Author Topic: BFR and ITS Q&A  (Read 1255 times)

Offline Dalhousie

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BFR and ITS Q&A
« on: 11/30/2017 01:02 AM »
I am trying to find the following numbers (and sources if possible)

BFR

Refuelled propellant for Mars mission
Payload sent to Mars
Mars surface payload
Pressurised volume

ITS

Mars surface payload
Return payload
Pressurised volume

Thanks
Dalhousie
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline nacnud

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Re: BFR and ITS Q&A
« Reply #1 on: 11/30/2017 02:39 AM »
You can probably find most of the numbers you're after by watching the videos here http://www.spacex.com/mars

Offline Dalhousie

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Re: BFR and ITS Q&A
« Reply #2 on: 11/30/2017 09:19 PM »
You can probably find most of the numbers you're after by watching the videos here http://www.spacex.com/mars

No, that's why I am asking here.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Online envy887

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Re: BFR and ITS Q&A
« Reply #3 on: 12/04/2017 08:04 PM »
BFS pressurized volume:
Quote
[Slide: Nose of BFR Spaceship: Pressurized Volume: 825 m^3, Greater than an A380
cabin. Mars Transit Configuration: 40 cabins and large common areas. Central storage,
galley, and solar storm shelter]
[19:26] Let's look at a couple of things in detail. So the cargo area has a pressurized
volume of 825 cubic meters. This also is greater than the pressurized area of an A380. So,
really is capable of carrying a tremendous amount of payload.

From the transcript of the 2017 IAC presentation here:
https://forum.nasaspaceflight.com/index.php?topic=43839.msg1731195#msg1731195

Online envy887

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Re: BFR and ITS Q&A
« Reply #4 on: 12/04/2017 08:10 PM »
Mars surface payload for ITS: 300 t (450 t with payload transfer in LEO). This is called out explicitly in the 2016 IAC presentation.

Mars surface payload for BFS: 150 t if limited by LEO launch, presumably 225 t with LEO transfer. This is not cited explicitly anywhere I know.

Online envy887

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Re: BFR and ITS Q&A
« Reply #5 on: 12/04/2017 08:14 PM »
Does "Refuelled propellant for Mars mission" mean refueling in LEO? If so, the 2017 presentation explicitly calls out payload with "full tanks" having 6 km/s delta-v with 150 tonnes payload. This is the exact requirement for both fast transit and EDL at Mars, and the limiting payload by mass for a single LEO launch, probably not by coincidence.

I would infer from the presentation that the 1100 tonnes of propellant in a full BFS in LEO enables 150 tonnes landed mass with a fast Earth-Mars transit.

Offline Dalhousie

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Re: BFR and ITS Q&A
« Reply #6 on: 12/07/2017 04:02 AM »
Does "Refuelled propellant for Mars mission" mean refueling in LEO? If so, the 2017 presentation explicitly calls out payload with "full tanks" having 6 km/s delta-v with 150 tonnes payload. This is the exact requirement for both fast transit and EDL at Mars, and the limiting payload by mass for a single LEO launch, probably not by coincidence.

I would infer from the presentation that the 1100 tonnes of propellant in a full BFS in LEO enables 150 tonnes landed mass with a fast Earth-Mars transit.

Elsewhere I understand Musk to have said that it would be four or five tanker flights to refuel the BFR.  That's a lot less fuel - no more than 350 tonnes.  That would be enough for a normal transit with full payload for fast transit with a lot less.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Online envy887

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Re: BFR and ITS Q&A
« Reply #7 on: 12/07/2017 03:41 PM »
Does "Refuelled propellant for Mars mission" mean refueling in LEO? If so, the 2017 presentation explicitly calls out payload with "full tanks" having 6 km/s delta-v with 150 tonnes payload. This is the exact requirement for both fast transit and EDL at Mars, and the limiting payload by mass for a single LEO launch, probably not by coincidence.

I would infer from the presentation that the 1100 tonnes of propellant in a full BFS in LEO enables 150 tonnes landed mass with a fast Earth-Mars transit.

Elsewhere I understand Musk to have said that it would be four or five tanker flights to refuel the BFR.  That's a lot less fuel - no more than 350 tonnes.  That would be enough for a normal transit with full payload for fast transit with a lot less.

Probably more than 350 tonnes, as that's only 3 flights of the heavier crewed BFS.

The ITS tanker could lift 27% more than the ITS crew vehicle (380 vs. 300 t). If the same ratio of crew:cargo payload applies to BFS then it can lift 190 tonnes of fuel per flight, and launching 1100 tonnes only requires 5.7 refueling flights.

We don't know what the payload is for cargo/tanker versions, or if Elon was talking about the cargo vehicle flying as a tanker (which is the initial plan) or a dedicated tanker (which is the longer term plan).

Offline Dalhousie

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Re: BFR and ITS Q&A
« Reply #8 on: 12/09/2017 01:23 AM »
Does "Refuelled propellant for Mars mission" mean refueling in LEO? If so, the 2017 presentation explicitly calls out payload with "full tanks" having 6 km/s delta-v with 150 tonnes payload. This is the exact requirement for both fast transit and EDL at Mars, and the limiting payload by mass for a single LEO launch, probably not by coincidence.

I would infer from the presentation that the 1100 tonnes of propellant in a full BFS in LEO enables 150 tonnes landed mass with a fast Earth-Mars transit.

Elsewhere I understand Musk to have said that it would be four or five tanker flights to refuel the BFR.  That's a lot less fuel - no more than 350 tonnes.  That would be enough for a normal transit with full payload for fast transit with a lot less.

Probably more than 350 tonnes, as that's only 3 flights of the heavier crewed BFS.

The ITS tanker could lift 27% more than the ITS crew vehicle (380 vs. 300 t). If the same ratio of crew:cargo payload applies to BFS then it can lift 190 tonnes of fuel per flight, and launching 1100 tonnes only requires 5.7 refueling flights.

We don't know what the payload is for cargo/tanker versions, or if Elon was talking about the cargo vehicle flying as a tanker (which is the initial plan) or a dedicated tanker (which is the longer term plan).

Do you have a source for that?  The orbited mass is 150 tonnes but the 2nd stage mass is given as 85 tonnes try, which leaves a maximum of 65 tonnes for propellant
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline brickmack

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Re: BFR and ITS Q&A
« Reply #9 on: 12/09/2017 02:40 AM »
No,150 tons is useful payload, not counting the vehicle or propellant.

Offline Dalhousie

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Re: BFR and ITS Q&A
« Reply #10 on: 12/09/2017 06:17 AM »
No,150 tons is useful payload, not counting the vehicle or propellant.

Do you have an actual statement of that? 
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline nacnud

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Re: BFR and ITS Q&A
« Reply #11 on: 12/09/2017 07:21 AM »

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