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#1 2018-05-02 09:35:20
- louis
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- From: UK
- Registered: 2008-03-24
- Posts: 7,208
BFR landing on Mars...(video)
Nice video someone's done but the BFR sadly doesn't have legs...
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#2 2018-05-02 09:46:47
- GW Johnson
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- From: McGregor, Texas USA
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Re: BFR landing on Mars...(video)
That video was fiction made by an amateur, not anybody at Spacex. The entry sequence depicted has nothing to do with the entry sequence posted on Spacex's website.
The shallow entry angle ain't there, the inverted attitude for downlift early in the entry ain't there (necessary until speed drops below orbit speed), the reversal into uplift for the last part of the entry ain't there, the end of hypersonics more-or-less traveling horizontally at 4-5 km altitude ain't there, the rise to the Mach 1-ish tail-first flip nearer 10 km altitude ain't there.
And as you noted, the landing legs ain't there.
And as I have pointed out elsewhere, the terrain is as depicted, is far too rough for a BFS to land reliably. Some of the photos from Chryse Planitia in another posting here show terrain too rough for a BFS. The landers that made it down on Chryse were all height/span under unity. That's how they made it. That and the luck not to hit a boulder. Or a gully.
GW
Last edited by GW Johnson (2018-05-02 10:01:13)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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#3 2018-05-02 16:11:31
- louis
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- From: UK
- Registered: 2008-03-24
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Re: BFR landing on Mars...(video)
Oh well, they tried! 
I don't think Chryse's too rough for a landing. Yes, you need to avoid v. large boulders, but an area with a mix of sand, clay, rocks and smallish boulders is probably going to be the best area to land. The v. large boulders can be identified and avoided.
No one is going to head off to Mars with a BFS until all this has been tested in rocky deserts on Earth.
That video was fiction made by an amateur, not anybody at Spacex. The entry sequence depicted has nothing to do with the entry sequence posted on Spacex's website.
The shallow entry angle ain't there, the inverted attitude for downlift early in the entry ain't there (necessary until speed drops below orbit speed), the reversal into uplift for the last part of the entry ain't there, the end of hypersonics more-or-less traveling horizontally at 4-5 km altitude ain't there, the rise to the Mach 1-ish tail-first flip nearer 10 km altitude ain't there.
And as you noted, the landing legs ain't there.
And as I have pointed out elsewhere, the terrain is as depicted, is far too rough for a BFS to land reliably. Some of the photos from Chryse Planitia in another posting here show terrain too rough for a BFS. The landers that made it down on Chryse were all height/span under unity. That's how they made it. That and the luck not to hit a boulder. Or a gully.
GW
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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