Author Topic: Elon Musk Reddit AMA on BFR (Read 17615 times)

FutureSpaceTourist · « **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

nacnud · « **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.

Michael Baylor · « **Reply #22 on:** 10/14/2017 09:10 PM »

Quote from: nacnud 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.

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.

vaporcobra · « **Reply #23 on:** 10/14/2017 09:14 PM »

Quote from: Next Spaceflight on 10/14/2017 09:10 PM

Quote from: nacnud 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.
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.

calapine · « **Reply #24 on:** 10/14/2017 09:15 PM »

Michael Baylor · « **Reply #25 on:** 10/14/2017 09:16 PM »

Quote from: vaporcobra on 10/14/2017 09:14 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!

nacnud · « **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.

calapine · « **Reply #27 on:** 10/14/2017 09:26 PM »

Next one...
Edit: fixed image

FutureSpaceTourist · « **Reply #28 on:** 10/14/2017 09:30 PM »

Tanker design

FutureSpaceTourist · « **Reply #29 on:** 10/14/2017 09:33 PM »

BFS heat shield mounting

FutureSpaceTourist · « **Reply #30 on:** 10/14/2017 09:40 PM »

BFS thrusters

FutureSpaceTourist · « **Reply #31 on:** 10/14/2017 09:44 PM »

BFR heat exchangers

calapine · « **Reply #32 on:** 10/14/2017 09:48 PM »

Raptor and 3D printing

FutureSpaceTourist · « **Reply #33 on:** 10/14/2017 09:55 PM »

BFS wings

FutureSpaceTourist · « **Reply #34 on:** 10/14/2017 09:57 PM »

BFS cylindrical shape

FutureSpaceTourist · « **Reply #35 on:** 10/14/2017 10:01 PM »

Why no BFS tail

nacnud · « **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.

FutureSpaceTourist · « **Reply #37 on:** 10/14/2017 10:10 PM »

4k rocket video (and with that I’m out of time, not sure how much more Elon is going to do)

nacnud · « **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

nacnud · « **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.