Gwynne Shotwell Interview - June 22, 2017 on The Space Show

[Marslauncher]

That was kinda my question too, (yes sorry! I should have specified 190k lbf thrust single engine x 9 but assumed it was implied by definition of F9 )

Still though, a 25% margin is quite significant unto itself.

[Lobo]

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

I speculated about maybe that means using Falcon as a test bed for Raptor, rather than as an upgrade to the production Falcon.

Musk has before indicated this, and been coy as to the long term intent with F9. As this comment continues.

Suggest there are three options - test stage (in advance of BFS), performance stage (funded in parallel to ACES?), and fully recoverable stage (follow on to F9US).

If you were to fly as a test stage, perhaps even on top of a F9US as a payload (or with Dragon or RD), the issues would involve prop load/drain & GSE. Most of the cost would be in the pad mods. Keep in mind the upgrades that they did to the E-2 test stand at Stennis. It would be an addition and not interfere with existing F9 flights.

If a performance stage (F9US's Achilles heel is C3 performance), it might be a reformulated F9US that functioned within a redone fairing. It would place a considerable burden on F9 and likely delay BFS as well as increasing F9 launch costs, as maintaining dual US capability would almost certainly be a 30-50% increase in costs, competing with ROI of booster reuse. But the financial impact might be absorbed by some of that, because of lack of competition (if you're the only one actively driving down launch costs, it doesn't help if you are too effective because you can only launch so many). You'd get more flight history this way.

Reminds of the decision to move to subcooled fuels and the additional expanse/AMOS6 incident.

If a reusable stage (arriving at a fully reusable vehicle as intended with the original Shuttle program), you'd phase over to a dual fuel vehicle like Atlas V, while losing the GHe pressurization issues in the US. This would play to Musk's ego and possibly a power play to up the competition with Bezos/Airbus Safran/others. Making it about BFR/BFS level competition that it could stretch too.

However, if she does mean they are looking at actually upgrading production Falcon to ssRaptor, I would guess they'd only do the upper stage if they have success with a reusable FUS, because it's a complex, expensive engine compared to Merlin.  If it's going to be expended, might as well keep expending the cheaper engine.  Then they get the Raptors back on the booster, as well as (presumably) easier reuse with less soot and coking than kerolox, as well as probably some performance boost. (Better engine efficiency, but less propellant capacity, unless the try to stretch the core more.)

Yes.

Could it be that in confronting BFS as the next vehicle, they've desired ... an interim step?

Space ghost.  Good input as always. 

So, just spitballing here.  It would seem to make sense to test a reusable biconic upper stage ahead of a BFR or even a miniBFR.  That's new tech and it'd be good to get real data before you finalize your design.
But, using falcon has its drawbacks as discussed.  Interrupting pad flow is probably not something they want to do.
But...over there at 39B there is a nice big clean pad sitting unused, designed to accommodate various LV designs.  Maybe a Falcon-Raptor test vehicle uses an existing MLP, and one of the old SRB ports, like The Ares 1 test launch did?
LCH4 would have to be added, but that wouldn't tie up a working Falcon Pad.  Lots of room in the VAB to lease to stack and tweak it.  It's a test vehicle so working with existing KSC personnel shouldn't cause too many issues like it might with regular launch operations.

Also, they'll probably use a modified FUS for initial reentry testing, but ITS will be composite.  What if they created a composite raptor upper stage, in the same basic shapes as the PLF?  Falcon should be fine with that aerodynamically.  And that gives them the extra propellant volume to most effectively use a Raptor upper stage.   It's already a nice coned cylinder shape like ITS.    And would be the same composit structure as ITS, so a good test there too.
That could allow them a reusable test vehicle (or two), using mostly existing tech and hardware, that they can operate on a pad and integration building that wouldn't interfere with any of their standard kerolox Falcon pads.
NASA is looking for customers in the VAB and 39B anyway, right?

If the test vehicle works well, they may upgrade Falcon into this at some point down the road?
Various possibilities available if tests go well.

[MP99]

If a performance stage (F9US's Achilles heel is C3 performance), it might be a reformulated F9US that functioned within a redone fairing. It would place a considerable burden on F9 and likely delay BFS as well as increasing F9 launch costs, as maintaining dual US capability would almost certainly be a 30-50% increase in costs, competing with ROI of booster reuse. But the financial impact might be absorbed by some of that, because of lack of competition (if you're the only one actively driving down launch costs, it doesn't help if you are too effective because you can only launch so many). You'd get more flight history this way.

Reminds of the decision to move to subcooled fuels and the additional expanse/AMOS6 incident.

If the upper-stage has a greater dV capability, would that allow a greater proportion of F9 flights to be RTLS?

That would save costs and decrease turnaround times.

Cheers, Martin

[su27k]

Just "putting raptor on falcon for purposes of testing" would still require big changes to the GSE to support the additional propellant. It's not a cheap test.

You are correct, it wouldn't.  But it might be "cheaper" than testing a new engine on a new booster and upper stage...especially given how large scale those new stages would be.  Might be good to have some flight history on the engine first perhaps?

I don't see the need for flight testing an engine, SpaceX did not do this before, I don't see why they want to do it now. It would be super expensive, it's not just GSE, they'll have to design an entirely new stage around Raptor, basically the same as Atlas V to Vulcan transition, all these work just for testing the engine? No way.

Raptor will be well tested on test stand, this should be more than sufficient for first stage engines. For Raptor Vac, I think they can test it using sub-orbital flights of BFS. They won't fly the new engine on both new booster and new upper stage at the same time, the IAC timeline shows they'll test BFS first, this would reduce the risk a lot comparing to all up testing of the whole ITS.

[GORDAP]

Some thoughts:

1) If they go this route, (implement Raptor on essentially the existing Falcon line), they could do so in an evolutionary rather than revolutionary way.  They could start with development of the Raptor US that would work with an existing F9 (or FH) 1st stage.  All the while continuing with flights with their existing rockets/pads.  Then introduce the new US on a test flight.  When confident, slowly transition from existing US to new US.  With multiple pads (and perhaps a new pad as someone suggested) available, they could pretty easily modify pads serially to accommodate Methane for the new US.  Following this, they could repeat this process with development of a 'Raptor 9' 1st stage.  So all in all, they could transition the existing Falcon line to be Raptor based with little or no impact to their existing flow.

2) Setting aside the idea of this being a risk reducing exercise for ITS development, I think this would be extremely appealing to Musk just to complete his 'full reuseability' vision.  Not reusing the 2nd stage has got to stick in his craw.  He'd previously stated that the Merlin 2nd stage just didn't have the ISP to make it worth trying to make it reusable.  That may still be the case, even with his recent pronouncements about having a reusable 2nd stage by the end of next year.  He may have been talking about a Raptor based US, and just using 'Elon time'. 

3) If they go this route, I'd think the new US would switch to 5.5 to 6 meters in diameter.  Yes I know they'd be forgoing road transport, but that is not as big an issue when each stage you transport will be used 10-100 times.  Q.  What is the largest diameter of US that could feasibly fit atop an F9/FH?  I think I'd seen somewhere that hammerhead stages/payloads were practically limited to 1.5X the diameter of the 1st stage for aerodynamic/stability reasons, which would limit things to 5.5 meters.  Does anyone have a handle on this?

4) A 'Raptor 9' first stage (same diameter and coupled with new new US), would effectively replace the FH.  (This is Mike Atkinson's 'Medium' launcher.)  If they implement the new US as a scaled BFS (i.e. 'captive' fairing), then you have a system that should be dramatically cheaper than the FH.  Consider, it's a single stick design (1/3 the processing involved in landing, handling, refurb and zero mating), plus no operations involved in retrieving and refurbishing the fairings.  Plus the engines should last longer between overhauls compared with the Merlins.  I'd be surprised if it doesn't end up a good bit cheaper to use than the current 'reusable' F9.

5) If the new US is implemented as a scaled BFS, it does much more than just serve to test the Raptors for the upcoming ITS.  It could also prove out biconic reentry and landing modes, composite tanks, on-orbit refuling(?), and autege... er, autogen.. er,  non-Helium based pressurization :-) 

6) Mike, in your list you have the 'small' launcher as the one targeted for constellation deployment.  But I think if the 'Raptor 9' is deployed, it would be the vehicle of choice for this.  Agree?

7) I don't think they'd develop a Raptor based replacement for the current F9 core.  But it may be the case that the Raptor 9 (FH replacement) would be so cheap to operate that it effectively replaces the F9 as well.

[guckyfan]

Chris, can you change the thread names back to BFR/BFS please?

While I intensely dislike ITS, it may be too early. They will hopefully come up with a new name. I don't dare hope they go back to MCT, which I always liked best.

[MikeAtkinson]

4) A 'Raptor 9' first stage (same diameter and coupled with new new US), would effectively replace the FH.  (This is Mike Atkinson's 'Medium' launcher.)

Not quite, my small launcher would have 20 tonnes to LEO, by refueling there it can do  just about all the FH missions. My medium launcher would have about 15 3MN Raptors and be about twice the effective payload to LEO as the FH.

6) Mike, in your list you have the 'small' launcher as the one targeted for constellation deployment.  But I think if the 'Raptor 9' is deployed, it would be the vehicle of choice for this.  Agree?

The small launcher would carry about 60 of the LEO constellation, the medium about than 300. There are about 50 satellites in each plane so the small can launch a plane at a time. The medium could launch several planes in one go, the satellites would then have to drift into the correct plane over a few weeks. My medium launcher would only be from the east coast, as the pad at Vandenberg is probably a bit too small for it, if that is the case much of the constellation would need to launch on the small version.

I think what you are proposing is a SpaceX endgame of two launchers at 50 and 300 tonnes to LEO, while I think they will have three 20, 80-100 and 300-400 tonnes to LEO.

In terms of passengers my small would have 25 to LEO, medium 50 to the Moon and large 100 to Mars (or 300+ to LEO).

[guckyfan]

I think it depends on what they build first. If they build your medium they have very little incentive to build the small. Even if they have to build a larger pad in Vandenberg. With cost of less than $2 million/launch why build a smaller one that needs to recover its initial investment.

I am afraid they would also have very little incentive to build the big one until they get serious with building a settlement for thousands of people. It would be big enough to even support a base with hundred people.

[FutureSpaceTourist]

Just in case others, like me, haven't spotted it - although the show isn't yet up on iTunes/podcasts app the MP3 can be downloaded from the show's page at:

http://www.thespaceshow.com/show/22-jun-2017/broadcast-2934-ms.-gwynne-shotwell

[GORDAP]

4) A 'Raptor 9' first stage (same diameter and coupled with new new US), would effectively replace the FH.  (This is Mike Atkinson's 'Medium' launcher.)

Not quite, my small launcher would have 20 tonnes to LEO, by refueling there it can do  just about all the FH missions. My medium launcher would have about 15 3MN Raptors and be about twice the effective payload to LEO as the FH.

6) Mike, in your list you have the 'small' launcher as the one targeted for constellation deployment.  But I think if the 'Raptor 9' is deployed, it would be the vehicle of choice for this.  Agree?

The small launcher would carry about 60 of the LEO constellation, the medium about than 300. There are about 50 satellites in each plane so the small can launch a plane at a time. The medium could launch several planes in one go, the satellites would then have to drift into the correct plane over a few weeks. My medium launcher would only be from the east coast, as the pad at Vandenberg is probably a bit too small for it, if that is the case much of the constellation would need to launch on the small version.

I think what you are proposing is a SpaceX endgame of two launchers at 50 and 300 tonnes to LEO, while I think they will have three 20, 80-100 and 300-400 tonnes to LEO.

In terms of passengers my small would have 25 to LEO, medium 50 to the Moon and large 100 to Mars (or 300+ to LEO).

Hmm, I'm missing something here.  At 3 MN, a 'Raptor 9' would have 18% more thrust than a 27 Merlin FH, even using the new 190 Klbs thrust numbers.  So with significantly greater 1st stage thrust and ISP, coupled with a higher thrust and ISP second stage, I'd think this rocket would deliver a good deal more than the 64 tonnes to orbit currently claimed for the FH.  So why 15 engines on your proposed 'medium' vehicle?  I'd think a 'Raptor 9' would already deliver 80+ tonnes to LEO.  Is my math wrong Mike?

[MikeAtkinson]

Hmm, I'm missing something here.  At 3 MN, a 'Raptor 9' would have 18% more thrust than a 27 Merlin FH, even using the new 190 Klbs thrust numbers.  So with significantly greater 1st stage thrust and ISP, coupled with a higher thrust and ISP second stage, I'd think this rocket would deliver a good deal more than the 64 tonnes to orbit currently claimed for the FH.  So why 15 engines on your proposed 'medium' vehicle?  I'd think a 'Raptor 9' would already deliver 80+ tonnes to LEO.  Is my math wrong Mike?

You are missing reusable upper stage, a 9 Raptor launcher would give a bit less than 9/42 * 300 tonnes = a bit less than 64. (300 tonnes & 42 x Raptor  are from Musk's IAC speech, a bit less because smaller launchers are a bit less efficient than bigger ones).

[GORDAP]

Hmm, I'm missing something here.  At 3 MN, a 'Raptor 9' would have 18% more thrust than a 27 Merlin FH, even using the new 190 Klbs thrust numbers.  So with significantly greater 1st stage thrust and ISP, coupled with a higher thrust and ISP second stage, I'd think this rocket would deliver a good deal more than the 64 tonnes to orbit currently claimed for the FH.  So why 15 engines on your proposed 'medium' vehicle?  I'd think a 'Raptor 9' would already deliver 80+ tonnes to LEO.  Is my math wrong Mike?

You are missing reusable upper stage, a 9 Raptor launcher would give a bit less than 9/42 * 300 tonnes = a bit less than 64. (300 tonnes & 42 x Raptor  are from Musk's IAC speech, a bit less because smaller launchers are a bit less efficient than bigger ones).

Ah, so if the US were expendable, an R9 probably would deliver a good bit more than 64 tonnes to orbit, but the reusability penalty probably drops this back to under 64, as confirmed by your sanity check using ITS number.  Got it.  Thanks!

[FutureSpaceTourist]

Apologies if I missed but a re-use detail I haven't seen mentioned is that SpaceX expect 2 or 3 flights out of current boosters, for block 5 expect to refly a dozen or so times.

[meekGee]

I don't see the need for flight testing an engine, SpaceX did not do this before, I don't see why they want to do it now.

F1 begs to differ

[FutureSpaceTourist]

One other note, Gwynne said the key reason SpaceX's launch cadence has improved is the ramp up in production. Going from 6 F9s a year 3 or so years ago to over 20 this year.

Clearly rocker availability is a pre-requisite but I thought it interesting that she didn't mention anything about launch pad ops etc.

[gongora]

One other note, Gwynne said the key reason SpaceX's launch cadence has improved is the ramp up in production. Going from 6 F9s a year 3 or so years ago to over 20 this year.

Clearly rocker availability is a pre-requisite but I thought it interesting that she didn't mention anything about launch pad ops etc.

Launch pad ops aren't a holdup if you don't have rockets to fly (except when you blow up a launch pad, that slows things down).

[Robotbeat]

One thing that's striking about the last few months of SpaceX ITS info/rumors is the degree to which these two things are happening simultaneously:
1) accelerating in timescale, with lots of actual work being done and
2) significantly in flux. All sorts of things which we thought or were told were true are now up in the air.

It really seems to me we're much closer to SpaceX being able to land people on Mars, including the hardware needed to do so, while also having much LESS of a firm plan than we did in September.

Grand plans are over-rated. Execution and dynamic flexibility are much better.

[gospacex]

Some thoughts:

1) If they go this route, (implement Raptor on essentially the existing Falcon line), they could do so in an evolutionary rather than revolutionary way.  They could start with development of the Raptor US that would work with an existing F9 (or FH) 1st stage.  All the while continuing with flights with their existing rockets/pads.  Then introduce the new US on a test flight.  When confident, slowly transition from existing US to new US.  With multiple pads (and perhaps a new pad as someone suggested) available, they could pretty easily modify pads serially to accommodate Methane for the new US.

My thoughts exactly.

Following this, they could repeat this process with development of a 'Raptor 9' 1st stage.  So all in all, they could transition the existing Falcon line to be Raptor based with little or no impact to their existing flow.

Well, a problem here. Falcon 1st stage is dimensions-limited. Diameter can't be changed, and it's pretty much maxed out on stretch too. They already are at a point where more powerful engines give them less benefits than they could, since they can't increase fuel mass.

If you use the same overall dimensions (apart from changing O/F tanks ratio) and switch to methane, you would have even less fuel, because of lower density. So "F9 methane first stage" is a lot of work for very little gain. Raptor 1st stage has to be larger diameter to be useful.

3) If they go this route, I'd think the new US would switch to 5.5 to 6 meters in diameter.  Yes I know they'd be forgoing road transport, but that is not as big an issue when each stage you transport will be used 10-100 times.  Q.  What is the largest diameter of US that could feasibly fit atop an F9/FH?

Current fairing is 5.2m. You can safely assume that at least 5.2m dia second stage is okay.

[GORDAP]

Well, a problem here. Falcon 1st stage is dimensions-limited. Diameter can't be changed, and it's pretty much maxed out on stretch too. They already are at a point where more powerful engines give them less benefits than they could, since they can't increase fuel mass.

If you use the same overall dimensions (apart from changing O/F tanks ratio) and switch to methane, you would have even less fuel, because of lower density. So "F9 methane first stage" is a lot of work for very little gain. Raptor 1st stage has to be larger diameter to be useful.

I thought I'd addressed this in my point 4: "4) A 'Raptor 9' first stage (same diameter and coupled with new new US), would effectively replace the FH...".  But now I see my language was ambiguous.  By "same diameter" for the new Raptor booster, I meant same diameter as the new upper stage (i.e. 5.5 or 6 meters).

So we are in violent agreement.  :-)

[docmordrid]

ISTM,

The downsides to a 5.x meter RUS are 1) loss of road transportability and 2) it may need a new fairing - unless they go with a wasp-waisted connection.

Downsides to a 2m stage stretch are 1) increasing fineness and 2) TEL mods.

EITHER needs other GSE & plumbing mods.

Which is easier/cheaper?