but I was there

We later got a tour of the place, and I saw the fairings being built.

They are made of carbon fiber and honeycomb aluminum, and constructing them actually takes slightly longer than putting together the rest of the rocket. There's a lot more to them than meets the eye. It makes sense that they'd want to reuse them if they could.

It seems that wasn't actually in the plans until recently, when a returned fairing washed up somewhere and they got a good look at it. They strapped cameras to a subsequent flight, and saw that it was tearing itself up due to wobbling as it reentered. Hence the plan to control their descent using small thrusters and steerable chutes.

The problem with recovery though is that seawater pretty much ruins them, and they can't (yet) be guided down with the same precision as the booster. If they touch water, they're done, so they are trying to come up with a plan to either snag them out of the sky (D-21 payload style) or possibly use what amounts to a very, very large bouncy castle on the sea.

Cheers
The bouncy castle item is new to me. Sounds like an inflatable ASDS. Also sounds like why they're going with the steerable parachute. It's probably more economically efficient than paying for helicopters to recover the two fairings.
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Old 04-04-2017, 10:11 PM   #78
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Originally Posted by HarvesteR View Post
 The problem with recovery though is that seawater pretty much ruins them, and they can't (yet) be guided down with the same precision as the booster. If they touch water, they're done, so they are trying to come up with a plan to either snag them out of the sky (D-21 payload style) or possibly use what amounts to a very, very large bouncy castle on the sea.
Or option C: Use materials that don't corrode in seawater or have sacrificial anodes on the fairing.

After all, the same was necessary for the first carrier planes, since you can't construct a ships deck high enough for not letting the planes get into contact with salt water.
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Old 04-05-2017, 01:37 PM   #79
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Originally Posted by Urwumpe View Post
 Well, a modern rocket fairing is a really complicated device, since it has to fullfill many roles, aside of protecting the payload from the air flow.

It has to be as light-weight as possible.
And still it has to be rigid enough to not damage the payload.
It has to have RF windows for communication with the payload.
It also has to protect the payload from the noise during launch and early ascent.
It needs to provide access panels for technicians.
Often it needs to have a properly defined air flow on the launch pad for keeping the payload cooled.
It often is part of the fairing separation system
Mariner 3 probe launched in 1964 failed when the fairing encasing the probe
failed to release pinning probe inside until batteries died.

Indications were that the fairing collapsed by aerodynamic stress during launch.....
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Old 04-05-2017, 10:21 PM   #80
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 ..Indications were that the fairing collapsed by aerodynamic stress during launch.....
Would the 'auto-pilot' be able to control the unbalanced forces resulting from that ?

Most likely went out of control and crashed beyond camera view ?

---------- Post added at 12:21 AM ---------- Previous post was at 12:13 AM ----------

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Originally Posted by Frilock View Post
 Erm....

Interesting... looks like a rigged engine test.. BUT that's just my eyesight
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Old 04-06-2017, 03:05 AM   #81
Thunder Chicken
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Some nice video of the landing from the ASDS:



If you look at the video at the end that shows the stage standing you can see how much the deck rolls. Amazing it can land so solidly.

Last edited by Thunder Chicken; 04-06-2017 at 03:09 AM.
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Old 04-06-2017, 09:40 AM   #82
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Originally Posted by Col_Klonk View Post
 Would the 'auto-pilot' be able to control the unbalanced forces resulting from that ?

Most likely went out of control and crashed beyond camera view ?
No, it reached heliocentric orbit. "Collapsed" is sounding a lot more impression than it likely was, a pressure difference between the composite outer shell and the metal inner shell simply made the shells detach and collapse inside the fairing, so the separation system did no longer work.

For the next launch a few weeks later, they used a heavier all-metal fairing.
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