Author Topic: F9 Block 5 Updates and Discussion  (Read 313195 times)

Online Lars-J

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Re: F9 Block 5 Updates and Discussion
« Reply #120 on: 03/10/2017 09:16 PM »
Have a look at the time line. 24 hours refurbishment time enables about one flight per week (because of the other, non-refurbishment activities). The 24 hours are the time it takes to stuff the stage back into the pipeline.
This would nicely reconcile the statement by Gwynne Shotwell and Jim.

Exactly. Why is this so hard to grasp? No need to go to conspiracy theories...

Offline cscott

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Re: F9 Block 5 Updates and Discussion
« Reply #121 on: 03/10/2017 11:38 PM »
When Gwynne says that Elon "gave them 24 hours" I interpret that as a design specification. During the design process every component would presumably be allocated some refurbishment time budget, and the sum of those (averaged across N flights? Or "in the typical case"? Or "in the best case"?) is 24 hours.  There would be a written plan on how to get each component to its target on that budget.  That doesn't mean that they'll actually take every step on that plan: some may not be cost effective or may conflict with the desire for a stable configuration or be preempted by future learning or a future rocket.  But at design time, that was the target time budget.

When they locked down the "block 5" configuration, they presumably had a version of this documentation in front of them, and were acceptably satisfied that the block 5 design (or "GSE interface") would let them take the necessary steps.
« Last Edit: 03/11/2017 01:43 AM by cscott »

Online launchwatcher

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Re: F9 Block 5 Updates and Discussion
« Reply #122 on: 03/11/2017 01:16 AM »
(averaged across N flights? Or "in the typical case"? Or "in the best case"?)
In a very different context I've seen percentiles used - like "95th percentile", "99th percentile", etc.

These compound in interesting ways that cause you to worry about long tail latency more than might be obvious.

Hypothetically, if, say, 9 engines in 10 can be serviced in an hour, but the 10th takes two days - 90th percentile time on an engine is 1 hour, 99th is 2 days - then almost every first stage is going to have one slow engine and will take at least two days to complete.

Offline cscott

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Re: F9 Block 5 Updates and Discussion
« Reply #123 on: 03/11/2017 01:43 AM »
Right. My point is that we don't know the exact "units" that go with that "24 hours" target, but presumably they do.

Offline meekGee

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Re: F9 Block 5 Updates and Discussion
« Reply #124 on: 03/11/2017 02:20 AM »
Have a look at the time line. 24 hours refurbishment time enables about one flight per week (because of the other, non-refurbishment activities). The 24 hours are the time it takes to stuff the stage back into the pipeline.
This would nicely reconcile the statement by Gwynne Shotwell and Jim.

Exactly. Why is this so hard to grasp? No need to go to conspiracy theories...

Why conspiracy theory?

There are three options, and at least by the people who posted so far, the majority thinks that F9B5 will be able to achieve (in time) "readiness to proceed" in 24 hours.

I'm good with that - I'm glad so many people think it's no big deal and almost self-evident.
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Offline Robotbeat

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Re: F9 Block 5 Updates and Discussion
« Reply #125 on: 03/11/2017 04:44 AM »
Remember this is Elon frakking Musk. He has this idea they're going to get Falcon 9 to do single day turnarounds and launches. But it probably won't end up happening, it's just something that Musk knows isn't literally against the laws of physics. Maybe they'll get it to work on some other vehicle.
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Offline Jim

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Re: F9 Block 5 Updates and Discussion
« Reply #126 on: 03/11/2017 12:56 PM »

There are three options, and at least by the people who posted so far, the majority thinks that F9B5 will be able to achieve (in time) "readiness to proceed" in 24 hours.

I'm good with that - I'm glad so many people think it's no big deal and almost self-evident.


No, the majority believes thats what Spacex's goal is.  Nowhere did anyone say they believed it.

It is far from self-evident and it is only belief based.  Much like a religion.  There is no evidence to support the claim.  It is further evidence of the cult of personality surrounding Spacex


Offline cscott

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Re: F9 Block 5 Updates and Discussion
« Reply #127 on: 03/11/2017 01:24 PM »
Can I take an intermediate position?  Like I said, I believe this was a design goal.  So they have on paper a plan which "isn't literally against the laws of physics" which would let them do 24hr refurbishment.  I think everyone (including SpaceX!) agrees this is somewhat aspirational. But it works on paper, nothing is literally impossible, only the usual factors of time, money, Murphy, and the distance between theory and practice will prevent them from reaching it... which means it's likely they never quite will. ;). And, returning to the original topic question, for those same reasons it's likely block 5 isn't quite enough to get them there.  But it's too early to tell whether their response will be to give in and make a "block 5 1/2" or settle for larger-than-24hr refurb or something else.  I'd argue it's too early for SpaceX to tell as well: they have to find out what's going to go wrong with their plan before they can figure out what to do about it.
« Last Edit: 03/11/2017 01:25 PM by cscott »

Offline Herb Schaltegger

Re: F9 Block 5 Updates and Discussion
« Reply #128 on: 03/11/2017 01:32 PM »

There are three options, and at least by the people who posted so far, the majority thinks that F9B5 will be able to achieve (in time) "readiness to proceed" in 24 hours.

I'm good with that - I'm glad so many people think it's no big deal and almost self-evident.


No, the majority believes thats what Spacex's goal is.  Nowhere did anyone say they believed it.

It is far from self-evident and it is only belief based.  Much like a religion.  There is no evidence to support the claim.  It is further evidence of the cult of personality surrounding Spacex



To further elaborate on Jim's comment, personally I believe those quotes are, in fact, what SpaceX people have said. But I do not believe they will ever achieve it in the simplistic fashion interpreted by the most optimistic, at least not with any version of F9. That is to say, "launch, landing, and ready to launch again" will not occur in a 24 hour period.

More realistically, I can believe SpaceX hopes they can get their pad flow to the point where they can surge and launch daily in support of CommX and/or ITS operations in 10 - 20 years, but I don't think that means any one vehicle launches on a 24 hour cadence.
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Offline M.E.T.

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Re: F9 Block 5 Updates and Discussion
« Reply #129 on: 03/11/2017 01:34 PM »
Elon aims for 24 hour refurbishment. That doesn't mean that the rocket is going to launch again after 24 hours. Just that it will require only 24 hours worth of resource time to get into a launchable state again.

And as for a launch per week being the maximum a launch facility can handle, well, that's probably one of the reasons they are building multiple launch facilities.

And who knows, maybe they eventually get the pad turnaroud time down to something like 4-5 days. That creates a scenario where a launch a day from alternating SpaceX facilities is indeed possible.
« Last Edit: 03/11/2017 01:34 PM by M.E.T. »

Online rockets4life97

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Re: F9 Block 5 Updates and Discussion
« Reply #130 on: 03/11/2017 01:49 PM »
[snip]
 But it's too early to tell whether their response will be to give in and make a "block 5 1/2" or settle for larger-than-24hr refurb or something else.  I'd argue it's too early for SpaceX to tell as well: they have to find out what's going to go wrong with their plan before they can figure out what to do about it.

I think there will be a block 5 and a half (or for simplicity block 6). Block 5 is for commercial crew (and potentially first DoD launches), so it will stay stable. They may even keep one line making those cores while the transition the other line to an updated version.

I think there will be continued development. That is SpaceX's style. What I think will be different is that the changes will be smaller. More like fine tuning, then all the changes required for densified propellant for example. I take SpaceX at its word that they will transition most of the F9 and then FH development teams over to ITC.

On the other topic of the 24 hour turnaround: SpaceX's development strategy is to set highly aspirational goals and see how close they can get. Their management thinks they will get better results that way then if they simply say "that's not possible, set realistic goals". You can disagree with that management approach. Long-time observers have learned to calibrate the words of management. Hence, Elon time. This strategy seems to be working for SpaceX. Time will tell whether they get close to achieve a high flight right with rapid re-use.

Offline rcoppola

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Re: F9 Block 5 Updates and Discussion
« Reply #131 on: 03/11/2017 02:14 PM »
It took 4 months to refurbish the their very first stage for reuse. Not unreasonable for something they've never done before. They think they can get that down to 2 months with perhaps a few small design tweaks, experience and efficiencies which sounds perfectly reasonable. We all do things today that took us twice as long when we first did them. Both 4 months and 2 months seems like it should apply to the current generation of Falcon.

And then Gwynne says they'd like to get that refurb time down to a day. It's reasonable to think that would require the F9B5 variant. This is about having previously flown boosters ready to get back into the flow in 24 hours, not launch again. After all, you're going to have a large stash of these boosters after not too long.
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Offline Jim

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Re: F9 Block 5 Updates and Discussion
« Reply #132 on: 03/11/2017 02:14 PM »

I think there will be a block 5 and a half (or for simplicity block 6). Block 5 is for commercial crew (and potentially first DoD launches), so it will stay stable. They may even keep one line making those cores while the transition the other line to an updated version.


No, this is exactly what Spacex said it will not do.  There will be only version of F9 for all users.

Online rockets4life97

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Re: F9 Block 5 Updates and Discussion
« Reply #133 on: 03/11/2017 02:31 PM »
No, this is exactly what Spacex said it will not do.  There will be only version of F9 for all users.

You are right. Maybe the changes will be small enough and slow enough to appease NASA and the DoD? In other words, normal iterative change like what ULA does.

Online matthewkantar

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Re: F9 Block 5 Updates and Discussion
« Reply #134 on: 03/11/2017 02:31 PM »
These figures, four months for the completed refurb, one day for an aspirational refurb, are both nearly meaningless. On the one hand, the four months could have been one tech working for two hours after lunch on Tuesdays. On the other, I believe it is possible to have a twenty four hour turn around for a more evolved F-9, but if it takes three eight hour shifts with 50,000 workers each, not going to happen.

The meaningful figure would be person-hours to refurb a stage and any long poles in the process. I wouldn't hold my breath on getting any insight into that.

Matthew

Offline IanThePineapple

Re: F9 Block 5 Updates and Discussion
« Reply #135 on: 03/11/2017 02:31 PM »
I honestly think Block 5 will NEVER be the final F9 version, they'll find more thrust in the Merlins, or have some more minor improvements along the way. I think the fact that Block 3 was called "Full Thrust", and then they found 2 more major ways to increase engine thrust, will indicate that they'll most likely make a Block 6 or "Upgraded Block 5".

Offline Robotbeat

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Re: F9 Block 5 Updates and Discussion
« Reply #136 on: 03/11/2017 02:55 PM »
I honestly think Block 5 will NEVER be the final F9 version, they'll find more thrust in the Merlins, or have some more minor improvements along the way. I think the fact that Block 3 was called "Full Thrust", and then they found 2 more major ways to increase engine thrust, will indicate that they'll most likely make a Block 6 or "Upgraded Block 5".
It's not like Falcon 9 block 5 will be the last rocket they make, but they're going to transition the development team away from Falcon to ITS (and, perhaps one can speculate, an ITS-derived satellite launcher down the road).
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Offline envy887

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Re: F9 Block 5 Updates and Discussion
« Reply #137 on: 03/11/2017 03:00 PM »
I honestly think Block 5 will NEVER be the final F9 version, they'll find more thrust in the Merlins, or have some more minor improvements along the way. I think the fact that Block 3 was called "Full Thrust", and then they found 2 more major ways to increase engine thrust, will indicate that they'll most likely make a Block 6 or "Upgraded Block 5".

There aren't 2 thrust upgrades from v1.2/FT/Block 3. The only announced upgrade is the 1.7 Mlbf (7600 kN) SL thrust level. It's not clear if that is Block 4 or 5 or if it's flown yet.

The Wiki page on Falcon 9 lists the 1.7 Mlbf version as (late 2016) but the reference given is for v1.1 at 1.32 Mlbf. It also lists Block 5 as 1.9 Mlbf, which is really the vacuum thrust of the same vehicle that gets 1.7 Mlbf at sea level.

These are the correct liftoff thrust levels:
Block 2/v1.1: 1.3 Mlbf
Block 3/FT: 1.5 Mlbf
Block 4: either 1.5 or 1.7?
Block 5: 1.7 Mlbf

Online Semmel

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Re: F9 Block 5 Updates and Discussion
« Reply #138 on: 03/11/2017 03:08 PM »
I think all of you forget something when interpreting the statement. SpaceX wants to launch more than 1000 satelites for their constellation per year. Even if they go with 20 sats per launch, thats 50 launches per year on CommX alone. An average of one per week. They probably cant to it with one first stage alone, but they wouldnt be cost effective either if refurbishment and flight readying is a huge thing.

I think CommX is impossible if they dont have an assembly line like approach to launches. They need to mass produce second stages, process at least 3 or 4 stages in parallel at the launch site and launch like a clockwork. They cant even stop for investigation of failures.

In this context, having a refurbishment of 24 hours fits perfectly into the picture. It means, that this part of the launch assembly line takes 24 hours. As many said before, a turnaround (launch to launch) of a single stage of 24 hours makes no sense.

With the current way to do launches, CommX is impossible. Since the Mars project depends on CommX, I expect many more statements and action to make a launch cadence of more than 1 per week possible. The launch pad needs to be ready as well, etc. There is a ton of streamlining going to happen. And if Jim is right and F9B5 is the last version of F9, then meekGee is right and it will be a much larger leap forwards in recovery and refurbishment as well as the entire processing than is anticipated right now.

Online macpacheco

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Re: F9 Block 5 Updates and Discussion
« Reply #139 on: 03/11/2017 03:42 PM »
The reason there won't be a Block VI or 5 1/2 is F9 will be more capable than needed for 80% of missions with ASDS landing and FH can pick up the slack. What's the point in tinkering for tinkering sake ? Better performance that doesn't make a difference in revenue.

Plus there's little reason not to develop a fully reusable pure Raptor rocket, simple two stage, that can do everything F9 can expendable and everything FH can with 3 boosters landing on ASDS. Except this new rocket will accomplish that will full reuse.

Its not something I expect SX to announce at least until late 2018 or even 2019. They first want to learn EVERYTHING they can for booster reuse on F9/FH and have firmed numbers on Raptor performance. Figure out what happens with Block V boosters after 10+ reflights, what kind of refurb is really needed.

That will be a rocket to fly for several decades. They will take their time designing it.

Stop dreaming folks. SX needs billions of revenue to build ITS. It won't spend money improving F9/FH unless there's quantifiable reduction in costs. Revenue wise, a 10% more capable F9 won't bring in more money. Nor a 15% more capable FH.
« Last Edit: 03/11/2017 03:46 PM by macpacheco »
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