Author Topic: General Falcon and Dragon discussion (Thread 13)  (Read 396548 times)

Offline Robotbeat

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #780 on: 06/24/2016 05:06 pm »
It's beginning to sound like Shuttle all over again if there's to be a reprocessing facility - no "gas-n-go".

It's unclear to me how much this "reprocessing facility" would actually reprocess versus being just another hangar.

Flush residual fuel, hose down the stage, prepare for trailing, stick on a trailer. As you suggest temporary storage as well.

Cannot see it being used for much more than housekeeping.

There is more to refurbishment than that.  There is removal of TPS and reapplication of the same.  There is R&R of avionics.  There is some structural and propulsion system repair.  Maybe painting.  Stuff that takes more time, access, GSE and tools than what is done in the processing hangars.
They will have to transition away from that in order to accomplish their goals.
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Offline Jim

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #781 on: 06/24/2016 05:19 pm »

I think they will have an integrated reusable second stage / dispenser.

The whole thing will integrate to the first stage.

For >50 launches per year, I see no other way.

Having independent second stages makes it easier.  The payloads, second stages and first stages can be easily interchanged and be more responsive.  The vehicle can be ready to accept any payload and would be a higher throughput.  An integrated second stage / dispenser would require a separate facility from the pad hangar and the payload processing building.

Preparing the whole vehicle separately from the payload, as is done now, is much like artillery munitions, where the warhead and charge are kept separate until loaded into the piece.

Offline envy887

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #782 on: 06/24/2016 06:00 pm »
Even if payloads are integrated to the second stage separately, that whole package has to be integrated with S1 near the pad. That process can be pretty streamlined, but still requires some dedicated facilities and equipment.

Offline MP99

Re: General Falcon and Dragon discussion (Thread 13)
« Reply #783 on: 06/24/2016 06:15 pm »


It's beginning to sound like Shuttle all over again if there's to be a reprocessing facility - no "gas-n-go".

It's unclear to me how much this "reprocessing facility" would actually reprocess versus being just another hangar.

Flush residual fuel, hose down the stage, prepare for trailing, stick on a trailer. As you suggest temporary storage as well.

Cannot see it being used for much more than housekeeping.

There is more to refurbishment than that.  There is removal of TPS and reapplication of the same.  There is R&R of avionics.  There is some structural and propulsion system repair.  Maybe painting.  Stuff that takes more time, access, GSE and tools than what is done in the processing hangars.
They will have to transition away from that in order to accomplish their goals.

I would expect a lot more instrumentation on the stages, to detect issues with stuff like avionics, structure and propulsion.
IMO, in the short term, all stages will go through refurb until they build up confidence in their correlation between instrumentation and the real world.

ISTM this will be the form that this transition takes.

Cheers, Martin

Offline Jim

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #784 on: 06/24/2016 06:45 pm »
I would expect a lot more instrumentation on the stages, to detect issues with stuff like avionics, structure and propulsion.


They have been trending the other way.  Instrumentation cost money and takes time to install. 

Offline baldusi

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #785 on: 06/24/2016 08:14 pm »
I would expect a lot more instrumentation on the stages, to detect issues with stuff like avionics, structure and propulsion.


They have been trending the other way.  Instrumentation cost money and takes time to install.
And time to analyze, and telemetry bandwidth. All costs, mass and complexity.

Offline meekGee

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #786 on: 06/24/2016 09:39 pm »

I think they will have an integrated reusable second stage / dispenser.

The whole thing will integrate to the first stage.

For >50 launches per year, I see no other way.

Having independent second stages makes it easier.  The payloads, second stages and first stages can be easily interchanged and be more responsive.  The vehicle can be ready to accept any payload and would be a higher throughput.  An integrated second stage / dispenser would require a separate facility from the pad hangar and the payload processing building.

Preparing the whole vehicle separately from the payload, as is done now, is much like artillery munitions, where the warhead and charge are kept separate until loaded into the piece.
We'll see.

My guess is that commX will be such a full time job that it will have its own processing facility.


Since it's all LEO, they'd get the second stage back, and save mass by integrating the two. (Second stage and dispenser)

This is not some random launch.  This is 50-per-year on an ongoing basis...  at least...  It's almost like the rest of the launch market combined...

And if you can save the cost of the second stage and dispenser and fairing...  Aince you're your own customer, it's straight into your bottom line...
« Last Edit: 06/24/2016 09:54 pm by meekGee »
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Offline Jim

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #787 on: 06/24/2016 10:23 pm »

1.  My guess is that commX will be such a full time job that it will have its own processing facility.

2.  Since it's all LEO, they'd get the second stage back, and save mass by integrating the two. (Second stage and dispenser)

3.  This is not some random launch.  This is 50-per-year on an ongoing basis...  at least...  It's almost like the rest of the launch market combined...

And if you can save the cost of the second stage and dispenser and fairing...  Aince you're your own customer, it's straight into your bottom line...


1.  And that still doesn't play in this.  The spacecrafts and the dispensers can be off in a dedicated facility away from the launch pad, doing their own thing.    Launch vehicle and spacecraft processing are two separate tasks that have different requirements and environments.

2.  There is no mass to be saved by that.  It doesn't change that the second stage is still just tanks, forward skirt with avionics, adapter with dispenser, and fairing.   Making it "integral" doesn't change anything.

3.  And is the main reason for keeping the payload processing away from the pad and launch vehicle testing and doing the spacecraft mate late as possible.  Bringing the upperstage with the payload will push it to the right and increase pad time for the payload.  Booster and upperstage have not been tested together.  They are not separate vehicles that fly independently.  Most the time in the hangar is spent testing the whole vehicle and not just the parts.

4.  There is no savings from the integral design.  Just more since the design different than the others.  Spacex MO is to minimize configurations.   They aren't designing for LEO but for Mars

Offline meekGee

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #788 on: 06/24/2016 11:21 pm »

1.  My guess is that commX will be such a full time job that it will have its own processing facility.

2.  Since it's all LEO, they'd get the second stage back, and save mass by integrating the two. (Second stage and dispenser)

3.  This is not some random launch.  This is 50-per-year on an ongoing basis...  at least...  It's almost like the rest of the launch market combined...

And if you can save the cost of the second stage and dispenser and fairing...  Aince you're your own customer, it's straight into your bottom line...


1.  And that still doesn't play in this.  The spacecrafts and the dispensers can be off in a dedicated facility away from the launch pad, doing their own thing.    Launch vehicle and spacecraft processing are two separate tasks that have different requirements and environments.

2.  There is no mass to be saved by that.  It doesn't change that the second stage is still just tanks, forward skirt with avionics, adapter with dispenser, and fairing.   Making it "integral" doesn't change anything.

3.  And is the main reason for keeping the payload processing away from the pad and launch vehicle testing and doing the spacecraft mate late as possible.  Bringing the upperstage with the payload will push it to the right and increase pad time for the payload.  Booster and upperstage have not been tested together.  They are not separate vehicles that fly independently.  Most the time in the hangar is spent testing the whole vehicle and not just the parts.

4.  There is no savings from the integral design.  Just more since the design different than the others.  Spacex MO is to minimize configurations.   They aren't designing for LEO but for Mars

Concentrate on the cost savings.

In a conventional design.  Generic second stage reuse is not pursued, because there's a large mass penalty, and because most non-Dragon flights are currently GEO, which is even harder.

In CommX, it's LEO, and it's probably not mass constrained, because of the way orbital slots work.

So what they need is a very low cost to launch often, and launch light.

Everything comes together to make it the best case for re-using a second stage.

When you're throwing away a second stage, a dispenser, and fairing every time (and ocean fairing recovery is not exactly ideal) - EVERY WEEK - I'm sure you're starting to think about how to solve this.

Especially when you can't pass the cost to the customer, because the customer is you...

If they can do this, they can launch really really cheaply, and have a huge advantage on competitors.
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Offline Jim

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #789 on: 06/25/2016 02:42 am »


Concentrate on the cost savings.

In a conventional design.  Generic second stage reuse is not pursued, because there's a large mass penalty, and because most non-Dragon flights are currently GEO, which is even harder.

In CommX, it's LEO, and it's probably not mass constrained, because of the way orbital slots work.

So what they need is a very low cost to launch often, and launch light.

Everything comes together to make it the best case for re-using a second stage.

When you're throwing away a second stage, a dispenser, and fairing every time (and ocean fairing recovery is not exactly ideal) - EVERY WEEK - I'm sure you're starting to think about how to solve this.

Especially when you can't pass the cost to the customer, because the customer is you...

If they can do this, they can launch really really cheaply, and have a huge advantage on competitors.


And as stated there are no cost savings associated with an "integral" dispenser and upperstage.  Since they are manufactured separately and there is no advantage in joining them earlier.   A fairing is going to a separate item from the second stage.  The only way of eliminating the fairing and dispenser is to make them like the Dragon.   So take the original Orbcomm pancake spacecraft.  Make the outer edge with the ability to handle the ascent environment.  Stack ten to 20 of them and add a simple nose cone on the last one.  There is your integral dispenser and fairing.

Offline Jcc

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #790 on: 06/25/2016 03:04 am »
They are working on getting the fairing back and reusing it. I presume they have identified a viable way to do that, and we will be wonderfully surprised to see how that will happen. At least that is ejected at suborbital velocity. Getting the second stage back is a difficult problem since any additional mass or fuel retained on the second stage for the purpose of recovery directly subtracts from the usable payload capacity. It can be done, but at what cost? The dispenser would also be a great challenge to recover as it is at orbital velocity by the time it's used. Maybe if it stays with the second stage, but at what cost to payload capacity?

Offline Kabloona

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #791 on: 06/25/2016 03:45 am »
Quote
And as stated there are no cost savings associated with an "integral" dispenser and upperstage.  Since they are manufactured separately and there is no advantage in joining them earlier.   A fairing is going to a separate item from the second stage.  The only way of eliminating the fairing and dispenser is to make them like the Dragon.   So take the original Orbcomm pancake spacecraft.  Make the outer edge with the ability to handle the ascent environment.  Stack ten to 20 of them and add a simple nose cone on the last one.  There is your integral dispenser and fairing.

Like this. The satellites are their own "dispensers." With a regular fairing, of course.
« Last Edit: 06/25/2016 03:55 am by Kabloona »

Offline meekGee

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #792 on: 06/25/2016 04:02 am »


Concentrate on the cost savings.

In a conventional design.  Generic second stage reuse is not pursued, because there's a large mass penalty, and because most non-Dragon flights are currently GEO, which is even harder.

In CommX, it's LEO, and it's probably not mass constrained, because of the way orbital slots work.

So what they need is a very low cost to launch often, and launch light.

Everything comes together to make it the best case for re-using a second stage.

When you're throwing away a second stage, a dispenser, and fairing every time (and ocean fairing recovery is not exactly ideal) - EVERY WEEK - I'm sure you're starting to think about how to solve this.

Especially when you can't pass the cost to the customer, because the customer is you...

If they can do this, they can launch really really cheaply, and have a huge advantage on competitors.


And as stated there are no cost savings associated with an "integral" dispenser and upperstage.  Since they are manufactured separately and there is no advantage in joining them earlier.   A fairing is going to a separate item from the second stage.  The only way of eliminating the fairing and dispenser is to make them like the Dragon.   So take the original Orbcomm pancake spacecraft.  Make the outer edge with the ability to handle the ascent environment.  Stack ten to 20 of them and add a simple nose cone on the last one.  There is your integral dispenser and fairing.

Not unless you get them back.  Which is the whole rationale to do it.  In CommX, if you can get your 2nd stage dispenser back, then it doesn't matter you lost payload mass.  Just launch a lot.  You need many orbital planes anyway.
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Offline Space Ghost 1962

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #793 on: 06/25/2016 04:29 am »
The only way of eliminating the fairing and dispenser is to make them like the Dragon.   So take the original Orbcomm pancake spacecraft.  Make the outer edge with the ability to handle the ascent environment.  Stack ten to 20 of them and add a simple nose cone on the last one.  There is your integral dispenser and fairing.

The aeroloads would need to have load paths through each spacecraft. The thermal environments for ground, ascent, and LEO would have to be taken into account for the entire unit and as separate SC. The latching mechanism/seals for SC/cone would have to be qualified for launch environment including vibratory modes that would be induced due to external flows. The connectors between sats and ventilation/power signal umbilical attachment would require a base "segment" to attach to the payload adapter. You'd need to test the deployment mechanism in a vacuum chamber after a thermal cycle and a cold soak.

Cost/weight increase per sat likely better then with expendable shroud. Additional development costs and forced form factor might limit desirability of such a concept to a constellation where it fit, that had large enough deployments/launches.

Offline MP99

Re: General Falcon and Dragon discussion (Thread 13)
« Reply #794 on: 06/25/2016 06:57 am »


I would expect a lot more instrumentation on the stages, to detect issues with stuff like avionics, structure and propulsion.


They have been trending the other way.  Instrumentation cost money and takes time to install.
And time to analyze, and telemetry bandwidth. All costs, mass and complexity.

No need for telemetry - just plug into a laptop after recovery.

Yes, there would be some time spent analysing the data on earlier stages, but that's when I believe there will be inspection and refurb going on, anyway. Instrumentation could evolve to monitor those elements that experience shows would affect gas-and-go, ultimately reducing the hands-on to cycle a stage.

Cheers, Martin


Offline Jim

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #795 on: 06/25/2016 10:33 am »


I would expect a lot more instrumentation on the stages, to detect issues with stuff like avionics, structure and propulsion.


They have been trending the other way.  Instrumentation cost money and takes time to install.
And time to analyze, and telemetry bandwidth. All costs, mass and complexity.

No need for telemetry - just plug into a laptop after recovery.


Whether it is transmitted or kept on board, it is not much different.  There still has to be a data system with sensors and wiring.  That is where all the work is.  Keeping it onboard not only eliminates the transmitter but also impedes the ability to find out what went wrong.

Offline gongora

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #796 on: 06/25/2016 04:46 pm »
I was looking for SpaceX stories on Google News and the Daily Mail has a "This date in history" article for next Tuesday, June 28.  It will be the one year anniversary of the CRS-7 launch.  With all the stuff SpaceX is busy working on now, a regular launch cadence going, and seven more flights under their belt it seems longer ago than that.

Offline the_other_Doug

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #797 on: 06/25/2016 04:51 pm »


I would expect a lot more instrumentation on the stages, to detect issues with stuff like avionics, structure and propulsion.


They have been trending the other way.  Instrumentation cost money and takes time to install.
And time to analyze, and telemetry bandwidth. All costs, mass and complexity.

No need for telemetry - just plug into a laptop after recovery.


Whether it is transmitted or kept on board, it is not much different.  There still has to be a data system with sensors and wiring.  That is where all the work is.  Keeping it onboard not only eliminates the transmitter but also impedes the ability to find out what went wrong.

Yeah -- I mean, yes, maintaining a developmental instrumentation system to report on a lot of things is mildly helpful in establishing the data points for normal operations.  But keeping it all onboard means that, if you lose the vehicle, in the very case you might want all that data, it could easily go kabloom with the rest of the stage and leave nothing left to "plug into a laptop" once the debris settles.

And I don't see SpaceX hiring the kinds of resources needed to find a survivable black box on the deep ocean floor after a launch failure.  The NTSB might do that, especially on airline accidents that claimed hundreds of lives.  But SpaceX likely won't, so even putting your recorder into a black box isn't that much of a help.  You still have an overwhelming likelihood of losing the data you want in just the situations when you might really want it.

Cheaper to carefully select the critical parameters you want to monitor -- the ones from which you already know how to extrapolate the general health of the vehicle -- and make sure you get that data back real-time.
-Doug  (With my shield, not yet upon it)

Offline IainMcClatchie

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #798 on: 06/26/2016 12:29 am »
I've never understood the problem with black boxes.

  • 3 to 5 cm diameter
  • overall density lower than water, biased center of gravity so that radio beacon is "up"
  • 1 cm outer layer of PICA-X
  • detaches from rocket on loss of power to solenoid magnet
  • radio beacon, pulses several watts for 1 ms every ten seconds for two weeks
  • 2 gram lithium-ion cell with 0.3 watt-hours
  • 1 GB/s write speed at 1 watt over something convenient like PCIe
  • TB of flash

  • It might be challenging to make it survive terminal-velocity impact with a granite slab, but otherwise this seems straightforward.  I'd probably put several of them on the rocket, just to avoid the weight of running instrumentation wiring for long distances.

    Offline spacenut

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    Re: General Falcon and Dragon discussion (Thread 13)
    « Reply #799 on: 06/26/2016 12:33 am »
    The idea against black boxes is I think, that rockets have so many sensors giving real time signals.  More sensors than any other means of transportation, that there is no need for duplicate data from a black box.

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