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A rocket a day keeps the high costs away (1993)

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Re: A rocket a day keeps the high costs away (1993)

#41

Post by bryanlarsen »

LeifCarrotson wrote: post #29
cma wrote: post #22

Earlier quoted context omitted.

Elon said by 2028 they will be in active passenger service replacing long haul aviation for cheaper than a business class ticket.

That's not realistic simply because of the carbon requirements. Long haul aviation only burns a couple hundred kg of jet fuel per passenger. (I don't know how the top-level comment is calculating 1-3 tonnes of CO2 per passenger, Contrail effects? Construction of the plane? Altitude? Incomplete combustion? but a 250-passenger 787 doesn't carry 750,000 kg of fuel, it only fits 100,000 kg at most, plus plenty of reserve…

Starship has the size to carry about 400 passengers. Both stages together carry about 5,000t of propellant. But over 3/4 of that is liquid oxygen, and most of that is the first stage. The second stage alone with 1200t of propellant can't put humans into orbit, but it does have a range comparable to that of a 787. So 300t of liquid methane will get 400 passengers about as far as a 787 can get 250 passengers with 100t of kerosene.

A starship ticket could theoretically cost A rocket may be less efficient than a turbofan but it gains it back by coasting through space for all but 3 minutes rather than pushing through air for the entire flight.

Re: A rocket a day keeps the high costs away (1993)

#42

Post by twic »

foobarian wrote: post #36
twic wrote: post #13

Earlier quoted context omitted.

Before Starlink, SpaceX assumed/hoped that a mass of new customers would come out of the woodwork when cheap launches became available (the easyJet strategy!). When they didn't, they came up with Starlink to be that customer.

Although, aren't they launching something pretty much daily or weekly, even without accounting for Starlink? It just isn't in the news much.

I picked September last year [1] more or less at random; SpaceX launches by day of the month:

  01 - Starlink
  02 - military
  04 - Starlink
  09 - Starlink
  12 - Starlink
  16 - Starlink
  20 - Starlink
  24 - Starlink
  25 - Starlink
  30 - Starlink
A skim through the other months suggests that per month, there is usually one US government launch, zero to two commercial or rideshare launches, and a bunch of Starlink launches. There is an amazing range of stuff on the rideshares!

[1] https://en.wikipedia.org/wiki/List_of_spaceflight_launches_i...

Re: A rocket a day keeps the high costs away (1993)

#43

Post by Workaccount2 »

cma wrote: post #22
lkbm wrote: post #17

Earlier quoted context omitted.

There are thousands of long-haul flights—and something like 100k flights overall—per day. If we're doing 10k+ rocket launches per day, then that's a huge problem. If we're doing 1 per day, it's a rounding error. This is premature optimization. (Either way, the solution, of course, is a carbon tax to price in the emissions.)

Elon said by 2028 they will be in active passenger service replacing long haul aviation for cheaper than a business class ticket.

If I had a list of "Elon said by x we will have y"...

Re: A rocket a day keeps the high costs away (1993)

#44

Post by panick21_ »

promiseofbeans wrote: post #40
actinium226 wrote: post #6

According to Ashlee Vance's "When The Heavens Went On Sale" this was the inspiration for Astra (the book links to this same article in the relevant chapter). The company hoped to produce and launch >300 rockets a year without re-use. The goal was to get economy of scale in manufacturing. Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so…

Isn't Astra developing a reusable launch system now?

Astra is functionally bankrupt. They ain't developing nuting anytime soon.

Re: A rocket a day keeps the high costs away (1993)

#45

Post by panick21_ »

actinium226 wrote: post #6

According to Ashlee Vance's "When The Heavens Went On Sale" this was the inspiration for Astra (the book links to this same article in the relevant chapter). The company hoped to produce and launch >300 rockets a year without re-use. The goal was to get economy of scale in manufacturing. Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so…

> Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so it wouldn't be such a big deal if a rocket failed every now and then. This would let them use automotive grade parts in some areas as opposed to aerospace grade and reduce costs.

Lets be real here. The business plan 'assumed' a whole lot of nonsense just so they could claim absurd totally unrealistic growth potential. The story shifted to whatever was 'hip' at the time.

It very much started with 'cube-sats' are the future. And when it was clear this was wrong, they started to make up other stuff.

Re: A rocket a day keeps the high costs away (1993)

#46

Post by sitkack »

looofooo wrote: post #35
actinium226 wrote: post #6

According to Ashlee Vance's "When The Heavens Went On Sale" this was the inspiration for Astra (the book links to this same article in the relevant chapter). The company hoped to produce and launch >300 rockets a year without re-use. The goal was to get economy of scale in manufacturing. Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so…

What would another James Webb Telescope would have cost? Far far less then the first. Sure it is costly to destroy a prototype, but not as much as you think.

In my ideal universe, we have a JWST assembly line.

Re: A rocket a day keeps the high costs away (1993)

#47

Post by panick21_ »

btilly wrote: post #11
SCM-Enthusiast wrote: post #4

Earlier quoted context omitted.

the novelty is how to handle such scale. Sure, if we build a million rockets it'll be cheaper, but how do we USE those rockets and get funding at "relative peace time". SpaceX's real innovation was starlink in allowing it to "Soak up" excess production. Besides the obvious of reusability, which wasn't that "Obvious" considering the temperatures of reentry.

Actually, reusability was an obvious idea from the start. For example the Space Shuttle and the McDonnell Douglas DC-X are examples of attempts at reusability in the USA, and other countries had their own experiments. It just became non-obvious that it was the right approach after a long history of failed attempts at it.

The Shuttle was the only serious attempt. And even then, they dropped the largest structural part and used solids that can't practically be reused anyway. The DC-X is just a research project, that they would ever develop a reusable launch was basically fantasy.

The same in other countries, very little actual large investments.

The Soviet Shuttle was even less reusable then the US one. And that was actually pretty smart of them.

So I don't think that were that many real failed attempts. There was practically speaking one real attempt.

Re: A rocket a day keeps the high costs away (1993)

#48

Post by actinium226 »

looofooo wrote: post #35
actinium226 wrote: post #6

According to Ashlee Vance's "When The Heavens Went On Sale" this was the inspiration for Astra (the book links to this same article in the relevant chapter). The company hoped to produce and launch >300 rockets a year without re-use. The goal was to get economy of scale in manufacturing. Part of the business plan assumed that people would be using the rocket to launch replacement satellites for constellations, and so…

What would another James Webb Telescope would have cost? Far far less then the first. Sure it is costly to destroy a prototype, but not as much as you think.

The companies launch prototypes because they want to test out technology and build methods that will go into the production satellite. Hence losing the prototype is a huge loss in time and/or increase in risk (if they decide to go ahead with certain technologies despite lacking on-orbit validation).

Re: A rocket a day keeps the high costs away (1993)

#49

Post by panick21_ »

twic wrote: post #42
foobarian wrote: post #36

Earlier quoted context omitted.

Although, aren't they launching something pretty much daily or weekly, even without accounting for Starlink? It just isn't in the news much.

I picked September last year [1] more or less at random; SpaceX launches by day of the month: 01 - Starlink 02 - military 04 - Starlink 09 - Starlink 12 - Starlink 16 - Starlink 20 - Starlink 24 - Starlink 25 - Starlink 30 - Starlink A skim through the other months suggests that per month, there is usually one US government launch, zero to two commercial or rideshare launches, and a bunch of Starlink launches. There…

There are lots of new costumers. The thing is just that most of those don't need the huge sats of the past.

And also people lose perspective. What we have to remember is how few launches other large rockets used to have. Ariane 5 the commercial success story peaked at 7 launches.

So yes, new costumers, but not enough to go from 7 to 100+.

Re: A rocket a day keeps the high costs away (1993)

#50

Post by pi-e-sigma »

bryanlarsen wrote: post #41
LeifCarrotson wrote: post #29

Earlier quoted context omitted.

That's not realistic simply because of the carbon requirements. Long haul aviation only burns a couple hundred kg of jet fuel per passenger. (I don't know how the top-level comment is calculating 1-3 tonnes of CO2 per passenger, Contrail effects? Construction of the plane? Altitude? Incomplete combustion? but a 250-passenger 787 doesn't carry 750,000 kg of fuel, it only fits 100,000 kg at most, plus plenty of reserve…

Starship has the size to carry about 400 passengers. Both stages together carry about 5,000t of propellant. But over 3/4 of that is liquid oxygen, and most of that is the first stage. The second stage alone with 1200t of propellant can't put humans into orbit, but it does have a range comparable to that of a 787. So 300t of liquid methane will get 400 passengers about as far as a 787 can get 250 passengers with 100t…

It doesn't gain anything back, what are you on. Before landing it has to shed all the speed it gained that was needed for the ballistic trajectory. That energy is lost. Orbital or suborbital flights will never, ever be competitive to flying with regards to required energy expended.
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