Author Topic: Fairing reuse  (Read 565090 times)

Offline Kaputnik

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Re: Fairing reuse
« Reply #660 on: 03/21/2017 07:24 PM »
I don't think we can extrapolate directly from a human parachutist to a fairing descending under a foil.

The human has three distinct advantages: great control authority (big control actuators, aka arms), extremely good undercarriage with long travel (aka legs), and much higher density (this varies from human to human, of course).

So a human can come in at a relatively higher speed, without being blown around by the wind, and make a fairly forceful impact whilst remaining intact.

Gut feeling is that a fairing half is not the sturdiest of things, when it comes to sudden impact loads. But anybody with insight into this please chip in.
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Online RoboGoofers

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Re: Fairing reuse
« Reply #661 on: 03/21/2017 07:53 PM »
The catch idea seems a bit crazy to me because if you could catch a fairing, why not a second stage?
If you have to ask, you need to do more research
The fairings don't re-enter from orbital speed, come in not too far from the launch site, have low ballistic coefficients and terminal velocity, have much lower mass, and detract from payload at well below the 1:1 ratio of the second stage.

yeah I'm just hand-waving away all of that. I'm only talking about the difficulty of the catch and the effects on the aircraft. After all, catching something as large as a fairing hasn't been done before, either.

Then again ULA plans to air-catch their Vulcan engines. ::)

(Edited for clarity)

another edit:
At the end of this video they say "it's conceivable that this technique can be scaled up to payloads up to 22,000 lbs" so maybe catching the fairing isn't that crazy, though the logistics are still hard.
« Last Edit: 03/21/2017 09:01 PM by RoboGoofers »

Online Comga

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Re: Fairing reuse
« Reply #662 on: 03/21/2017 08:03 PM »
The catch idea seems a bit crazy to me because if you could catch a fairing, why not a second stage?
If you have to ask, you need to do more research
The fairings don't re-enter from orbital speed, come in not too far from the launch site, have low ballistic coefficients and terminal velocity, have much lower mass, and detract from payload at well below the 1:1 ratio of the second stage.

yeah just hand-waving away all of that. After all, catching something as large as a fairing hasn't been done before, either.
Then again ULA plans to air-catch their Vulcan engines. ::)

It is not clear who you are accusing of "hand waving".
Vulcan engine recovery will also be from speeds well below orbital, plan on using a massive heat shield, and are again part of the first stage, not the second.  (Fairings come off around staging, so their trajectories and mass impacts are very much like first stage elements.)  And it's still a decade out on ULA's plan.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline manoweb

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Re: Fairing reuse
« Reply #663 on: 03/21/2017 08:32 PM »
Do you think ULA was serious when they said they will catch the engines? Was it not only because at the time, SpaceX announced something crazy about landing a stage, and they felt compelled to say something as crazy? Sorry I do not follow the ULA forum so maybe I do not have new info on the subject.

Online Comga

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Re: Fairing reuse
« Reply #664 on: 03/21/2017 09:57 PM »
Do you think ULA was serious when they said they will catch the engines? Was it not only because at the time, SpaceX announced something crazy about landing a stage, and they felt compelled to say something as crazy? Sorry I do not follow the ULA forum so maybe I do not have new info on the subject.

Many years ago, before SpaceX landed any rockets, "our own" Jonathan Goff posted about recovering the RD-180 engines of an Atlas-V using helicopter caught parafoils.  ULA has studied this.  It's not impossible.  If they need to address the issue that they are developing a new expendable rocket while a competitor is perfecting reusability, they throw up that slide.  How serious they are is hard to know.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online TrevorMonty

Re: Fairing reuse
« Reply #665 on: 03/21/2017 10:11 PM »
The catch idea seems a bit crazy to me because if you could catch a fairing, why not a second stage?
If you have to ask, you need to do more research
The fairings don't re-enter from orbital speed, come in not too far from the launch site, have low ballistic coefficients and terminal velocity, have much lower mass, and detract from payload at well below the 1:1 ratio of the second stage.

yeah just hand-waving away all of that. After all, catching something as large as a fairing hasn't been done before, either.
Then again ULA plans to air-catch their Vulcan engines. ::)

It is not clear who you are accusing of "hand waving".
Vulcan engine recovery will also be from speeds well below orbital, plan on using a massive heat shield, and are again part of the first stage, not the second.  (Fairings come off around staging, so their trajectories and mass impacts are very much like first stage elements.)  And it's still a decade out on ULA's plan.
The SMART system could be applied to 2nd stage or its engines, as HIAD is design for orbital reentry speeds.
At one stage NASA considered testing HIAD using Cygnus.

Online meekGee

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Re: Fairing reuse
« Reply #666 on: 03/22/2017 01:13 AM »
We're *drifting* off topic.

Sorry, had to say it.

But yeah, the difficult part in second stage recovery is not snagging it, since it actually can occur closer to home base than the fairings can.  The problem is whether the weight penalty of the heat shield and maybe structural reinforcement is worth it.

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Offline darkenfast

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Re: Fairing reuse
« Reply #667 on: 03/22/2017 02:52 AM »
Okay, I KNOW they said they don't want to get it wet, but I can't help but notice that the fairing halves are most of the way to being a boat.  Seal up any openings and perhaps an inflatable "bulkhead" at the back (bottom, when on the rocket) and a parachute.  The insides of the fairing are probably what they don't want to get a lot of salt-water on.  If the paint (or SPAM, or whatever coats the outside) is tolerant, the halves will just float until pick-up.  I wouldn't tow them, I would crane them into a cradle.

But...they said they wouldn't want to get them wet.  I imagine they have something else planned.  Oh, well.

Offline manoweb

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Re: Fairing reuse
« Reply #668 on: 03/22/2017 04:58 AM »
darkenfast, yes I was also surprised by that declaration. What I mean is: composites should have a pretty good resistance to saltwater, the fairing is not made out of mild steel; we are also talking about few hours max, not years floating in the sea. If recoveries become the norm they can always invest in better paint, sealing etc.

Online meekGee

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Re: Fairing reuse
« Reply #669 on: 03/22/2017 07:03 AM »
darkenfast, yes I was also surprised by that declaration. What I mean is: composites should have a pretty good resistance to saltwater, the fairing is not made out of mild steel; we are also talking about few hours max, not years floating in the sea. If recoveries become the norm they can always invest in better paint, sealing etc.
Maybe the problem is bouncing around unpredictably on the waves?
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Offline darkenfast

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Re: Fairing reuse
« Reply #670 on: 03/22/2017 08:09 AM »
darkenfast, yes I was also surprised by that declaration. What I mean is: composites should have a pretty good resistance to saltwater, the fairing is not made out of mild steel; we are also talking about few hours max, not years floating in the sea. If recoveries become the norm they can always invest in better paint, sealing etc.
Maybe the problem is bouncing around unpredictably on the waves?
Obviously, in rough weather, some water is going to get in.  As hulls go, this is a very buoyant potential boat.  In the kind of waves and swells that you get out in deep water, I believe it would just ride over everything, responding very quickly.  It would probably roll a lot because of its circular cross section.  Something called a "flopper-stopper" might help (it hangs over the side, like a sea anchor, but straight down - the drag slows the roll).  The chute(s) would make something of a sea-anchor, unfortunately if it didn't collapse, it would be like chasing a light dinghy flying a spinnaker!  Jettison capability might be good. 

Having said all that, it will be interesting to see what they REALLY have planned.

Online AncientU

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Re: Fairing reuse
« Reply #671 on: 03/22/2017 10:27 PM »
darkenfast, yes I was also surprised by that declaration. What I mean is: composites should have a pretty good resistance to saltwater, the fairing is not made out of mild steel; we are also talking about few hours max, not years floating in the sea. If recoveries become the norm they can always invest in better paint, sealing etc.

The fairing uses honeycomb aluminum and carbon composites as I recall.
Question: Are the void areas in the honeycomb filled and/or vented*? 

Doesn't seem like a good idea to have them air-filled and working to de-laminate the structure when under vacuum (zero pressure) externally.  But if vented, they could fill with sea water if landed in the pond which would destroy the fairing or at least make it unfit for reuse.

*All of the vacuum components we build are provided a means to vent each of the void areas to ensure no gas is trapped after vacuum is drawn.
« Last Edit: 03/22/2017 10:30 PM by AncientU »
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Offline iamlucky13

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Re: Fairing reuse
« Reply #672 on: 03/23/2017 09:24 PM »
Oh great, inflight refueling...

This is looking more and more like a bad idea.

Most of the combat SAR helos of the USAF are already equipped with the inflight refueling kit. They need it for extended operational radius and/or time on station.

They have unlimited cash, and own the refueling tankers...and they ain't cheap.

And they're able to keep up with a C-130 because they're not towing a giant air brake.


How in the world is precision touchdown on ship/barge/raft unworkable?

Airborne Systems Dragonfly precision drop system, good for 10,000 lbs, only specs a 250m accuracy.

http://airborne-sys.com/wp-content/uploads/2016/08/ASG-DragonFly-20170206-English.pdf

Is that because 250m is the best theoretically achievable with current technology, or because there has been minimal incentive so far to improve the system to better than 250m accuracy?

It has not been demonstrated as workable, but that is different from being known to be unworkable.

darkenfast, yes I was also surprised by that declaration. What I mean is: composites should have a pretty good resistance to saltwater, the fairing is not made out of mild steel; we are also talking about few hours max, not years floating in the sea. If recoveries become the norm they can always invest in better paint, sealing etc.

The composites are probably not their concern. The fairing is more than just a shell. There are mechanical systems inside it like pushers and latch actuators that are potentially susceptible to both corrosion and salt fouling.

Online Robotbeat

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Re: Fairing reuse
« Reply #673 on: 03/23/2017 10:29 PM »
You can get GPS-guided parafoil payload systems that, with tweaking, can reliably hit the barge deck of an ASDS (50m x 90m). So maybe put a huge net on 4 poles (one on each corner of an ASDS) 15m high.
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Offline virnin

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Re: Fairing reuse
« Reply #674 on: 03/23/2017 10:36 PM »
You can get GPS-guided parafoil payload systems that, with tweaking, can reliably hit the barge deck of an ASDS (50m x 90m). So maybe put a huge net on 4 poles (one on each corner of an ASDS) 15m high.

That leads to the, unanswerable by us, question of how many fairings would they have to recover to pay for at least two, but more likely four, additional ASDS?

Online Robotbeat

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Re: Fairing reuse
« Reply #675 on: 03/23/2017 10:38 PM »
Could be a smaller and simpler vessel than an ASDS, but here's a shot:
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Offline nacnud

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Re: Fairing reuse
« Reply #676 on: 03/23/2017 10:39 PM »
I still like the scaneagle method of capture. Rather that thinking of landing these think of flying them through a volume of space within which they can be captured.

Offline LouScheffer

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Re: Fairing reuse
« Reply #677 on: 03/23/2017 10:58 PM »

Is that because 250m is the best theoretically achievable with current technology, or because there has been minimal incentive so far to improve the system to better than 250m accuracy?

250m is definitely not a theoretical limit.    Human in the loop systems have hit 17m (50% of the time), 42m 90% of the time.  Automated systems have hit 30 m (50%).

Offline Jet Black

Re: Fairing reuse
« Reply #678 on: 03/24/2017 08:13 AM »
You can get GPS-guided parafoil payload systems that, with tweaking, can reliably hit the barge deck of an ASDS (50m x 90m). So maybe put a huge net on 4 poles (one on each corner of an ASDS) 15m high.

That leads to the, unanswerable by us, question of how many fairings would they have to recover to pay for at least two, but more likely four, additional ASDS?

It's not the cost of the farings themselves, but whether they provide a bottleneck in launches. Even if they only cost $100 each, if they can't make them fast enough to keep up with their launch cadence, it would still be worth investing $100,000 per launch to catch them, because it would mean that they would be able to launch more rockets, earning millions of dollars each time.
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Offline guckyfan

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Re: Fairing reuse
« Reply #679 on: 03/24/2017 08:38 AM »
You can get GPS-guided parafoil payload systems that, with tweaking, can reliably hit the barge deck of an ASDS (50m x 90m). So maybe put a huge net on 4 poles (one on each corner of an ASDS) 15m high.

That leads to the, unanswerable by us, question of how many fairings would they have to recover to pay for at least two, but more likely four, additional ASDS?

They would be a lot simpler than the Falcon ASDS. Also unlike a Falcon core it is perfectly feasible to transfer fairing halves to a ship for transport and leave the ASDS at position for a while. So just 2.

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