Author Topic: Commercial Crew (CCtCAP) - Discussion Thread  (Read 331073 times)

Online speedevil

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1180 on: 05/10/2018 08:23 PM »
We can load the prop then load the astronauts.
Six months later after a sign of relief from NASA, then
Quote
You meant you want to load the dragon 2 with astronauts propulsively on the rocket!?

Offline envy887

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1181 on: 05/10/2018 08:24 PM »
Tweets from Brendan Byrne:
Quote
Musk on 'Load and Go" - The issue has been overblow. We can load the prop then load the astronauts.

Musk: Load and go is not a safety issue for astronauts. Can do before astros load. But this is an overblown issue. #SpaceX #Falcon9 #Block5

Nothing like a good old NSF forum "tempest in a teapot" based on incomplete information...

It was a lot more than that; the issue got a lot of mainstream media coverage.

But that negates the question of whether SpaceX would back out of CC if NASA insisted on fueling first.

Online DigitalMan

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1182 on: 05/10/2018 08:30 PM »
Isn't that the answer right there?  SpaceX is not going to back out they can do it the NASA way.  If NASA signs off on the SpaceX method however, great.

Offline jak Kennedy

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1183 on: 05/11/2018 07:30 AM »
Elon Musk: “Yeah, yeah, absolutely, yeah. I think that issue's been somewhat overblown. We certainly could load the propellant and then have the astronauts board Dragon. That's certainly something we could do.”

So not to start another tempest, someone could perhaps ask Elon if the propellants have to be sub cooled? Or just extra chilly is enough.

Offline woods170

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1184 on: 05/11/2018 07:56 AM »
Elon Musk: “Yeah, yeah, absolutely, yeah. I think that issue's been somewhat overblown. We certainly could load the propellant and then have the astronauts board Dragon. That's certainly something we could do.”

So not to start another tempest, someone could perhaps ask Elon if the propellants have to be sub cooled? Or just extra chilly is enough.

Sub-cooling is tied-in hard to the propellant loading GSE. By the time the crew has finally been loaded, and the rocket is ready to go, most, if not all, of the density advantage is gone. Which is probably fine for CCP missions given that the payload is only going to LEO. Propellant sub-cooling, followed by immediate launch, is primarily beneficial for heavy lift to GTO/GEO.

Reading between the lines of Elon's comment it is clear that 'Load-n-go' is still his preferred way of launching CCP missions. Note his use of the words "could" in stead of "will".

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1185 on: 05/11/2018 04:45 PM »
Elon Musk: “Yeah, yeah, absolutely, yeah. I think that issue's been somewhat overblown. We certainly could load the propellant and then have the astronauts board Dragon. That's certainly something we could do.”

So not to start another tempest, someone could perhaps ask Elon if the propellants have to be sub cooled? Or just extra chilly is enough.

Sub-cooling is tied-in hard to the propellant loading GSE. By the time the crew has finally been loaded, and the rocket is ready to go, most, if not all, of the density advantage is gone. Which is probably fine for CCP missions given that the payload is only going to LEO. Propellant sub-cooling, followed by immediate launch, is primarily beneficial for heavy lift to GTO/GEO.

Reading between the lines of Elon's comment it is clear that 'Load-n-go' is still his preferred way of launching CCP missions. Note his use of the words "could" in stead of "will".
I have a dumb question. As the LOX warms it'll vent, no big deal.  As the RP-1 warms and expands do they use the feed line to "vent" (like when draining after an abort), or is there a separate umbilical to capture overflow? I assume they don't run it down the side of the rocket. :)
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Offline Comga

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1186 on: 05/11/2018 05:43 PM »
Tweets from Brendan Byrne:
Quote
Musk on 'Load and Go" - The issue has been overblow. We can load the prop then load the astronauts.

Musk: Load and go is not a safety issue for astronauts. Can do before astros load. But this is an overblown issue. #SpaceX #Falcon9 #Block5

Here's the whole transcript of that question and answer
Quote
Stephen Clark, Spaceflight Now: Hi Elon. Thanks for chatting with us before the launch. We know astronauts will one day be launching on the Block 5, and I understand NASA is still studying whether they're going to be comfortable with the Load and Go fueling process. And I know you and SpaceX have a different view of the risk in that operation. So do you think you can convince NASA of the safety of the Load and Go fueling process? And would you be willing to change or adjust that procedure for Commercial Crew if NASA requests it. Thanks.

Elon Musk: Yeah, yeah, absolutely, yeah. I think that issue's been somewhat overblown. We certainly could load the propellant and then have the astronauts board Dragon. That's certainly something we could do. But I don't think it's going to be necessary, anymore than passengers on an aircraft need to wait until the aircraft is fully fueled before boarding. I mean, that would be a crazy delay if everyone off of the aircraft and until it gets fueled, now you can't board. But no, it's normal to load propellant, to load fuel on an aircraft while boarding, or have the fuel fully loaded before boarding. It's not a fundamental risk. You know, we need to make sure about things like the COPVs. I'd say like, the only material risk I'm aware of is the COPV, and the amount of testing and research that's gone into COPV safety is gigantic. This is by far the most advanced pressure vessel ever developed by humanity. It's nuts. And I've personally gone over the test design, I've lost count how many times. But the top engineering minds at SpaceX have agonized over this. We've tested the living daylights out of it. We've been in deep, deep discussions with NASA about this. And I think we're in a good situation. We do have a contingency plan for the COPV, which I'd say would really be the only thing that represents a risk of any materiality. Which would be a switch from high-strength carbon fiber with aluminum liner to a, sort of like, an Inconel sphere. We have a contingency plan for that, if need be. But I think that is unlikely to be necessary. But that's really the only thing that I'd consider to be the most [legitimate?] of the risks. But yeah, this is really not something that should be needed. I mean, we obviously have competitors that are willing to make hay out of it, but I really do not see this as a risk representing any materiality. And worst case scenario, we've already demonstrated that Dragon is fully capable of a safe abort from zero velocity, zero altitude, and escaping whatever fireball that may occur on the pad, even in a worst case situation. So I really do not think this represents a safety issue for astronauts. But if, for any reason, NASA felt different, we can adjust our operational procedures to load propellant before the astronauts board. But I really think this is an overblown issue.

So potentially a "COPV 3.0" or "feul before crew" options.
It didn't seem that the COPVs were really the issue for "crew before load".
Rather it was Jim's points of stable vs dynamic conditions in general.
Musk's being so sanguine is fascinating.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline cppetrie

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1187 on: 05/14/2018 11:13 PM »
Tweets from Brendan Byrne:
Quote
Musk on 'Load and Go" - The issue has been overblow. We can load the prop then load the astronauts.

Musk: Load and go is not a safety issue for astronauts. Can do before astros load. But this is an overblown issue. #SpaceX #Falcon9 #Block5

Here's the whole transcript of that question and answer
Quote
Stephen Clark, Spaceflight Now: Hi Elon. Thanks for chatting with us before the launch. We know astronauts will one day be launching on the Block 5, and I understand NASA is still studying whether they're going to be comfortable with the Load and Go fueling process. And I know you and SpaceX have a different view of the risk in that operation. So do you think you can convince NASA of the safety of the Load and Go fueling process? And would you be willing to change or adjust that procedure for Commercial Crew if NASA requests it. Thanks.

Elon Musk: Yeah, yeah, absolutely, yeah. I think that issue's been somewhat overblown. We certainly could load the propellant and then have the astronauts board Dragon. That's certainly something we could do. But I don't think it's going to be necessary, anymore than passengers on an aircraft need to wait until the aircraft is fully fueled before boarding. I mean, that would be a crazy delay if everyone off of the aircraft and until it gets fueled, now you can't board. But no, it's normal to load propellant, to load fuel on an aircraft while boarding, or have the fuel fully loaded before boarding. It's not a fundamental risk. You know, we need to make sure about things like the COPVs. I'd say like, the only material risk I'm aware of is the COPV, and the amount of testing and research that's gone into COPV safety is gigantic. This is by far the most advanced pressure vessel ever developed by humanity. It's nuts. And I've personally gone over the test design, I've lost count how many times. But the top engineering minds at SpaceX have agonized over this. We've tested the living daylights out of it. We've been in deep, deep discussions with NASA about this. And I think we're in a good situation. We do have a contingency plan for the COPV, which I'd say would really be the only thing that represents a risk of any materiality. Which would be a switch from high-strength carbon fiber with aluminum liner to a, sort of like, an Inconel sphere. We have a contingency plan for that, if need be. But I think that is unlikely to be necessary. But that's really the only thing that I'd consider to be the most [legitimate?] of the risks. But yeah, this is really not something that should be needed. I mean, we obviously have competitors that are willing to make hay out of it, but I really do not see this as a risk representing any materiality. And worst case scenario, we've already demonstrated that Dragon is fully capable of a safe abort from zero velocity, zero altitude, and escaping whatever fireball that may occur on the pad, even in a worst case situation. So I really do not think this represents a safety issue for astronauts. But if, for any reason, NASA felt different, we can adjust our operational procedures to load propellant before the astronauts board. But I really think this is an overblown issue.

So potentially a "COPV 3.0" or "feul before crew" options.
It didn't seem that the COPVs were really the issue for "crew before load".
Rather it was Jim's points of stable vs dynamic conditions in general.
Musk's being so sanguine is fascinating.
If it’s an Inconel PV it isn’t really a COPV because it lacks the CO. So more just PV 3.0.  Unless I totally misunderstood what he was suggesting with the Inconel comment.

Online JBF

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1188 on: 05/15/2018 10:54 AM »

If it’s an Inconel PV it isn’t really a COPV because it lacks the CO. So more just PV 3.0.  Unless I totally misunderstood what he was suggesting with the Inconel comment.
Without any knowledge of what they did, I could see using a thin Inconel shell in place of the Aluminum one.
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Offline soltasto

Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1189 on: 05/15/2018 12:55 PM »

If it’s an Inconel PV it isn’t really a COPV because it lacks the CO. So more just PV 3.0.  Unless I totally misunderstood what he was suggesting with the Inconel comment.
Without any knowledge of what they did, I could see using a thin Inconel shell in place of the Aluminum one.

Which would help since Inconel has a lower Coefficient of Linear Thermal Expansion than aluminium. This would put less stress on the carbon part of the COPV.

Online gongora

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1190 on: 05/15/2018 01:58 PM »
The Inconel pressure vessels are not COPVs

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1191 on: 05/17/2018 03:22 PM »
Listening to ASAP meeting, some discussion of CC program. 

The panel reviewed reports from NASA NESC on SpaceX's SE&I practices and on the potential risks of fueling the vehicle with crew on board.  They also met with NASA NESC this week.  NESC apparently has a very low opinion of the SE&I practices at SpaceX after doing a 16 month study.  The ASAP panel was pretty clear that they think resolving this issue is very important for the CC program.  Several members did speak about the need to allow SpaceX and other commercial partners to develop and use their own tools/processes to get the job done instead of just adopting NASA's practices, they just didn't seem convinced SpaceX is quite there yet.

Some ASAP members toured LC-39A, focusing on F9 launch ops.

There is still some concern about the COPVs on F9 but progress is being made in studying those issues, both SpaceX and NASA very focused on it.  The testing allows them to determine boundary conditions and set margins for the COPV usage.  Still some work to do there.

The discussion about Load and Go (fueling F9 with crew on board) was fairly neutral this time, a couple members who commented on the topic said it might be acceptable as long as controls are in place to address the potential hazards that have been identified.  They seemed more concerned about COPVs than Load and Go at this point.

Some discussion of the activities to potentially add a third member and lengthen the first Boeing test flight, panel seems to think it's a good idea as a contingency plan if the CC program schedule slips more.

They expect the schedule to slip from the current offical dates (which have crewed flights this year), said having both uncrewed demos in 2018 would probably be a good year for CC program.

Offline ngilmore

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1192 on: 05/17/2018 10:34 PM »
The Los Angeles Times' take on the ASAP meeting (paywall after article limit reached per month I think):

Quote
Several members of the Aerospace Safety Advisory Panel said that as long as potential hazards can be controlled, loading crew before fueling is finished could be acceptable.

"My sense is that, assuming there are adequate, verifiable controls identified and implemented for the credible hazard causes, and those which could potentially result in an emergency situation … it appears load-and-go is a viable option for the program to consider," panel member Capt. Brent Jett Jr. (Ret.) said during Thursday's meeting.
...
The Aerospace Safety Advisory Panel said the NASA Commercial Crew program is expected to make a decision soon on the appropriate sequence for loading crew and fuel into SpaceX's Falcon 9 rocket.

http://www.latimes.com/business/la-fi-spacex-load-and-go-20180517-story.html


Offline Brovane

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1193 on: 05/18/2018 03:10 AM »
Why do I have the feeling that Musk has just called NASA's bluff about the fueling procedure. 

By retaining the ability to fly the F9 without super-cooled propellant SpaceX has given NASA the choice.

#1- Either fly with the normal process of astronauts load and then the F9 is fueled.

#2- Or fly with the process of not using super-cooled propellant and the astronauts load after the rocket is fueled.

NASA's knows that option #2 isn't a good choice because they would be using a different fueling procedure than the rest of SpaceX's launches.  This introduces a whole new set of possibilities for things to go wrong because SpaceX would be dramatically changing a critical launch process for just 1-2 launches a year.  Despite all the noise made by certain groups about the fueling process, NASA knows the safest process is #1. 

It also looks like SpaceX really made a effort to prove to NASA that the design changes in block-5 for the COPV will prevent a repeat of AMOS-6.  SpaceX was also smart by not backing itself into the corner about using super-cooled propellant by retaining the option to not use super-cooled propellant.  Despite all the postings on this thread that SpaceX had backed itself into a corner about using super-cooled propellant.  This flexibility in fueling procedure was required to allow SpaceX to call NASA's bluff on the subject. 
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Offline Ike17055

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1194 on: 05/20/2018 04:01 PM »
No. Those are the options. Either NASA certifies (or waivers) "fuel-n-go" or Crew Dragon won't be certified at all.

We fuel airplanes with passengers aboard.

Guess we have to learn to do it with rockets, too.

Not at all a valid analogy.  Cryogens are not involved.

Jim, don’t bother them with facts. They will believe what they want to believe, and play word games just to say “i won.” I stopped responding to the ridiculous posts. They can’t argue for greater reliance on LAS as the solution to “fuel and go” potential risks, and then say nothing is different from how launches have always been conducted...but that is pretty much what has happened here.

Offline envy887

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Re: Commercial Crew (CCtCAP) - Discussion Thread
« Reply #1195 on: 05/20/2018 05:17 PM »
They can’t argue for greater reliance on LAS as the solution to “fuel and go” potential risks,
And you can't say the LAS is irrelevant to the probability of LOC calculation.

"The solution" to the risk is a thorough qualification and test flight program. That has to establish a LOM risk at a low and acceptable level, since a fueling anomaly would be LOM.

The LAS them further reduces the probability of LOC below the probability of LOM.

Quote
and then say nothing is different from how launches have always been conducted...but that is pretty much what has happened here.

What? Who said "nothing is different" with load and go?

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