Author Topic: How BFR Earth-to-Earth Might Actually Get Started  (Read 124271 times)

Offline guckyfan

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #220 on: 04/30/2018 06:25 am »
A fully fueled BFR has fuel cost that makes one wonder how they could reach the price per ticket for 100 passengers. For a very low orbit, like 180km, how much delta-v does the BFB need to provide? How much propellant would they put on it?

Offline Zed_Noir

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #221 on: 04/30/2018 07:00 am »
A fully fueled BFR has fuel cost that makes one wonder how they could reach the price per ticket for 100 passengers. For a very low orbit, like 180km, how much delta-v does the BFB need to provide? How much propellant would they put on it?

100 passengers at average of 125 kg allocated mass each means the payload for the flight is only about 13 tonnes with a handful of flight attendants. Don't think you need to fully top off the propellant tanks to the maximum. The P2P BFS will probably be lighter than 85 tonnes empty, since you could fitted everyone on a single open deck.


Offline noogie

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #222 on: 04/30/2018 07:24 am »


Basically I figure you'll want BFR ports in deserts or patches of sea that aren't used by shipping traffic, which are central to the continent they are in but will be in out of the way places with only an hour or two flight to your final destination.  For a bit of fun I've made and attached a notional map of BFR spaceports - mostly in deserts, except for Kwajalein and maybe one of the barrier islands off the coast of the Netherlands would be best for Europe.

I don't think shipping lanes are that big of a problem - as long as it's not as busy as the Malacca Strait or straight in front of the entrance to the harbour or port, after all it's a big ocean and the likelihood of a collision is low (once you have proven safety enough of course).
I think the P2P BFR business case needs business travellers and high net worth individuals, at least to make back the initial investments once commercial operations have started . For this, BFR platforms will need to be near large coastal cities, preferably where you can get a ferry right into the CBD from the coast, without going up a long estuary or across a large bay. I would think of cities like LA, San Francisco, New York, Sydney, Rio and Jakarta are the places where a BFR terminal off the coast (20km isn't that long to town by fast ferry from these cities) would be the most profitable.
I think that that fits into the vision shown in the IAC video and what Gwynne said. High paying business customers being able to go straight to a meeting is probably how it is going to pay for the company.
« Last Edit: 04/30/2018 07:44 am by noogie »

Offline Welsh Dragon

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #223 on: 04/30/2018 07:32 am »
<snip> and maybe one of the barrier islands off the coast of the Netherlands would be best for Europe.
Absolutely zero chance this will happen. Most of those are nature reserves, and the bits that aren't are big tourist destinations. An offshore rig in the middle of the North Sea is far more likely.

Offline noogie

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #224 on: 04/30/2018 08:08 am »

In this case it's the bit where they move 100 people 90+ metres into the air without any problem.

I doubt it will be a 90m high moveable escalator.

I thought about that too. Getting on and off planes is already a drag.
You would think more than one entry door with separate elevator would be more efficient - is this feasible?
Say an entrance higher and lower on the BFS with different walkways and elevators on the service tower.
Would 2 service towers (one on each side) with 2 levels for entrance (4 doors in total) ever be possible?
If that did work, would you instead opt for multiple smaller ferries (with passengers grouped by elevator and therefore ship section)?
« Last Edit: 04/30/2018 08:10 am by noogie »

Offline speedevil

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #225 on: 04/30/2018 09:28 am »
I've learned it's much more interesting to see what SX leave out of their videos.

In this case it's the bit where they move 100 people 90+ metres into the air without any problem.

I doubt it will be a 90m high moveable escalator.

I still like the idea - which hasn't I think been mentioned in this thread yet - of pre-loading the cabins, and then they are all just slid inside through the door automatically, closed, before a rail system on the body locks them into place as seen at IAC. (the rails are not seen).
This has problems hitting the highest densities.

Would obviously be good for cargo and smallsats.

You can get a lot of people into a circular 3.6m elevator cage, which loads through the doors and comes directly to the floor to drop passengers at their desired floor, before they exit all sides.  (around 50 at normal elevator densities)

A member of staff or two in the middle may speed things up.
Pre-stack these cages with people, and four decks loading/unloading at the same time, and you're suddenly getting quite fast.
You might even go to the extreme of loading them all in their seats.

For obvious reasons, moving the clearance of people to fly onto the vehicles going to BFR or before would be great.

Two versus thirty minute loading and unloading for the first vehicles is not going to make much difference though.

Offline Robotbeat

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #226 on: 04/30/2018 01:15 pm »
And I dare say that VTVL actually reduces infrastructure costs as you don't need vast tracks of land for a runway.
Not if you want to operate out in deep water you don't.
Even better! Land costs are even lower. ;)

What is the value of land of an airport?
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Offline philw1776

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #227 on: 04/30/2018 04:17 pm »
And I dare say that VTVL actually reduces infrastructure costs as you don't need vast tracks of land for a runway.
Not if you want to operate out in deep water you don't.
Even better! Land costs are even lower. ;)

What is the value of land of an airport?

Question from ignorance.  Is there a distance km/miles beyond which major cities (US) have no jurisdiction and its "just" federal?  Might be a way to avoid entanglement with local pols which is often problematical.

Note that The Boring Company so far seems to have excellent relations with said local pols maybe making my question & concern moot.  But a tunnel that affects nothing and nobody and whose operation is undetectable is very different than a noisy LNG tanker flying overhead with its tail spouting flames.
« Last Edit: 04/30/2018 04:18 pm by philw1776 »
FULL SEND!!!!

Offline DistantTemple

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #228 on: 04/30/2018 09:25 pm »
<snip> and maybe one of the barrier islands off the coast of the Netherlands would be best for Europe.
Absolutely zero chance this will happen. Most of those are nature reserves, and the bits that aren't are big tourist destinations. An offshore rig in the middle of the North Sea is far more likely.
London?? Thames Estuary... for years there has been the "Thames Gateway" idea of building a massive 4th airport. That would be disastrous... However a Musk platform would be minuscule by comparison, and noise being the major objection. The high speed train from "St Pancras International" passes within 20 miles, and and a fast hydrofoil from Rochester would make a reasonable connection, in the first instance.
We can always grow new new dendrites. Reach out and make connections and your world will burst with new insights. Then repose in consciousness.

Offline CameronD

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #229 on: 04/30/2018 11:30 pm »
And I dare say that VTVL actually reduces infrastructure costs as you don't need vast tracks of land for a runway.
Not if you want to operate out in deep water you don't.
Even better! Land costs are even lower. ;)

What is the value of land of an airport?

Not very much compared to the cost of the associated infrastructure needed to run it.  Aside from the air-services and the people/cargo transportation, there's vehicle maintenance provisions (a hangar or two on a floating platform at the mercy of wind and waves?), electric power and fuel supply.

Speaking of airports, a potential problem that I haven't seen discussed yet is how the launching facility could be allowed to operate anywhere within 50 miles of a major airport/city given the disruption smacking an infinite-height danger area in the middle of documented flight paths would cause to aircraft approach and landing.  Advanced VTVL may be a great leap forward, but unfortunately existing aircraft fly horizontally (and don't always look up!).


EDIT:  During lease re-negotiations few years back, Sydney Airport Corporation told the oil company operating the airport's fuel system that they wanted to use the site of their tank farm for car parking and would give them  some land someplace else.  Only when it was explained to them that there were 3 different pipelines coming into the site from 3 different parts of the city, plus several to various parts of the airport and that moving any part of their infrastructure would shut the airport down for months, did they decide to renew the lease and shut up.  Funny story, but true.

{EDIT 2:  Removed reference to RP-1 not relevant to this discussion...}
« Last Edit: 05/01/2018 12:46 am by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline Robotbeat

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #230 on: 05/01/2018 12:00 am »
Ummm... BFR isn’t using RP-1. Where did you get that idea?

It’s super odd that you’ve been having conversations on this forum for years and didn’t realize this...
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline CameronD

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #231 on: 05/01/2018 12:44 am »
Ummm... BFR isn’t using RP-1. Where did you get that idea?

It’s super odd that you’ve been having conversations on this forum for years and didn’t realize this...

Brain fart.  Happens sometimes as you get older and the pace picks up. :)

With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline FutureSpaceTourist

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #232 on: 05/16/2018 10:45 am »
In response to a TED Talks tweet about Gwynne Shotwell's recent talk:

Quote
Boring Company Hyperloop will take you from city center under ground & ocean to spaceport in 10 to 15 mins

https://twitter.com/elonmusk/status/996691566851801088

Offline docmordrid

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #233 on: 05/16/2018 12:39 pm »
Guess that settles the ferry type and fixed platform vs drone ship questions.
DM

Offline DaveGee66

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #234 on: 05/16/2018 01:52 pm »
In response to a TED Talks tweet about Gwynne Shotwell's recent talk:

Quote
Boring Company Hyperloop will take you from city center under ground & ocean to spaceport in 10 to 15 mins

https://twitter.com/elonmusk/status/996691566851801088

First I think we all knew this would be the way things were going to go.... Elon would NEVER be the captain of a Ferry Boat even if it was a high speed one! :lol:

So a launch platform at sea ...  given a hyperloop pod traveling at say 500 mph (yes 700 max speed but given it has to build speed and reduce speed lets say the trips actual speed over time is 500 mph Elons tweet indicates the platform would be apx ... 80 to 125 miles off shore? (edit: fixed my numbers)

Does that sound like a realistic distance to be launching BFRs off the coat of NY / CA / TX / FL etc....

Also where do you imagine launch platforms going?

West Coast - CA maybe 2x and WA?
Gulf coast - TX, LA (?)
East Coast - FL, DC, NY, MA

Finally what will this do for the bigger US cities that are landlocked I would imagine not having a spaceport is going to be a real decision maker in the years to come.
« Last Edit: 05/16/2018 02:54 pm by DaveGee66 »

Offline Manubria

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #235 on: 05/16/2018 02:22 pm »
I don't know that being inland is going to be too much of a showstopper with this, especially if hyperloops are going to be used for transport to and from the launch site.  There are plenty of decommissioned air force bases dotting the United States that are remote enough to work as P2P launch sites.  SpaceX could place all of the ground side operations (baggage check/claim, security, etc.) in the city that is being served, transport from there to the launch site, fly and reverse the sequence on the other side.  That way, you can staff the thing without having to have people live in the middle of nowhere.   

Offline Ludus

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #236 on: 05/16/2018 02:48 pm »
I don't know that being inland is going to be too much of a showstopper with this, especially if hyperloops are going to be used for transport to and from the launch site.  There are plenty of decommissioned air force bases dotting the United States that are remote enough to work as P2P launch sites.  SpaceX could place all of the ground side operations (baggage check/claim, security, etc.) in the city that is being served, transport from there to the launch site, fly and reverse the sequence on the other side.  That way, you can staff the thing without having to have people live in the middle of nowhere.   

There are a lot of reasons for SpaceX to emphasize ocean spaceports. They necessarily have fewer problems with oversight. Any land location will have overlapping legal and regulatory authorities. More people would have standing to bring lawsuits. Off the coast, especially out of sight of Land, things get simpler legally. South Texas was a pretty favorable location in terms of regulation for SpaceX to build a spaceport. Even so, it’s limited to 12 launches per year and has a lot of constraints and opposition. If they wanted to launch rockets that are much larger 100x as frequently it wouldn’t be very accommodating.

On Land, every construction is a unique set of issues. Ocean Spaceports can be produced to a standard template in shipyards and taken all over the world.

Many of the largest cities that are the prime market are on the ocean and it’s possible to locate nearer the city center with an ocean spaceport than any practical land alternative.

Offline Manubria

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #237 on: 05/16/2018 02:58 pm »
I agree with you that it is a lot more complicated to build inland and that the majority of places that this is meant to service are costal anyway.  The two places I really had in mind for needing an inland launch site were Dallas/Ft. Worth and Chicago.  Both places are business centers and would be desirable destinations should this whole enterprise take off the way we hope that it will.  The DFW metroplex should be able to use a launch site within a radius of around 250 miles, assuming hyperloop support.  That opens up a large section of Texas and western Oklahoma for potential launch sites.   I don't have as solid of an idea on how to serve the Chicago area, but I do think that it could be pulled off.

Offline Tulse

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #238 on: 05/16/2018 03:16 pm »
Chicago could have a platform in Lake Michigan.  But is the problem for landlocked cities a lack of launch sites, or noise?  The US does not currently permit supersonic overflights of the country due to sonic boom, and I would think the problem would be similar for BFR.  In addition, overflight of populated areas brings potential for huge loss of life if the vehicle fails, which is another reason most launches are over ocean.

Offline envy887

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Re: How BFR Earth-to-Earth Might Actually Get Started
« Reply #239 on: 05/16/2018 03:27 pm »
Chicago could have a platform in Lake Michigan.  But is the problem for landlocked cities a lack of launch sites, or noise?  The US does not currently permit supersonic overflights of the country due to sonic boom, and I would think the problem would be similar for BFR.  In addition, overflight of populated areas brings potential for huge loss of life if the vehicle fails, which is another reason most launches are over ocean.

BFR/BFS does not produce a sonic boom during overflight, as it is exoatmospheric.

There is a sonic boom around the landing area, for both vehicles. This isn't likely to be an issue beyond the distance that launch noise is also an issue.

There can also a downrange sonic boom during launch, although trajectory shaping could likely eliminate it. This is not the same as a supersonic transport, since the boom is localized to a specific area, rather than continuous under the entire flight from launch to landing point.

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