Author Topic: Fairing reuse  (Read 590224 times)

Offline Alastor

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Re: Fairing reuse
« Reply #880 on: 04/04/2017 03:54 PM »
Any form of moving target would either require precise pre-planning, which doesn't work if you don't compensate the effects of winds, or require real time communication between the target and the fairing.

Comms means more weight, and the risks of communication failiures.
They already avoid doing that for the first stage and use a fixed rendez-vous point instead.

My bet is they will use the same strategy for the fairing, as it removes a lot of requirements and additional failiure modes:  fixed predetermined rendez-vous point.

Offline iamlucky13

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Re: Fairing reuse
« Reply #881 on: 04/04/2017 05:51 PM »
Very cool to see they recovered a half, even if visibly quite damaged.

Unfortunately we have no way of knowing how the damage in the pictures was sustained. On descent? On contact with the water? While in the water floating waiting to be picked up? While bringing aboard? Note they don't have the proper lifting equipment on the vessel to lift it out of the water. As others noted, it was probably dragged aboard likely resulting in significant damage.

True, but the damage looks pretty extensive to me. Depending which end we're looking at (I think aft), either nose or the boat tail seems to be largely broken off. As discussed upthread, the fairing is a much more substantial structure than most people realize. It seems likely to me it sustained non-trivial damage on entry and/or splashdown, and handling it aboard the vessel no doubt made it worse.

I doubt we'll get detailed comments from SpaceX on their findings, but this should be quite helpful to them in understanding what it takes for a fairing to survive.

Note that there have been some references in the past to "Fairing 2.0." Some changes are already in the works, so there could be a major improvement in re-entry performance pending.

By the way, Musk mentioned in the post-launch press conference that the fairing has thrusters to stabilize it during entry. I don't think that had been confirmed before.

Offline OnWithTheShow

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Re: Fairing reuse
« Reply #882 on: 04/05/2017 01:27 AM »
Why not put the "bouncy castle" in the fairing?

Offline JamesH65

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Re: Fairing reuse
« Reply #883 on: 04/05/2017 08:45 AM »
Any form of moving target would either require precise pre-planning, which doesn't work if you don't compensate the effects of winds, or require real time communication between the target and the fairing.

Comms means more weight, and the risks of communication failiures.
They already avoid doing that for the first stage and use a fixed rendez-vous point instead.

My bet is they will use the same strategy for the fairing, as it removes a lot of requirements and additional failiure modes:  fixed predetermined rendez-vous point.

I still cannot see how, without knowing the instantaneous wind conditions at the LZ, how they expect to accurately land under parachute. Remember, parachutes are much more affected by the wind, and have more time to be affected than the 1st stage. You always want to land in to the wind to reduces ground speed, so you NEED to know the wind direction, which could easily have changed between launch and landing.

If you are preprogramming the wind direction, what is the last point at which you can do so? Days in advance? Just prior to launch? There needs to be some mechanism to tell the fairing the wind direction, even before launch.

Online JJB

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Re: Fairing reuse
« Reply #884 on: 04/05/2017 09:45 AM »

Landing on the "Bouncy Castle" Is not that hard, I do this without instruments,with instruments and a 360 overhead even a computer can do this.
There is probably still life clinging to thermal vents, giggling about the absurdity of growing a backbone.-KZ.

Offline JamesH65

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Re: Fairing reuse
« Reply #885 on: 04/05/2017 09:55 AM »

Landing on the "Bouncy Castle" Is not that hard, I do this without instruments,with instruments and a 360 overhead even a computer can do this.

Can you do it so accurately when flying downwind? You clearly turned in to the wind for the final landing approach.

Online JJB

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Re: Fairing reuse
« Reply #886 on: 04/05/2017 10:03 AM »

Landing on the "Bouncy Castle" Is not that hard, I do this without instruments,with instruments and a 360 overhead even a computer can do this.

Can you do it so accurately when flying downwind? You clearly turned in to the wind for the final landing approach.
Thats why you do a 360 turn overhead the target, gps derived wind speed and direction.
There is probably still life clinging to thermal vents, giggling about the absurdity of growing a backbone.-KZ.

Online Kaputnik

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Re: Fairing reuse
« Reply #887 on: 04/05/2017 11:05 AM »
Why not put the "bouncy castle" in the fairing?

A big enough inflatable to keep the fairing completely out of the water is probably far too big/heavy to carry on the fairing.
Waiting for joy and raptor

Offline JamesH65

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Re: Fairing reuse
« Reply #888 on: 04/05/2017 11:27 AM »

Landing on the "Bouncy Castle" Is not that hard, I do this without instruments,with instruments and a 360 overhead even a computer can do this.

Can you do it so accurately when flying downwind? You clearly turned in to the wind for the final landing approach.
Thats why you do a 360 turn overhead the target, gps derived wind speed and direction.

Ah ha, thanks for the explanation. That's the missing information.  Question is now -does a falling fairing have enough time to do a 360 loop round the target to assess wind speed/direction. Which is a question we don;t have an answer for without knowing the glide ratio.

Offline speedevil

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Re: Fairing reuse
« Reply #889 on: 04/05/2017 12:01 PM »
Ah ha, thanks for the explanation. That's the missing information.  Question is now -does a falling fairing have enough time to do a 360 loop round the target to assess wind speed/direction. Which is a question we don;t have an answer for without knowing the glide ratio.

It doesn't need it - there are various ways of getting live wind data from the landing platform, up to and including a dozen $1K drones standing off 500m and reporting live windspeeds and gusts 10s before they hit.

Online cppetrie

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Re: Fairing reuse
« Reply #890 on: 04/05/2017 01:49 PM »
Ah ha, thanks for the explanation. That's the missing information.  Question is now -does a falling fairing have enough time to do a 360 loop round the target to assess wind speed/direction. Which is a question we don;t have an answer for without knowing the glide ratio.

It doesn't need it - there are various ways of getting live wind data from the landing platform, up to and including a dozen $1K drones standing off 500m and reporting live windspeeds and gusts 10s before they hit.
It also has onboard thrusters that could assist with positioning/trajectory.

Offline kaiser

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Re: Fairing reuse
« Reply #891 on: 04/05/2017 03:31 PM »
Ah ha, thanks for the explanation. That's the missing information.  Question is now -does a falling fairing have enough time to do a 360 loop round the target to assess wind speed/direction. Which is a question we don;t have an answer for without knowing the glide ratio.

It doesn't need it - there are various ways of getting live wind data from the landing platform, up to and including a dozen $1K drones standing off 500m and reporting live windspeeds and gusts 10s before they hit.

If you had a good multi-hypothesis navigation filter, you might be able to fairly accurately tell the wind speed just during normal descent based upon the transfer function between your control inputs and positional change during the descent.

Offline Alastor

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Re: Fairing reuse
« Reply #892 on: 04/05/2017 03:33 PM »
It also has onboard thrusters that could assist with positioning/trajectory.

I'm not sure using RCS thrusters while hanging from a parafoil is the best of ideas. At best, I would expect it to send you spinning. Also idoubt they have very significant margins on the fuel used. If the system is designed to help for stability and attitude before and during reentry only, expect thet there won't be much propellant left after reentry has occured.

Online Kaputnik

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Re: Fairing reuse
« Reply #893 on: 04/05/2017 05:00 PM »
It also has onboard thrusters that could assist with positioning/trajectory.

I'm not sure using RCS thrusters while hanging from a parafoil is the best of ideas. At best, I would expect it to send you spinning. Also idoubt they have very significant margins on the fuel used. If the system is designed to help for stability and attitude before and during reentry only, expect thet there won't be much propellant left after reentry has occured.

Yup. All you would do is set the fairing swinging or slewing, with little effect on course.
Waiting for joy and raptor

Online FutureSpaceTourist

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Re: Fairing reuse
« Reply #894 on: 04/05/2017 06:15 PM »
Quote
Shotwell: did recover one half of payload fairing from this launch, not sure about the other. One we did “looked pretty good” #33SS
https://twitter.com/jeff_foust/status/849680344135720960

Quote
More fairing recoveries to come from @SpaceX in 2017 #SpaceSymposium #33SS
https://twitter.com/jacoblhacker/status/849680353052831746

Offline JamesH65

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Re: Fairing reuse
« Reply #895 on: 04/05/2017 07:49 PM »
Ah ha, thanks for the explanation. That's the missing information.  Question is now -does a falling fairing have enough time to do a 360 loop round the target to assess wind speed/direction. Which is a question we don;t have an answer for without knowing the glide ratio.

It doesn't need it - there are various ways of getting live wind data from the landing platform, up to and including a dozen $1K drones standing off 500m and reporting live windspeeds and gusts 10s before they hit.

This is clear, but the point is that currently, there is NO apparent transmission from ground to the stage, fairings etc on descent. I personally think simply putting an rx'er on the fairing so it can be told the wind direction is the way to go, but others think that is simply another point of failure. I was simply wondering what alternatives there were.

Offline deruch

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Re: Fairing reuse
« Reply #896 on: 04/06/2017 03:23 AM »
I haven't seen any info on how close they came to hitting their target.  I'm trying to get an estimated accuracy for this first attempt.  Clearly they were close enough so that the recovery boat could still get to it before it sank.  Which seems a significant achievement in addition to the feat of it just surviving to sea level, but maybe they are quite buoyant in salt water and this isn't so incredible.
http://www.bbc.co.uk/news/uk-england-cornwall-34941462
It indeed floats long-term.

This is a fairing which bobbed along just under/on the surface all the way to the UK.

Though this method of recovery is probably not useful for reflight :)
That's a bit of the interstage, not the fairing.  Though we have also seen fairings washed up in the Bahamas, IIRC.  I know they don't necessarily sink to the bottom of the sea.  The question was more along the lines of how long it will stay on the surface to allow them to be spotted and then recovered.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline Steve D

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Re: Fairing reuse
« Reply #897 on: 04/11/2017 07:24 PM »
I haven't seen any info on how close they came to hitting their target.  I'm trying to get an estimated accuracy for this first attempt.  Clearly they were close enough so that the recovery boat could still get to it before it sank.  Which seems a significant achievement in addition to the feat of it just surviving to sea level, but maybe they are quite buoyant in salt water and this isn't so incredible.
http://www.bbc.co.uk/news/uk-england-cornwall-34941462
It indeed floats long-term.

This is a fairing which bobbed along just under/on the surface all the way to the UK.

Though this method of recovery is probably not useful for reflight :)
That's a bit of the interstage, not the fairing.  Though we have also seen fairings washed up in the Bahamas, IIRC.  I know they don't necessarily sink to the bottom of the sea.  The question was more along the lines of how long it will stay on the surface to allow them to be spotted and then recovered.

A friend of mine found a large piece of a fairing from an Ariane rocket washed up on the beach in the Yucatan. These things just wont sink.

Offline cartman

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Re: Fairing reuse
« Reply #898 on: 04/22/2017 05:25 PM »
Quote
SpaceX‏ Verified account @SpaceX 16m16 minutes ago

View from the fairing during SES-10 mission. #EarthDay pic.twitter.com/zPYQRQ3BkR

Offline CharlieWildman

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Re: Fairing reuse
« Reply #899 on: 04/22/2017 08:48 PM »
Quote
SpaceX‏ Verified account @SpaceX 16m16 minutes ago

View from the fairing during SES-10 mission. #EarthDay pic.twitter.com/zPYQRQ3BkR

Really cool.  Probably dumb question... Do we know if this is the half that was recovered? 
A small amount of knowledge can be a dangerous thing.

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