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

[gongora]

She said Merlin has been pushed that high on a test stand, not that it has any margin at that level or they would ever fly it at that level.

[Marslauncher]

Oh I know sure, just spitballing hypotheticals..


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[Marslauncher]

Even if they split the difference (for a possible future block 1.5 increase) that would still indicate at least the capacity for a 2m lbf vehicle. We have seen SpaceX increase thrust options before, 1.3 core with a 1.4 US for example.


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[WindyCity]

How long does it take to archive the show?

Usually 1-2 days, depending on David's activities.

[meekGee]

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

That would be the SpaceX way.

Develop the engines on a smaller vehicle, then start with a larger vehicle using the proven engines, then develop the engines further.

Glad to see the emphasis off RD.  It was a great concept before we learned of the greater Mars plan.
At that point, a precursor to BFS makes a lot more sense than a "chaser" to Dragon.  The latter is kind of a dead-end project.

And ho ho ho am I glad they're back to big effing nomenclature.

[TrevorMonty]

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

That would be the SpaceX way.

Develop the engines on a smaller vehicle, then start with a larger vehicle using the proven engines, then develop the engines further.

A Raptor US would be easier to implement and means they don't need to support a mix bag of used Merlin and Raptor boosters.

[TrueBlueWitt]

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?


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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..

[QuantumG]

More people interested in space tourism flights than she expected.

Did she actually say "tourism"?

[gongora]

More people interested in space tourism flights than she expected.

Did she actually say "tourism"?

I don't recall if she used the word tourism, but that's the topic she was addressing.  If I'd realized we couldn't play back the interview for a couple days I would have tried to jot down more actual quotes.

[russianhalo117]

More people interested in space tourism flights than she expected.

Did she actually say "tourism"?

I don't recall if she used the word tourism, but that's the topic she was addressing.  If I'd realized we couldn't play back the interview for a couple days I would have tried to jot down more actual quotes.

I recall her saying it when I listened.

[gongora]

A Reddit user posted some additional notes, I forgot to put anything about the carbon fiber tanks.  I highly recommend listening to the interview when it's available.

sol3tosol4's notes on Reddit

[GWH]

Third hearing the line on tourism,  and I believe she also said not just lunar like they have planned but also orbital.

[meekGee]

A Reddit user posted some additional notes, I forgot to put anything about the carbon fiber tanks.  I highly recommend listening to the interview when it's available.

sol3tosol4's notes on Reddit

Most notable:

Initially, Elon was not sold on nuclear propulsion - his position may have changed somewhat. SpaceX is looking at nuclear power sources (not necessarily propulsion).

Personally, I'm surprised at the first, not at the second.

I wonder what it was that caused him to take a second look.

[Robotbeat]

Mueller and the possibility of 30 day transits.

SpaceX is targeting ~90 day transits with methane/oxygen. You could do a little better if you rendezvoused in high orbit (instead of just LEO), but you're probably going to need that triple Isp of NTR to get all the way down to 30 days (and better aero thermodynamics...). Also, if you have really good T/W and really lightweight tanks, then the usual drawback of using liquid hydrogen propellant isn't so bad and Isp starts to be important again.

But I doubt this is near term. Just that Musk can't help himself when he sees some way to do something others though impossible.

[yokem55]

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?


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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..

There would have to be a substantial vertical structure integrated into any liquid boosters to support the core stage   which makes them nearly nonstarters.

[woods170]

"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.

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.

[Nathan2go]

Initially, Elon was not sold on nuclear propulsion - his position may have changed somewhat. SpaceX is looking at nuclear power sources (not necessarily propulsion).

I wonder what it was that caused him to take a second look.

Mueller and the possibility of 30 day transits.

Or maybe the prospect of cutting the number of launches in half for the same cargo delivery to Mars.

Or maybe LEO parking and propellant transfer is falling out of favor.  A nuclear thermal 2nd stage would be great for throwing a methalox third stage (Mars lander/return vehicle) to a Lagrange parking orbit (or LDRO).

Or maybe they are considering an architecture with a nuclear mothership that travels back and forth from Earth orbit to Mars orbit (using propulsive capture), without landing during it's 30 year lifetime.  The BFR/BFS which was sized to carry 100 people all the way to Mars (in mini-cabins) could probably carry 300-400 to a mothership in LEO (in airline-style seats).

Remember that nuclear thermal is not helpful on Mars surface.  Making 1 ton of H2 mono-propellant costs exactly the same as making 7 tons of hydrolox (the O2 would have been discarded in the former case), and it costs only slightly more to make 20 tons of methalox (since H is 5% of methalox: CH4+2O2), and the methalox will lift much more cargo.  So a nuclear thermal stage is most interesting for a 2nd or 3rd stage for getting to high Earth orbit.

A nuclear 2nd stage could be a hybrid, with oxygen for thrust boosting for the first couple of minutes of the burn.

[woods170]

Initially, Elon was not sold on nuclear propulsion - his position may have changed somewhat. SpaceX is looking at nuclear power sources (not necessarily propulsion).

I wonder what it was that caused him to take a second look.

Mueller and the possibility of 30 day transits.

Or maybe the prospect of cutting the number of launches in half for the same cargo delivery to Mars.

No, what Robotbeat said. The only way to make space viable is to launch often and to launch many. Economies of scale is what it is all about. Doing as much as you can in as few launches possible initially looks like "being efficient" but in reality is asking for cost overruns and delays. NASA can tell you all about that.

Why do think Falcon Heavy exists? Not because it can supposedly lift 64 mT to LEO. It's purpose is not being a heavy lifter but launching medium payloads often and cheaply. The performance overkill is there for reusability purposes first, and greater lift-capacity second. It is no coincidence that first attempts to recover the upper stage will be performend on Falcon Heavy, not Falcon 9.

[meekGee]

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.

[rakaydos]

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.