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SpaceX BFR [video]

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Re: SpaceX BFR [video]

#51

Post by Shivetya »

corradio wrote: post #50

wait and what's the energy usage of that thing? Carbon footprint?

sadly this is all I started thinking, but only because of how much he pushes EVs and Solar. It seems like a complete opposite move but given current technology there isn't a clean method to do what he wants.

I would be really curious how much works has gone into neutral fuels. pretty sure lox and such can be made neutrally with solar powered chillers but what is his other fuel? a hydrogen type would be similar would it not?

Re: SpaceX BFR [video]

#53

Post by willyt »

pvsukale1 wrote: post #49

I know people have valid reasons to be skeptical about such projects. But maybe after 50 years or so when this kind of transport will be very common we will remember this day as one of the most historic events in the course of humanity.

And if it becomes that common, in 150 years time, New York will be under water. I remember reading that the instantaneous power output of one Apollo rocket taking off is roughly the equivalent of the entire average electricity load of the UK. Surely burning a country's worth of rocket fuel every time you want to travel long distance is not sustainable?

Re: SpaceX BFR [video]

#54

Post by frafra »

corradio wrote: post #50

wait and what's the energy usage of that thing? Carbon footprint?

Musk said that the fuel (methane and oxygen) for Mars expeditions has to be produced on Mars, using solar panels, water and capturing carbon dioxide available in the atmosphere, and he also stated that the very same procedure could be used on Earth.

Re: SpaceX BFR [video]

#55

Post by usrusr »

InclinedPlane wrote: post #41
ojosilva wrote: post #27

I'm not sure here, but I think weather could play a major role in disrupting launches, greater than with jet liners, right? And not just due to windy conditions (which planes can better withstand up to a certain point), but also rough waters. Another issue is noise. I don't see rockets happening that close to shore in large cities. A long pad-to-city commute, with ship trip included, would be another inconvenience.

Maybe. Rockets can actually fly through a variety of rough weather conditions. Indeed, they can even survive being struck by lightning (as Apollo 12 was). However, they are not, as a rule, designed to do so. And because they are multi-million dollar equipment that are only used once before being discarded it's easier to simply avoid launching in weather that might be too severe. However, in practice a rocket could be…

Punching through the atmosphere layer at speeds that are economical when every two extra minutes spent there waste more than one km/s of precious delta-v make every storm look tame. But solving the control problem for the "suicide burn" landing? I would not be so sure about that.

Re: SpaceX BFR [video]

#56

Post by awiesenhofer »

willyt wrote: post #53
pvsukale1 wrote: post #49

I know people have valid reasons to be skeptical about such projects. But maybe after 50 years or so when this kind of transport will be very common we will remember this day as one of the most historic events in the course of humanity.

And if it becomes that common, in 150 years time, New York will be under water. I remember reading that the instantaneous power output of one Apollo rocket taking off is roughly the equivalent of the entire average electricity load of the UK. Surely burning a country's worth of rocket fuel every time you want to travel long distance is not sustainable?

Well, New York City probably will be largely underwater in 150 years anyways, but not because of the BFRs. SpaceX plans to synthesize the fuel by using water, solar power and captured carbon dioxide from the earths athmosphere - just like it will be done on mars.

Re: SpaceX BFR [video]

#58

Post by eightysixfour »

Shivetya wrote: post #51
corradio wrote: post #50

wait and what's the energy usage of that thing? Carbon footprint?

sadly this is all I started thinking, but only because of how much he pushes EVs and Solar. It seems like a complete opposite move but given current technology there isn't a clean method to do what he wants. I would be really curious how much works has gone into neutral fuels. pretty sure lox and such can be made neutrally with solar powered chillers but what is his other fuel? a hydrogen type would be similar would…

Methane + oxygen (methalox).

Re: SpaceX BFR [video]

#59

Post by LeonM »

kensai wrote: post #29

I wonder if they can compete with Boom Supersonic [ https://boomsupersonic.com/ ] at the fuel cost. One reason Concorde failed was NOISE and FUEL COSTS.

If I have to believe Elon, the fuel for the BFR is 'incredibly cheap' to produce. And the concorde flew over land and cities, a rocket goes straight up (for the first part) so noise problems should be acceptable.

Re: SpaceX BFR [video]

#60

Post by jimmcslim »

fludlight wrote: post #48
InclinedPlane wrote: post #41

Earlier quoted context omitted.

Maybe. Rockets can actually fly through a variety of rough weather conditions. Indeed, they can even survive being struck by lightning (as Apollo 12 was). However, they are not, as a rule, designed to do so. And because they are multi-million dollar equipment that are only used once before being discarded it's easier to simply avoid launching in weather that might be too severe. However, in practice a rocket could be…

ICBMs also typically launch from underground, which helps a bit with the noise and maybe even the weather. Also, you'd have to dig a pretty wide hole to make it land-able and reusable.

Presumably several ICBMs are launched at a particular destination at the same time; unlike a payload of paying passengers an ICBM's payload is somewhat fungible so more risks can be taken.
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