Author Topic: BFR First Private Passenger POST-announcement (BFR 2018 version) - DISCUSSION  (Read 101206 times)

Offline woods170

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There are "petals" at the back end of the most recent ITS rendering.  I've read some musings that these petals could be a kind of variable expansion nozzle.

You are not up to speed on latest developments. Elon revealed that those "petals" are not petals but cargo containers that can be easily dropped to the surface after landing.


Edit: Ninja'd by docmordrid by just 3 seconds.
« Last Edit: 10/17/2018 07:52 AM by woods170 »

Offline deruch

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“I don’t think that most people even in the aerospace industry know what question to ask. It took us a long time to even frame the question correctly. Once we could frame the question correctly the answer flowed.” Elon Musk recent presentation

{video}  ~18 mins in

What was that question? And why didn’t anybody ask him what it was? I assume the question relates to the raptor engine because he made this point directly after talking about it and praising the raptor development team.

Given your username, I think it's only fitting to say that I don't know what the question is but the answer is undoubtedly 42.  So, maybe something about the optimum number of engines?
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Online OneSpeed

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There are "petals" at the back end of the most recent ITS rendering.  I've read some musings that these petals could be a kind of variable expansion nozzle.

They may not be petals, but the shape of the cargo bins is nonetheless appropriate for the redirection of the recirculating jets that will occur once the individual Raptor plumes begin to interact at high altitudes.
« Last Edit: 10/17/2018 01:35 PM by OneSpeed »

Offline gongora

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“I don’t think that most people even in the aerospace industry know what question to ask. It took us a long time to even frame the question correctly. Once we could frame the question correctly the answer flowed.” Elon Musk recent presentation

Why is space travel so expensive and how can we make it more affordable? /guess

How do we eliminate single point failures (in active systems)? /guess

I suspect that it is something specific to the raptor engine itself given when he said it. My guess would be how large should we make this engine? But this is just a guess. Is there any practical way of asking him a question?

When I was watching the presentation I didn't think that comment had anything specifically to do with Raptor, I thought he was talking about the new launch system in general.

Online Slarty1080

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“I don’t think that most people even in the aerospace industry know what question to ask. It took us a long time to even frame the question correctly. Once we could frame the question correctly the answer flowed.” Elon Musk recent presentation

Why is space travel so expensive and how can we make it more affordable? /guess

How do we eliminate single point failures (in active systems)? /guess

I suspect that it is something specific to the raptor engine itself given when he said it. My guess would be how large should we make this engine? But this is just a guess. Is there any practical way of asking him a question?

When I was watching the presentation I didn't think that comment had anything specifically to do with Raptor, I thought he was talking about the new launch system in general.
I might be wrong but if you look closely from 17:27 on he is heaping praise on the Raptor team in spades for the design then immediately after says "this is a stupidly hard problem and spacex engineering team have done a great job with this design" so I assume he was still talking about raptor at that point. Then at 18:23 he almost says the "engine" before correcting himself to say this "question". So I'm thinking he was still talking about the Raptor at this point up till 18:35 when there is a clear break and he changes topic.
The first words spoken on Mars: "Humans have been wondering if there was any life on the planet Mars for many decades … well ... there is now!"

Offline MikeM8891

“I don’t think that most people even in the aerospace industry know what question to ask. It took us a long time to even frame the question correctly. Once we could frame the question correctly the answer flowed.” Elon Musk recent presentation

What was that question? And why didn’t anybody ask him what it was? I assume the question relates to the raptor engine because he made this point directly after talking about it and praising the raptor development team.

I think the question was about how to optimize the raptor. How to balance weight, efficiency, size, and reliability.

Offline Jcc

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“I don’t think that most people even in the aerospace industry know what question to ask. It took us a long time to even frame the question correctly. Once we could frame the question correctly the answer flowed.” Elon Musk recent presentation

What was that question? And why didn’t anybody ask him what it was? I assume the question relates to the raptor engine because he made this point directly after talking about it and praising the raptor development team.

I think the question was about how to optimize the raptor. How to balance weight, efficiency, size, and reliability.

Yes and go go into detail about the questions would reveal proprietary and ITAR controlled information. He loves  to drop hints, though.

Offline cuddihy

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I think the “question” is probably shorthand for the process of identifying the correct set of tradeoffs to get to an acceptable capability worthy of being funded as a BFS/BFR.

I actually suspect Raptor’s necessary specs were the earliest subset of this set to reach precision—based on empirical data from the prototype Raptor.

I could go further into speculation about what the last parts of this question to be framed were, based on the changes from 2016->2017->now...but that really belongs in the BFS Engineering, not Evolution of Raptor thread.

Online Llian Rhydderch

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From the UPDATES thread, this quotation from AFP after the 9 October Tokyo news conference appeared:

Main points from AFP https://www.afp.com/en/news/826/japan-space-tourist-says-moon-training-shouldnt-be-too-hard-doc-19v81h2
--- snip ---
Quote
Maezawa said he had received "safety guarantees" that allowed him to be able to invite the artists along on the trip, although he confirmed he had not yet begun negotiations with potential fellow-travellers.

I think the folks at AFP may have missed the point of that statement by Maezawa.  I listened to the press conference, and believe the point he made was more that the "safety guarantees" would have to come in and build up with respect to BFR, prior to the 2023 trip, in order for him to most properly play his role as "host curator" of the trip.

That is to say, he's not the least bit interested in taking anyone on a trip without such a growing and reasonable safety record of the craft, before the final and firm-ish invitations would be extended to artists to join him.

It was definitely NOT that he had already received "safety guarantees"

Edit:  fixed a typo
« Last Edit: 10/21/2018 03:32 PM by Llian Rhydderch »
Re arguments from authority on NSF:  "no one is exempt from error, and errors of authority are usually the worst kind.  Taking your word for things without question is no different than a bracket design not being tested because the designer was an old hand."
"You would actually save yourself time and effort if you were to use evidence and logic to make your points instead of wrapping yourself in the royal mantle of authority.  The approach only works on sheep, not inquisitive, intelligent people."

Offline Hominans Kosmos

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“I don’t think that most people even in the aerospace industry know what question to ask. It took us a long time to even frame the question correctly. Once we could frame the question correctly the answer flowed.” Elon Musk recent presentation

  ~18 mins in

What was that question? And why didn’t anybody ask him what it was? I assume the question relates to the raptor engine because he made this point directly after talking about it and praising the raptor development team.
 

Nit picking is not a good method for helping with comprehension of intended meaning. With the added context (which can be found in the sentences leading up to the quote in the video) of extending the praise from strictly the propulsion department, to other departments and the company as a whole, that question setting problem is obviously coming with a change of subject and scope. The phrasing ia clearly chosen to reflect a more general scope - system architecture.

Offline Hominans Kosmos

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IAC2016 BFS was a large slice of the way towards this, but it was implicitly assuming massive funding.
If you look at the numbers in that post, it implied launching only 100 times, which is about what you need for Mars.

But, it was horribly geared for the F9 replacement role, and pretty much would need massive initial funding to do anything on Mars.

It may have become clear that it was unaffordable.
2017/18 is not notably worse for Mars use, especially with in-orbit payload transfer and retanking.
It may in fact be cheaper, given lower more streamlined launch costs - the aim is sub $300K or so cost to launch BFS, neglecting amortisation of the airframe and infrastructure costs. (to make $1M 'cheaper than an economy flight' possible with pad and amortisation costs and profit).

Making it cheaper enough to operate, with high enough cycle counts means that instead of being only somewhat able to compete in the satellite market, it can get enough profit out of it to be worth ditching F9 for is the other part.
Never mind the possible opportunity of point to point and tourism as a revenue generator, both of which are more plausible at IAC2017/18 scale.
 
In addition 2016 ITS was not the correct size for competing against Boeing 787. Long haul point to point with intermodal handycap.

edit/gongora: moved from Raptor thread
« Last Edit: 10/22/2018 08:59 PM by gongora »

Offline JamesH65

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IAC2016 BFS was a large slice of the way towards this, but it was implicitly assuming massive funding.
If you look at the numbers in that post, it implied launching only 100 times, which is about what you need for Mars.

But, it was horribly geared for the F9 replacement role, and pretty much would need massive initial funding to do anything on Mars.

It may have become clear that it was unaffordable.
2017/18 is not notably worse for Mars use, especially with in-orbit payload transfer and retanking.
It may in fact be cheaper, given lower more streamlined launch costs - the aim is sub $300K or so cost to launch BFS, neglecting amortisation of the airframe and infrastructure costs. (to make $1M 'cheaper than an economy flight' possible with pad and amortisation costs and profit).

Making it cheaper enough to operate, with high enough cycle counts means that instead of being only somewhat able to compete in the satellite market, it can get enough profit out of it to be worth ditching F9 for is the other part.
Never mind the possible opportunity of point to point and tourism as a revenue generator, both of which are more plausible at IAC2017/18 scale.
 
In addition 2016 ITS was not the correct size for competing against Boeing 787. Long haul point to point with intermodal handycap.

I think timescales for P2P will mean they will need to compete with the 797.


Offline meekGee

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“I don’t think that most people even in the aerospace industry know what question to ask. It took us a long time to even frame the question correctly. Once we could frame the question correctly the answer flowed.” Elon Musk recent presentation

  ~18 mins in

What was that question? And why didn’t anybody ask him what it was? I assume the question relates to the raptor engine because he made this point directly after talking about it and praising the raptor development team.
 

Nit picking is not a good method for helping with comprehension of intended meaning. With the added context (which can be found in the sentences leading up to the quote in the video) of extending the praise from strictly the propulsion department, to other departments and the company as a whole, that question setting problem is obviously coming with a change of subject and scope. The phrasing ia clearly chosen to reflect a more general scope - system architecture.

Exactly.

You can look at the overall EDL strategy as well.  Instead of asking "how to make a heat shield that can survive X degrees", or "how to make a stiff hydraulic leg system", they asked "How do we even approach EDL".

They also had to address "ship as second stage" vs. "empty ship on top of second stage", etc.

Those are very fundamental architectural issues, and I'm very happy they're willing to stay in that mode for an extended amount of time - it makes for a better system afterwards.  They won't regret it.
ABCD - Always Be Counting Down

Offline Hominans Kosmos

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I think timescales for P2P will mean they will need to compete with the 797.

Which has even less range, which doesn't mean it's not competition, many types will compete. However, 797 has even smaller passenger capacity, removing it even further from ITS. The smaller they can reasonably make it the higher the probability they can fill the seats at high flight rate, unlike the A380. 

Regardless, further downsizing makes it uncompetitive against Falcon Heavy GEO, so that option is out.
« Last Edit: 10/22/2018 08:53 PM by Hominans Kosmos »

Online Slarty1080

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Shame nobody asked him what the question actualy was
The first words spoken on Mars: "Humans have been wondering if there was any life on the planet Mars for many decades … well ... there is now!"

Offline Hominans Kosmos

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SpaceX wants to get down to airline-levels of frequency. I can't find it now, but I believe Elon said at one point that he wants the BFR to be ready to fly again in an hour. Any time spent getting the booster back to the pad is lost money. Will BFR have hourly flights to start with? Of course not. But it's all about allowing the system to improve as smoothly as possible.
I think the small increase in mission costs will be massively outweighed by the added performance and lowered $/kg to orbit.

No orbital launches are priced per kilogram. While eventually there will be such service, for propellant, every other type of cargo cares about price per flight, not price per kilogram. The operational overhead of high seas recovery (which will add it's own flight delays due to weather at landing site) is simply not worth the expense.
« Last Edit: 10/22/2018 10:05 PM by Hominans Kosmos »

Online KelvinZero

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Shame nobody asked him what the question actualy was
I see what you did there, Mr Bartfast :)

Offline JamesH65

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I think timescales for P2P will mean they will need to compete with the 797.

Which has even less range, which doesn't mean it's not competition, many types will compete. However, 797 has even smaller passenger capacity, removing it even further from ITS. The smaller they can reasonably make it the higher the probability they can fill the seats at high flight rate, unlike the A380. 

Regardless, further downsizing makes it uncompetitive against Falcon Heavy GEO, so that option is out.

TBH, I made up 797, didn't even know it was in planning. The aim of the phrase was to indicate that p2p transport is a LONG way away. In my opinion, it get mentioned much too much as if it just around the corner. It's decades away in my view.

Offline speedevil

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TBH, I made up 797, didn't even know it was in planning. The aim of the phrase was to indicate that p2p transport is a LONG way away. In my opinion, it get mentioned much too much as if it just around the corner. It's decades away in my view.
This is not wholly unreasonable, but it can inform certain things, if in fact P2P class operation is possible at all.

P2P as an operating mass service means failures as a hard cap less than 1 loss of vehicle per 30000 flights. (at this point, insurance costs based on average payouts of air accidents start to eat your profits).

If you have a vehicle design which could do mass P2P profitably, that means a number of things are possible, even if mass P2P is not for some reason.

It means launches cost you under a million dollars, including vehicle amortisation.
It means the cost of payload to orbit is $10/kg.
it means the cost of payload on the moon is $100/kg.
It means the cost of mass thrown through TMI in cargo containers is some $40/kg.

It means that you can have a lot go wrong with your initial design and still have plenty of margin for error.
If you have a vehicle which could do it, but the heatshield can only cope with 4.5km/s entry, not 7.8, then meh, cost of payload to orbit is now $30/kg, and the moon is $400/kg.


Offline Cinder

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TBH, I made up 797, didn't even know it was in planning. The aim of the phrase was to indicate that p2p transport is a LONG way away. In my opinion, it get mentioned much too much as if it just around the corner. It's decades away in my view.
This is not wholly unreasonable, but it can inform certain things, if in fact P2P class operation is possible at all.

P2P as an operating mass service means failures as a hard cap less than 1 loss of vehicle per 30000 flights. (at this point, insurance costs based on average payouts of air accidents start to eat your profits).

If you have a vehicle design which could do mass P2P profitably, that means a number of things are possible, even if mass P2P is not for some reason.

It means launches cost you under a million dollars, including vehicle amortisation.
It means the cost of payload to orbit is $10/kg.
it means the cost of payload on the moon is $100/kg.
It means the cost of mass thrown through TMI in cargo containers is some $40/kg.

It means that you can have a lot go wrong with your initial design and still have plenty of margin for error.
If you have a vehicle which could do it, but the heatshield can only cope with 4.5km/s entry, not 7.8, then meh, cost of payload to orbit is now $30/kg, and the moon is $400/kg.


Replied elsewhere to keep on topic
https://forum.nasaspaceflight.com/index.php?topic=46583.msg1870092#msg1870092
The pork must flow.

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