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

[FutureSpaceTourist]

It did sound to me like it wasn't a planned test failure. Gwynne was careful about what she said but given what she did say (not giving up, needing good design and build) I'm confident that if it was a planned failure she would have said so.

[punder]

Sounds like they definitely weren't happy with the CF tank test. Imho.

Can you give a time stamp when she said that?  I listened live and had it drop out for a few min, so I might have missed something. But I thought I did hear her talk about carbon fiber and the test tank and I didn't take away that they weren't happy. I thought she was just avoiding definitive statements about how testing has gone, that more work was required, but that they still would work toward CF tanks.

Like I said, it was sort of reading between the lines on my part. She basically said yeah we did the test, and we have a lot of work to do, but we think we can make it work--which all adds up to, things didn't go as well as we'd hoped. Sorry I couldn't find it in a quick search and the Google player doesn't show the time anyway (not that I can find).

[LouScheffer]

Not to mention helicopter it to any boat in the LA harbor, and be in the cape a couple of weeks later.

SpaceX *might* be able to air-lift second stages out of Hawthorne Muni airport.  It's a small airport (4956 ft x 100 ft) but it might still be possible.  They would need detailed information on the odd planes that can carry such cargo (Super Guppy, Beluga, DreamLifter),but it's not intrinsically absurd.  The C17, for example, is designed to lift much heavier stuff from even smaller runways (3500 ft x 90 ft).

There are 3 factors that might help make this possible.
(a) Runway is basically at sea level;
(b) Load is light (perhaps 5000 kg for a second stage)
(c) Plane needs hardly any fuel (LAX is just 4 km away, where it can refuel and use a larger runway).

Here is a case of DreamLifter (based on a 747(!), and with a 787 fuselage inside) taking off from a 6101 ft runway.  Airbus rents out Belugas for charter flights.  But as mentioned above, you'd need a detailed analysis.  Also, this would only work, at most, for second stages.  First stages are too long....

[IainMcClatchie]

Sounds like they definitely weren't happy with the CF tank test. Imho.

Yep.  Six months ago I think they were a lot more sure that ITS was going to be built of carbon fiber.  Now, I think they are looking at metal again.

CF looks difficult for anything going through reentry with a mostly-empty propellant tank.  At 300 C, 2091-T3 loses half its strength.  Polyimide is at half strength at a little over 200 C, and epoxy is significantly worse than that.

Given that they have to bake the CF anyway, and so build a large high pressure oven, I wonder if they might crank the cure temperature up to 600 C so that they can use aluminum as the matrix rather than epoxy or phenol.  Metal matrix composites have better high temperature properties than CFRP.

I wonder if they might spray the upper interior of the tank with liquid propellant.  The heat transfer should be excellent, but I'd wonder if you could effectively keep liquid on all the walls through the upper portion of re-entry (maybe you'd need something like a spinning rainbird inside the tank).  Cooling liquid would not add weight, as you'd shut down the cooling system tens of seconds before the landing burn.  Obviously only for an autogenously pressurized vehicle.

[GORDAP]

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

No, you can't.  The current fairing halves are road transportable.

The question was "What is the largest diameter of US that could feasibly fit atop an F9/FH?"

If it can't get to the launch site by the current means or use the existing TEL, then 5.2m does not fit "feasibly".

I interpreted the question as asking about aero loads and the like. For 5.2m US, aero loads don't change at all. So 5.2m US is feasible in that sense.

You are right that 5.2m is not road transportable, I did not imply it is. I agree that moving 5.2m out of Hawthorne factory is very difficult bordering on impossible, and if SpaceX would want to make them, it will do it elsewhere.

Yes, you interpreted my question exactly right, as in the sentence just above my query I said "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."  Apparently Jim missed my disclaimer.  :-)

[Jeff Lerner]

Sounds like they definitely weren't happy with the CF tank test. Imho.

Guess we don't have the details but is there something inherently difficult about CF tanks....is this x-33 all over again ??

[gongora]

I added the link to the download page and the time index that DOCinCT was nice enough to provide for us in the top post of the thread so they will be easier to reference.

[speedevil]

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

Moving away from ITS acronym back to BFR/BFS

Neglecting a pile of stuff.
190*9 ~=240*7.

This means that in principle, F9 could survive an engine out immediately after liftoff, even if it needed to shut down the opposite engine completely. (assuming no other damage).

As it does not need to shut down the opposite engine completely, but can take the opposite couple of engines to ~85% thrust, and the rest to ~118, with modest gimballing, it would seem there is moderate margin there.

Even if we accept (as seems reasonable) 240 is not reliable, if 230 is 'will not explode and will work for one flight 90% of the time', you can modestly crank the thrust to the point you expect an engine loss 1% of the time, and get >3 nines reliability as you can cope with an engine out.

(this of course assumes that there is a predictable and known relationship between thrust profile and likelyhood of explosions.

[DOCinCT]

Sounds like they definitely weren't happy with the CF tank test. Imho.

Can you give a time stamp when she said that?  I listened live and had it drop out for a few min, so I might have missed something. But I thought I did hear her talk about carbon fiber and the test tank and I didn't take away that they weren't happy. I thought she was just avoiding definitive statements about how testing has gone, that more work was required, but that they still would work toward CF tanks.

37:40

[Space Ghost 1962]

Space ghost.  Good input as always. 

Thanks. Sometimes reticent to comment and otherwise intrude into other posters "perfect worlds".

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.

Agree that with BFR/BFS they've bitten off more than they can chew. (As an aside, have been pleased at the turn of things so far with F9 reuse, because it bore a slight resemblance to suggestions I made in the 1970's that totally PO'd the pre-EELV/CELV crowd and caused my departure into Silicon Valley for a decade - have lived long enough to be able to say "I told you so" at certain retirement parties ... but I digress. Would have never had such a broad and fascinating career otherwise, so it was a blessing.)

As far as an interim vehicle, two things are likely. First, is keep in mind MVac was only testable on F9US, in flight. There was no vacuum test stand. Second, Musk sets targets where he thinks no one else will dare reach.

So RVac on the vehicle, and likely something that ends up in 100% total LV reuse seem to be the minimum.

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?

Yes, Jim's comments on what you'd have to do to have a mixed fuel vehicle are spot on. And what I think you're suggesting is to allow a third pad by reusing some of 39A's propellant field to support such.

Falcon integrates horizontally, and the method it fuels the US would have to be modified substantially to allow any RVac vehicle to be added, which would carry-on to GSE as well. Use of a MLP would require support costs to maintain the MLP and its mods, and going between horizontal to vertical multiple times would mean you'd have the worst of both worlds cost wise.

The trouble with using part time 39B would be that you'd need a specialized TEL with its own hydraulic lift, which would have to negotiate the roadways (pneumatic tires?) to exit the integration facility and trundle to/from 39B. Look how delayed its been to get 39A's operational.

Too much special one time stuff. And anything that might in theory compromise SLS schedules will cause a full stop.

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.

There's regular operations and "one time" operations. Everything around Falcon is designed for horizontal operations - jigs/fixtures/equipment/operations. Now you have to rework the vehicle and everything else. What's the gain for this loss?

SX seems to work by sideways leveraging to the max things, so they might be willing to make small exceptions to this while keeping the rest in place.

I'd say if they had to launch on an MLP (say an absurd govt request), they'd integrate the entire vehicle, payload and fairing onto some TE, truck it to the MLP possibly in the VAB (or not), and crane it onto a launch mount with masts attached to an adapter that attached to the MLP. To service the payload/vehicle, they'd reverse the process.

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?

More likely they'd follow the mold line for BFS - because they'd be able to model/windtunnel the new LV to confirm and build upon a subscale design. Use a hinge/door to allow payload sep with a pneumatic plunger.

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.

Yes.

Here's a key point - it would seem they need more experience with composites on the LV/SC at scale and in use. That's another guiding light for an interim vehicle.

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?

Or Musk could knock on Bezos door and ask him to borrow launch facilities while he gets his BE4 working? 

Yes, they'd like use, but ... without stepping on any issues and cost multipliers.

How I'd do it would be to have a minimal TEL like the LC-40 one and use a crane. Never attempt anything but the minimum for a low flight rate system that would work with portable facilities including methane tankage, likely the issue would be around propellant chilling (ideal if you could avoid it).

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.

Keep in mind Jim's excellent comments about the cost of mixed propellant architecture.

The only thing that fights them is the potential need to slow down Falcon 9 reuse economics and industry consolidation. If you don't have enough payloads to launch, perhaps factoring in a such a hybrid vehicle isn't such a bad thing, because you'd be topped out anyways and could afford the disruption.

[envy887]

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 know a larger diameter was the intent of the post you were responding to, but this bit isn't strictly true. Raptor will be designed to be easier to reuse. And it would allow much higher thrust, which enables higher thrust levels, allowing a larger upper stage. That lets the booster stage lower and still get better performance, enabling easier reuse.

[John Alan]

I listened to the mp3 several times thru... good interview... 

As Jim pointed out... (and I agree 100% with him on this point)
Road Transport of ALL pieces is a KEY SpaceX Falcon 9 system attribute that they will NOT give up lightly.

SpaceX is more likely (in my opinion) to built a couple new sets of FH side boosters with Meth/Lox tank splits and  Raptor engines on the side boosters only... RP-1/Lox still on the Center Core and S2...
Size and number engines still TBD... Obviously land able on one engine (engines not too big IOW)...
Higher peak thrust from the side boosters... Work on the gravity losses...
Push hard up to short of Max-Q... back off... then push hard again...
Peel off and RTLS... Refurb and repeat...

The only change to the GSE is the launch mount... Boosters are bottom fill and drained anyway...
The TE tower is not changed... Still RP-1 and LOX...

If anything... this is a way SpaceX can leverage Raptor to increase F9 Heavy performance with few changes to GSE and no changes to single stick flight hardware and GSE...

I honestly think (in my opinion) that it's cheaper to throw away 15% (as MS stated in the talk, 70/15/15 cost splits) then give up so much making a F9 RUS that can be recovered...

Just my opinion on topic... 

[Robotbeat]

I think the IAC-era plan for ITS was to initially fly both ITS and Falcon family from 39a, so they would've needed to have both methane and kerosene GSE anyway.

If they decided to do Raptor US, my guess is it'd be done initially for a small fraction of missions. The primary point would be to demonstrate the technology and help pay for its development, then transition to a pure ITS-based launcher, probably subscale. The Raptor US and associated GSE would be a down payment on this pure methane infrastructure.

But I could easily see them skip a Raptor US and go straight to subscale ITS. I honestly can't tell what they'll do at this point, but they'll do one of those two options.

[Robotbeat]

I find the idea that they might go straight to subscale ITS at Brownsville intriguing. They seem to be able to maintain quite the launch rate from a single pad, and they haven't even flown block 5 yet (which should allow an even higher flightrate per pad). Once both LC40 and LC39a are operational and in the swing of things starting in 2018, they probably won't need Brownsville until later anyway, say 2020 or so. Brownsville itself likely won't be ready for high flight rate operations until 2019. Just in time for suborbital tests of a subscale ITS (and suborbital tests are in the paperwork for Brownsville, right?).

Makes a lot of sense to skip installing kerosene infrastructure in Boca Chica/Brownsville.

[QuantumG]

Full reusability within a few years is a worthy goal.

[Mader Levap]

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.

It is nicest spin I've seen ever for "Damn, it is harder than we thought, more costly than we anticipated and way, way too ambitious. Time to scale it down! A lot. ITS is no more.".

[MATTBLAK]

I never expected ITS when it was announced - even though the rumours had been strong. What I had expected was a planned launch vehicle the next step up from Falcon Heavy in scale. Perhaps something that could push a rather large version of Dragon on Trans-Mars injection. A craft scaled for a crew of four or six that could make a short stay, manned Martian 'scout' mission; what we would traditionally call - and sometimes disparagingly so - a 'Flags & Footprints' event.

A bit like the traditional 'Mars Direct' architecture that we all know and some of us even love. I wondered about a mission like this - free of the slow, drawn-out, poorly funded NASA way of doing business. I imagined Elon announcing a rocket slightly bigger in size and capability than SLS; powered by the 'Generation 1.0' LOX/Methane Raptor engines. I had in mind a triple-core launcher, similar to Falcon Heavy in configuration - but with each stage being much wider than Falcon's. Perhaps each as much as 6 meters in diameter - each stage powered by a cluster of Raptors and the upper stage/Earth Departure Stage powered by 1 or 2 Raptors. Without getting too much into 'Rocket Lego' at this point - I imagined the notional launcher as being capable of placing 200 metric tons into LEO in fully expendable mode and about 140 tons in reusable mode. Twinned launches of these could send the 'super-sized' Dragon Mars Landers on a fast track to Mars.

I had reasoned that the Falcon Heavy sending Red Dragons to Mars would be the subscale, proof of concept for a larger system to come later. Never in my wildest dreams did I imagine the monstrous, mega-sized ITS system that Elon did announce last year - a system that would need veritable small oceans of propellants transferred in space and manufactured on Mars. I fully expected some kind of intermediate step between Falcon Heavy/Red Dragon and ITS... 

[high road]

When she said '2020 is very agressive', I didn't get the feeling she was talking about BFS, but in general. Especially with her not committing to Spacex sending a red dragon before they do the big one, I interpret this as meaning that there will be no launch to Mars in 2020. Any alternative views on that?

[MATTBLAK]

In as much as Falcon Heavy is years late - made so presumably because of the numerous changes to the Falcon 9 series. I don't expect to see Red Dragon to Mars before the next launch window in 2022.

[john smith 19]

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

No, you can't.  The current fairing halves are road transportable.

The question was "What is the largest diameter of US that could feasibly fit atop an F9/FH?"

ULA in their Atlas V manual said they had looked at PLF's up to 5.2m in dia. That's a ratio of 1.889:1.
Taking F9's Dia at 3.7m that's a potential 6.98m diameter PLF

Caveats. 
Rather obviously F9 <> Atlas V.  OTOH F9 is built to human rating safety factors.
Detailed analysis is needed to confirm no show stoppers throughout any planned trajectory.
PLF to core dia ratio for Atlas V is a baseline number only. It depends how much of a design driver a PLF bigger than the core dia was during the design process for F9.
[EDIT Looking at that number I can't help seeing Musk talking to the aerodynamics team and saying "Let's see if we can do 2:1 on the PLF ratio."  After all we do know that Musk likes to "push the envelope" (size)  ]