Author Topic: Elon has changed BFR design again - what does this mean  (Read 520572 times)

Offline docmordrid

  • Senior Member
  • *****
  • Posts: 6334
  • Michigan
  • Liked: 4207
  • Likes Given: 2
Re: Elon has changed BFR design again - what does this mean
« Reply #60 on: 11/18/2018 01:12 am »
Musk needs to get the CGI people busy and schedule that AMA. Soon. Sooner than soon.
DM

Offline Rocket Science

  • Senior Member
  • *****
  • Posts: 10586
  • NASA Educator Astronaut Candidate Applicant 2002
  • Liked: 4548
  • Likes Given: 13523
Re: Elon has changed BFR design again - what does this mean
« Reply #61 on: 11/18/2018 01:14 am »
He's come to his senses and is building this at 1/10th the NASA's current cost and flying next year...
« Last Edit: 11/18/2018 01:06 pm by Rocket Science »
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline robert_d

  • Full Member
  • ***
  • Posts: 356
  • Liked: 72
  • Likes Given: 118
Re: Elon has changed BFR design again - what does this mean
« Reply #62 on: 11/18/2018 01:22 am »

Second Idea:

Upper stage will use a ring of raptor-based linear aerospike engines and the payload will be able to be unloaded on the bottom

Totally concentric construction might solve some problems and work well with the carbon composite construction.

Offline ZachF

  • Full Member
  • ****
  • Posts: 1610
  • Immensely complex & high risk
  • NH, USA, Earth
  • Liked: 2604
  • Likes Given: 531
Re: Elon has changed BFR design again - what does this mean
« Reply #63 on: 11/18/2018 01:22 am »
Here's what I mean:

The counter-intuitive part would be that the giant window would be facing "down" on the manned version.

it would be immeasurably easier to load and unload cargo.

could also "hot stage" with this design.

EDIT: Also when refueling you could connect the manned areas,
« Last Edit: 11/18/2018 01:25 am by ZachF »
artist, so take opinions expressed above with a well-rendered grain of salt...
https://www.instagram.com/artzf/

Offline robert_d

  • Full Member
  • ***
  • Posts: 356
  • Liked: 72
  • Likes Given: 118
Re: Elon has changed BFR design again - what does this mean
« Reply #64 on: 11/18/2018 01:26 am »
Here's what I mean:

The counter-intuitive part would be that the giant window would be facing "down" on the manned version.

it would be immeasurably easier to load and unload cargo.

could also "hot stage" with this design.
Hard to see how aerospike could accelerate development, however. Couldn't they just put two engines in each of the fins and call it good?

Offline ZachF

  • Full Member
  • ****
  • Posts: 1610
  • Immensely complex & high risk
  • NH, USA, Earth
  • Liked: 2604
  • Likes Given: 531
Re: Elon has changed BFR design again - what does this mean
« Reply #65 on: 11/18/2018 01:28 am »
Here's what I mean:

The counter-intuitive part would be that the giant window would be facing "down" on the manned version.

it would be immeasurably easier to load and unload cargo.

could also "hot stage" with this design.
Hard to see how aerospike could accelerate development, however. Couldn't they just put two engines in each of the fins and call it good?

They could use a ring of SL raptors at first and upgrade to linear aerospikes later.
artist, so take opinions expressed above with a well-rendered grain of salt...
https://www.instagram.com/artzf/

Offline ZachF

  • Full Member
  • ****
  • Posts: 1610
  • Immensely complex & high risk
  • NH, USA, Earth
  • Liked: 2604
  • Likes Given: 531
Re: Elon has changed BFR design again - what does this mean
« Reply #66 on: 11/18/2018 01:29 am »
Putting the payload bay on the bottom would probably smooth out ground operations as well.
artist, so take opinions expressed above with a well-rendered grain of salt...
https://www.instagram.com/artzf/

Offline Oli

  • Senior Member
  • *****
  • Posts: 2467
  • Liked: 605
  • Likes Given: 60
Re: Elon has changed BFR design again - what does this mean
« Reply #67 on: 11/18/2018 01:31 am »
Putting the payload bay on the bottom would probably smooth out ground operations as well.

Yep, it would enter bottom-first and create a nice crater on impact.  ;)

Offline daveklingler

  • Full Member
  • ****
  • Posts: 703
  • Liked: 346
  • Likes Given: 66
Re: Elon has changed BFR design again - what does this mean
« Reply #68 on: 11/18/2018 02:44 am »
Hm. Counterintuitive...

Counterintuitive, to me, would mean they've dropped Mars as a destination, adopted plans to build O'Neill colonies, and BFR is now SSTO.

Offline zodiacchris

  • Full Member
  • ****
  • Posts: 432
  • Port Macquarie, Australia
  • Liked: 1473
  • Likes Given: 1311
Re: Elon has changed BFR design again - what does this mean
« Reply #69 on: 11/18/2018 02:53 am »
Oh boy, what have you guys been smoking??? ::)

Offline OxCartMark

  • Full Member
  • ****
  • Posts: 1836
  • Former barge watcher now into water towers
  • Michigan
  • Liked: 2072
  • Likes Given: 1555
Re: Elon has changed BFR design again - what does this mean
« Reply #70 on: 11/18/2018 03:07 am »
Rotate engines 90 degrees so that exhaust now goes out perpendicular to vertical, all engines arrayed around cylinder so as to create rotation around long axis.  Add DaVinci helicopter rotor to nose end of BFS to generate lift in lower atmosphere.  Once high enough that atmospheric lift is no longer effective the liquid propellants will be rotating around tank perimeter with enough speed that strategically placed tank vents could be opened to jet the rapidly moving fuel in the direction needed to provide the remainder of necessary thrust.  Side benefits: artificial gravity, exposes all sides to reentry heating, magnus effect steering. 

Its not intuitive.

edit: upon further reflection I see another side benefit, a significant one: centrifuged cryogenic fuel against outer skin during reentry would reduce the need for heat shielding.  I've not done the calculations but one possibility is that with cryogenic liquids on the back side of the carbon composite skin there may(?) be no need for any heat shielding at all.
« Last Edit: 11/18/2018 03:26 am by OxCartMark »
Actulus Ferociter!

Offline su27k

  • Senior Member
  • *****
  • Posts: 6414
  • Liked: 9100
  • Likes Given: 885
Re: Elon has changed BFR design again - what does this mean
« Reply #71 on: 11/18/2018 03:31 am »
I bet none of us can guess correctly what SpaceX is up to, it's the aft-cargo fiasco all over again.

1. SSTO: Too early in the prototyping process to bet on this. Besides, it's the intuitive solution, not counter-intuitive
2. Move cargo to the bottom: They already considered this option before and rejected it due to cost/complexity(?) reasons, don't see why they want to get back to it when they are "accelerating"
3. Capsule: Same as #2
4. Dome nose: This one actually makes sense and it's sort of counter-intuitive, but I don't think it's a "radical change".


Offline DanielW

  • Full Member
  • ****
  • Posts: 628
  • L-22
  • Liked: 577
  • Likes Given: 85
Re: Elon has changed BFR design again - what does this mean
« Reply #72 on: 11/18/2018 03:38 am »
I take this tweet as confirmation that Musk has latched on to my idea of launching the BFS into space sideways. The raptors point in the direction of the heat shield allowing a horizontal entry and landing.

The important bit is that for a few blessed days or months all of our pet ideas are back in play, unbound by inconvenient realities.

Offline kessdawg

  • Full Member
  • *
  • Posts: 174
  • Liked: 316
  • Likes Given: 1554
Re: Elon has changed BFR design again - what does this mean
« Reply #73 on: 11/18/2018 03:42 am »
BFS now stands for Big Falcon Skyhook, and is now a rotating cable in orbit that flings payloads from the upper atmosphere into orbit?

Offline dwheeler

  • Full Member
  • *
  • Posts: 119
  • USA
  • Liked: 104
  • Likes Given: 283
Re: Elon has changed BFR design again - what does this mean
« Reply #74 on: 11/18/2018 04:19 am »
Hope I'm wrong, but before we get too carried away there is another interpretation that should be considered:

"Btw, SpaceX is no longer planning to upgrade Falcon 9 second stage for reusability. Accelerating BFR instead. New design is very exciting! Delightfully counter-intuitive."

I think Musk means the "new" (but previously announced) 2018 version BRF tintin design is very exciting and delightfully counter-intuitive. I don't think there's been any further change. He's just commenting on the current design which is "new".

I'm leaning this way. In the Sept 2018 presentation he referred to the new skydiver design specifically as "counter-intuitive". That's the "radical" change he's talking about IMO. I would speculate there was an internal project still investigating a plan to make F9 S2 reusable and that plan is now quashed. So I think the mini-BFR F9 S2 plan is still full speed ahead (as a re-entry test bed IMO).

Offline groundbound

  • Full Member
  • ***
  • Posts: 383
  • Liked: 405
  • Likes Given: 15
Re: Elon has changed BFR design again - what does this mean
« Reply #75 on: 11/18/2018 04:49 am »
Rotate engines 90 degrees so that exhaust now goes out perpendicular to vertical, all engines arrayed around cylinder so as to create rotation around long axis.  Add DaVinci helicopter rotor to nose end of BFS to generate lift in lower atmosphere.  Once high enough that atmospheric lift is no longer effective the liquid propellants will be rotating around tank perimeter with enough speed that strategically placed tank vents could be opened to jet the rapidly moving fuel in the direction needed to provide the remainder of necessary thrust.  Side benefits: artificial gravity, exposes all sides to reentry heating, magnus effect steering. 

Its not intuitive.

edit: upon further reflection I see another side benefit, a significant one: centrifuged cryogenic fuel against outer skin during reentry would reduce the need for heat shielding.  I've not done the calculations but one possibility is that with cryogenic liquids on the back side of the carbon composite skin there may(?) be no need for any heat shielding at all.

IIRC, our own HMXHMX has more or less been-there-done-that.  :)

Offline drzerg

  • Full Member
  • *
  • Posts: 117
  • Kyiv
  • Liked: 56
  • Likes Given: 24
Re: Elon has changed BFR design again - what does this mean
« Reply #76 on: 11/18/2018 05:02 am »
Bfs will sit on sls for nasa missions.

Offline KelvinZero

  • Senior Member
  • *****
  • Posts: 4286
  • Liked: 887
  • Likes Given: 201
Re: Elon has changed BFR design again - what does this mean
« Reply #77 on: 11/18/2018 05:54 am »
My guess is that instead of a https://en.wikipedia.org/wiki/Magic_8-Ball , Elon just emits random tweets and then reads up all the zany brainstorming on NSF  :)

Btw, that rotating to keep cool idea was sort of random but interesting. I know that there is that trick where a  water filled balloon is much more fire resistant than you would expect. That is just the sort of WTF idea that might actually just work if someone has not done the math already to eliminate it.

Offline tyrred

  • Full Member
  • ****
  • Posts: 920
  • Seattle
  • Liked: 750
  • Likes Given: 20639
Re: Elon has changed BFR design again - what does this mean
« Reply #78 on: 11/18/2018 06:05 am »
Until we see flight-test hardware doing short hops at Boca Chica this is all just so tedious.  I am seriously starting to think that Elon is fed up with everyone trying to figure this out for him and is spamming us all.  And it's beginning to work.  It's getting to unprecedented levels of pseculative fan fiction for this beast.  Just look at the thread title.  What is a BRF anyway?  I'm pretty sure a BLT tastes better.

Offline darkenfast

  • Member
  • Full Member
  • ****
  • Posts: 1539
  • Liked: 1829
  • Likes Given: 8739
Re: Elon has changed BFR design again - what does this mean
« Reply #79 on: 11/18/2018 07:07 am »
Three extended BFRs with cross-feed, placing a fully-fuelled BFS in orbit in one mission. The two outer boosters recover on Marmac-400 derived barges and the center returns from orbit to the launch site a day later.

Hey, I can dream, can't I?

Edit to add:  Needless to say, there would be a Chomper-version, replacing the BFS with some serious volume.
« Last Edit: 11/18/2018 07:11 am by darkenfast »
Writer of Book and Lyrics for musicals "SCAR", "Cinderella!", and "Aladdin!". Retired Naval Security Group. "I think SCAR is a winner. Great score, [and] the writing is up there with the very best!"
-- Phil Henderson, Composer of the West End musical "The Far Pavilions".

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1