Author Topic: BFR Private Passenger Moonflight - DISCUSSION THREAD  (Read 197236 times)

Offline sanman

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #520 on: 09/16/2018 11:27 pm »
Yeah the parallel gaps threw me for a loop for a while, but if you think about a motion that's a little bit inwards (closing the gaps) and otherwise axially aft, you get pretty much the macro-nozzle.

I even tried at one time (in my head) and even-odd arrangement, where the odds ones extend twice as far as the even ones, and everything shrinks inwards.  This is how desperate I got   :)

Static radiators would also be beneficial.  You need to press the tanks, and that's a great way to grab heat from the engines.

Oh Monday, deliver us.

Has anybody else ever proposed or done a macro-nozzle before? Or is this idea completely all-new and original?

Hope somebody asks about whether it's a macro-nozzle, if questions are allowed at the press conference.
« Last Edit: 09/16/2018 11:28 pm by sanman »

Offline groundbound

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #521 on: 09/16/2018 11:43 pm »
I would hope that SpaceX would consider a lifetime NSF member with engineering degrees as possible crew.

I imagine the required skills are running zero-G shuffleboard games and putting on extravagant shows for the passengers.

Offline DaveH62

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #522 on: 09/17/2018 12:10 am »
For earth and mars they stated they will use the body to energy on entry before going vertical and landing upright. On the moon that would not add any value. Basically a combination of shuttle and falcon. Protecting the engines on re-entry is, I believe, the challenge and you have much more surface area using the body of BFR rather than the base.

Offline vaporcobra

Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #523 on: 09/17/2018 12:27 am »
Earlier in this thread - because of Elon's Japanese flag tweet - Yusaku Maezawa's name was thrown about as the potential SpaceX moon traveler.  I followed his twitter account, and have since seen a series of tweets I find very interesting.

And today... he's put up a cryptic tweet with a picture of his watch here:
https://twitter.com/yousuck2020/status/1041135281653465088



Note the date/time.  0946 hrs on September the 19th... which if you account for the timezone difference, is 46 minutes after the SpaceX event is due to start.  Time for Elon to give a presentation on how BFS now works, and then introduce the customer :)

tuesday is september 18. the first september 19 that falls on a tuesday is 2023...

This may actually not be mutually exclusive... late 2023 is a rather fitting NET for this sort of crewed lunar mission, at least in SpaceX's 'aspirational' schedule parlance.

Offline RotoSequence

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #524 on: 09/17/2018 12:33 am »
This may actually not be mutually exclusive... late 2023 is a rather fitting NET for this sort of crewed lunar mission, at least in SpaceX's 'aspirational' schedule parlance.

Doubly so since the Commercial Space Launch Competitiveness Act of 2015 states:

Quote
No person may operate a reusable launch vehicle (or, as currently, a reusable suborbital rocket) under an experimental permit for carrying any property or human being for compensation or hire.

Offline Robotbeat

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #525 on: 09/17/2018 12:51 am »
https://twitter.com/elonmusk/status/1041482806600204294
Quote
Elon Musk (@elonmusk)
Replying to @johnkoetsier
Design has been changed so the  lands on legs that extend from the tips of the three fins, two of which actuate (mostly for pitch control)
7:23 PM - 16 Sep 2018



Note: We need an update thread now, there's a lot of discussion.
« Last Edit: 09/17/2018 12:54 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline garcianc

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #526 on: 09/17/2018 01:26 am »
This leads me to think that there would be plenty of other opportunities to support multiple other mission objectives other than tourism.
I would hope that the announcement covers that and also that, if anyone from NSF is given the opportunity to ask, they would press SpaceX to discuss any such plans.

What other mission objectives do you have in mind? Its seems to me that SpaceX will have only two objectives on this flight: 1. Testing hardware, procedures etc, and 2. Earning money. Though I'm sure that if they have the spare capacity they'll consider taking extra cargo and personnel along for the appropriate fee (see 2).

I have nothing in mind, but I am hoping that SpaceX or someone with money does. It can take some imagination, which is at a premium these days. The taxpayer in me looks at the proposed SLS schedule, or the Lunar Orbital Platform-Gateway, and wonder if SpaceX could take some of that load while they take one single tourist around the Moon. I am sure that there are many other initiatives that I have no knowledge of or have not thought about.

Please don't follow up with another demand for me to provide specifics that I can't give. Otherwise, I would not have posted suggesting that more questions be asked and that those with more knowledge that me weigh in.



Offline Rocket Science

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #527 on: 09/17/2018 01:26 am »
https://twitter.com/elonmusk/status/1041482806600204294
Quote
Elon Musk (@elonmusk)
Replying to @johnkoetsier
Design has been changed so the  lands on legs that extend from the tips of the three fins, two of which actuate (mostly for pitch control)
7:23 PM - 16 Sep 2018



Note: We need an update thread now, there's a lot of discussion.
Chris already set one up... The man never sleeps!
https://forum.nasaspaceflight.com/index.php?topic=46372.0
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline Lars-J

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #528 on: 09/17/2018 01:36 am »
https://twitter.com/elonmusk/status/1041482806600204294
Quote
Elon Musk (@elonmusk)
Replying to @johnkoetsier
Design has been changed so the  lands on legs that extend from the tips of the three fins, two of which actuate (mostly for pitch control)
7:23 PM - 16 Sep 2018

As many of us have already guessed from the image, good to know it *is* accurate.  :)

Offline Robotbeat

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #529 on: 09/17/2018 01:37 am »
https://twitter.com/elonmusk/status/1041482806600204294
Quote
Elon Musk (@elonmusk)
Replying to @johnkoetsier
Design has been changed so the  lands on legs that extend from the tips of the three fins, two of which actuate (mostly for pitch control)
7:23 PM - 16 Sep 2018



Note: We need an update thread now, there's a lot of discussion.
Chris already set one up... The man never sleeps!
https://forum.nasaspaceflight.com/index.php?topic=46372.0
I guess I meant a general update thread for BFR, not necessarily just the event. But I guess that explains why we don't have one, yet.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline John Alan

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #530 on: 09/17/2018 01:44 am »
This may actually not be mutually exclusive... late 2023 is a rather fitting NET for this sort of crewed lunar mission, at least in SpaceX's 'aspirational' schedule parlance.

Doubly so since the Commercial Space Launch Competitiveness Act of 2015 states:

Quote
No person may operate a reusable launch vehicle (or, as currently, a reusable suborbital rocket) under an experimental permit for carrying any property or human being for compensation or hire.

The above is while the vehicle is in experimental status with the FAA...
(Think R&D and test flights of all kinds starting late next year for BFS it seems)

It then goes to the next level (operational for hire it seems) where this policy statement is given
Quote
Currently, commercial spaceflight crew and participants engage in spaceflight operations through “informed consent.” Informed consent regulations require crew and spaceflight participants to be informed, in writing, of mission hazards and risks, vehicle safety record, and the overall safety record of all launch and reentry vehicles. Prior to flight, crew and spaceflight participants must provide their written consent to participate.

Source dated August 17, 2018
https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=19074

The above policy statement is why I so want SpaceX to develop BFS/BFR under FAA regs ONLY, and stay at arms length from NASA rules and regs as used on D2
« Last Edit: 09/17/2018 02:13 am by John Alan »

Offline KelvinZero

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #531 on: 09/17/2018 01:50 am »
I guess I meant a general update thread for BFR, not necessarily just the event. But I guess that explains why we don't have one, yet.
Might be worth a spin off on specific topics.. eg a new thread on just this "actuated" confirmation and totally separate from the weird petals at the back, and the moon mission. There is probably a fair history behind this idea.. and at the same time it is rare for movable wings to actually be implemented (I think someone brought up one example upthread?)

Offline Robotbeat

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #532 on: 09/17/2018 01:54 am »
I guess I meant a general update thread for BFR, not necessarily just the event. But I guess that explains why we don't have one, yet.
Might be worth a spin off on specific topics.. eg a new thread on just this "actuated" confirmation and totally separate from the weird petals at the back, and the moon mission. There is probably a fair history behind this idea.. and at the same time it is rare for movable wings to actually be implemented (I think someone brought up one example upthread?)
The XB-70 Valkyrie bomber is probably the closest. It has winglets that deflect downward in flight of roughly comparable size.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline sanman

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #533 on: 09/17/2018 02:03 am »
https://twitter.com/elonmusk/status/1041482806600204294
Quote
Elon Musk (@elonmusk)
Replying to @johnkoetsier
Design has been changed so the  lands on legs that extend from the tips of the three fins, two of which actuate (mostly for pitch control)
7:23 PM - 16 Sep 2018

So the hinged wings help with angle-of-attack(AoA) -- what are the risks from the hinged wings?

Can thermal expansion from re-entry heating potentially cause problems for those hinges?
I know it's not landing on the Moon - yet - but could that devilish moondust potentially cause problems for those hinges?

How do you avoid such problems?

Offline Robotbeat

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #534 on: 09/17/2018 02:07 am »
https://twitter.com/elonmusk/status/1041482806600204294
Quote
Elon Musk (@elonmusk)
Replying to @johnkoetsier
Design has been changed so the  lands on legs that extend from the tips of the three fins, two of which actuate (mostly for pitch control)
7:23 PM - 16 Sep 2018

So the hinged wings help with angle-of-attack(AoA) -- what are the risks from the hinged wings?

Can thermal expansion from re-entry heating potentially cause problems for those hinges?
I know it's not landing on the Moon - yet - but could that devilish moondust potentially cause problems for those hinges?

How do you avoid such problems?
The dust wouldn't really penetrate until after the vehicle has landed on Mars or the Moon. On the return trip, the wings can be actuated before leaving Mars/Moon orbit to ensure they work fine.

Bigger problem is excavating a crater while landing, a problem that is reduced by using this larger legspan.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline sanman

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #535 on: 09/17/2018 02:22 am »
The XB-70 Valkyrie bomber is probably the closest. It has winglets that deflect downward in flight of roughly comparable size.

That machine famously lost the debate between aircraft-vs-rockets back in its day. I wonder if spaceflight history would have been different if it had prevailed?


https://twitter.com/elonmusk/status/1041482806600204294
Quote
Elon Musk (@elonmusk)
Replying to @johnkoetsier
Design has been changed so the  lands on legs that extend from the tips of the three fins, two of which actuate (mostly for pitch control)
7:23 PM - 16 Sep 2018

So the hinged wings help with angle-of-attack(AoA) -- what are the risks from the hinged wings?

Can thermal expansion from re-entry heating potentially cause problems for those hinges?
I know it's not landing on the Moon - yet - but could that devilish moondust potentially cause problems for those hinges?

How do you avoid such problems?
The dust wouldn't really penetrate until after the vehicle has landed on Mars or the Moon. On the return trip, the wings can be actuated before leaving Mars/Moon orbit to ensure they work fine.

That camera designed to examine the Shuttle underside (thermal protection system) in orbit could only help detect a problem, but there wasn't necessarily a useful fix if a serious problem was detected. If you test-actuate the BFR wings and they don't work, and you can't fix it on the way back, then what are you supposed to do?

Quote
Bigger problem is excavating a crater while landing, a problem that is reduced by using this larger legspan.

You mean the increase in radial span reduces the problem, or the increase in height/clearance? That could avoid problems with altering the terrain unfavorably for leg placement, but your excavation could still kick up enough moondust that gets into the hinges.

Offline KelvinZero

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #536 on: 09/17/2018 02:25 am »
So the hinged wings help with angle-of-attack(AoA) -- what are the risks from the hinged wings?
What about uneven forces and heating? The shuttle, the 2017 BFS and every reentry vehicle I can think of has aimed for an extremely simple purely convex shape to the heat shield. This BFS is not only potentially non-convex (unless the fins are always swept way back) it also has a range of shapes to solve for.

With a slight repositioning of the lower fins I think there would have been a much larger range over which the heat shield was at least convex, but they don't seem to have gone for that. Instead they have gone for what looks like trilateral symmetry despite the top and side wings having very different purposes. Even for legs.. wouldn't the heat shield tend to make one side heavier?

Offline x15_fan

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #537 on: 09/17/2018 02:30 am »
I guess I meant a general update thread for BFR, not necessarily just the event. But I guess that explains why we don't have one, yet.
Might be worth a spin off on specific topics.. eg a new thread on just this "actuated" confirmation and totally separate from the weird petals at the back, and the moon mission. There is probably a fair history behind this idea.. and at the same time it is rare for movable wings to actually be implemented (I think someone brought up one example upthread?)
The XB-70 Valkyrie bomber is probably the closest. It has winglets that deflect downward in flight of roughly comparable size.

Perfect excuse to pull the XB-70 reference off the shelf. The compression lift drooping wing tips are around 500 square feet.




Offline sanman

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #538 on: 09/17/2018 02:47 am »
Perfect excuse to pull the XB-70 reference off the shelf. The compression lift drooping wing tips are around 500 square feet.

And yet in the case of this updated BFR, it's the entire wing/fin that's hinged, not just the tip.
Musk has only mentioned that the hinged wings/fins are for pitch-control.

Would significant compression-lift be possible, given what's known from the image?

Offline Robotbeat

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Re: BFR Private Passenger Moonflight - DISCUSSION THREAD
« Reply #539 on: 09/17/2018 02:58 am »
I guess I meant a general update thread for BFR, not necessarily just the event. But I guess that explains why we don't have one, yet.
Might be worth a spin off on specific topics.. eg a new thread on just this "actuated" confirmation and totally separate from the weird petals at the back, and the moon mission. There is probably a fair history behind this idea.. and at the same time it is rare for movable wings to actually be implemented (I think someone brought up one example upthread?)
The XB-70 Valkyrie bomber is probably the closest. It has winglets that deflect downward in flight of roughly comparable size.

Perfect excuse to pull the XB-70 reference off the shelf. The compression lift drooping wing tips are around 500 square feet.
...hehe, "magnesium-thorium" as a high performance structural alloy. Now those were the days...
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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