Author Topic: Spaceport America set for SpaceX reusability testing  (Read 46547 times)

Offline meekGee

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Re: Spaceport America set for SpaceX reusability testing
« Reply #80 on: 03/21/2015 03:52 PM »
Why am I reading pages of posts about pins?
Because you know that people can only understand how something works by undersanding the most basic details. The great engineers aren't the ones who memorized the manual the best. They're the ones who understand the machine at the gut level because they know how it works down to the pins and switches.
 At least, that's my take after a barrel sized mug of beer in a Tunisian bar and grill.

That's cool. But this thread is about the thread title and the article. Perhaps we could concentrate on that here and not get into a few people going on about pins! ;D

Fair enough about the pins, but this conversation actually is "included" in the topic.

What will happen at SPA was the topic of much debate - the multiple flights to demonstrate longevity, the proving ground for rapid reusability, etc.

Stage integration is a big part of it, and if it can be simplified, it will remove obstacles to both.

Not only is a simplified mating process important for rapid reusability, but also for how many times you can fly the rocket.  If the connectors deteriorate after 3-4 mating cycles, you've got a serious problem, since it will increase cost and increase the time to recycle.

The kind of connectors I mentioned above are designed for tens of thousand of cycles, under pretty extreme conditions.

From what I hear, non of those are in use today.  That is something SpaceX will have to get into as they work towards rapid reusability, but it is very much possible with today's technologies.

Since Musk is also involved in car manufacturing, he'll have an inside line to all of this.

*And I will repeat the lesson that seems to be lost on some.  When Musk is talking about what SpaceX will do, he's typically 1-2 years ahead of what outsiders on this site know.  Even if they have some insight into what's happening at the cape.  That's why his statements and goals seem outlandish, but they do tend to materialize, so there must be a plan in the works.  It could be that Elon actually has inside information into what that plan is.

So if automated rocket integration seems impossible to you, there are two choices.  Either Musk is clueless, or he has charted a technological path towards that goal, and we can just play a guessing game at this point what that path is.  So far, the "Musk is clueless" option has been the losing side of the argument.
« Last Edit: 03/21/2015 03:58 PM by meekGee »
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Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #81 on: 03/21/2015 03:54 PM »


You also keep telling me that it's impossible to be done, cannot be done, because it's not how it's done today.

That's where we differ.

No, for the falcon 9, the second stage will always control the first stage because that is the more efficient, safer and less risky way of doing it. That way one set of software deals with the mission and the customer is assured that it is stable and Spacex can tinker with the first stage recovery guidance all they want.  They have no plans of doing any other way.  First stage guidance system is only for recovery and not ascent.
« Last Edit: 03/21/2015 04:01 PM by Jim »

Offline meekGee

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Re: Spaceport America set for SpaceX reusability testing
« Reply #82 on: 03/21/2015 04:00 PM »


You also keep telling me that it's impossible to be done, cannot be done, because it's not how it's done today.

That's where we differ.

No, for the falcon 9, the second stage will always control the first stage because that is the more efficient, safer and less risky way of doing.  They have no plans of doing any other way.  First stage guidance system is only for recovery and not ascent.

I'm done arguing about it, we'll live and see.  I'll just note that this was but one of several approaches I've outlined to help achieving what you dismiss offhand as impossible.
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Offline Jim

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Re: Spaceport America set for SpaceX reusability testing
« Reply #83 on: 03/21/2015 04:02 PM »

I'm done arguing about it, we'll live and see.  I'll just note that this was but one of several approaches I've outlined to help achieving what you dismiss offhand as impossible.

Show me where I said "impossible". 
« Last Edit: 03/21/2015 04:05 PM by Jim »

Online Robotbeat

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Re: Spaceport America set for SpaceX reusability testing
« Reply #84 on: 03/21/2015 07:56 PM »
BTW, where does this idea come from that they'd automatically stack and integrate and fuel the two stages together?

Anyone?
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Offline john smith 19

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Re: Spaceport America set for SpaceX reusability testing
« Reply #85 on: 03/22/2015 08:22 AM »
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.
That can be an issue with signal sampling rates being too low and so the high on one line (sampled later) is a bit behind the high on an earlier line when they were actually simultaneous.

That said the MIDI interface (musical note are all time sensitive) found ways around that (at 31.25Kbs) 3 decades ago suggest it's possible.

Readers may think this is all a bit pedantic but AFAIK the baseline spec for most (all) of these wires seems to be carrying a 5A current, IOW firing an explosive bolt. The connectors are heavy. The wire is heavy and there's a lot of it.  :(
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Offline john smith 19

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Re: Spaceport America set for SpaceX reusability testing
« Reply #86 on: 03/22/2015 08:34 AM »
Moving from the specific to the more general I'm excited to see the first one recovered will be used to see how many refurb cycles it can undergo.

This will be a key parameter to any price and cost modelling.

Hmm, I wonder.

Time for a poll? 2 Reuses? 5? 10? 20+? 100+?
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Online AncientU

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Re: Spaceport America set for SpaceX reusability testing
« Reply #87 on: 03/22/2015 12:56 PM »
I'm curious to see if they test out new retrieving and ground handling equipment... Assuming the stage goes back to the barn between flights.  If it stays vertical between flights, all the better.
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Offline fthomassy

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Re: Spaceport America set for SpaceX reusability testing
« Reply #88 on: 03/22/2015 05:10 PM »
Time for a poll? 2 Reuses? 5? 10? 20+? 100+?
Or when we will see the first reuse flight and the first one-month, one-week, one-day and same-day reuse cycles!

Unrelated to the Spaceport America topic are the same questions for commercial operation.
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Offline StuffOfInterest

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Re: Spaceport America set for SpaceX reusability testing
« Reply #89 on: 03/22/2015 07:43 PM »
I'm not going to go near the arguments over how many pins are used but the overall method of communication is of interest to me based on my network engineering background.  I recalled reading about Ethernet on Falcon rockets from around 10 years ago and I was right.  Found this from 2005:

http://www.spacex.com/news/2005/12/19/june-2005-december-2005

Quote
Engine electronics for the Merlin 1B in Falcon 9 have been simplified down to just three boxes that are responsible for all digital and analog activity. Each set of engine electronics is essentially a self contained plug and play module, dealing with its own activity in accordance with high level commands issued by the flight computer on the upper stage. The only wires between the stage and each engine are an Ethernet cable and a power cable.

Now, I have no reason to doubt Jim's assertion that the 2nd stage flight computer controls the entire ascent but this does lead to an interesting scenario about how things communicate.  Ethernet is a bus which doesn't have a master device.  So, as the engines are nodes on that bus do you think they communicate directly to the 2nd stage computer until stage separation and then directly to the 1st stage computer for descent or do you think the engines always talk to the 1st stage computer and that computer takes orders from the 2nd stage computer during ascent?  I could see arguments for it being done either way.

Offline clongton

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Re: Spaceport America set for SpaceX reusability testing
« Reply #90 on: 03/22/2015 07:50 PM »
In my engineering background I would opt for the 2nd scenario. Stage separation is a critical event. The engines do not need to be switching and validating data source at that time. They should be tied to the 1st stage, which takes its direction from the second so long as the Ethernet connection remains intact, seamlessly defaulting to its own instruction set once stage 2 no longer overrides them.
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Offline oiorionsbelt

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Re: Spaceport America set for SpaceX reusability testing
« Reply #91 on: 08/02/2015 04:35 PM »
Spaceport America will remain Airport America for some time yet.

Offline meekGee

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Re: Spaceport America set for SpaceX reusability testing
« Reply #92 on: 08/02/2015 04:39 PM »
In my engineering background I would opt for the 2nd scenario. Stage separation is a critical event. The engines do not need to be switching and validating data source at that time. They should be tied to the 1st stage, which takes its direction from the second so long as the Ethernet connection remains intact, seamlessly defaulting to its own instruction set once stage 2 no longer overrides them.

Exactly so.  The less stuff goes through the interstage boundary, the better.    Also makes for easier stage integration, since you don't need a myriad of individual control or sense lines.
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Offline matthewkantar

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Re: Spaceport America set for SpaceX reusability testing
« Reply #93 on: 12/05/2015 11:43 AM »
Over on the Spaceport America thread yg1968 posted an aerial video of the facility. At 40 seconds it seems to show a really good shot of a Grasshopper type launch stand:https://www.youtube.com/watch?v=oxgE02nhOL8

Enjoy, Matthew

Offline meekGee

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Re: Spaceport America set for SpaceX reusability testing
« Reply #94 on: 12/06/2015 04:54 AM »
hmmm....
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Offline rpapo

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Re: Spaceport America set for SpaceX reusability testing
« Reply #95 on: 12/06/2015 10:39 AM »
And what about this?  It sure looks a lot like SpaceX landing pads, at least to me.  But why three?
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Offline Ohsin

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Re: Spaceport America set for SpaceX reusability testing
« Reply #96 on: 12/06/2015 11:31 AM »
And what about this?  It sure looks a lot like SpaceX landing pads, at least to me.  But why three?

And if you look closely at least one of them is made to have certain terrain like features(boulders strewn around). So it is likely to test autonomous landing on varied terrain like Morpheus.
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Online eriblo

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Re: Spaceport America set for SpaceX reusability testing
« Reply #97 on: 12/06/2015 01:11 PM »
And what about this?  It sure looks a lot like SpaceX landing pads, at least to me.  But why three?

I'm willing to bet a lot on the fact that they are completely unrelated to SpaceX. They are located 1 km WSW of their launch mount while the landing pad is 200 m E, so they are certainly close enough. However, checking them out in TerraServer and Google Maps reveals that they predate SpaceX by quite a bit, being present at least since January 2010.

Also, I don't know what use SpaceX could have of them - check the wheel tracks in the video. They are only 10 m in diameter :)

Online Llian Rhydderch

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Re: Spaceport America set for SpaceX reusability testing
« Reply #98 on: 12/06/2015 06:15 PM »
And what about this?  It sure looks a lot like SpaceX landing pads, at least to me.  But why three?

I believe those are the (quite old) small pads constructed for the Lunar Lander Challenge, complete with embedded rocks for simulated Lunar obstructions.
« Last Edit: 12/06/2015 06:17 PM by Llian Rhydderch »
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Offline meekGee

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Re: Spaceport America set for SpaceX reusability testing
« Reply #99 on: 12/06/2015 06:19 PM »
hmmm....

so how tall are those mounts?

It's interesting to compare shadow lengths, between them and that pipe coming in from the top - if only we knew how far off the ground it was.  The truck in the corner isn't helping much.
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