Author Topic: General Falcon and Dragon discussion (Thread 12)  (Read 350211 times)

Offline deruch

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #80 on: 03/04/2015 04:17 am »
<snip quote>
Target orbit:  407.59 x 63928 @ 24.83 degrees  -> Delta V to GEO = 1592.5 m/s
Achieved:      432       x 63401 @ 24.71 degrees  -> Delta V to GEO = 1591.7 m/s  (0.8 m/s better than target)
Achieved       400       x 63293 @ 24.86 degrees  -> Delta V to GEO = 1595.5 m/s  (probably the second stage)
Achieved       406       x 63066 @ 24.84 degrees  -> Delta V to GEO = 1595.8 m/s  (3.3 m/s worse than target)

I don't know what the spec on injection error was, but these seem like very typical numbers.  I can't imagine 3.3 m/s is more than 3 sigma out.

Lou posted this in the ABS/Eutelsat discussion thread.  Ignoring the accuracy issue, I was surprised to see that the orbits were closer to the 1500m/s-to-GTO than the 1800m/s-to-GTO range. 
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline su27k

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #81 on: 03/04/2015 04:32 am »
Is there a thread with a discussion about the key people at SpaceX, specifically about the designers and decision makers?  Who, for example, made the decisions to drop the original Merlin 1 in favor of Merlin 1C, then to go to 1D?  Who invented Octoweb?  Who created the landing legs and grid fins and, especially, the flight software to make recovery attempts?  Who decided that a hypersonic reentry burn might work?  Who decided that Falcon Heavy was the way to go, rather than, say, adding a high energy upper stage atop Falcon 9?  Who are the key designers, of hardware and of industrial processes?  Who runs the show at McGregor and at the launch pads?  Ect.

 - Ed Kyle

Sounds like this is a job for an author with inside access to SpaceX...a la Tracy Kidder's "Soul of a New Machine." But maybe already too late for that, unfortunately, unless someone is already on the case...

The COTS part is documented at http://www.jsc.nasa.gov/history/oral_histories/c3po.htm

Offline macpacheco

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #82 on: 03/04/2015 05:39 am »
<snip quote>
Target orbit:  407.59 x 63928 @ 24.83 degrees  -> Delta V to GEO = 1592.5 m/s
Achieved:      432       x 63401 @ 24.71 degrees  -> Delta V to GEO = 1591.7 m/s  (0.8 m/s better than target)
Achieved       400       x 63293 @ 24.86 degrees  -> Delta V to GEO = 1595.5 m/s  (probably the second stage)
Achieved       406       x 63066 @ 24.84 degrees  -> Delta V to GEO = 1595.8 m/s  (3.3 m/s worse than target)

I don't know what the spec on injection error was, but these seem like very typical numbers.  I can't imagine 3.3 m/s is more than 3 sigma out.

Lou posted this in the ABS/Eutelsat discussion thread.  Ignoring the accuracy issue, I was surprised to see that the orbits were closer to the 1500m/s-to-GTO than the 1800m/s-to-GTO range.
What was the closest DeltaV to GEO any launch has achieved ?
How close could a FHR get a 6 ton payload to GEO, with RTLS+center booster barge landing ?
I predict FHR will get large payloads so close to GEO there will be little incentive not to go electric, like 1-2 months transit time.
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Offline Nomadd

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #83 on: 03/04/2015 01:06 pm »
Please go and look in the archive, this particular issue has been discussed to death! But in a nutshell, there are issues with cooling and seats, plus air supply/ scrubbing, and the Caro Dragon can't undock itself...
Cheers,
Chris
That's a pretty bad nutshell. The issues are mostly minor for a fast track re-entry as long as it's not a major ISS systems failure requiring a total evacuation. One person isn't going to overheat the interior in a few hours and an SCBA could take care of air for that long. You're not talking about a regular thing. Lots of people in those discussions didn't seem to grasp the meaning of the term "emergency".  The Apollo 13 capsule would still be out there if some folks had been in charge of coming up with a solution.
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Offline JamesH

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #84 on: 03/04/2015 02:40 pm »
Please go and look in the archive, this particular issue has been discussed to death! But in a nutshell, there are issues with cooling and seats, plus air supply/ scrubbing, and the Caro Dragon can't undock itself...
Cheers,
Chris
That's a pretty bad nutshell. The issues are mostly minor for a fast track re-entry as long as it's not a major ISS systems failure requiring a total evacuation. One person isn't going to overheat the interior in a few hours and an SCBA could take care of air for that long. You're not talking about a regular thing. Lots of people in those discussions didn't seem to grasp the meaning of the term "emergency".  The Apollo 13 capsule would still be out there if some folks had been in charge of coming up with a solution.

Indeed. If you are stuck on a disintegrating ISS and the options are a cargo Dragon or certain death, I think I know which I would go for.

Offline Ben the Space Brit

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #85 on: 03/04/2015 03:13 pm »
The one issue no-one seems to have addressed (or, instead, just hand-waved away as irrelevant) is how a Cargo Dragon could detach from the ISS if, assuming a serious emergency, the berthing bolt motors and the Candarm-2 were both depowered.

NOTE: Invoking 'explosive bolts' would require a large scale redesign of the Dragon's berthing mechanism and the hull around it.
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Online Mongo62

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #86 on: 03/04/2015 03:39 pm »
The one issue no-one seems to have addressed (or, instead, just hand-waved away as irrelevant) is how a Cargo Dragon could detach from the ISS if, assuming a serious emergency, the berthing bolt motors and the Candarm-2 were both depowered.

NOTE: Invoking 'explosive bolts' would require a large scale redesign of the Dragon's berthing mechanism and the hull around it.

In that specific situation, I would think that they would be up the creek.

But if there still was internal power to the relevant bits of the ISS, could not the berthing mechanism and Canadarm be operated remotely from the ground, perhaps with a jury-rigged setup?

Offline Nomadd

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #87 on: 03/04/2015 04:19 pm »
The one issue no-one seems to have addressed (or, instead, just hand-waved away as irrelevant) is how a Cargo Dragon could detach from the ISS if, assuming a serious emergency, the berthing bolt motors and the Candarm-2 were both depowered.

NOTE: Invoking 'explosive bolts' would require a large scale redesign of the Dragon's berthing mechanism and the hull around it.
If they were serious about this, a battery powered inverter to back up the berthing bolt motors wouldn't be too hard. I'm not sure what other latches you'd have to manually disengage to release the ship. Would the Candarm really be needed for unberthing if you were willing to forgo procedure and use thrusters to back out?
 The main reason I could see for doing this is if a Soyuz became unaccessible or unusable for some reason during a total evacuation.
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Offline nlec

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #88 on: 03/04/2015 04:20 pm »
The one issue no-one seems to have addressed (or, instead, just hand-waved away as irrelevant) is how a Cargo Dragon could detach from the ISS if, assuming a serious emergency, the berthing bolt motors and the Candarm-2 were both depowered.

NOTE: Invoking 'explosive bolts' would require a large scale redesign of the Dragon's berthing mechanism and the hull around it.

In that specific situation, I would think that they would be up the creek.

But if there still was internal power to the relevant bits of the ISS, could not the berthing mechanism and Canadarm be operated remotely from the ground, perhaps with a jury-rigged setup?

Robonaut?

Offline BobHk

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #89 on: 03/04/2015 04:54 pm »
The one issue no-one seems to have addressed (or, instead, just hand-waved away as irrelevant) is how a Cargo Dragon could detach from the ISS if, assuming a serious emergency, the berthing bolt motors and the Candarm-2 were both depowered.

NOTE: Invoking 'explosive bolts' would require a large scale redesign of the Dragon's berthing mechanism and the hull around it.

How many pressure/space suits do they have on ISS? 

Offline Kansan52

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #90 on: 03/04/2015 05:09 pm »
Don't know about the bolts but the Candarm can be operated from Mission Control, if the comms, power, ect is available.

Online GalacticIntruder

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #91 on: 03/04/2015 11:07 pm »
Musk will talk at the GPU conference March 17, with CEO of Nvidia.
I have no idea what he will talk about. I assume it is about Nvidia hardware, which SpaceX and Tesla use, and maybe the new Tegra K1.

http://www.gputechconf.com/
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Online gongora

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #92 on: 03/05/2015 03:58 pm »
Thought this was interesting in regards to AF visibility for the SpaceX launches:
Florida Today article on new AF launch support center http://www.floridatoday.com/story/tech/science/space/spacex/2015/03/04/th-space-wing-unveils-new-launch-support-center/24380797/

Offline CJ

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #93 on: 03/05/2015 10:02 pm »
Second stage reuse (sorry, couldn't find a specific thread for it, and it sort of fits here)

SpaceX nixed making the second stage reusable for cost-benefit reasons, but would their calculation change if somebody offered them, say, a billion dollar prize to make it work?  I'm not going wildly hypothetical here, BTW, because such a prize is part of some legislation currently before congress, the CATS act. what follows is a quote from the linked article; (Edit: I was wrong, it's not before congress yet, as it hasn't been sponsored or introduced.) 

Quote
Specifically, the bill offers $1 billion to the first fully reusable launch vehicle, capable of placing a payload of one metric ton (including two people) into orbit, which flies two missions in one week. A second $1-billion prize would go to the first RLV, with the same payload requirement, that flies ten times in ten weeks. Both milestones would also have $750-million second prizes.

http://www.thespacereview.com/article/2705/1

If that bill passes and the prize becomes official, I have two questions; #1 could they go for it, and #2, would they go for it?
My SWAG is that it's feasible if they can make the second stage reusable, AND do RTLS for both stages. That one-week turnaround is a very tight window.   

« Last Edit: 03/05/2015 11:26 pm by CJ »

Online gongora

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #94 on: 03/05/2015 10:46 pm »
Second stage reuse (sorry, couldn't find a specific thread for it, and it sort of fits here)

SpaceX nixed making the second stage reusable for cost-benefit reasons, but would their calculation change if somebody offered them, say, a billion dollar prize to make it work?  I'm not going wildly hypothetical here, BTW, because such a prize is part of some legislation currently before congress, the CATS act. what follows is a quote from the linked article;

Quote
Specifically, the bill offers $1 billion to the first fully reusable launch vehicle, capable of placing a payload of one metric ton (including two people) into orbit, which flies two missions in one week. A second $1-billion prize would go to the first RLV, with the same payload requirement, that flies ten times in ten weeks. Both milestones would also have $750-million second prizes.

http://www.thespacereview.com/article/2705/1

If that bill passes and the prize becomes official, I have two questions; #1 could they go for it, and #2, would they go for it?
My SWAG is that it's feasible if they can make the second stage reusable, AND do RTLS for both stages. That one-week turnaround is a very tight window.   

The article specifically says that the bill has NOT been introduced to Congress yet and doesn't have a sponsor.  If a bill like that ever did pass then for $1B of course they'd go for it.

Offline CJ

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #95 on: 03/05/2015 11:27 pm »
Second stage reuse (sorry, couldn't find a specific thread for it, and it sort of fits here)

SpaceX nixed making the second stage reusable for cost-benefit reasons, but would their calculation change if somebody offered them, say, a billion dollar prize to make it work?  I'm not going wildly hypothetical here, BTW, because such a prize is part of some legislation currently before congress, the CATS act. what follows is a quote from the linked article;

Quote
Specifically, the bill offers $1 billion to the first fully reusable launch vehicle, capable of placing a payload of one metric ton (including two people) into orbit, which flies two missions in one week. A second $1-billion prize would go to the first RLV, with the same payload requirement, that flies ten times in ten weeks. Both milestones would also have $750-million second prizes.

http://www.thespacereview.com/article/2705/1

If that bill passes and the prize becomes official, I have two questions; #1 could they go for it, and #2, would they go for it?
My SWAG is that it's feasible if they can make the second stage reusable, AND do RTLS for both stages. That one-week turnaround is a very tight window.   

The article specifically says that the bill has NOT been introduced to Congress yet and doesn't have a sponsor.  If a bill like that ever did pass then for $1B of course they'd go for it.

Mea culpa; my reading comprehension sucks today. I'll fix my post, thanks.

My guess, if they decided (for the prize, or any other reason) to make the 2nd stage reusable, is they'd deal with the stability-during-reentry issue by spinning the stage. I really don't see any other option, given its far-aft CG and the fact they'd need to put the TPS on the nose (or would they? An active RCS system to give stability during reentry would mass too much. Could the Nobium engine bell withstand reentry if they covered the rest of the stage base with TPS?) They'd have to land nose-first anyway, due to the size of that engine bell, plus the fact the Merlin would be worse than useless for landing.

My guess; TPS on the nose, extended slightly to form a protruding flange to protect the sides from direct plasma flow (the sides would need SPAM). A pair of Dracos for spin-up, and a single SuperDraco in the nose for landing. The landing legs would be Dragon 2 style, in the nose TPS. A pair of grid fins (smaller than the stage 1 ones) would be deploy from the stage base, and be used for control plus post-entry de-spin.   

The added mass to the second stage would mainly be the TPS, the tiny landing legs, 2 small grid fins, 1 super draco and 2 dracos, some structural changes to create the needed strong points, and the hydrazine tankage.
« Last Edit: 03/05/2015 11:28 pm by CJ »

Online Mongo62

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #96 on: 03/06/2015 12:33 am »
Quote
Specifically, the bill offers $1 billion to the first fully reusable launch vehicle, capable of placing a payload of one metric ton (including two people) into orbit, which flies two missions in one week. A second $1-billion prize would go to the first RLV, with the same payload requirement, that flies ten times in ten weeks. Both milestones would also have $750-million second prizes.

Could a Falcon Heavy be able to do this in the near future with modifications to the upper stage? A D2 with one tonne of payload and two human occupants might mass around six tonnes (just guessing here, I assume that it's close to the Cargo Dragon mass), so assuming the full 45 tonne performance to LEO, there might be around 39 tonnes for extra mass in the second stage, including propellant (both kerolox and hypergolic), tankage for the hypergolic propellant, and the SuperDracos to land it propulsively.

I know that the actual mass would be different, because the 'extra' mass would be contained in the US instead of being a separate payload on top of the US, but I don't know how to calculate the actual number.

Could a Falcon upper stage with that mass dedicated to landing perform a propulsive deceleration to a velocity that allows a first-stage style propulsive landing, with no more atmospheric heating than the first stage gets?

If a fully reusable FH in this configuration can indeed put a (partly loaded) D2 into LEO, would a full F9-sized payload to LEO also be achievable with a fully reusable FH? Would it be cheaper to place this size of payload into LEO using a partly reusable F9 with expended US, or the same sized payload into LEO with a fully reusable FH with returning US? (Obviously, if there's several billion dollars in prize money available, the profitability of the payload by itself would not matter, this is about regular non-contest payloads.)
« Last Edit: 03/06/2015 12:53 am by Mongo62 »

Offline Robotbeat

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #97 on: 03/06/2015 01:42 am »
http://www.wsj.com/articles/BL-DGB-40041

Quote
SpaceXís Valuation Rockets to $12 Billion With Google Investment

SpaceX now ranks fourth on The Wall Street Journalís list of billion-dollar private companies, securing a $12 billion valuation.
>

I'm not sure I would have taken up that deal if I were google.
12 billion is a hell of a lot. If they launch 10 times and launch a couple of dragons as well, they have a yearly revenue of a billion. This is already stretching their revenue expectations for this year. So their valuation is 12 times their revenue? How many companies outside of websites have such a valuation?
Airbus group (note they make a couple of planes, fighterjets, helicopters and missiles as well) has a valuation of only 50B.

SpaceX just got handed a shitload of money. Which of course is great, rather see Google wasting it on SpaceX than giving it to people that try to make an algorithm to present me the best personalized add on my screen.
Because the Constellation could make $12 billion profit in a single year, easy, if (IF! If, if, if!) it is deployed successfully to the scale Musk has talked about and SpaceX remains solvent long enough for them to build up the subscriber base (which seems likely as SpaceX is fairly diversified--well, more than Iridium was--and seems likely to dominate the commercial launch industry as well as being well-capitalized and starting up in an era of low interest rates).
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Offline Mariusuiram

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #98 on: 03/06/2015 05:25 am »
http://www.wsj.com/articles/BL-DGB-40041

Quote
SpaceXís Valuation Rockets to $12 Billion With Google Investment

SpaceX now ranks fourth on The Wall Street Journalís list of billion-dollar private companies, securing a $12 billion valuation.
>

I'm not sure I would have taken up that deal if I were google.
12 billion is a hell of a lot. If they launch 10 times and launch a couple of dragons as well, they have a yearly revenue of a billion. This is already stretching their revenue expectations for this year. So their valuation is 12 times their revenue? How many companies outside of websites have such a valuation?
Airbus group (note they make a couple of planes, fighterjets, helicopters and missiles as well) has a valuation of only 50B.

SpaceX just got handed a shitload of money. Which of course is great, rather see Google wasting it on SpaceX than giving it to people that try to make an algorithm to present me the best personalized add on my screen.
Because the Constellation could make $12 billion profit in a single year, easy, if (IF! If, if, if!) it is deployed successfully to the scale Musk has talked about and SpaceX remains solvent long enough for them to build up the subscriber base (which seems likely as SpaceX is fairly diversified--well, more than Iridium was--and seems likely to dominate the commercial launch industry as well as being well-capitalized and starting up in an era of low interest rates).

$12 billion in profit in a single year is a pretty big if (at least 1 more if than you listed :) ). But you dont need that really.

We've done this before, but SpaceX is aiming for more than 10 launches per year. Even conservatively in 2015-2018, with 3-4 pads but no "revolutions", they should be doing 15-20 launches per year and 6-8 dragons between Crew & Cargo (and DragonLab????).

That's a lot closer to US$2 billion in revenue (20*$80 = 1.6 billion, 6*$70 = 420 million). Operational margins (before investing in R&D, etc) might be 20% giving them US$400 million a year. Now all of that is getting dumped back into new projects and expansions, but a 30x valuation isnt unreasonable for a company that is growing exponentially.

Offline cosmicvoid

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Re: General Falcon and Dragon discussion (Thread 12)
« Reply #99 on: 03/06/2015 06:29 am »
Because the Constellation could make $12 billion profit in a single year...

The Constellation??  What?? :o
Infiinity or bust.

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