Author Topic: Spaceport America set for SpaceX reusability testing  (Read 36304 times)

Offline Robotbeat

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Re: Spaceport America set for SpaceX reusability testing
« Reply #40 on: 03/20/2015 07:45 PM »
Here ya go:
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Offline JasonAW3

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Re: Spaceport America set for SpaceX reusability testing
« Reply #41 on: 03/20/2015 07:52 PM »

Which is where a more automated design comes in.

And how are they going accommodate all the connectors with scores of these fat fingered pins?
This kind of work is what I do.

There are ways, and it's a combination  of interface design and automation.

You certainly don't want to try to design robots that try to mate standard MIL connectors which were designed for human hands.

But if designed for automated processing, it's not a hard challenge.

Meek,

     No offense intended, but there are just WAY to many natural variables that could cause serious problems with an automated refueling system for rockets.  I can envision how technology could reduce the overall workload so that the refuel, checkout and relaunch would run similar to that of an airliner's proceedure, (It'll never be as simple as there is an exponentially greater number of things that could go boom or otherwise kill the ground crew as well as those on the space craft) but never fully automating the ground servicing.

     Space, on the other hand, could have a great deal of automation built into the system, but would still requitre a number of people still in the loop for orbital or deep space refueling.  (Again, a lot of things that can go boom, but vacume helps reduce the risk, slightly).

     I'm just not quite sure where you're going with the automated refueling idea.
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Offline Robotbeat

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Re: Spaceport America set for SpaceX reusability testing
« Reply #42 on: 03/20/2015 07:58 PM »
The auto refueling idea comes from the idea of refueling a landed first stage on the barge and flying it back to land.

A little nuts, but not impossible.
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Offline Chris Bergin

Chris, a question regarding this from the article:
Quote
While efforts to achieve this goal are in the pipeline for the Upper Stage
My understanding was SpaceX has abandoned the idea of recovering S2 on F9.  Is that not the case?

During a recent chat I was told they were looking at some solutions to that problem. Didn't say what, understandably, but that is why I worded it as I did.

Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #44 on: 03/20/2015 08:04 PM »

Unlike other manufacturers SpaceX gives each stage its own avionics. That greatly reduces need for interconnnection. One serial data link can be enough. Make that three for triple redundancy.


Still doesn't change anything.  The upper stage still controls the whole stack.  And there are range safety connections and telemetry too.

Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #45 on: 03/20/2015 08:06 PM »

This kind of work is what I do.

There are ways, and it's a combination  of interface design and automation.

You certainly don't want to try to design robots that try to mate standard MIL connectors which were designed for human hands.

But if designed for automated processing, it's not a hard challenge.

Just takes massively large connectors.

Offline Robotbeat

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Re: Spaceport America set for SpaceX reusability testing
« Reply #46 on: 03/20/2015 08:09 PM »

This kind of work is what I do.

There are ways, and it's a combination  of interface design and automation.

You certainly don't want to try to design robots that try to mate standard MIL connectors which were designed for human hands.

But if designed for automated processing, it's not a hard challenge.

Just takes massively large connectors.
Or you use a different connector type.
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Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #47 on: 03/20/2015 08:14 PM »
Or you use a different connector type.

Show me robust automated connections for around 100 conductors that are less than 5x the profile of existing connectors.
« Last Edit: 03/20/2015 08:15 PM by Jim »

Offline Space Ghost 1962

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Re: Spaceport America set for SpaceX reusability testing
« Reply #48 on: 03/20/2015 08:20 PM »
Why hundred? Other ways to do it.

add:
I apologize for starting this distraction. Down thread it's called out that Falcon has these connectors. That's the point that should be raised here. Redirect the "why does it have to be this way" to a Q/A and/or "potential future change" thread. If it matters, my issue was about highly intrusive vehicle health sensing signalling requirements not matching such a connector approach, might not fit this.
« Last Edit: 03/21/2015 04:48 PM by Space Ghost 1962 »

Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #49 on: 03/20/2015 08:27 PM »
Why hundred? Other ways to do it.

that is about the rough number between stages.

Offline symbios

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Re: Spaceport America set for SpaceX reusability testing
« Reply #50 on: 03/20/2015 08:51 PM »
Here ya go:


Just for your information Fulematics has been at this since before 2003 and has gone through more than one company reconstruction. That they have not been able to sell this "revolutionary" product after all this time should be a warning that it is not easy.
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Offline john smith 19

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Re: Spaceport America set for SpaceX reusability testing
« Reply #51 on: 03/20/2015 09:34 PM »
Why hundred? Other ways to do it.
True.

It's always seems odd to me that rocket stages seem to like a lot of separate wires (the "parallel" data approach) while transmitting data on serial buses.

I can only presume this design decision (and it is a design decision, not a law of the universe) dates from the time when any electronics were complex, heavy and power hungry. Direct wiring from sensors and actuators made sense.

Today sensors and actuators with built in networking through things like the CANbus standard are common, lightweight and support up to around 2000 devices.
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Offline Space Ghost 1962

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Re: Spaceport America set for SpaceX reusability testing
« Reply #52 on: 03/20/2015 10:04 PM »
Why hundred? Other ways to do it.
True.

It's always seems odd to me that rocket stages seem to like a lot of separate wires (the "parallel" data approach) while transmitting data on serial buses.

I can only presume this design decision (and it is a design decision, not a law of the universe) dates from the time when any electronics were complex, heavy and power hungry. Direct wiring from sensors and actuators made sense.

Today sensors and actuators with built in networking through things like the CANbus standard are common, lightweight and support up to around 2000 devices.

One of the things at the beginning of my career was needing to replace a large connector with an even larger connector for a few more conductors. I got all kinds of reasons, most poor (we always did it that way) and few good (asynch trigger/level). In the end, the connectors had no conductors (optical), solved some ground loop issues, and added the equivalent of several hundred more conductors beyond the the original few more.

Sampling and control for this is non trivial. But not ill conceived. When you automate checkout of a vehicle, you  have a much greater need for control/sense then even a hundred conductors provide for.

The auto/aircraft vehicle manufacturers have learned this too.

Offline meekGee

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Re: Spaceport America set for SpaceX reusability testing
« Reply #53 on: 03/20/2015 10:39 PM »

Unlike other manufacturers SpaceX gives each stage its own avionics. That greatly reduces need for interconnnection. One serial data link can be enough. Make that three for triple redundancy.


Still doesn't change anything.  The upper stage still controls the whole stack.  And there are range safety connections and telemetry too.

There are many ways to approach the problem.

1. No need for hundreds of pins.  That's got to be historical baggage.  Serialize the data.

2. There's no reason to have the second stage drive the first.  The first is already fully autonomous, has identical avionics, and knows all there is to know.  It can make the same decisions the second stage does, can drop it off within an envelope that the second stage can continue from.  Given that the first stage has to continue flight anyway, I don't see why it has to go through the shock of "switching commanders" on stage separation.  The first stage should be working like a carrier airplane.

This is another case of historical baggage.  An EELV is a single vehicle that's dropping parts until only the upper stage is left.  That's why it's built the way it is.   An F9R is a different type of beast.  A highly reusable first stage that continues flight and RTLS right away, and a an upper stage that even if it comes back, does so much later.  They have different operations cycles, and are their own self-contained entities.  Fewer failure modes this way, too - rockets have been lost because of failure of inter-stage connectors. (can't remember which right now)

3. Look at spacecraft dockings.  Connections are made, after the two heavy bodies mate.  And those are free-flying vehicles.  You can do much better if the bodies are guided.  You can do precision guidance by the jig, or you can have pilot pins and such on the flight hardware.

4. The connectors can be rigidly connected to the master bodies and everything connect at once, or you can have them execute a secondary motion after the mechanical mate.  Either way, if you pre-plan for automation, it's alot easier than if you try to make automation work in a less structured environment.

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Offline StuffOfInterest

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Re: Spaceport America set for SpaceX reusability testing
« Reply #54 on: 03/20/2015 10:59 PM »
I remember reading years (possibly a decade) ago now that SpaceX was using an industrial Ethernet variant for all control system communications.  In this case you are dealing with a packet based serial line with no more than eight wires.  In theory, one small connector between stages is all you need for full communication.  Of course, there will likely be triple redundant paths, but you are still only talking three connectors.

SpaceX obviously has advanced avionics on the first stage or you wouldn't see it trying to land.  How those avionics play in to initial flight is another matter.  Is it a network with the upper stage calling to shots and the first stage just carrying them out or are both stages working together?

Offline deruch

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Re: Spaceport America set for SpaceX reusability testing
« Reply #55 on: 03/20/2015 11:06 PM »
Could the data transfer be done wirelessly?
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Offline Robotbeat

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Re: Spaceport America set for SpaceX reusability testing
« Reply #56 on: 03/20/2015 11:10 PM »
Here ya go:


Just for your information Fulematics has been at this since before 2003 and has gone through more than one company reconstruction. That they have not been able to sell this "revolutionary" product after all this time should be a warning that it is not easy.
Not easy given their market, which is existing, unmodified cars. Also, refueling your own car is easy.

Making the business case close may not be easy, but that most certainly doesn't mean it's especially difficult technically. Two very, very different things.
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Offline Robotbeat

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Re: Spaceport America set for SpaceX reusability testing
« Reply #57 on: 03/20/2015 11:21 PM »
Honestly, the electrical connector is the easy bit of this whole thing.

Something like a self-aligning Magsafe connector with more (and stiffer) pins and a solenoid or servo locking mechanism to ensure a tight fit.

It's not, um, rocket science.

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Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #58 on: 03/20/2015 11:41 PM »

1. No need for hundreds of pins.  That's got to be historical baggage.  Serialize the data.

2. There's no reason to have the second stage drive the first.  The first is already fully autonomous, has identical avionics, and knows all there is to know.  It can make the same decisions the second stage does, can drop it off within an envelope that the second stage can continue from.  Given that the first stage has to continue flight anyway, I don't see why it has to go through the shock of "switching commanders" on stage separation.  The first stage should be working like a carrier airplane.

This is another case of historical baggage.  An EELV is a single vehicle that's dropping parts until only the upper stage is left.  That's why it's built the way it is.   An F9R is a different type of beast.  A highly reusable first stage that continues flight and RTLS right away, and a an upper stage that even if it comes back, does so much later.  They have different operations cycles, and are their own self-contained entities.  Fewer failure modes this way, too - rockets have been lost because of failure of inter-stage connectors. (can't remember which right now)

3. Look at spacecraft dockings.  Connections are made, after the two heavy bodies mate.  And those are free-flying vehicles.  You can do much better if the bodies are guided.  You can do precision guidance by the jig, or you can have pilot pins and such on the flight hardware.

4. The connectors can be rigidly connected to the master bodies and everything connect at once, or you can have them execute a secondary motion after the mechanical mate.  Either way, if you pre-plan for automation, it's alot easier than if you try to make automation work in a less structured environment.



Quit with the flippant responses.   It is not historical baggage.  You have nothing to base that assertion on.

1.   for the very many reasons I listed. 

2.  You have been proven wrong on this over and over. How many times do I have say it. Reality is that the second stage controls the first. The first stage is passive until after separation.  That is a fact.

3. Most connections are manual by the crew internally and there are very few conductors.

4.  I am not ask how to do it, but how to accommodate all the conductors.
« Last Edit: 03/20/2015 11:45 PM by Jim »

Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #59 on: 03/20/2015 11:44 PM »
Honestly, the electrical connector is the easy bit of this whole thing.

Something like a self-aligning Magsafe connector with more (and stiffer) pins and a solenoid or servo locking mechanism to ensure a tight fit.


And how small would that connector be without the magsafe feature?  That is my point.

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