Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3  (Read 814023 times)

Online Lar

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1860 on: 03/03/2017 07:15 PM »
First what we know:
* SpaceX stated they want to fly stages back from the barge to land (as unlikely as that seems)
* SpaceX want to land BFR on a launch cradle

Ok, complete, full force speculation mode from here.
Lets take both statements at face value and assume they still want to do this. So we accept the two above statements as axioms and do not question them. Following is a speculation run on what conclusion would follow given the above axioms.

It would make sense for SpaceX to be able to test the landing on launch mounts before doing it with BFR. So that would imply tests with F9.

How can they fly a stage from the barge back to land? Its not possible using the legs. They would have to land folded out, then fold them in again and than launch and land on land. But for folding the legs up before launch, F9 needs to sit on a launch mount on the barge. It cant get there without a large crane. Therefore, the only good option would be to land on the launch mount in the first place, not using the legs.

What about an alternative?
* SpaceX builds a launch/landing mount on the barge (I know I know, its not possible. Remember the full fledged speculation mode, ok?)
* The Roomba Garage olds a robot that brings RP1 and LOX lines to the first stage, hooks it up and refills it partly. The access ports are at the bottom, so it should be possible.
* The stage flies back to land and lands at LZ1

Obviously it would not start like that. The first try to land on a launch/land mount would be at LZ1. Once that works, it might be tried on the barge. It has been pointed out that the barge is not stable enough for a precision landing. However, the landing mount might have a homing beacon that the first stage targets in the last meters of descend instead of the GPS coordinates that are used now. It might be tough but I dont think impossible.


This is just crazy enough to work. (accepting your axioms as written)

But I think maybe you're thinking about cradles too hard. Launch Mounts hold rockets. Instead of trying to land exactly in the launch mount, just land somewhere on the barge.... anywhere[1].... Be there, on legs for a bit. Wait. Something trundles up, has launch mount type fixture, grabs the spot on the bottom of the stage that is the place where the mount fixture holds it. 4 of these do this, and maybe also bring the fuel/lox lines with them... fuel up the rocket just enough, fold up the legs, launch.]2\

Or heck maybe don't even fold up the legs if you're not going to be flying that fast????  You kind of don't want to fly fast if what you have is an empty interstage without a nose cone cap anyway.... (Putting a cap up there requires the very crane we're trying to avoid needing) too much buffeting.

1 - somewhere kind of close to the center probably is helpful for tipping reasons, but since you're not trying to hit a mount, anywhere fairly close is close enough.
2 - details about how do you return the lox/fuel lines safely so they aren't fried by the stage leaving left as exercise
« Last Edit: 03/03/2017 07:23 PM by Lar »
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Online meekGee

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1861 on: 03/03/2017 07:16 PM »
Notice the ground clean spots on the beam.

Matthew

It's actually very resilient to surface conditions.  The tip of the stud is a point, and it melts both sides of the material, then pushes the stud into the molten pool.  The ceramic shapes the outflow.  There's no remnant of what used to be the surface.

This is unlike, for example, spot welding, where the mixing is limited.  (and is still a very good weld, but is sensitive to surface conditions.)

Just like spot welding, btw, the machine monitors the current profile and tells you whether the resultant weld was good.  And they make auto-feeders of course.
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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1862 on: 03/03/2017 07:19 PM »
First what we know:
* SpaceX stated they want to fly stages back from the barge to land (as unlikely as that seems)
* SpaceX want to land BFR on a launch cradle

Ok, complete, full force speculation mode from here.
Lets take both statements at face value and assume they still want to do this. So we accept the two above statements as axioms and do not question them. Following is a speculation run on what conclusion would follow given the above axioms.

It would make sense for SpaceX to be able to test the landing on launch mounts before doing it with BFR. So that would imply tests with F9.

How can they fly a stage from the barge back to land? Its not possible using the legs. They would have to land folded out, then fold them in again and than launch and land on land. But for folding the legs up before launch, F9 needs to sit on a launch mount on the barge. It cant get there without a large crane. Therefore, the only good option would be to land on the launch mount in the first place, not using the legs.

What about an alternative?
* SpaceX builds a launch/landing mount on the barge (I know I know, its not possible. Remember the full fledged speculation mode, ok?)
* The Roomba Garage olds a robot that brings RP1 and LOX lines to the first stage, hooks it up and refills it partly. The access ports are at the bottom, so it should be possible.
* The stage flies back to land and lands at LZ1

Obviously it would not start like that. The first try to land on a launch/land mount would be at LZ1. Once that works, it might be tried on the barge. It has been pointed out that the barge is not stable enough for a precision landing. However, the landing mount might have a homing beacon that the first stage targets in the last meters of descend instead of the GPS coordinates that are used now. It might be tough but I dont think impossible.

I like this a lot.  In short, a lot of the difficulty of barge-relaunch goes away if a future version of F9 can fly legless and land in a cradle.

Cradle-landing on the barge will require closed-loop (homing) terminal guidance, to eliminate location uncertainties, but I think that's a piece of cake and will be surprised if the current algorithms are not ready to accept an external position-error signal.  (which will replace the existing GPS position-error value at the terminal approach phase)
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Offline gospacex

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1863 on: 03/03/2017 07:20 PM »
Maybe electromagnets can be used to attach to the steel deck.

Offline rsdavis9

First what we know:
* SpaceX stated they want to fly stages back from the barge to land (as unlikely as that seems)
* SpaceX want to land BFR on a launch cradle

Ok, complete, full force speculation mode from here.
Lets take both statements at face value and assume they still want to do this. So we accept the two above statements as axioms and do not question them. Following is a speculation run on what conclusion would follow given the above axioms.

It would make sense for SpaceX to be able to test the landing on launch mounts before doing it with BFR. So that would imply tests with F9.

How can they fly a stage from the barge back to land? Its not possible using the legs. They would have to land folded out, then fold them in again and than launch and land on land. But for folding the legs up before launch, F9 needs to sit on a launch mount on the barge. It cant get there without a large crane. Therefore, the only good option would be to land on the launch mount in the first place, not using the legs.

What about an alternative?
* SpaceX builds a launch/landing mount on the barge (I know I know, its not possible. Remember the full fledged speculation mode, ok?)
* The Roomba Garage olds a robot that brings RP1 and LOX lines to the first stage, hooks it up and refills it partly. The access ports are at the bottom, so it should be possible.
* The stage flies back to land and lands at LZ1

Obviously it would not start like that. The first try to land on a launch/land mount would be at LZ1. Once that works, it might be tried on the barge. It has been pointed out that the barge is not stable enough for a precision landing. However, the landing mount might have a homing beacon that the first stage targets in the last meters of descend instead of the GPS coordinates that are used now. It might be tough but I dont think impossible.

I like this a lot.  In short, a lot of the difficulty of barge-relaunch goes away if a future version of F9 can fly legless and land in a cradle.

Cradle-landing on the barge will require closed-loop (homing) terminal guidance, to eliminate location uncertainties, but I think that's a piece of cake and will be surprised if the current algorithms are not ready to accept an external position-error signal.  (which will replace the existing GPS position-error value at the terminal approach phase)

I have a feeling that stronger RCS is needed then GN2. I think that's why musk suggested this for ITS with the gox/gch4 RCS. Basically gimballing can get you real close but for that last foot or inch it is real nice to just translate sideways real quick without leaning. Maybe a stronger RCS will debut on falcon. It could be lighter than legs.
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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1865 on: 03/03/2017 07:43 PM »
First what we know:
* SpaceX stated they want to fly stages back from the barge to land (as unlikely as that seems)
* SpaceX want to land BFR on a launch cradle

Ok, complete, full force speculation mode from here.
Lets take both statements at face value and assume they still want to do this. So we accept the two above statements as axioms and do not question them. Following is a speculation run on what conclusion would follow given the above axioms.

It would make sense for SpaceX to be able to test the landing on launch mounts before doing it with BFR. So that would imply tests with F9.

How can they fly a stage from the barge back to land? Its not possible using the legs. They would have to land folded out, then fold them in again and than launch and land on land. But for folding the legs up before launch, F9 needs to sit on a launch mount on the barge. It cant get there without a large crane. Therefore, the only good option would be to land on the launch mount in the first place, not using the legs.

What about an alternative?
* SpaceX builds a launch/landing mount on the barge (I know I know, its not possible. Remember the full fledged speculation mode, ok?)
* The Roomba Garage olds a robot that brings RP1 and LOX lines to the first stage, hooks it up and refills it partly. The access ports are at the bottom, so it should be possible.
* The stage flies back to land and lands at LZ1

Obviously it would not start like that. The first try to land on a launch/land mount would be at LZ1. Once that works, it might be tried on the barge. It has been pointed out that the barge is not stable enough for a precision landing. However, the landing mount might have a homing beacon that the first stage targets in the last meters of descend instead of the GPS coordinates that are used now. It might be tough but I dont think impossible.

I like this a lot.  In short, a lot of the difficulty of barge-relaunch goes away if a future version of F9 can fly legless and land in a cradle.

Cradle-landing on the barge will require closed-loop (homing) terminal guidance, to eliminate location uncertainties, but I think that's a piece of cake and will be surprised if the current algorithms are not ready to accept an external position-error signal.  (which will replace the existing GPS position-error value at the terminal approach phase)

I have a feeling that stronger RCS is needed then GN2. I think that's why musk suggested this for ITS with the gox/gch4 RCS. Basically gimballing can get you real close but for that last foot or inch it is real nice to just translate sideways real quick without leaning. Maybe a stronger RCS will debut on falcon. It could be lighter than legs.

Agreed. A hypothetical legless F9 will likely have RCS at the base, and maybe not even GN2.  But that will still weigh less than legs...
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Offline Jim

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1866 on: 03/03/2017 08:00 PM »

I like this a lot.  In short, a lot of the difficulty of barge-relaunch goes away if a future version of F9 can fly legless and land in a cradle.


There is no future version of the F9.  Development stops at Block 5 and then all the design engineers move over to ITS.

Offline rsdavis9

And as cool as legless cradle landing would be I have to agree with Jim that is best left for ITS when it flys.
Without legless cradle and flyback I think we are left with anyway to streamline moving the stage from landing to launch pad.
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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1868 on: 03/03/2017 08:13 PM »
You're not reading the instructions.

This was about the hypothetical engineering proposition that a legless F9 would make barge flyback much easier.

We all know about SpaceX saying block 5 is the final version.
« Last Edit: 03/03/2017 08:38 PM by meekGee »
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Offline Semmel

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1869 on: 03/03/2017 09:15 PM »
There is no future version of the F9.  Development stops at Block 5 and then all the design engineers move over to ITS.

I know. But I would think a software update for the landing sequence and a homing sensor at the bottom do not qualify for a new 'block' of F9. There is nothing in the proposal that would not be possible with the current 'block' version.

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1870 on: 03/03/2017 10:08 PM »
There is no future version of the F9.  Development stops at Block 5 and then all the design engineers move over to ITS.

I know. But I would think a software update for the landing sequence and a homing sensor at the bottom do not qualify for a new 'block' of F9. There is nothing in the proposal that would not be possible with the current 'block' version.

Plus, I remember the consternation the same people had when we proposed that there will be future versions beyond 1.1.   And then beyond 1.2

So maybe block 5 is "final version for now".
Or maybe block 5 is "legless ready" and flying legless is an option they can later try without changing the design. (so the design is ready to accept some RCS at the base)
Or maybe legless experiments will never become mainstream but rather be risk mitigation trials as part of ITS development. (In which case legless landings can be done on land)

The point is, Semmel's observation makes a lot of sense - there's a lot of synergy between barge-flyback and cradle landing.

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Offline Herb Schaltegger

This hypothetical nonsense about landing cradles/launch mounts on the barge isn't really about the barge anymore. Exactly why I asked - a number of weeks ago - that someone create an ITS landing cradle thread. And someone else agreed and said thread was born.

Yet here we are again ...
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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1872 on: 03/03/2017 11:13 PM »
There is no future version of the F9.  Development stops at Block 5 and then all the design engineers move over to ITS.

I know. But I would think a software update for the landing sequence and a homing sensor at the bottom do not qualify for a new 'block' of F9. There is nothing in the proposal that would not be possible with the current 'block' version.

Yes, it does.  The current vehicle can't make pinpoint landings

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1873 on: 03/03/2017 11:17 PM »
The falcon 9 block 5 used for manned and DOD launches may have to freeze but that doesn't mean that the software and bolt on parts for non-manned and DOD flights would have to be included in a block 5 freeze.

If SpaceX was going to experiment with the falcon 9 to land in some kind of a landing cradle it would need to put something on to the bottom of the falcon 9 obviously. A straightforward way to accomplish this (as you obviously will not be using the legs) would be to develop some kind of a kit that could bolt on in place of the landing legs. It would seem that in this landing cradle kit you could also place the thrusters needed to guide the bottom of the rocket into the cradle. You would obviously also need to modify the software for such tests for that software would only be used on these test rockets not on the above-mentioned block 5 frozen rockets.

This way you could freeze the falcon 9 at the block 5 and continue to do landing experiments if SpaceX thinks that this is desirable or needed.


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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1874 on: 03/04/2017 02:49 AM »
Well, in the context of "flyback from barge as per one isolated comment by Musk"....

We haven't seen the mythological block 5 yet, and do not know what they loaded into it, and what "options" it can accept.

I'm fine leaving it at that.
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Offline Semmel

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1875 on: 03/04/2017 09:21 AM »
This hypothetical nonsense about landing cradles/launch mounts on the barge isn't really about the barge anymore. Exactly why I asked - a number of weeks ago - that someone create an ITS landing cradle thread. And someone else agreed and said thread was born.

Yet here we are again ...

The connection is the interpretation of what comes out of the roomba garage. A robot grabbing the stage from below and securing it is certainly a possibility. But it does not fit the usual SpaceX 'synergy'. So I bet we are missing something. My proposal was an attempt to provide an alternative interpretation. I agree its crazy and relies on blind belief of the old statement of flying back a stage from the barge. But its not about the landing cradle. Its just a component.

Well, in the context of "flyback from barge as per one isolated comment by Musk"....

We haven't seen the mythological block 5 yet, and do not know what they loaded into it, and what "options" it can accept.

I'm fine leaving it at that.

I am looking forwards to it :)

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1876 on: 03/04/2017 03:07 PM »
This hypothetical nonsense about landing cradles/launch mounts on the barge isn't really about the barge anymore. Exactly why I asked - a number of weeks ago - that someone create an ITS landing cradle thread. And someone else agreed and said thread was born.

Yet here we are again ...

The connection is the interpretation of what comes out of the roomba garage. A robot grabbing the stage from below and securing it is certainly a possibility. But it does not fit the usual SpaceX 'synergy'. So I bet we are missing something. My proposal was an attempt to provide an alternative interpretation. I agree its crazy and relies on blind belief of the old statement of flying back a stage from the barge. But its not about the landing cradle. Its just a component.

Well, in the context of "flyback from barge as per one isolated comment by Musk"....

We haven't seen the mythological block 5 yet, and do not know what they loaded into it, and what "options" it can accept.

I'm fine leaving it at that.

I am looking forwards to it :)
Ah.  I'd be hugely surprised if the robot is anything but a "secure in place and maybe service" device.

A landing cradle would be much larger, wouldn't be mobile, and might be preceded by an on shore cradle.

IMO
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Offline rsdavis9


Ah.  I'd be hugely surprised if the robot is anything but a "secure in place and maybe service" device.

A landing cradle would be much larger, wouldn't be mobile, and might be preceded by an on shore cradle.

IMO

Spacex will surprise you!  :)
So far every new gadget or operation has surprised me.
But I don't think it will be landing cradle. More like something more than securing.
What is everybody's opinion as to how much crane handling slows things down?
I know they crane handle at mcgregor, KSC,
hawthorne?
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Offline old_sellsword

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1878 on: 03/04/2017 03:58 PM »

Ah.  I'd be hugely surprised if the robot is anything but a "secure in place and maybe service" device.

A landing cradle would be much larger, wouldn't be mobile, and might be preceded by an on shore cradle.

IMO

Spacex will surprise you!  :)
So far every new gadget or operation has surprised me.
But I don't think it will be landing cradle. More like something more than securing.
What is everybody's opinion as to how much crane handling slows things down?
I know they crane handle at mcgregor, KSC,
hawthorne?

SpaceX has used cranes to move their boosters at every location they've had a Falcon 9, although I'm unsure about VAFB. I would be really surprised if crane operations were the long pole in port recovery operations.

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #1879 on: 03/04/2017 04:31 PM »

Ah.  I'd be hugely surprised if the robot is anything but a "secure in place and maybe service" device.

A landing cradle would be much larger, wouldn't be mobile, and might be preceded by an on shore cradle.

IMO

Spacex will surprise you!  :)
So far every new gadget or operation has surprised me.
But I don't think it will be landing cradle. More like something more than securing.
What is everybody's opinion as to how much crane handling slows things down?
I know they crane handle at mcgregor, KSC,
hawthorne?

SpaceX has used cranes to move their boosters at every location they've had a Falcon 9, although I'm unsure about VAFB. I would be really surprised if crane operations were the long pole in port recovery operations.

Agreed. Simplest way to get large cargo from ship to shore is a crane.

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