Author Topic: Tom Mueller interview 02 May 2017  (Read 96861 times)

Offline meekGee

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Re: Tom Mueller interview 02 May 2017
« Reply #20 on: 05/14/2017 07:31 am »
Power on Mars- fission is the way to go but will have to be solar initially.
Need solar panels covering 4 football fields to make fuel for the trip home over 2 years, and keep dust off them.
SpaceX is just offering a cheap ticket to Mars, it will take other companies, investors, governments to make everything else.
That's the bit that puts my mind at rest.  I couldn't see how solar would cut it in any meaningful scale - and I guess they couldn't either.
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Offline Jimmy Murdok

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Re: Tom Mueller interview 02 May 2017
« Reply #21 on: 05/14/2017 08:15 am »
Tom's talk starting to get media attention:

Quote
Top SpaceX employee throws shade at just about all of his competitors
The price that government programs “charge for their rockets is just ridiculous.”

by Eric Berger - May 14, 2017 1:24am BST

https://arstechnica.com/science/2017/05/a-top-spacex-employee-throws-shade-at-just-about-all-of-his-competitors/

Eric is just highliting the controversial stuff of a very interesting interview. It does not help to have more of these in the future.
The foldable legs, F9 24 hour turn around in few months (as a matter of HR costs, not much on time), Tesla factory using coke manufacturing as a model (physical limits of machinery), Merlin D strategy.... are FMPOV much more interesting parts of the interview. Don't let the reality spoil a good headline.

Offline Dante80

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Re: Tom Mueller interview 02 May 2017
« Reply #22 on: 05/14/2017 09:33 am »
Given the cost goal Elon gave him for the Merlin 1D, depending on how close he got, those engines could be a whole lot cheaper than people have estimated them to be. That was a pretty seriously low price he was targeting.

Reading the transcript gives me the impression that Merlin 1C had a marginal manufacturing cost of around $600K. And that Merlin 1D brought this number down,..a lot.

Musk approaching things like engine cost from first principles (in a - deceptively - naive way too) fits the description. And also provides some insight on how differently some choices/decisions are made in this company.

This is both good and bad, as Mueller has stated. I fully remember the ordeals of bringing the octaweb and M9 to service.

Offline AncientU

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Re: Tom Mueller interview 02 May 2017
« Reply #23 on: 05/14/2017 10:07 am »
I'm just glad to see that someone with so much influence in today's space development has such a huge night and day difference in attitude compared to the status quo of most of the experts on this forum.

A bit too broad...  Most of the experts on this forum are enthralled by what SpaceX is doing because they know much better than the rest of us how friggin' hard it is to do what they have done -- and are getting ready to do.

There are notable exceptions...
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Offline AncientU

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Re: Tom Mueller interview 02 May 2017
« Reply #24 on: 05/14/2017 10:11 am »
Merlin 1D uses a method called “Phase shut off”, removes most valves reducing chances of failure by removing components and removing a lot of risk of a hard start.
I think he means "face shutoff", meaning propellants are "shut off" at the injector face.

See e.g. http://www.rocket-propulsion.info/resources/articles/TRW_PINTLE_ENGINE.pdf.

The interesting bit...
Quote
And, uh, I’ve seen that hurt us before, I’ve seen that fail, but I’ve also seen— where nobody thought it would work— it was the right decision. It was the harder way to do it, but in the end, it was the right thing. One of the things that we did with the Merlin 1D was; he kept complaining— I talked earlier about how expensive the engine was. <inaudible> [I said,] “[the] only way is to get rid of all these valves. Because that’s what’s really driving the complexity and cost.” And how can you do that? And I said, “Well, on smaller engines, we’d go phase-shutoff, but nobody’s done it on a really large engine. It’ll be really different.” And he said, “We need to do phase-shutoff. Explain how that works?” So I drew it up, did some, you know, sketches, and said “here’s what we’d do,” and he* said “That’s what we need to do.” And I advised him against it; I said it’s going to be too hard to do, and it’s not going to save that much. But he made the decision that we were going to do phase-shutoff.

So we went and developed that engine; and it was hard. We blew up a lot of hardware. And we tried probably tried a hundred different combinations to make it work; but we made it work.

* love the speed of that trade
« Last Edit: 05/14/2017 10:14 am by AncientU »
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Offline mlindner

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Re: Tom Mueller interview 02 May 2017
« Reply #25 on: 05/14/2017 12:14 pm »
Tom's talk starting to get media attention:

Quote
Top SpaceX employee throws shade at just about all of his competitors
The price that government programs “charge for their rockets is just ridiculous.”

by Eric Berger - May 14, 2017 1:24am BST

https://arstechnica.com/science/2017/05/a-top-spacex-employee-throws-shade-at-just-about-all-of-his-competitors/

Eric is just highliting the controversial stuff of a very interesting interview. It does not help to have more of these in the future.
The foldable legs, F9 24 hour turn around in few months (as a matter of HR costs, not much on time), Tesla factory using coke manufacturing as a model (physical limits of machinery), Merlin D strategy.... are FMPOV much more interesting parts of the interview. Don't let the reality spoil a good headline.

Yes, Eric is doing a huge disservice to all of space media reporting by posting such absurd comments. He should retract such articles. He's writing hit pieces to get clicks rather than to actually inform. Shame on him.
« Last Edit: 05/14/2017 12:18 pm by mlindner »
LEO is the ocean, not an island (let alone a continent). We create cruise liners to ride the oceans, not artificial islands in the middle of them. We need a physical place, which has physical resources, to make our future out there.

Offline alang

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Re: Tom Mueller interview 02 May 2017
« Reply #26 on: 05/14/2017 12:53 pm »
Interested to hear what Tom Mueller said about staffing at Stennis being traditionally  100 people whereas they could get away with 5 to 10 at their site.
I wonder how much that influences engine development? Perhaps it's a significant reason they've been able to do more radical things like the "face shut off" being discussed.

Offline GORDAP

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Re: Tom Mueller interview 02 May 2017
« Reply #27 on: 05/14/2017 01:09 pm »
One nugget I found interesting was when he was talking about the CommX constellation(s), he said something to the effect, 'Now imagine that you could deploy these with a rocket that can put hundreds of tons into orbit at a time...'.  I guess that solidly confirms SpaceX's plans to use the ITS (as opposed to, say, FH) as the main vehicle to deploy CommX. 

Though that presents a bit of chicken/egg problem, as I think Musk had previously indicated that they needed CommX revenues to help pay development costs for ITS.

Offline meekGee

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Re: Tom Mueller interview 02 May 2017
« Reply #28 on: 05/14/2017 01:19 pm »
One nugget I found interesting was when he was talking about the CommX constellation(s), he said something to the effect, 'Now imagine that you could deploy these with a rocket that can put hundreds of tons into orbit at a time...'.  I guess that solidly confirms SpaceX's plans to use the ITS (as opposed to, say, FH) as the main vehicle to deploy CommX. 

Though that presents a bit of chicken/egg problem, as I think Musk had previously indicated that they needed CommX revenues to help pay development costs for ITS.
Unless constellation 2.0 will use much larger satellites, but still as many.

Remember the statistics on how fast data traffic is growing, and factor in self driving cars and other upcoming developments, and constellation capability will have to grow accordingly...
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Offline Herb Schaltegger

Re: Tom Mueller interview 02 May 2017
« Reply #29 on: 05/14/2017 01:59 pm »
One nugget I found interesting was when he was talking about the CommX constellation(s), he said something to the effect, 'Now imagine that you could deploy these with a rocket that can put hundreds of tons into orbit at a time...'.  I guess that solidly confirms SpaceX's plans to use the ITS (as opposed to, say, FH) as the main vehicle to deploy CommX. 

Though that presents a bit of chicken/egg problem, as I think Musk had previously indicated that they needed CommX revenues to help pay development costs for ITS.
Unless constellation 2.0 will use much larger satellites, but still as many.

Remember the statistics on how fast data traffic is growing, and factor in self driving cars and other upcoming developments, and constellation capability will have to grow accordingly...

Admittedly, it's been a while since I last looked through the FCC database, but I don't think they've even approved constellation 1.0. All the spacecraft general physical details, nominal orbital elements for each plane, RF characteristics at ground level for each altitude, etc. have to be detailed by the applicant, reviewed by the FCC (and arguably the ITU if service is being performed outside of FCC jurisdiction), and then approved before the constellation can begin operating.

If SpaceX is going to massively revise the plans for their satellites, there will be a several year regulatory lag from the time they make their plans to the time the can make good on those plans ... I don't think SpaceX is the kind of organization that likes being behind that kind of curve.
Ad astra per aspirin ...

Offline envy887

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Re: Tom Mueller interview 02 May 2017
« Reply #30 on: 05/14/2017 02:21 pm »
His examples about the Merlin have some interesting numbers:

About 1000 lbs engine mass. Roughly 450 kg, which is a bit lower than the previous estimates I've seen.

About 800 lbs/s propellant mass flow rate. That's​ about 360 kg/s, which is quite a bit higher than the 275 to 300 kg/s typically quoted for Merlin.

About 10,500 ft/s exhaust velocity. He also says about Mach 10 exhaust velocity. Those are 3200 and 3400 m/s or 325/345 second ISP.

These don't add up to the stated thrust of Falcon 9, which is 7606 kN. With those flow rates and velocities it would be 10000 kN or 11000 kN.

But maybe Merlin is considerably more capable than we expected?
« Last Edit: 05/14/2017 02:22 pm by envy887 »

Offline cppetrie

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Re: Tom Mueller interview 02 May 2017
« Reply #31 on: 05/14/2017 03:04 pm »
One nugget I found interesting was when he was talking about the CommX constellation(s), he said something to the effect, 'Now imagine that you could deploy these with a rocket that can put hundreds of tons into orbit at a time...'.  I guess that solidly confirms SpaceX's plans to use the ITS (as opposed to, say, FH) as the main vehicle to deploy CommX. 

Though that presents a bit of chicken/egg problem, as I think Musk had previously indicated that they needed CommX revenues to help pay development costs for ITS.
I interpret that to mean the full deployment and refreshes would be done via ITS or Mini-ITS variant. The initial deployment of the number of satellites headed to make it operational and generating revenue will be via F9/FH. That sort of addresses the chicken/egg issue you mentioned.

Offline x15_fan

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Re: Tom Mueller interview 02 May 2017
« Reply #32 on: 05/14/2017 03:18 pm »
There wasn't actually a lot new in here. A lot of the stuff was extrapolatable.

A lot of the "new" content is simply taking stuff Musk has already said seriously.

I could not agree more. But, to me, one reason Musk is consistently underestimated is his delivery of this type of content. To take the 24 hour turn around for example, he leaves it somewhat vague on what the actual benchmarks are (you or I get a feel for it) but others take it to extreme, like turning around a pad , same booster, in 24 hours by next year.  Also, he tends to deliver these engineering requirements in a somewhat whimsical fashion, sort of off the cuff feel with quips about how you'll have 24 hours to look at it (what more could you need in terms of inspection). I like this about him because it constantly seems to befuddle many observers and offers us a tease to the actual hard engineering requirements and trades. It seems like a game he plays with us and his detractors to troll them.

Offline Basto

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Re: Tom Mueller interview 02 May 2017
« Reply #33 on: 05/14/2017 03:36 pm »
His examples about the Merlin have some interesting numbers:

About 1000 lbs engine mass. Roughly 450 kg, which is a bit lower than the previous estimates I've seen.

About 800 lbs/s propellant mass flow rate. That's​ about 360 kg/s, which is quite a bit higher than the 275 to 300 kg/s typically quoted for Merlin.

About 10,500 ft/s exhaust velocity. He also says about Mach 10 exhaust velocity. Those are 3200 and 3400 m/s or 325/345 second ISP.

These don't add up to the stated thrust of Falcon 9, which is 7606 kN. With those flow rates and velocities it would be 10000 kN or 11000 kN.

But maybe Merlin is considerably more capable than we expected?

It seemed like he was just pulling approximate numbers off the cuff. I would not read too much into that.

Offline AncientU

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Re: Tom Mueller interview 02 May 2017
« Reply #34 on: 05/14/2017 03:54 pm »
His examples about the Merlin have some interesting numbers:

About 1000 lbs engine mass. Roughly 450 kg, which is a bit lower than the previous estimates I've seen.

About 800 lbs/s propellant mass flow rate. That's​ about 360 kg/s, which is quite a bit higher than the 275 to 300 kg/s typically quoted for Merlin.

About 10,500 ft/s exhaust velocity. He also says about Mach 10 exhaust velocity. Those are 3200 and 3400 m/s or 325/345 second ISP.

These don't add up to the stated thrust of Falcon 9, which is 7606 kN. With those flow rates and velocities it would be 10000 kN or 11000 kN.

But maybe Merlin is considerably more capable than we expected?

It seemed like he was just pulling approximate numbers off the cuff. I would not read too much into that.

TM breathes this stuff. 
I'd take him literally before believing our numbers to the slightest degree.
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Offline Basto

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Re: Tom Mueller interview 02 May 2017
« Reply #35 on: 05/14/2017 04:42 pm »
His examples about the Merlin have some interesting numbers:

About 1000 lbs engine mass. Roughly 450 kg, which is a bit lower than the previous estimates I've seen.

About 800 lbs/s propellant mass flow rate. That's​ about 360 kg/s, which is quite a bit higher than the 275 to 300 kg/s typically quoted for Merlin.

About 10,500 ft/s exhaust velocity. He also says about Mach 10 exhaust velocity. Those are 3200 and 3400 m/s or 325/345 second ISP.

These don't add up to the stated thrust of Falcon 9, which is 7606 kN. With those flow rates and velocities it would be 10000 kN or 11000 kN.

But maybe Merlin is considerably more capable than we expected?

It seemed like he was just pulling approximate numbers off the cuff. I would not read too much into that.

TM breathes this stuff. 
I'd take him literally before believing our numbers to the slightest degree.

Mach 10 is an imprecise number and generally not used when referring to engine performance.  That was the point I was making.  I agree that he lives and breathes this stuff and could probably pull very precise numbers off the top of his head, but I had the impression that he was pulling approximations to make the subject matter less technical.

I think sometimes we try too hard to parse every word that was said.



Offline meekGee

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Re: Tom Mueller interview 02 May 2017
« Reply #36 on: 05/14/2017 04:42 pm »
One nugget I found interesting was when he was talking about the CommX constellation(s), he said something to the effect, 'Now imagine that you could deploy these with a rocket that can put hundreds of tons into orbit at a time...'.  I guess that solidly confirms SpaceX's plans to use the ITS (as opposed to, say, FH) as the main vehicle to deploy CommX. 

Though that presents a bit of chicken/egg problem, as I think Musk had previously indicated that they needed CommX revenues to help pay development costs for ITS.
Unless constellation 2.0 will use much larger satellites, but still as many.

Remember the statistics on how fast data traffic is growing, and factor in self driving cars and other upcoming developments, and constellation capability will have to grow accordingly...

Admittedly, it's been a while since I last looked through the FCC database, but I don't think they've even approved constellation 1.0. All the spacecraft general physical details, nominal orbital elements for each plane, RF characteristics at ground level for each altitude, etc. have to be detailed by the applicant, reviewed by the FCC (and arguably the ITU if service is being performed outside of FCC jurisdiction), and then approved before the constellation can begin operating.

If SpaceX is going to massively revise the plans for their satellites, there will be a several year regulatory lag from the time they make their plans to the time the can make good on those plans ... I don't think SpaceX is the kind of organization that likes being behind that kind of curve.
Of course, but constellation 2.0 can be 5 years down the line.

Ironically, it will be easier to update the constellation​ hardware than it will be to update towers...
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Offline livingjw

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Re: Tom Mueller interview 02 May 2017
« Reply #37 on: 05/14/2017 04:44 pm »
With regards to the mixture ratio range of 3.6 - 3.8. A mixture ratio of 3.6 has ~10% excess fuel where as 3.8 has ~5%. Where it ends up will depend on combustion efficiency trends. It is easier to get high combustion efficiency with a larger excess of fuel, harder with lower excess, and really hard at stoichiometric. They may even allow for tuning between these mixture ratios for different uses. For example, the Mars burn will favor ISP over density*ISP, which the booster will favor.
« Last Edit: 05/14/2017 04:49 pm by livingjw »

Offline meekGee

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Re: Tom Mueller interview 02 May 2017
« Reply #38 on: 05/14/2017 05:00 pm »
This was a good interview since it gave context and insight.

For example, we knew about "24 hours", but now we know that it was originally 12, staff pushed back, and they settled on 24, giving confidence that this is not just an aspirational goal, but something they think they can achieve.

He's actually very clear about that.  "We don't plan on launching a rocket every day  but we could.", And "we can turn around a rocket in 24 hours".

I'm pretty sure by "rocket" he means "stage", and according to the laws of physics (and of common Sense engineering) you can stack a second stage and payload on top in a few hours.

But I'll buy once every 2-3 days too...
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Offline tdperk

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Re: Tom Mueller interview 02 May 2017
« Reply #39 on: 05/14/2017 05:28 pm »
Tom's talk starting to get media attention:

Quote
Top SpaceX employee throws shade at just about all of his competitors
The price that government programs “charge for their rockets is just ridiculous.”

by Eric Berger - May 14, 2017 1:24am BST

https://arstechnica.com/science/2017/05/a-top-spacex-employee-throws-shade-at-just-about-all-of-his-competitors/

Eric is just highliting the controversial stuff of a very interesting interview. It does not help to have more of these in the future.
The foldable legs, F9 24 hour turn around in few months (as a matter of HR costs, not much on time), Tesla factory using coke manufacturing as a model (physical limits of machinery), Merlin D strategy.... are FMPOV much more interesting parts of the interview. Don't let the reality spoil a good headline.

Yes, Eric is doing a huge disservice to all of space media reporting by posting such absurd comments. He should retract such articles. He's writing hit pieces to get clicks rather than to actually inform. Shame on him.

I read that article and I didn't read a hit piece.

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