Author Topic: SpaceX: General Falcon and Dragon discussion (Thread 3)  (Read 562155 times)

Offline Chris Bergin

Thread 3 for general discussion on SpaceX and their vehicles.

Thread 1:
http://forum.nasaspaceflight.com/index.php?topic=19228.0

Thread 2:
http://forum.nasaspaceflight.com/index.php?topic=22769.0

Over half a million views for the two threads above, and while it doesn't really matter if a thread has 10 views or a million, remember that a lot of views are coming from 'guests/visitors' (the vast majority) - not actual members/posters - on here, so don't let yourself down by getting argumentative to the point you are being uncivil. We won't stand for armwaving or general rudeness. It costs too much money to host this site to allow people to run into this forum without wiping their shoes on the doorstep beforehand.

Don't be tempted to dominate the thread either. That tends to annoy people on these very long threads. Threads aren't person to person phone calls, they are large gatherings where everyone has something to say and may wish to jump in with a question without feeling they are interrupting.

Some links:

SpaceX news articles on this site:
Old: http://forum.nasaspaceflight.com/index.php?topic=21862.0 (links)
Recent: http://www.nasaspaceflight.com/tag/spacex/

L2 SpaceX:
http://forum.nasaspaceflight.com/index.php?action=tags&tags=SpaceX

Remember, this is for SpaceX related chat, and that only. It allows the other threads on the SpaceX section of the forum to remain specific to that particular news.

So, keep it on SpaceX and use it for discussion. For new news, use the SpaceX section, which contains threads for the F9 launches and new news from SpaceX etc.

Did I mention to remain civil and treat other members as if you were talking to them in real life? Oh yeah, I did! ;)

Online meekGee

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #1 on: 02/22/2011 03:22 AM »
(deep breath) I'll go first then...   

An observation that occurred to me - there was an uptick in SpaceX planning recently - talk of accelerated F9H, etc.

I don't have an insight into their financials, but I am sure they still have a contingency financial plan for the case an F9 fails, and probably a second one for the case a Dragon fails.

They were not 100% sure that either of them will fly right the first time.

While they are nowhere near "out of the woods", they could be now making plans in the 1-year outlook in case things continue to go smoothly - to the rough extent of about two F9 launches worth of funds.

-- with all the disclaimers that must accompany second guessing financial plans... I'm an engineer, dammit, not a bean counter.
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Offline mr. mark

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #2 on: 02/22/2011 03:36 AM »
I'm just a Space enthusiast, I'm here to learn what I can and as much as I can. With that said, I would assume that Spacex is going from the testing stage to the successful production stage of Phase 1 as far as Falcon 9 is concerned. It will take several more successful launches though before that can happen. Remember, Spacex is still evolving. They have stated that they intend to build 3 launch vehicles Falcon 1E, Falcon 9 and Falcon 9 Heavy. Only one version in that series, Falcon 9, has ever flown. They have a long way to go but, so far so good. I'm continuing to hope for their success.
« Last Edit: 02/22/2011 03:37 AM by mr. mark »

Offline Dave G

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #3 on: 02/22/2011 03:55 AM »
While they are nowhere near "out of the woods", they could be now making plans in the 1-year outlook in case things continue to go smoothly - to the rough extent of about two F9 launches worth of funds.

Yes, exactly.

In other words, you need contingency plans in case of failures, but you also need to plan for success.


Offline Proponent

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #4 on: 02/22/2011 04:18 AM »
Does anybody have a pointer to an analysis of the the Soyuz/Foton accident?

Offline Dave G

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #5 on: 02/22/2011 05:06 AM »
Remember, Spacex is still evolving. They have stated that they intend to build 3 launch vehicles Falcon 1E, Falcon 9 and Falcon 9 Heavy.

Looks like Falcon1e is history, or back burner at the very least.
http://www.floridatoday.com/article/20110218/BUSINESS/102180316/SpaceX-changes-focus-rockets?odyssey=tab

(Replaced link. Always cite the original source, not blog sites which reharsh other people's work - Chris)
« Last Edit: 02/22/2011 02:57 PM by Chris Bergin »

Offline Ben the Space Brit

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #6 on: 02/22/2011 07:24 AM »
An observation that occurred to me - there was an uptick in SpaceX planning recently - talk of accelerated F9H, etc.

I'm not sure if that bit of news reflected SpaceX policy or if it was just reporting what DoD wants of them if they want a substantive slice of the government launch pie.

Quote
I don't have an insight into their financials, but I am sure they still have a contingency financial plan for the case an F9 fails, and probably a second one for the case a Dragon fails.

Well, SpaceX do have a significant number of satellite launch contracts.  However, I would argue that there is no long-term 'failure option' for Dragon, only a provision for keeping the wheels spinning until the problem is ironed out.  Dragon represents their real core product at this time and, without it, the company would be hard-pressed to maintain its momentum.
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Offline spacejulien

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #7 on: 02/22/2011 04:51 PM »
Does anybody have a pointer to an analysis of the the Soyuz/Foton accident?

Even when discussing EOC this level of detail may qualify for "off-topic". And I don't have any access to original Russian documentation on the accident. But nonetheless, here is my state of knowledge:

One has to rely i.e. on this indirect source for the root cause:
http://esapub.esrin.esa.it/onstation/onstation13/page7-9.pdf
Quote
The report of the Russian State Investigation Commission concluded that a ‘foreign metallic object’ caused a turbopump to fail, cutting the engine propellant flow.

So the engine of one booster died. The boosters have no separation-system, when their thrust tails off, they simply slip out of their connection brackets.

This can be seen in the video exactly at 0:23, about 6 seconds after lift-off.


It is noteworthy, that the launcher continues to climb even with one booster missing. Then, at 0:42 the thrust is commanded to cut-off, about 25 seconds after lift-off. This is the Russian style of range-safety, there are no explosives on board to destroy the vehicle. There is also no uplink from the ground to trigger a cut-off. Thus, the avionics determined the off-nominal parameters of the flight and shut-down the engines.

But for the first seconds any action the range safety system would take is suppressed in order not to have the vehicle fall back on the launch table and destroy it, which is why the shutdown occured ~19 seconds after the anomaly.

In fact, changing the range safety system (providing an uplink) is a major change for launching Soyuz out of Kourou.
« Last Edit: 02/22/2011 05:09 PM by spacejulien »
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Offline Antares

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #8 on: 02/22/2011 05:09 PM »
Am I dreaming that there was a post-flight report published for F9-001?  I'm wondering if one is in works for F9-002.
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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #9 on: 02/22/2011 05:18 PM »
After F9-001 Elon said there would be one, but that it wouldn't be released to the public.

Online meekGee

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #10 on: 02/22/2011 05:30 PM »
Me, I got a quite a chuckle out of the note about "booster simply slides away" design.

It's a lot more complicated to pull off than it sounds, so I'm very curious - Does anyone here have more detailed knowledge or a pointer to that design? 
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Online ugordan

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #11 on: 02/22/2011 06:02 PM »
Get a load of what they appear to be contemplating, from Tim Hughes' AIAA presentation:

The image in the PDF is called 'Falcon 9 Heavy extended'. Stretched tanks don't exactly strike me as being just 2 more first stages strapped to the side.

Online meekGee

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #12 on: 02/22/2011 06:14 PM »
Here's a thought.

Let's assume for a moment that a 9-engine cluster has EOC.  (or to prevent flames, has EOC to some degree).

Now if you have three cores and 27 engines, then at a minimum you can have one engine fail in each, and so the failure figure is just Pf^3, same as it would have been for three engines.

But!  if the rocket can handle the thrust imbalance, which it should, then you can have three engines fail *anywhere* in the 27 cluster, and  probably have even more engines fail if the distribution is favorable.

So if cascade-failure is properly mitigates, the three-core will be very reliable indeed, especially if all engines are verified good before the rocket is released.

The one daemon that slips through this analysis is a systematic production bug that affects a significant portion of the engines.  However, since this hypothetical bug is systematic, it is basically no more dangerous than the same bug on a 1-engine per core rocket.

[EDIT] ugordan - someone mentioned that block 1 Merlins are under-performing a bit.  Could this be a simple fix for that until the block 2 Merlins come online (well, prolly they'll do Merlin block 2 before the F9H flies, but still)
« Last Edit: 02/22/2011 06:21 PM by meekGee »
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Offline jimvela

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #13 on: 02/22/2011 06:22 PM »
Get a load of what they appear to be contemplating, from Tim Hughes' AIAA presentation:

The image in the PDF is called 'Falcon 9 Heavy extended'. Stretched tanks don't exactly strike me as being just 2 more first stages strapped to the side.

That only makes sense to me if:
+ Significantly higher thrust is forthcoming in the next Merlin 1 engines to be used, with the core having engines deleted
  -or-
+ Cross-feed capabilities from the boosters back to the core.

Either way, definitely not "just 2 more first stages strapped to the side".

Offline Lars_J

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #14 on: 02/22/2011 06:23 PM »
Get a load of what they appear to be contemplating, from Tim Hughes' AIAA presentation:

The image in the PDF is called 'Falcon 9 Heavy extended'. Stretched tanks don't exactly strike me as being just 2 more first stages strapped to the side.

That appears to make little sense... Unless they can throttle down the core significantly. (which they cannot do on the current Merlin 1c, AFAIK). With this layout, the core would run out of fuel/oxidizer first - not desirable.

Offline HMXHMX

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #15 on: 02/22/2011 06:29 PM »
Get a load of what they appear to be contemplating, from Tim Hughes' AIAA presentation:

The image in the PDF is called 'Falcon 9 Heavy extended'. Stretched tanks don't exactly strike me as being just 2 more first stages strapped to the side.

Makes sense.  Barrel stretches are straightforward, and this allows one to add propellant to max up GLOW, since the three barrel version has excess t/w.

Offline Lars_J

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #16 on: 02/22/2011 06:32 PM »
But it makes more sense to stretch the core instead of the boosters.

Offline kevin-rf

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #17 on: 02/22/2011 06:43 PM »
But it makes more sense to stretch the core instead of the boosters.

Makes more sense if it flies often to go with a single core.
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Offline HMXHMX

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #18 on: 02/22/2011 06:47 PM »
But it makes more sense to stretch the core instead of the boosters.

Surely, from a delta-v perspective.  But they may have other reasons not to do that.  Limiting fineness ratio might be one.  Another may be that they just don't want to mess with the core for some obscure interface reason.

More Kremlinology.  ;)

Offline Antares

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Re: SpaceX: General Falcon and Dragon discussion (Thread 3)
« Reply #19 on: 02/22/2011 06:47 PM »
But!  if the rocket can handle the thrust imbalance, which it should, then you can have three engines fail *anywhere* in the 27 cluster, and  probably have even more engines fail if the distribution is favorable.

So if cascade-failure is properly mitigates, the three-core will be very reliable indeed, especially if all engines are verified good before the rocket is released.

More incomplete, anumerical thoughts from an amateur.  Fail 3 engines on one of the strap-ons.  Now the other strap-on is burning 50% faster than that one.  Whatcha gonna do?  Cut 3 engines or throttle back the good one?  Performance lost.  LOM.  And again, you'd have to design the fairing to take the aeroloads of flying at an angle of attack.
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