Author Topic: Elon Musk Reddit AMA on BFR  (Read 47113 times)

Online FutureSpaceTourist

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Re: Elon Musk Reddit AMA on BFR
« Reply #20 on: 10/14/2017 09:05 PM »
Bit of info on BFS development steps

Edit to add: more follow-up detail in 2nd attachment
« Last Edit: 10/14/2017 09:17 PM by FutureSpaceTourist »

Offline nacnud

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Re: Elon Musk Reddit AMA on BFR
« Reply #21 on: 10/14/2017 09:08 PM »
*Speculation*

Perhaps this is the plan for Boca Chita now that flights from McGregor are a no no.

Offline Michael Baylor

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Re: Elon Musk Reddit AMA on BFR
« Reply #22 on: 10/14/2017 09:10 PM »
*Speculation*

Perhaps this is the plan for Boca Chita now that flights from McGregor are a no no.
Only other possibility is the Cape from a modified launch site. Doubtful that they could make that work though at a reasonable cost. This is going to need a serious flame trench, even though it will be possibly be less thrust.
« Last Edit: 10/14/2017 09:12 PM by Next Spaceflight »

Offline vaporcobra

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Re: Elon Musk Reddit AMA on BFR
« Reply #23 on: 10/14/2017 09:14 PM »
*Speculation*

Perhaps this is the plan for Boca Chita now that flights from McGregor are a no no.
Only other possibility is the Cape from a modified launch site. Doubtful that they could make that work though at a reasonable cost. This is going to need a serious flame trench, even though it will be possibly be less thrust.

FWIW, LC-39A was overengineering for Nova from the start. It can handle BFR and even ITS-level thrust. The question is if SpaceX could realistically modify 39A to support Falcon and BFR while still satisfying their Commercial Crew obligations.

Offline calapine

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Re: Elon Musk Reddit AMA on BFR
« Reply #24 on: 10/14/2017 09:15 PM »

Offline Michael Baylor

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Re: Elon Musk Reddit AMA on BFR
« Reply #25 on: 10/14/2017 09:16 PM »
FWIW, LC-39A was overengineering for Nova from the start. It can handle BFR and even ITS-level thrust. The question is if SpaceX could realistically modify 39A to support Falcon and BFR while still satisfying their Commercial Crew obligations.
I am aware of that. I just logically ruled it out since the current timeline is before 2022. I suppose I maybe should not have ruled that out though. I just don't see them getting Pad 39A ready in time. It would take some serious modifications to an active launch site. But anything is possible!

Offline nacnud

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Re: Elon Musk Reddit AMA on BFR
« Reply #26 on: 10/14/2017 09:25 PM »
The development plan for BFS seems like what the follow on to the DC-X should have been.

Offline calapine

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Re: Elon Musk Reddit AMA on BFR
« Reply #27 on: 10/14/2017 09:26 PM »
Next one...
Edit: fixed image
« Last Edit: 10/14/2017 09:28 PM by calapine »

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Re: Elon Musk Reddit AMA on BFR
« Reply #28 on: 10/14/2017 09:30 PM »
Tanker design
« Last Edit: 10/14/2017 09:31 PM by FutureSpaceTourist »

Online FutureSpaceTourist

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Re: Elon Musk Reddit AMA on BFR
« Reply #29 on: 10/14/2017 09:33 PM »
BFS heat shield mounting

Online FutureSpaceTourist

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Re: Elon Musk Reddit AMA on BFR
« Reply #30 on: 10/14/2017 09:40 PM »
BFS thrusters

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Re: Elon Musk Reddit AMA on BFR
« Reply #31 on: 10/14/2017 09:44 PM »
BFR heat exchangers

Offline calapine

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Re: Elon Musk Reddit AMA on BFR
« Reply #32 on: 10/14/2017 09:48 PM »
Raptor and 3D printing

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Re: Elon Musk Reddit AMA on BFR
« Reply #33 on: 10/14/2017 09:55 PM »
BFS wings

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Re: Elon Musk Reddit AMA on BFR
« Reply #34 on: 10/14/2017 09:57 PM »
BFS cylindrical shape

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Re: Elon Musk Reddit AMA on BFR
« Reply #35 on: 10/14/2017 10:01 PM »
Why no BFS tail

Offline nacnud

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Re: Elon Musk Reddit AMA on BFR
« Reply #36 on: 10/14/2017 10:04 PM »
Very interesting about the wings, if you watch the Mars descent video from the IAC presentation you can see the BFR entry is nothing like a shuttle or any other lifting body.

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Re: Elon Musk Reddit AMA on BFR
« Reply #37 on: 10/14/2017 10:10 PM »
4k rocket video (and with that Iím out of time, not sure how much more Elon is going to do)
« Last Edit: 10/14/2017 10:11 PM by FutureSpaceTourist »

Offline nacnud

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Re: Elon Musk Reddit AMA on BFR
« Reply #38 on: 10/14/2017 10:15 PM »
Why was the number of BFS landing legs increased from 3 to 4?

The BFS/2016 design used three landing legs, while the new BFS/2017 design uses four.
What is the motivation behind this change?

Elon Musk-Because 4

Elon Musk-Improves stability in rough terrain

Offline nacnud

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Re: Elon Musk Reddit AMA on BFR
« Reply #39 on: 10/14/2017 10:17 PM »
This is an odd answer, three legs are more stable than four. I'll be back with links.

Edit: Can't find the link I was after (NASA study for lander legs, Mars Phoenix if I recall correctly) but basically three points define a plane so the lander won't rock. Where it is unlikely that four points on a rough surface form a plane, so it will wobble. Suspension can correct for this.
« Last Edit: 10/14/2017 10:24 PM by nacnud »

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