Author Topic: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3  (Read 711967 times)

Offline chad1011

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #980 on: 05/29/2016 02:13 AM »
If I am not mistaken, the support jacks are hydraulic. They should be able to lift the low side level.  Attached is an example from the USAF.

Offline gadgetmind

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #981 on: 05/29/2016 06:59 AM »
That assumes the stage isn't riding so low that they can't get the jacks under.

Offline Kabloona

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #982 on: 05/29/2016 11:48 AM »
That assumes the stage isn't riding so low that they can't get the jacks under.

Fortunately someone has already invented shorter jacks.  :)

http://tinyurl.com/jr3wmyr
« Last Edit: 05/31/2016 08:56 PM by Kabloona »

Offline jaufgang

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #983 on: 05/29/2016 12:42 PM »
That assumes the stage isn't riding so low that they can't get the jacks under.
The fact that this landing was said to have "used up contingency crush core" implies that this compression of the legs was within (although approaching the limits of) the design specifications. I'd expect that any jacks they have are designed to fit under the stage in the event of maximum possible compression of the crush core on all four legs.

Online CJ

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #984 on: 06/02/2016 11:09 PM »
As we have now seen, the F9 had a major tilt, but more worrying, moved around a great deal after landing, probably due to wobbling back and forth as the ASDS rolled (due to having one leg shorter then the others). 

My guess is that SpaceX will want to address this sort of contingency in the future, due to the risk to both the F9 and the crew that has to go aboard.

My further guess is they will desire to have a remote capability to do so (to avoid risking crew).

Therefor, I think we have an excellent opportunity to speculate as to what such a capability might look like. I think it will certainly be cheap and simple if possible.

My current guess is based on what they did to shore up the highside leg; stacked some stuff under it, approximately a foot or so thick. Therefor, my guess is that to accomplish that remotely, they could use something akin to a largish remote control toy car, pushing a solid wedge (perhaps with furniture glade plates on the bottom). The remote control car would be equipped with a drone-type camera, and housed somewhere on the ASDS (just parked in a deck corner?). Would that be enough to give the ASDS a new capability to handle this sort of contingency?   

Offline cscott

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #985 on: 06/02/2016 11:41 PM »
I suspect that rather than invent new hardware they will just refine the procedures which seemed to work adequately in this case.  And optimize the landing software/hardware to ensure the situation doesn't arise again.

After all, that's what SpaceX did when we were busy inventing new barge hardware since landing on barges could never work without XYZ.  It turns out they didn't build XYZ they just fixed the rocket so they didn't need it.
« Last Edit: 06/02/2016 11:41 PM by cscott »

Online John Alan

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #986 on: 06/03/2016 12:11 AM »
I agree with cscott's thought... that there is room to work on the terminal phase to avoid repeating the landing angle incident that seems (at first glance) to be root issue...

However... My opinion...  ;)
I'm thinking that changing from a crush type suspension (single acting) to a compliant one (double acting) would be a worthwhile upgrade as insurance to the next 'woops moment'...

A suspension that can absorb the impact, then rebound to a nominal height would solve the leaning tower (with walking wobble) problem seen today...

The issue is... how to do that without adding much (if any) more weight...  :-\
I'm undecided how best to do that at this time...  :P

On edit...
http://forum.nasaspaceflight.com/index.php?topic=40255.msg1543914#msg1543914
Based on this L2 posting today from 'someone who would know" what changes are planned for F9...
I'm going to hope they are thinking the same thing and have a clever, lightweight solution...  8)
« Last Edit: 06/03/2016 12:47 AM by John Alan »

Online CJ

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #987 on: 06/03/2016 12:18 AM »
I suspect that rather than invent new hardware they will just refine the procedures which seemed to work adequately in this case.  And optimize the landing software/hardware to ensure the situation doesn't arise again.

After all, that's what SpaceX did when we were busy inventing new barge hardware since landing on barges could never work without XYZ.  It turns out they didn't build XYZ they just fixed the rocket so they didn't need it.

IMHO, they would not be building crush cores into the F9 legs unless they were there for a reason (contingency). It makes little sense IMHO to have those crush cores (cost and mass) if the F9 is going to be left in a very perilous (for both the f9 and the crew) state if they are used. *IF* this issue can be addressed easily and cheaply, I suspect they will do so rather than put lives, and an F9, at risk. You surely can minimize the frequency of recurrence via software tweaks, but bringing a F9 down on a deck that's changing angles will always have an element of risk regarding overloading one of the legs.

What they accomplished this time did work, but I truly do not envy the crew that had to go aboard and deal with an actively wobbling F9.

I do agree with John Allen that moving from single acting to double acting would be a better idea, but if, of course, it's feasible.  I suspect it'd be too much of a mass penalty though.


Offline yg1968

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #988 on: 06/03/2016 01:35 AM »
This has probably been discussed previously but I'll ask anyways. One of the legs was crushed during landing of the first stage. The fact that the leg crushed instead of breaking (like what happened previously) is an improvement in the design of the legs since it allows the landing to be less than perfect. Is that the gist of it?

Online envy887

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #989 on: 06/03/2016 02:15 AM »
This has probably been discussed previously but I'll ask anyways. One of the legs was crushed during landing of the first stage. The fact that the leg crushed instead of breaking (like what happened previously) is an improvement in the design of the legs since it allows the landing to be less than perfect. Is that the gist of it?

The JASON-3 stage leg didn't break on impact, it failed to latch in the extended position after opening. That failure want due to the speed of impact.

Offline Mongo62

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #990 on: 06/03/2016 01:23 PM »
This has probably been discussed previously but I'll ask anyways. One of the legs was crushed during landing of the first stage. The fact that the leg crushed instead of breaking (like what happened previously) is an improvement in the design of the legs since it allows the landing to be less than perfect. Is that the gist of it?

The leg is designed with crushable honeycomb "filler" so that in the event of a harder than intended landing, the energy would go into crushing the leg honeycomb rather than deforming the stage itself. Legs are cheap and can be easily replaced, so sacrificing one to save the stage makes good financial sense.

I am not aware of a leg breaking in the JASON-3 landing, it failed to latch due to ice buildup from the fog during launch.
« Last Edit: 06/03/2016 01:24 PM by Mongo62 »

Offline AC in NC

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #991 on: 06/03/2016 01:54 PM »
The leg is designed with crushable honeycomb "filler" so that in the event of a harder than intended landing, the energy would go into crushing the leg honeycomb rather than deforming the stage itself.  Legs are cheap and can be easily replaced, so sacrificing one to save the stage makes good financial sense.

The honeycomb "crush core" is designed to be replaced so the leg is not sacrificed.  Just the "crush core" and refurb costs.

Offline Mongo62

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #992 on: 06/03/2016 02:42 PM »
The leg is designed with crushable honeycomb "filler" so that in the event of a harder than intended landing, the energy would go into crushing the leg honeycomb rather than deforming the stage itself.  Legs are cheap and can be easily replaced, so sacrificing one to save the stage makes good financial sense.

The honeycomb "crush core" is designed to be replaced so the leg is not sacrificed.  Just the "crush core" and refurb costs.

Even better, then. The cost of designing and installing the crush cores has presumably already been paid for with this landing.
« Last Edit: 06/03/2016 02:45 PM by Mongo62 »

Online AncientU

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #993 on: 06/03/2016 05:15 PM »
I agree with cscott's thought... that there is room to work on the terminal phase to avoid repeating the landing angle incident that seems (at first glance) to be root issue...

However... My opinion...  ;)
I'm thinking that changing from a crush type suspension (single acting) to a compliant one (double acting) would be a worthwhile upgrade as insurance to the next 'woops moment'...

A suspension that can absorb the impact, then rebound to a nominal height would solve the leaning tower (with walking wobble) problem seen today...

The issue is... how to do that without adding much (if any) more weight...  :-\
I'm undecided how best to do that at this time...  :P

On edit...
http://forum.nasaspaceflight.com/index.php?topic=40255.msg1543914#msg1543914
Based on this L2 posting today from 'someone who would know" what changes are planned for F9...
I'm going to hope they are thinking the same thing and have a clever, lightweight solution...  8)

Seems to me that their existing clever, lightweight, (and passive) solution worked just fine.  Tweaks to the landing profile and split-second timing issues will continue to improve the situation, but this fall back solution probably saved a $30M stage.  Will be interesting to see what pieces are modified...
« Last Edit: 06/03/2016 05:17 PM by AncientU »
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Offline garidan

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #994 on: 06/03/2016 06:18 PM »
I think there was a thread where this was discussed, but I don't remeber where, so it could be I'm repeating well known opinions, sorry for this.
In my opinion, the most usefull aspect to work on is to speed up recovery operations. A "traditional" and faster (long) support ship with an high enough crane could meet the recovery drone ship while still far in the sea, take the stage and let remove the legs and secure it while still out of the port and on the way to it.
The drone ship would be ready faster to get another launch. It could get the fuel form this support ship and avoid going to the port for a long time.
To enter the port the support ship would not need a special permission, because the stage would be already secured and explosives deactivated.
And the crane of the support ship could be enough to lift the stage and put it on land for a truck to drive away.
All is needed is a faster and easier to use system to hook the stage on the top, and another system to use a single crane (and two indipendent wires) to bring the stage from vertical to horizontal.
I think this is all at hand, and repays itself quickly, at this or higher rate og flights.
« Last Edit: 06/03/2016 06:24 PM by garidan »

Online Chris Bergin

Could be a good splinter thread for the legs element? Someone feel free to set that up! :)

Offline Jim

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #996 on: 06/03/2016 06:52 PM »

I think this is all at hand, and repays itself quickly, at this or higher rate og flights.

Not really.  How can it save money?  You are only incurring more costs.  Bigger barge, larger crew to accommodate.  There is no need to speed up the process. The existing system works, there is no need to move the work out on to the barge.  The barge can go out just as fast.

Offline JasonAW3

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #997 on: 06/03/2016 07:08 PM »

I think this is all at hand, and repays itself quickly, at this or higher rate og flights.

Not really.  How can it save money?  You are only incurring more costs.  Bigger barge, larger crew to accommodate.  There is no need to speed up the process. The existing system works, there is no need to move the work out on to the barge.  The barge can go out just as fast.

On the other hand, were they to go with a similarly sized SWATH hulled barge, it would provide both better station keeping ability as well as a more stable landing platform.

Adding to the size or additional facilities at this stage?  Jim's right on that point.  The current basic configuration works best. 

The addition of a ratcheting system of a pair of pontoons, that would be submerged, lifting the barge out of the water, would reduce the stability issues of higher sea states, as well as reduce the influence of surface currents.
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Offline AC in NC

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #998 on: 06/03/2016 07:46 PM »
In my opinion, the most usefull aspect to work on is to speed up recovery operations. A "traditional" and faster (long) support ship with an high enough crane could meet the recovery drone ship while still far

There is not much value in chasing a faster recovery operation other than to free up the ASDS.  If you are launching at a rate that requires the ASDS freed up earlier, you build another ASDS. 

Everything else shouldn't matter because you are launching next out of inventory, not the last stage.

Offline WizZifnab

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Re: SpaceX's Autonomous Spaceport Drone Ship Discussion Thread 3
« Reply #999 on: 06/04/2016 05:20 AM »

I think this is all at hand, and repays itself quickly, at this or higher rate og flights.

Not really.  How can it save money?  You are only incurring more costs.  Bigger barge, larger crew to accommodate.  There is no need to speed up the process. The existing system works, there is no need to move the work out on to the barge.  The barge can go out just as fast.
I couldn't say whether the suggestions made would actually save money, but I also wouldn't say there is no value in speeding up the process.  There may not be any relaunch cadence pressure to speed things up.  However, process optimization could save costs.  Not worrying about those costs might be acceptable if you are just passing those costs onto someone else (plus whatever padding you could add on top of that...no lost opportunity to milk the cow).  That's not the case for SpaceX here.

I'd expect that some optimization that doesn't compromise safety will occur over time.  There are some costs per day involved.  The cost per day could be reduced or the number of days can be reduced.  I'm sure its a balance of many factors.  Also, there is clearly a skill to the process that will develop as well, given this is a new activity that's not exactly been done before.  Some process change too soon can also detract from efficiencies gained naturally from repetition/learning on the current process.

So in short, I'd guess that over time we'll see some process improvement.  Exactly what those process improvements look like, we'll see.  Seems likely it'll get faster.

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