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

[MP99]

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.

One interesting question is whether it makes sense to refly block 3 or 4 boosters once block 5 hits its stride.

If not, how about flying out the rest of their lives flying out of Spaceport America, lifting test versions of a Raptor upper stage?

Cheers, Martin

[meekGee]

It's ok, I remember when you considered landings and reuse to be amazing people fantasies, back in GH days.

[citaiton needed], because I can't remember when I said that "landings and reuse to be amazing people fantasies". I don't think I ever said something like that. I view and vieved reusability efforts achievable with current technology.

You probably mixed it up with my opinion about SpaceX's Mars ambitions. THAT one indeed I consider quite unrealistic.

I reviewed Mader's past posts quite a way back and actually his predictions were quite accurate. For example, he correctly predicted the number of F9 launches in both 2012 and 2013, as well as the year when the first reused booster flew.

I am very happy to see SpaceX is on way to launch way more in 2017 than I predicted.

If you are not getting pushbacks from reality, it means you're not trying hard enough. Trying to push into unbelievable fantasy land is the only way to know where the boundary of reality is.

It is nicest way possible to frame that problem.

I humbly stand corrected then.

I was having it out with someone back then, and I remembered it as having been you.

[watermod]

In the future when some first stages are nearing end of life with a high number of re-flights, those where confidence is getting lower I have a simple question.
It is that Shotwell hinted that full thrust really wasn't and some engines had been tested to 240... about 1/3rd to 1/4 higher thrust than when doing a safe launch.  So...  would there be any benefit to seeing what a first stage can really loft on a near end of life first stage so one can have a reference number?

[Space Ghost 1962]

In the future when some first stages are nearing end of life with a high number of re-flights, those where confidence is getting lower I have a simple question.

It is that Shotwell hinted that full thrust really wasn't and some engines had been tested to 240... about 1/3rd to 1/4 higher thrust than when doing a safe launch.

I took it as a measure of margin in the engines. Like you might desire if you had an engine failure and still had to ramp the remaining 8 or 2 engines to 120% or 170% to complete the burn/mission.

So...  would there be any benefit to seeing what a first stage can really loft on a near end of life first stage so one can have a reference number?

No, that's not how it works.

You have a vehicle, it has capability/margin/flaws, and as you use it these cause it to tend towards mission limits/failure, just as if you drive a car its service lifetime.

Some experience a catastrophic failure early on, other might run indefinitely (once had a car with an indefinite life, did a fair portion of a million miles, kept it just to see how far it would last, ended up salvaging it last year because it was outlasting me ...).

Heavy use airliners have airframes that are limited by microfractures, usually due to the pressurization changes (inflating/deflating) (in theory you could ameliorate these by annealing/remelting but it would be impractical). Likely a variation of this is what would limit reuse of any such vehicle, apart from engine wear, where engines could be rebuilt/re-qualified.

One could accurately project such materials limits on use, and confirm by sample tags.

Would be more accurate than testing one to exhaustion, because of sample size issues and lots.

[Lobo]

Space ghost.  Good input as always. 

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

Don't worry about it for me. :-)
 I always prefer clarity over agreement.   I'd rather learn something new when possible, even when it rains on my parade. Which is why I always appreciate Jim's posts.

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.

<snip>

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.

Ok, a couple of things here.

First, I'm not necessarily saying such a Falcon Test vehicle would be mixed fuel.  I think there's test data to be had with a modified Raptor booster as well.  Not because it would be much performance booster, but then at least a subscale Raptor could fly on a reusable booster prior to going on a larger purpose built vehicle.  The Falcon booster would serve as a test best for an mini-BFR or full BFR booster.  They could test various ascent trajectories, practice landing and reusing the engine.  And see what's going on with it after actual flight cycles.  So not saying they'd have to put both RP-1 and LCH4 out at 39B, but perhaps just LCH4.  It also could serve as test to a future Falcon variant that went to 100% methalox, at some point.

As far as horizontal vs. vertical integration, please excuse my lack of technical knowledge of it, but could an LV that's designed to be horizontally integrated, be vertically integrated as well?  (maybe with some minor mods?)  Seems like any LV that could stand up on a pad on it's on weight, could handle being stacked by cranes in the VAB with some sort of fixed TEL build onto the MLP to carry the umbilicals to the existing connections and such.  But it seems you are saying that an LV designed to be horizontally integrated, -cannot- be vertically integrated?
I'm assuming the need for the stack to go actually horizontal would be eliminated for such a test vehicle, and thus the VAB and MLP would be used as designed to be.  If the LV must go horizontal and vertical, then this idea becomes much less plausible.  Better to do it somewhere else that's specifically set up for horizontal.

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.

True.  Guess it depends on if they have BFS's OML decided upon yet (for real) or not.  But the Falcon PLF OML could be a very similar one, and it's already known to fly fine on the F9 booster.  But yes, if they have the BFS OML already figured out, might as well go for that, and then gain that data from the testing process.

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).

True.  I agreed with KISS.  But I was thinking of where?  If not 39B.  Seems like as it's available, and right there, and I'm sure Musk is wanting to help push SLS out there door, operating from it's very own pad might not hurt things optically any.  Plus it could be done without interrupting one of the working Falcon pads.  Once Boca Chica is done, it could be done there.  And it's final design could actually be tailored just for this purpose.  If Falcon must be integrated horizontally, then this would probably make much more sense than trying to go horizontal with it at 39B.
With 39A and LC-40 operating, that could be enough capacity to allow Boca Chica to have interruption of a test vehicle testing there.  Not sure what SpaceX's full manifest will be, but I think once 39A starts flying government payloads and crew, they'll want both LC-40 and Boca Chica to be operating without interruption to keep up with their commercial contracts.  SO that'd still beg the question of where they do it.  Perhaps VAFB, as there aren't nearly as many West Coast Launches as East Coast.

[sevaithan]

One idea that I haven't seen yet in this thread is the 240k thrust level as a contingency for a multiple engine failure. For example, if an engine failure takes out another engine or two right after liftoff and they have a reasonably light payload, maybe by pushing the rest of the engines to their limit they could still complete the mission, especially seeing as the F9 has a significantly larger margin than other boosters due to the reuse margin, which would obviously be used for the main mission in the case of engine failure. The Shuttle had contingency thrust levels so this isn't a new idea, and seeing as most of the Merlin thrust increases since the D upgrade have been software only there's no reason to think they couldn't incorporate the maximum test stand thrust into the code for if the mission would otherwise fail to give them an additional fallback before complete failure.

[Nomadd]

One idea that I haven't seen yet in this thread is the 240k thrust level as a contingency for a multiple engine failure. For example, if an engine failure takes out another engine or two right after liftoff and they have a reasonably light payload, maybe by pushing the rest of the engines to their limit they could still complete the mission, especially seeing as the F9 has a significantly larger margin than other boosters due to the reuse margin, which would obviously be used for the main mission in the case of engine failure. The Shuttle had contingency thrust levels so this isn't a new idea, and seeing as most of the Merlin thrust increases since the D upgrade have been software only there's no reason to think they couldn't incorporate the maximum test stand thrust into the code for if the mission would otherwise fail to give them an additional fallback before complete failure.

It's sort of like why 4 engine airliners aren't really much safer than two engine planes. Two unrelated engine failures would be extremely unlikely, and if multiple failures were from the same cause, it would almost always take all the engines out. (Which actually sounds really dumb from someone who was on a C-130 once that had two unrelated engine failures)

[Jim]

Been thinking about the mods to do chilled props. It might be the case that they might allow liquid methane anyways already, as they could have fill/drain lines that are the superset of LOX and chilled kero, then for cost savings use the same hardware for both lines. You might be able to just switch the feeds and have a parallel tank farm and associated GSE on the F9US - this is a believable means to field to an existing pad such a capability.

 chilled kero is no where the same as methane.  Much different designs. 

[S.Paulissen]

Been thinking about the mods to do chilled props. It might be the case that they might allow liquid methane anyways already, as they could have fill/drain lines that are the superset of LOX and chilled kero, then for cost savings use the same hardware for both lines. You might be able to just switch the feeds and have a parallel tank farm and associated GSE on the F9US - this is a believable means to field to an existing pad such a capability.

 chilled kero is no where the same as methane.  Much different designs.

Wouldn't methane use something akin to the LOX lines plus a flare stack?

[su27k]

Per Blue Origin retains engine lead as House considers limitations on launch system funding there's an attempt in the house to limit USAF funding to first stage engine only, I wonder if Gwynne Shotwell's vague comment about "looking into using Raptor on Falcon" is a response to this. If SpaceX can produce a credible plan to use Raptor on Falcon 9 first stage, they can claim it's a first stage engine and thus eligible to receive continued USAF funding.

[envy887]

Per Blue Origin retains engine lead as House considers limitations on launch system funding there's an attempt in the house to limit USAF funding to first stage engine only, I wonder if Gwynne Shotwell's vague comment about "looking into using Raptor on Falcon" is a response to this. If SpaceX can produce a credible plan to use Raptor on Falcon 9 first stage, they can claim it's a first stage engine and thus eligible to receive continued USAF funding.

That seems a bit unnecessary. SpaceX has always planned on using Raptor as a first stage engine.

Edit: and the proposed funding specifically does include both engines for new vehicles and methane engines. Raptor could be eligible for funding if SpaceX proposed a vehicle that uses it as a booster engine for EELV missions.

[gongora]

Opinions on whether Congress is corrupt really don't belong in the Gwynne Shotwell Interview thread.  The discussion about the proposed (not yet adopted) budgetary marks for RD-180 replacement really doesn't belong here either.

[Lobo]

Yes.

Because when you design it, you have to consider integration/checkout of the vehicle. There's already been a lot of work to streamline/fixtures/measurements that even have the "sag" of the vehicle factored in.

Now you'd have to start all over, find the surprises, and mitigate them.

Ok, thanks for the input and education. 

Perhaps VAFB, as there aren't nearly as many West Coast Launches as East Coast.

They have to rebuild the TEL to support FH there. Perhaps they could factor in an additional propellant/GSE chain.

Yea, seems they could probably best able to do pad mods and testing while not interrupting their normal operations as much as at their East Coast pads, as their manifest is pretty light in comparison.  So were there to be such a Falcon-Raptor test vehicle (and Shotwell did say specifically they were looking at Falcon for Raptor) then that might be a better location to work on it than 39B, on second thought.

[Lobo]

Been thinking about the mods to do chilled props. It might be the case that they might allow liquid methane anyways already, as they could have fill/drain lines that are the superset of LOX and chilled kero, then for cost savings use the same hardware for both lines. You might be able to just switch the feeds and have a parallel tank farm and associated GSE on the F9US - this is a believable means to field to an existing pad such a capability.

 chilled kero is no where the same as methane.  Much different designs.

So Shotwell both said that they were looking at Raptor for Falcon, and that the Merlin engines have tested out at 190klbs of thrust, and has margin to go over 200klbs.

We know from past Elon's comments that FH was harder to develop and since they introduced reusability, not very conducive to reusability given the tri-core configuration.  They do need it right now, but they may also be happy to move on from it as soon as they are able.  F9 has grown to almost fill in the payload ranges that FH was originally envisioned to be needed for, and FH now is pretty overpowered for most of that payload range if the center core is expended.

So maybe their testing Merlin to those higher thrust levels, and saying they are looking for Raptor on Falcon, is to have yet another upgraded Falcon 9 that will basically replace FH for their sat launching business.  Allowing full reuse on most launches, and maybe an expendable upper stage version for those bigger D4H class missions (rare, but they need to have an offering there).

They could widen such a Raptor upper stage to the PLF width, and use Dragon 2's propulsive landing systems on it.  I don't think something that wide would be road transportable any more, but it should be flyable from Hawthorne to the Cape or VAFB.  Since it would be typically reused, there'd be a fleet of them like there will be F9 boosters.   So it's not like a new one would be needed for every launch.

Now, this gets to the issues of mixed fuels on a pad, as Jim mentioned the added complexities of that.  But, how hard would it be to do that for the Falcon pads?  Is it feasible at all?
Seems like if it's doable, then there could be benefit.  It would allow them to just consolidate on single stick Falcon on all Falcon pads, an not need to accommodate FH.
Then back to just one Falcon core being built in Hawthorne.
Fully reusable system on most launches.
Learning process for a mini-BFS or full BFS later with a biconic style upper stage returning from orbit.

And, at the end of the day, I'm not quite sure how else to reconcile Shotwell's interview comments about both testing Merlin to higher thrust levels, as well as looking at Raptor on Falcon.  Why test the increased Merlins if not looking to possibly up the booster thrust and keep it kerolox?  Which means Raptor on Falcon could then mean only the upper stage, and they just make the necessary pad changes to accommodate mixed fuel LV's.

Although I guess they could be looking at two possible ways to upgrade Falcon.  One is keeping it kerolox and upping the thrust of both stages.  The other is going to all methalox so as to avoid having mixed fuels on the pad?

[whitelancer64]

Been thinking about the mods to do chilled props. It might be the case that they might allow liquid methane anyways already, as they could have fill/drain lines that are the superset of LOX and chilled kero, then for cost savings use the same hardware for both lines. You might be able to just switch the feeds and have a parallel tank farm and associated GSE on the F9US - this is a believable means to field to an existing pad such a capability.

 chilled kero is no where the same as methane.  Much different designs.

So Shotwell both said that they were looking at Raptor for Falcon, and that the Merlin engines have tested out at 190klbs of thrust, and has margin to go over 200klbs.

We know from past Elon's comments that FH was harder to develop and since they introduced reusability, not very conducive to reusability given the tri-core configuration.  They do need it right now, but they may also be happy to move on from it as soon as they are able.  F9 has grown to almost fill in the payload ranges that FH was originally envisioned to be needed for, and FH now is pretty overpowered for most of that payload range if the center core is expended.

So maybe their testing Merlin to those higher thrust levels, and saying they are looking for Raptor on Falcon, is to have yet another upgraded Falcon 9 that will basically replace FH for their sat launching business.  Allowing full reuse on most launches, and maybe an expendable upper stage version for those bigger D4H class missions (rare, but they need to have an offering there).

They could widen such a Raptor upper stage to the PLF width, and use Dragon 2's propulsive landing systems on it.  I don't think something that wide would be road transportable any more, but it should be flyable from Hawthorne to the Cape or VAFB.  Since it would be typically reused, there'd be a fleet of them like there will be F9 boosters.   So it's not like a new one would be needed for every launch.

Now, this gets to the issues of mixed fuels on a pad, as Jim mentioned the added complexities of that.  But, how hard would it be to do that for the Falcon pads?  Is it feasible at all?
Seems like if it's doable, then there could be benefit.  It would allow them to just consolidate on single stick Falcon on all Falcon pads, an not need to accommodate FH.
Then back to just one Falcon core being built in Hawthorne.
Fully reusable system on most launches.
Learning process for a mini-BFS or full BFS later with a biconic style upper stage returning from orbit.

And, at the end of the day, I'm not quite sure how else to reconcile Shotwell's interview comments about both testing Merlin to higher thrust levels, as well as looking at Raptor on Falcon.  Why test the increased Merlins if not looking to possibly up the booster thrust and keep it kerolox?  Which means Raptor on Falcon could then mean only the upper stage, and they just make the necessary pad changes to accommodate mixed fuel LV's.

Although I guess they could be looking at two possible ways to upgrade Falcon.  One is keeping it kerolox and upping the thrust of both stages.  The other is going to all methalox so as to avoid having mixed fuels on the pad?

Easiest reconciliation is that they are "looking into" a Falcon Raptor the same way NASA looked into adding crew to EM-1. They knew it was a terrible idea but needed to confirm that.

[Lobo]

Easiest reconciliation is that they are "looking into" a Falcon Raptor the same way NASA looked into adding crew to EM-1. They knew it was a terrible idea but needed to confirm that.

heh,
Well yes, there's always that too.

[starsilk]

And, at the end of the day, I'm not quite sure how else to reconcile Shotwell's interview comments about both testing Merlin to higher thrust levels, as well as looking at Raptor on Falcon.  Why test the increased Merlins if not looking to possibly up the booster thrust and keep it kerolox?  Which means Raptor on Falcon could then mean only the upper stage, and they just make the necessary pad changes to accommodate mixed fuel LV's.

Although I guess they could be looking at two possible ways to upgrade Falcon.  One is keeping it kerolox and upping the thrust of both stages.  The other is going to all methalox so as to avoid having mixed fuels on the pad?

Because human rating requires 20% margins. Easiest way to do that is to run the engines at 120+% during testing.

Sent from my BLN-L24 using Tapatalk

[Lobo]

Because human rating requires 20% margins. Easiest way to do that is to run the engines at 120+% during testing.

Point taken.  Perhaps they aren't looking at an upgraded booster in that case, but just a possible Raptor upper stage.  Or an all methalox Falcon if they didn't want mixed fuels at the pad.  If they choose to pursue it anyway.

[john smith 19]

RP1 freezing point  -36F / -37c

https://propellants.ksc.nasa.gov/commodities/RP1.pdf

Methane freezing point -295.6F/-182C

It's not a trivial difference.    You'd be unwise to try running liquid Methane through the same plumbing as RP1, so you're looking at a whole new set of plumbing, but only for the US.

I'll also note Shotwell said the FH test flight will attempt dual RTLS on the side boosters and barge recovery for the core but on the US she said they will try a "Long coast" for future NSS missions. From the Centaur flights "long coast" is normally < about 8 hours.

No mention of any attempt at US recovery for this flight. Perhaps (as others have speculated) it will be attempted by the test payload.

ITS is much too big for any of the existing pads that SX is using, so any pad would be a clean sheet, so spec'ing Methane rather than RP1 is no big deal. OTOH converting all pads to Methane, or worse still just the US supply, would be a major PITA.

SX's history is to make block changes, not warehouse un used inventory and generally not to look back.
That suggests if they do introduce Raptor into the F9 line they will go the whole hog, scrap Merlin and go Methane throughout. 

Between Merlins further potential thrust upgrades (190Klb?) and  the final introduction of cross feed (if needed) to FH F9 and FH have a very large potential performance stretch, before any engine or propellant changes. Most, if not all, of the Delta IVH payload/velocity profile should be viable with these architectures.

I'm guessing SX know exactly what they'd have to do put FH above the threshold for the SLS Block 1 as well in terms of payload (I think even the minimum PLF diam for SLS is too big a ratio for the F9 dia core), although I strongly doubt they will discuss this openly.   

[Negan]

Easiest reconciliation is that they are "looking into" a Falcon Raptor the same way NASA looked into adding crew to EM-1. They knew it was a terrible idea but needed to confirm that.

The motives concerning EM-1 were pretty clear. What's the motive for Shotwell to divulge that SpaceX is looking into such an obviously terrible idea?