Author Topic: Point-to-Point hub  (Read 1262 times)

Offline NotOnImpact

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Point-to-Point hub
« on: 10/05/2017 02:53 AM »
The Point-to-Point use case for BFR is compelling but it has a key flaw:  too many points for such a high capacity vehicle.   Even if you only include sea-side large cities in the map - there are dozens if not a hundred possible destinations.  If you wanted to get to city X - you might have to wait a few days before that destination comes back up again.   What good is it to you if the flight is only 37 minutes when you have to wait a week before it is available.   And this is not even taking into account the issue of getting a large number of people all wanting to go to the same destination on the same day.

The way the airlines handle this is by using a hub spoke system.  There is always a flight to the hub - and the hub has frequent flights to every destination.    In the case of the BFR you are now talking about two hops and a layover which would increase the time-to-destination.  But it would still be dramatically faster than long haul airline flights.

Now... imagine what a SpaceX BFR hub would look like.   (mind officially blown).  If it were ever built it would have to be the largest construction project ever undertaken!  Imagine 20-30 pads and boosters with one taking off every few minutes.   Ear protection is a must!  There would probably have to be a refinery on site for methane production.

And where would it be....

It isn't a destination so it could be anywhere on earth.  It would need to be isolated for obvious reasons.   You would want to be able to land/take off to/from any direction.

A very large pacific atoll would be a great candidate.

Or perhaps in the middle of the Sahara desert would be best since the dry weather would be less corrosive.  But then there are the dust storms...

Fun to think about, at least!





Online Coastal Ron

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Re: Point-to-Point hub
« Reply #1 on: 10/05/2017 03:11 AM »
The Point-to-Point use case for BFR is compelling but it has a key flaw:  too many points for such a high capacity vehicle....

...The way the airlines handle this is by using a hub spoke system.  There is always a flight to the hub - and the hub has frequent flights to every destination.

You are apparently not aware of airlines like Southwest, Allegiant Air, Ryanair and easyJet? Their business model is based on point-to-point transit. And of course the Boeing 787 and the Airbus A350 were specifically designed for point-to-point transportation.

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In the case of the BFR you are now talking about two hops and a layover which would increase the time-to-destination.  But it would still be dramatically faster than long haul airline flights.

Adding a stop negates the advantages of being able to get to your destination - anywhere in the world - in less than one hour.

Me personally, I always try to find flights that are direct, no matter where I'm going. And the people that will be flying point-to-point around the world will not only be price insensitive, but if they are going to pay that amount of money they will want the ultimate service - which is a direct flight.

If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline John Alan

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Re: Point-to-Point hub
« Reply #2 on: 10/05/2017 03:19 AM »
Would it be better at some point to put a destination or two in orbit with worldwide flights coming and going...  ???
A hub in the sky if you will...  ???

My opinion... the point to point seems well out in the future... 2050 ish...  :P
And in much later spacecraft...  ;)

Now... putting a Tanker Base in the middle of nowhere... That's a thought...
I wonder if Australia would host one someday... Hmmmm
« Last Edit: 10/05/2017 03:24 AM by John Alan »

Offline NotOnImpact

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Re: Point-to-Point hub
« Reply #3 on: 10/05/2017 03:27 AM »
You are apparently not aware of airlines like Southwest, Allegiant Air, Ryanair and easyJet? Their business model is based on point-to-point transit. And of course the Boeing 787 and the Airbus A350 were specifically designed for point-to-point transportation.
You are correct about airlines like SouthWest.   I live in Dallas, and SouthWest flies out of Love Field using about 20 gates.  So to provide point-to-point service with BFR that didn't require multi-day waits for your flight - you would need a huge launch complex at each city.  The cost alone would preclude it and the constant noise - if close enough to the city - would be a no-go.

Compare that to one launch a day from any one city and to be able to get around the globe in about 2 hours.

If anything, hub spoke makes more sense for the BFR use case than for the airline use case in my opinion.

Online Coastal Ron

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Re: Point-to-Point hub
« Reply #4 on: 10/05/2017 02:43 PM »
You are correct about airlines like SouthWest.   I live in Dallas, and SouthWest flies out of Love Field using about 20 gates.  So to provide point-to-point service with BFR that didn't require multi-day waits for your flight - you would need a huge launch complex at each city.

No airline starts out with 20 gates, and the passenger BFR/ITS would likely start with a few daily routes between the most popular end points.  Here is a Wikipedia list of 30 flights that take over 15 hours that would be candidates:

https://en.wikipedia.org/wiki/Longest_flights#Currently_scheduled_.28top_30.2C_by_distance.29

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The cost alone would preclude it...

Adding stops adds time and money to all involved. It's cheaper to go point to point.

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...and the constant noise - if close enough to the city - would be a no-go.

Safety is going to be a bigger concern, and Musk has already stated the launch sites would be far from the city.

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Compare that to one launch a day from any one city and to be able to get around the globe in about 2 hours.

If you use a hub system the intermediate stops would require far more time, and calculating the loading would take years of use to perfect.

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If anything, hub spoke makes more sense for the BFR use case than for the airline use case in my opinion.

I disagree. Hub & spoke is not what airlines started using when they launched, they only started using it when they had grown substantially. The infrastructure required for such operations is prohibitive when first starting out. Point-to-point is much easier to start service with, and as the link above shows there is plenty of existing demand for point-to-point transportation.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online launchwatcher

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Re: Point-to-Point hub
« Reply #5 on: 10/06/2017 12:05 AM »
it could be anywhere on earth.
An obvious place for it is off earth in low earth orbit.   Launch to a quick rendezvous, dock with station, trade passengers with other spacecraft, undock and land at your destination.  Somewhat slower than direct point-to-point hops, but you'll still beat the airlines for long-haul travel, and the layover will be a space tourism experience.   


Offline speedevil

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Re: Point-to-Point hub
« Reply #6 on: 10/06/2017 01:39 AM »
it could be anywhere on earth.
An obvious place for it is off earth in low earth orbit.   Launch to a quick rendezvous, dock with station, trade passengers with other spacecraft, undock and land at your destination.  Somewhat slower than direct point-to-point hops, but you'll still beat the airlines for long-haul travel, and the layover will be a space tourism experience.

Except that even with a modest number of stations in each inclination,, say 12 (if you're willing to wait around 45 minutes), and perhaps three inclinations, for a total of 36 stations, you're going to use up most-all of the fuel getting crossrange to the stations much of the time, and may  have problems taking a full load of passengers down without a refuel.

I don't think this is fundamentally impossible, but the inherent scale means that passenger rocketry needs to have pretty much taken over much of air transport. (Space tourism that incidentally drops you off at a different location than you came from at a time which might be oddly scheduled, perhaps with several day granularity requires much, much lower flight rates)

Online Coastal Ron

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Re: Point-to-Point hub
« Reply #7 on: 10/10/2017 05:38 PM »
Just saw this article that helps to identify the market SpaceX would go after for BFR Point-to-Point transportation:

How the journey of 1,000 miles or more grates on business travellersí nerves - Tnooz

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How the journey of 1,000 miles or more grates on business travellersí nerves

The journey may be part of the adventure for leisure travelers, but around 60% of business travelers find time spent in transit irritating, and nearly half find layovers draining, according to a new study by the Global Business Travel Association.

A neighbor of mine just got back from a work assignment in Asia, and he was exhausted from the 17 hour total transit time. Cutting that down to 30 minutes would be compelling for many.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline WBY1984

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Re: Point-to-Point hub
« Reply #8 on: 10/10/2017 05:48 PM »
Aren't we getting ahead of ourselves? There's no reason to think that a big, complex vehicle like BFR will have significantly better reliability than the safest rockets we have today, certainly not the order of magnitude improvement demanded by regular passengers. Why are we expecting this to be routine? Haven't we already made this mistake with shuttle?
« Last Edit: 10/10/2017 05:50 PM by WBY1984 »

Offline envy887

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Re: Point-to-Point hub
« Reply #9 on: 10/10/2017 06:04 PM »
Aren't we getting ahead of ourselves? There's no reason to think that a big, complex vehicle like BFR will have significantly better reliability than the safest rockets we have today, certainly not the order of magnitude improvement demanded by regular passengers. Why are we expecting this to be routine? Haven't we already made this mistake with shuttle?

This has been extensively argued here, if you want to weigh in:

http://forum.nasaspaceflight.com/index.php?topic=43849.0

Offline jded

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Re: Point-to-Point hub
« Reply #10 on: 10/11/2017 08:46 AM »
This idea seems to match what SpaceX has shown in the video. There is one BFS and one BFR on the floating platform. This is all that is need to go to Hub and back again, but in case of a network of interconnections, the logistics becomes much more complex (BFR stays in place, but you need to make sure that as many BFS come in as they go out plus the operations need to be extra fast or more probably, additional stacks are needed).

In Hub mode, it could work like this:

- 1 hub, N end stations
- 1 BFS + 1 BFR per end station
- N platforms, N BFS + N BFR in hub
- all the end stations launch so that BFS arrive at the hub at more-or-less the same time
- hub has 1 stack waiting for each destination
- all passengers transfer to their target BFS
- hub launches all the BFS to their destinations

In this way, everyone can travel everywhere with 1 launch/day/end station and only 1 identical launch platform everywhere except hub. And since the ships are swapping every launch, most of servicing could be done only at the hub.

I don't think added travel time is as big issue here as in case of airplanes. Difference between 15h and 25h is a lot more painful than between eg. 30m and 1h.

Critical item would be the time of exchanging all the passengers at the Hub. If it takes more than an hour it would not work well.

This mode would be a good fit especially for beginning of operation, when the prices are expected to be high, volume of traffic low, and the costs of creating big spaceports everywhere for multiple concurrent BFR operations would be prohibitive. It might naturally change to point-to-point operations over time, with more popular routes first, and Hub would become more of a servicing station for BFS (and central spaceport for massive Mars missions). Probably it should be put somewhere near equator for that...

Offline hkultala

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Re: Point-to-Point hub
« Reply #11 on: 10/11/2017 09:19 AM »
The Point-to-Point use case for BFR is compelling but it has a key flaw:  too many points for such a high capacity vehicle.   Even if you only include sea-side large cities in the map - there are dozens if not a hundred possible destinations.  If you wanted to get to city X - you might have to wait a few days before that destination comes back up again.   What good is it to you if the flight is only 37 minutes when you have to wait a week before it is available.   And this is not even taking into account the issue of getting a large number of people all wanting to go to the same destination on the same day.

You are looging this from the completely wrong perspective.

SpaceX does not need to instantly replace all traditional air travel with the BRF.


They can start by ferrying passengers between , lets say , LA an tokyo.

When they select big enough cities there are ENOUGH passengers going directly between those cities that the system can be profitable when when there is no easy transfer flight option available.

Then they start building more routes. Initially they take like 0.01% of all airline passerngers.
Then they build more launch/landing sites and mabe later take like 5%.

They will NEVER try to get 100% of all flight travel. Not even 30%.

And they don't have to. If they some day get 5% of all air travel, that's already big money.


« Last Edit: 10/11/2017 09:21 AM by hkultala »

Offline speedevil

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Re: Point-to-Point hub
« Reply #12 on: 10/11/2017 01:26 PM »
<snip>
Then they start building more routes. Initially they take like 0.01% of all airline passerngers.
Then they build more launch/landing sites and mabe later take like 5%.

They will NEVER try to get 100% of all flight travel. Not even 30%.

And they don't have to. If they some day get 5% of all air travel, that's already big money.

'NEVER' is a big word. (well, five letters, but that's not important right now).

If, and only if P2P takes off in a big way, launch becomes nearly free, and hence launching quite large numbers of large orbital stations becomes not quite ridiculous.

You get on the next launch to a station which is nearly overflying your target, with a scheduled departure from that station to the target.
This can in principle be somewhat less than twice the cost of a two-hop journey.

It may take rather longer, but you can throw in an orbital experience 'for free'.

Of course, this only applies for flights terminating on coastal regions.

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