SpaceX Tuesday...
Discussion
Eric Mc said:
I still can't see sub - orbital point to point travel being terribly successful.
Agreed - it will be costly enough to make Concorde fares look cheap. Also, for similar reasons to Concorde, its routes will be limited to locations where regular sonic booms will be tolerated.Some may think of military applications, i.e. getting troops to a conflict very quickly, but that ignores the infrastructure required at the far end to get it ready for a return trip - and a landed BFS will be a very big ( and expensive ) target
Eric Mc said:
I still can't see sub - orbital point to point travel being terribly successful.
Ignoring development and vehicle costs, your operating costs are fuel and maintenance.LOX is roughly $0.25/kg
CH4 is roughly $1.35/kg
BFS Fuel load is rated as (Wikipedia):
LOX : 860,000kg
CH4: 240,000kg
So:
LOX: $215,000
CH4: $324,000
Total $539,000
With 100 passengers and assuming full fuel load, fuel cost per passenger is $5390.
Initial flights will probably be expensive so $30k-$50, but there's plenty of margin to hit Business class prices of say $10k, when someone can do Europe to China in a day there will probably be a market.
There are also options for cargo and potentially adding more seats.
The question mark is obviously maintenance costs, but I think that is the gamble Musk is playing, economies of scale.
More ships = lower ship cost.
More usage = more data = improvements = better reliability.
There are obviously many steps to get there, but I respect the dream.
annodomini2 said:
The question mark is obviously maintenance costs, but I think that is the gamble Musk is playing, economies of scale.
Don't forget:Construction, maintenance, and staffing of terminal facilities at each end of every route
Construction of transport links to the terminal - expensive given that it will be far away from anywhere to alleviate the landing sonic boom, and engine landing and launch noise issues
Terminals would need to be much further away from cities etc. than an airport, adding to the total travel time - thus making it less competitive compared to aircraft. The problems of terminal location would also limit the number of locations and routes available
I don't see intercontinental rocket transport as ever being a thing. They're delayed days, or even months for the simplest thing as it is. Plus the launch & especially the re-entry & landing would be far too terrifying for you average, physically unfit punter to take. Any mishaps would wreck the entire concept, as it ultimately did the Concorde & Space Shuttle.
Polite M135 driver said:
can easily see people saying this about aeroplanes in the 1910s...
Bit of a difference I would say. The inherent problem with rockets is the huge amount of energy stored in the propellants and the need to release that energy in a very dramatic (but not too dramatic) manner. Even the slightest technical issues results in total loss of vehicle - pretty much 100% of the time.There is no margin for error with rockets - even after 100 years of developing modern liquid fueled systems. The first liquid fueled rocket flew only 13 years after the Wright brothers first flight so there is not a huge time difference in the period over which aviation and rocket technologies have been developed. Aviation is infinitely safer than it was in 1926. Rocket technology is not - and I don't think it ever will be safe enough - purely because of what it is.
If they manage to keep going with it I can see the bfr ship itself becoming successful and potentially continuing to improve reliability as they are just now.
However while earth-earth flights are an appealing idea I wouldn't be surprised if it falls by the wayside, both due to noise/ infrastructure.
One thought on the noise though, would it be possible for the impact from sonic booms to be limited by reducing speeds further from the pads? It'd obviously need a lot more fuel, but depending on overall efficiency, it may be worthwhile to make it more usable?
However while earth-earth flights are an appealing idea I wouldn't be surprised if it falls by the wayside, both due to noise/ infrastructure.
One thought on the noise though, would it be possible for the impact from sonic booms to be limited by reducing speeds further from the pads? It'd obviously need a lot more fuel, but depending on overall efficiency, it may be worthwhile to make it more usable?
If you have to retain more fuel to slow you down, it means that you have less fuel available to loft your payload - so the whole thing becomes completely unviable. At the moment, SpaceX have just about enough capacity with their Falcon 9 to retain re-entry fuel and still carry viable payloads that make the enterprise work out commercially for them. Doing the same for 100 fare paying passengers is whole different ball game.
Right on cue; Monday's Falcon 9 launch has been delayed "to conduct additional pre-flight inspections"
"Once complete, we will confirm a new launch date" - SpaceX
And in other news: "Btw, SpaceX is no longer planning to upgrade Falcon 9 second stage for reusability. Accelerating BFR instead. New design is very exciting! Delightfully counter-intuitive." - Elon Musk
"Once complete, we will confirm a new launch date" - SpaceX
And in other news: "Btw, SpaceX is no longer planning to upgrade Falcon 9 second stage for reusability. Accelerating BFR instead. New design is very exciting! Delightfully counter-intuitive." - Elon Musk
Eric Mc said:
Polite M135 driver said:
can easily see people saying this about aeroplanes in the 1910s...
Bit of a difference I would say. The inherent problem with rockets is the huge amount of energy stored in the propellants and the need to release that energy in a very dramatic (but not too dramatic) manner. <snip>What's actually risky is the limited margins everywhere on a rocket - by comparison, everything on a modern airliner is built like the proverbial locomotive.
CraigyMc said:
An A380 can carry about 250 tons of kerosene, so it's in the same ballpark in terms of fuel capacity as many of the modern rockets. That's the wrong thing to measure the risk by, other than "if it all goes bang, how big is the crater going to be?"
What's actually risky is the limited margins everywhere on a rocket - by comparison, everything on a modern airliner is built like the proverbial locomotive.
That's a really good point. A rocket converts a lot of it's fuel energy into kinetic energy of the payload, whereas an airliner is generally just replacing the lost energy from flying at 500 mph.What's actually risky is the limited margins everywhere on a rocket - by comparison, everything on a modern airliner is built like the proverbial locomotive.
CraigyMc said:
An A380 can carry about 250 tons of kerosene, so it's in the same ballpark in terms of fuel capacity as many of the modern rockets. That's the wrong thing to measure the risk by, other than "if it all goes bang, how big is the crater going to be?"
What's actually risky is the limited margins everywhere on a rocket - by comparison, everything on a modern airliner is built like the proverbial locomotive.
It's not the amount of fuel that's the issue. It's the way the fuel is consumed and how much energy is harnessed during the time period it is being released. I am sure you are aware that a rocket consumes fuel at a prodigious rate and for a very short period of time. That is a massive amount of energy released in minutes (sometimes seconds) - not hours. Making sure that energy is released in a controlled and safe manner is extremely difficult and places technology right at the edge of what it can do. One error, one flaw, one misplaced nut, washer, sensor, on pin prick leak - and you have pretty much an instant massive explosion.What's actually risky is the limited margins everywhere on a rocket - by comparison, everything on a modern airliner is built like the proverbial locomotive.
Dates for both Boeing and SpaceX crew module test flights have been announced.
Test Flight Planning Dates:
Boeing Orbital Flight Test (uncrewed): March 2019
Boeing Pad Abort Test: Between OFT and CFT
Boeing Crew Flight Test (crewed): August 2019
SpaceX Demo-1 (uncrewed): January 7, 2019
SpaceX In-Flight Abort Test: Between Demo-1 and Demo-2
SpaceX Demo-2 (crewed): June 2019
Test Flight Planning Dates:
Boeing Orbital Flight Test (uncrewed): March 2019
Boeing Pad Abort Test: Between OFT and CFT
Boeing Crew Flight Test (crewed): August 2019
SpaceX Demo-1 (uncrewed): January 7, 2019
SpaceX In-Flight Abort Test: Between Demo-1 and Demo-2
SpaceX Demo-2 (crewed): June 2019
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