Author Topic: General Falcon and Dragon Discussion (Thread 10)  (Read 606670 times)

Offline aero

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #340 on: 02/18/2014 09:01 pm »
Did anyone ever discover that the Merlin D nozzle diameter is?
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Offline beancounter

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #341 on: 02/19/2014 01:18 am »
The drought of news from SpaceX is awful.
The effects on NSF members are: loss of memory, confusion, disbelief, general uneasiness.
 ;D  ;D  ;D
SpaceX are getting as secretive as Blue Origin these days. We all wish SpaceX could become open again like they were in their early days. The lack of SpaceX news is definitely getting everyone on edge.


They are now doing stuff that is either innovative, and thus requires ITAR and trade secrets compliance, or they not doing so well and thus nothing to talk about.

Or they're doing standard stuff that's going ok and therefore nothing to talk about  :)
Beancounter from DownUnder

Offline dcporter

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #342 on: 02/19/2014 02:56 am »
SpaceX are getting as secretive as Blue Origin these days.

We basically only hear about it when either company puts something in orbit.

Offline docmordrid

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #343 on: 02/19/2014 04:30 am »
Perhaps we'll hear something new when LC-39A is officially handed over (L2).
DM

Offline cambrianera

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #344 on: 02/19/2014 08:14 am »
Did anyone ever discover that the Merlin D nozzle diameter is?
Best analysis I can remember is this by Hobbes-22:
http://forum.nasaspaceflight.com/index.php?topic=32983.msg1139226#msg1139226
Max diameter of nozzle about 94 cm.
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Offline 411rocket

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #345 on: 02/19/2014 12:37 pm »
The drought of news from SpaceX is awful.
The effects on NSF members are: loss of memory, confusion, disbelief, general uneasiness.
 ;D  ;D  ;D
SpaceX are getting as secretive as Blue Origin these days. We all wish SpaceX could become open again like they were in their early days. The lack of SpaceX news is definitely getting everyone on edge.

I do not remember, seeing any posts from PADRAT in the SpaceX threads, since shortly after the Thaicom6 launch. So there appears to be a total Blackout in effect  & GH2 news is not being sent by them, but by visitors to the area.

Offline Ben the Space Brit

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #346 on: 02/19/2014 03:38 pm »
This really shouldn't surprise us; it's a pattern that's been followed really since the Falcon-9 v.1.1 test anomaly. The company doesn't really mention anything except during the last few days of a launch campaign and, even then, it's relatively limited and information-poor. Similarly, their actual mission coverage is information-poor and very infrequent. I could draw conclusions about their actions but that would be drifting very much into op-ed territory.
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Offline fatjohn1408

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #347 on: 02/19/2014 03:42 pm »
I have a question:

I haven't seen any fuel lines on the outside of the vehicle to direct the propellant in the upper tank of the stage to the engine. The ariane V does this via a fuel line on the outside, the Atlas V as well, the Zenit has a toroidal kerosene tank and the oxidizer line goes through its center.
What does the F9 do, does it have a toroidal tank as well?

See here on Atlas



« Last Edit: 02/19/2014 03:52 pm by fatjohn1408 »

Offline Ben the Space Brit

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #348 on: 02/19/2014 03:55 pm »
@fatjohn148

The fuel lines don't have to be on the exterior of the vehicle. They can run through the interior if the fuel tanks are designed appropriately.
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Offline sublimemarsupial

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #349 on: 02/19/2014 04:01 pm »
F9 (both v1.0 and v1.1) has an interior LOX standpipe which runs from the center of the common dome down through the fuel dome and to the engine bay. You can just see it in red in the attached image (from v1.0).

Offline fatjohn1408

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #350 on: 02/19/2014 04:30 pm »
F9 (both v1.0 and v1.1) has an interior LOX standpipe which runs from the center of the common dome down through the fuel dome and to the engine bay. You can just see it in red in the attached image (from v1.0).

Ah so it is surrounded by the kerosene then. Neat, does it help structurally as well?
Would you know why Zenit uses a toroidal tank then?

Offline cambrianera

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #351 on: 02/19/2014 05:03 pm »
Ah so it is surrounded by the kerosene then. Neat, does it help structurally as well?

I don't believe.
It's difficult to foresee a structural member that shrinks due to the temperature of LOX flowing inside.
More likely some kind of dilatation joints supports the pipe only radially without loading it axially.

Would you know why Zenit uses a toroidal tank then?
Can't help, I leave this to others.

I add other pics of the internal LOX pipe (last one is the "octopus manifold" of F9 v1.0)
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Offline Lars_J

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #352 on: 02/19/2014 05:15 pm »
I have a question:

I haven't seen any fuel lines on the outside of the vehicle to direct the propellant in the upper tank of the stage to the engine. The ariane V does this via a fuel line on the outside, the Atlas V as well, the Zenit has a toroidal kerosene tank and the oxidizer line goes through its center.
What does the F9 do, does it have a toroidal tank as well?


F9 (both v1.0 and v1.1) has an interior LOX standpipe which runs from the center of the common dome down through the fuel dome and to the engine bay. You can just see it in red in the attached image (from v1.0).

Yep, the LOX pipe is indeed internal.

I think this is another example of how SpaceX designed the F9 (and the v1.1 even more so) with reusability in mind, since a clean exterior profile would be important for surviving re-entry.

Offline R7

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #353 on: 02/19/2014 05:19 pm »
why Zenit uses a toroidal tank then?

Zenit uses similar center standpipe in first stage. Toroidal tanks are used in second and third stage to make them shorter because you can pack large part of the engine in the center.
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Offline oiorionsbelt

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #354 on: 02/20/2014 01:13 am »

I think this is another example of how SpaceX designed the F9 (and the v1.1 even more so) with reusability in mind, since a clean exterior profile would be important for surviving re-entry.
and horizontal processing.

Offline Lars_J

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #355 on: 02/20/2014 01:25 am »

I think this is another example of how SpaceX designed the F9 (and the v1.1 even more so) with reusability in mind, since a clean exterior profile would be important for surviving re-entry.
and horizontal processing.

Lots of rockets use horizontal processing even when they have external LOX pipes and other protuberances. (see Angara pic below)

Also, the Atlas V is assembled horizontally, using a "BBQ roller" despite not being a clean cylinder. (pic #2)

Offline MP99

Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #356 on: 02/20/2014 09:58 am »
With 17.5% more thrust (if Elon Musks 85% is believable), I am wondering if they could simply fly a sort of 8 engine configuration (a sort of hepta- web with one in the middle). That would probably save quite a bit of weight on the stage. The problem is of course that you loose symmetry (you wont have 3 engines in a line), which could be a problem for first stage recovery. But reducing the number of engines and thus shedding off weight seems like a good way to increase the amount of payload they can deliver to orbit. A 17.5% increase in thrust is unfortunately just a little short of allowing a 7 engine configuration (about 8% less thrust than the current 9 engine configuration), which would have definitely shed a lot of weight of the first stage and would also have the 3 engines in a line.

Elon mentioned 165klb vs 147klb - more like 12% than the 17% implied.

Hepta would be a big engineering change.

Though I don't think it's likely:- losing the centre engine on an expendable flight, and running the remaining engines at 112% should give a very similar flight profile.

But, since they likely want to transition to flying reused stages expendably at the end of their life, this seems unlikely. Also, presumably way more analysis required of a new config than is justified by any slight benefits.

Cheers, Martin

Offline Elmar Moelzer

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #357 on: 02/20/2014 01:58 pm »
Elon mentioned 165klb vs 147klb - more like 12% than the 17% implied.


He said:
Quote from: Elon Musk
and we're only actually operating the engines at about 85% of their potential

Offline CuddlyRocket

Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #358 on: 02/23/2014 06:52 am »
Jeff Foust ‏@jeff_foust  · Feb 21 
Reisman: hope to have F9 1st stage do a powered landing with a year. 2nd stage reuse much harder, still being studied. #spaceuphou

Jeff Foust ‏@jeff_foust  · Feb 21 
Reisman: 39A at KSC will be for crewed missions & Falcon Heavy; 40 for other government missions; comm'l launches from new site. #spaceuphou

Jeff Foust ‏@jeff_foust  · Feb 21 
Reisman: SpaceX plans to eventually launch 20 rockets a year, 10 Falcon 9 and 10 Falcon Heavy. #spaceuphou


Offline AncientU

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Re: General Falcon and Dragon Discussion (Thread 10)
« Reply #359 on: 02/23/2014 12:55 pm »
Jeff Foust ‏@jeff_foust  · Feb 21 
Reisman: hope to have F9 1st stage do a powered landing with a year. 2nd stage reuse much harder, still being studied. #spaceuphou

Jeff Foust ‏@jeff_foust  · Feb 21 
Reisman: 39A at KSC will be for crewed missions & Falcon Heavy; 40 for other government missions; comm'l launches from new site. #spaceuphou

Jeff Foust ‏@jeff_foust  · Feb 21 
Reisman: SpaceX plans to eventually launch 20 rockets a year, 10 Falcon 9 and 10 Falcon Heavy. #spaceuphou

Nice... thanks CR.
One year seems reasonable, maybe a bit on conservative side to lower expectations.

Commercial launches from 'new site' should make some Texans happy!
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