Author Topic: Gwynne Shotwell Interview - June 22, 2017 on The Space Show  (Read 44011 times)

Offline meekGee

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #40 on: 06/23/2017 07:44 AM »
Remember musk said that the main change in plan 2.0 (or is it plan 1.1?) Is how to finance it  so we're guessing a smaller BFR with local commercial use.

I am not wrapping my brain around nuclear propulsion of either sort right now, but it's certainly not a small change, and certainly not a coat reducer.
If they are seriously considering a Raptor upper stage, I'm seeing a methalox ACES copy, testing orbital refueling and 2nd stage recovery. This makes a "smaller bfr" obsolete.
Way back up on the RUS thread, I called it a "Mars precursor vehicle", with the idea that it would provide a lot more value then RD will - in addition to being a kick ass upper stage.

But, I don't think it makes a SFR redudant.  It's just a good step on the way to one.

The RUS will reduce risk for the in-space part, but SFR is a good step before BFR.
ABCD - Always Be Counting Down

Offline guckyfan

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #41 on: 06/23/2017 08:36 AM »
If they are seriously considering a Raptor upper stage, I'm seeing a methalox ACES copy, testing orbital refueling and 2nd stage recovery.

ACES is not a reusable or recoverable second stage. 

Offline M.E.T.

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #42 on: 06/23/2017 08:55 AM »
When stating "the utility of Raptors for Falcon is being investigated", are we sure Shotwell was referring to the Upper Stage only? Not having heard the broadcast itself, the cryptic notes seem to leave her exact meaning slightly open to interpretation. Maybe someone can clarify.

Offline DJPledger

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #43 on: 06/23/2017 11:22 AM »
Haven't picked engine size for Mars vehicle yet, will be 2-3 (probably less than 3) times the size of the sub-scale Raptor
EM had selected the Raptor size at 3.05MN SL when ITS was announced at IAC2016. Now SpaceX say they have not selected the Raptor size yet. SpaceX should select a larger not smaller Raptor size for ITS to stop the engine no. of the ITS system spiraling out of control. There are rumors that the final ITS design may end up larger than that announced at IAC2016.

Offline envy887

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #44 on: 06/23/2017 11:23 AM »
When stating "the utility of Raptors for Falcon is being investigated", are we sure Shotwell was referring to the Upper Stage only? Not having heard the broadcast itself, the cryptic notes seem to leave her exact meaning slightly open to interpretation. Maybe someone can clarify.
I'm sure they are running the trades on both, but there are a number of reasons it would be less useful on the booster. It adds a lot of development effort and time with little gain, and SpaceX needs Block 5 flying for a while for crew and NSS.

Offline envy887

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #45 on: 06/23/2017 11:28 AM »
Haven't picked engine size for Mars vehicle yet, will be 2-3 (probably less than 3) times the size of the sub-scale Raptor
EM had selected the Raptor size at 3.05MN SL when ITS was announced at IAC2016. Now SpaceX say they have not selected the Raptor size yet. SpaceX should select a larger not smaller Raptor size for ITS to stop the engine no. of the ITS system spiraling out of control. There are rumors that the final ITS design may end up larger than that announced at IAC2016.
They might prefer a smaller engine, at least to start. Sounds like the 1000 kN version might have some utility if they have run lots of tests on it.

Offline rsdavis9

When stating "the utility of Raptors for Falcon is being investigated", are we sure Shotwell was referring to the Upper Stage only? Not having heard the broadcast itself, the cryptic notes seem to leave her exact meaning slightly open to interpretation. Maybe someone can clarify.
I have as the major technologies for BFR/BFS
1. CH4-LOX raptor engine.
2. autogenous pressurization.
3. composite structure.
4. Combined fairing/US/reentry craft

Given that they already have a subscale raptor working.  and 2. shouldn't be that difficult.
Maybe they will go for the booster first to get flight experience and retire those risks. Should be relatively faster to develop. 3 and 4 are big and possibly long development items.

If we had a raptor booster couldn't it go to higher stage separation m/s and reserve more fuel to reenter?
That would give a big boost to the payload of the already optimized Merlin S2. And maybe enough extra performance to add S2 recovery hardware to S2.

bob

Online TrevorMonty



"Looking at the utility of it [Raptor] on Falcon"


If old space "common sense" had prevailed at SpaceX there would be no Falcon 9 but a Falcon 3 at best. There would not have been any Grasshopper, let alone a reusable first stage. And there most decidedly would not have been ITS. And Dragon probably would not exist either given the old space mantra that launch service providers provide launches, not spacecraft.

It's undeniably a good thing that SpaceX is around. They are shaking things up. Disruptive. An industry that has been stuck in the same old patterns for the better part of 4 decades is finally beginning to move into a new direction.

It is "old school" NASA that financed CRS resulting in F9 and Dragon. Without which SpaceX may never have built F9.


Online TrevorMonty

If they are seriously considering a Raptor upper stage, I'm seeing a methalox ACES copy, testing orbital refueling and 2nd stage recovery.

ACES is not a reusable or recoverable second stage.
More likely ACES endurance and option to do distributed launch. NB ACES is fully reuseable in space, it just can't be returned to earth.
« Last Edit: 06/23/2017 01:53 PM by TrevorMonty »

Offline DOCinCT

Tweet from Dr. David Livingston
Quote
Gwynne Shotwell of SpaceX today for 1 hour, 2PM PDT, 5PM EDT; Listen @ http://www.thespaceshow.com ; Call Gwynne @ 1-866 687-7223. #fb #in.
Direct link to archive page: http://www.thespaceshow.com/show-search

Offline Jim

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #50 on: 06/23/2017 02:22 PM »
"Looking at the utility of it [Raptor] on Falcon"
And then to think that some folks here shot down the idea of Raptor on Falcon because it was (supposedly) not KISS and therefore not the SpaceX way. But those folks are forgetting that "doing things differently" is exactly what SpaceX is all about.


No, what has been shot down is a mixed vehicle of Raptors and Merlins.  Nothing about a full up F9 on methane.
« Last Edit: 06/23/2017 02:23 PM by Jim »

Offline Jim

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #51 on: 06/23/2017 02:24 PM »
Nothing she said pointed to just a RUS.  A mixed vehicle is not the Spacex way.

Offline Semmel

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #52 on: 06/23/2017 02:48 PM »
Nothing she said pointed to just a RUS.  A mixed vehicle is not the Spacex way.

What makes the mix of fuels between S1 and S2 so discouraging that an all-Raptor F9 seems doable but a mixed F9 does not? Also, I am not yet convinced that either variant will give SpaceX any advantage or capability it doesnt already have. If at all, a Raptor based launch vehicle would be more capable than FH to both LEO and GTO+, fully reusable, cheaper to operate and would retire F9 all together. THAT would seem like the SpaceXy way. Not some fiddling with current hardware that would be retired anyway when the next generation vehicle becomes reality within single digit years.

Offline Jim

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #53 on: 06/23/2017 03:00 PM »
Nothing she said pointed to just a RUS.  A mixed vehicle is not the Spacex way.

What makes the mix of fuels between S1 and S2 so discouraging that an all-Raptor F9 seems doable but a mixed F9 does not?

Not discouraging, but much more complex.  Plus the upper stage will have an engine with little flight history and unable to leverage off of first stage engine usage. And it won't be tested in vacuum before its flights and with its low flight rate customer confidence will climb slower than the MVac.

Mixed vehicle will require 3 different loading systems, 3 propellant farms, different pressure systems between stages, different loading times, etc

Offline starsilk

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #54 on: 06/23/2017 03:06 PM »
Nothing she said pointed to just a RUS.  A mixed vehicle is not the Spacex way.

What makes the mix of fuels between S1 and S2 so discouraging that an all-Raptor F9 seems doable but a mixed F9 does not?

Not discouraging, but much more complex.  Plus the upper stage will have an engine with little flight history and unable to leverage off of first stage engine usage. And it won't be tested in vacuum before its flights and with its low flight rate customer confidence will climb slower than the MVac.

Mixed vehicle will require 3 different loading systems, 3 propellant farms, different pressure systems between stages, different loading times, etc

so Jim, do you think it would be worth the pain to switch Falcon to all methane?

Offline Semmel

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #55 on: 06/23/2017 03:19 PM »
Nothing she said pointed to just a RUS.  A mixed vehicle is not the Spacex way.

What makes the mix of fuels between S1 and S2 so discouraging that an all-Raptor F9 seems doable but a mixed F9 does not?

Not discouraging, but much more complex.  Plus the upper stage will have an engine with little flight history and unable to leverage off of first stage engine usage. And it won't be tested in vacuum before its flights and with its low flight rate customer confidence will climb slower than the MVac.

Mixed vehicle will require 3 different loading systems, 3 propellant farms, different pressure systems between stages, different loading times, etc

Isnt most of what you say true regardless? There will be no flight heritage for Raptor. It will not have been tested in vacuum whether Raptor is used for S1 or not. The fuel lines and tanking procedures are different and separated between S1 and S2 already, you can hear that on the countdown net. The only difference is that you need an additional methane propellant farm, which would have to be build anyway if S1 becomes Raptor based as well.
A different engine between first and second stage didnt stop F1, so I wouldnt say its something totally new to SpaceX. Also, it was said often enough that Merlin SL and Merlin Vac are based on the same design but very different engines. Different enough that flight heritage from one doesnt necessarily count for the other.

You do have a point that if SpaceX replaces the second stage with a small Raptor, it might as well go all the way and redo the first stage too. But I doubt this is going to happen and nothing in Gwynnes Interview points to that. In the contrary, the concentration of personal on Mars after Block 5 indicates that they will not touch the F9 design at all. A position that you most prominently defended and I think is true based on many reasonable arguments.

Offline jak Kennedy

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Block 5 Merlin 190k lbf thrust, have tested current Merlin to around 240.

Moving away from ITS acronym back to BFR/BFS

I read this quote as "tested current Merlin to around 240 (ie maybe Block 3/4 tested to 240?)"

Thoughts?

Online wannamoonbase

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #57 on: 06/23/2017 03:38 PM »
Ok so I'm trying to wrap my head around these numbers, 1.9m lbf of thrust is more than the 1.71m listed for block 5 on the website yes? Which is 50k lbs to LEO, if 240k lbs thrust is doable and stable with margin, that would be what? 2.2m lbs thrust? If the Merlin 1D Vac is capable of increased thrust also, what is the theoretical payload ability for the FULLEST thrust Falcon 9 to LEO and GTO?


Sent from my iPhone using Tapatalk

If they could operate safely at that level, now you're almost talking about a replacement for SRBs on SLS ;) 
A pair per side should probably outdo even Black Knights on a Block 2, even with Recovery.. Right?
Not that anyone in their right mind would bet on ever seeing that Block 2 horse fly..

Maybe increased thrust to 240K decreases engine life for a re-useable first stage. 

However, for a disposable US, 240K at the start of the burn and till it hit maximum G's and throttled down would decrease gravity losses.
Excited to be finally into the first Falcon Heavy flow, we are getting so close!

Offline Lobo

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #58 on: 06/23/2017 03:51 PM »
Block 5 Merlin 190k lbf thrust, have tested current Merlin to around 240.

Moving away from ITS acronym back to BFR/BFS

Whoa, another 26% on the test stand, impressive.

Be interesting to see if that ever moves toward use or if it was a test to see how stressed the engine is at 190K.
If this Quora post is correct (and it ought to be, given who wrote it), Merlin 1D weighs 1030 pounds. That means on the test stand, it gets a T/W ratio of 233. I think that's twice as much as any other engine flying today, and nearly twice NK33.

https://www.quora.com/Is-SpaceXs-Merlin-1Ds-thrust-to-weight-ratio-of-150+-believable

190klbs of thrust per Merlin would mean a F9 would have more thrust than a Saturn 1B.  Impressive!

Offline Lobo

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Re: Gwynne Shotwell Interview - June 22, 2017 on The Space Show
« Reply #59 on: 06/23/2017 04:02 PM »
When stating "the utility of Raptors for Falcon is being investigated", are we sure Shotwell was referring to the Upper Stage only? Not having heard the broadcast itself, the cryptic notes seem to leave her exact meaning slightly open to interpretation. Maybe someone can clarify.
I have as the major technologies for BFR/BFS
1. CH4-LOX raptor engine.
2. autogenous pressurization.
3. composite structure.
4. Combined fairing/US/reentry craft

Given that they already have a subscale raptor working.  and 2. shouldn't be that difficult.
Maybe they will go for the booster first to get flight experience and retire those risks. Should be relatively faster to develop. 3 and 4 are big and possibly long development items.

If we had a raptor booster couldn't it go to higher stage separation m/s and reserve more fuel to reenter?
That would give a big boost to the payload of the already optimized Merlin S2. And maybe enough extra performance to add S2 recovery hardware to S2.

Could also be they may look at using the F9 as a test bed for a subscale Raptor, and not necessarily planning to replace it across the whole line.  Or they'd see how the test bed went before they look at that option.
But they could modify an F9 booster for methalox and the subscale Raptor, and then see how it launches and returns.  See what shape the engines are in after a flight, etc.  And use that info when the design the larger vehicle.  That'd give Raptor some actual real world flights and testing before they put it on a new vehicle.

So, sort of "both" could be true.  They could be looking to put Raptor on Falcon for purposes of testing, but still not replace the whole fleet.

Nothing she said pointed to just a RUS.  A mixed vehicle is not the Spacex way.

What makes the mix of fuels between S1 and S2 so discouraging that an all-Raptor F9 seems doable but a mixed F9 does not?

Not discouraging, but much more complex.  Plus the upper stage will have an engine with little flight history and unable to leverage off of first stage engine usage. And it won't be tested in vacuum before its flights and with its low flight rate customer confidence will climb slower than the MVac.

Mixed vehicle will require 3 different loading systems, 3 propellant farms, different pressure systems between stages, different loading times, etc

Such an F9-Raptor test vehicle would then give SpaceX the ability to test Raptor in space, etc.  Yet keep their commercial and government business going on normal Falcon uninterrupted while they test this.  If tests go good maybe they investigate upgrading the fleet to Raptor, or at least some of the fleet and operate them out of one pad set up for methalox while the existing kerolox booster fleet continues to operate out of the other pads.
But mainly it'd be to gain the necessary experience and data to build into the next vehicle.
« Last Edit: 06/23/2017 04:12 PM by Lobo »

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