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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)

#61

Post by njarboe »

avhon1 wrote: post #34
flashback2199 wrote: post #27

Earlier quoted context omitted.

Right, I think people are misunderstanding a key point here, which is that SpaceX, Blue Origin, etc would really like to see rockets be an alternative to airplanes, in which case we are talking about a dramatically increased number of launches.

> SpaceX, Blue Origin, etc would really like to see rockets be an alternative to airplanes Why? Rockets are intrinsically less efficient and less safe than airplanes. Why would they try to compete for use cases where they are at such a disadvantage, and where they have to-date shown no interest in competing with fixed-wing aircraft? The closest those companies have done to showing interest in pitching rockets against…

It would just be for very long flights. 45 minutes from New York to New Zealand instead of 17hr. That is a big difference. Plus you get to go into orbit (or close to it) for an amazing view/ride. You would have a huge number of people per year at $5-10k per ticket.

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

#62

Post by m4rtink »

twic wrote: post #13
mlsu wrote: post #12

Earlier quoted context omitted.

Starlink wasn't really considered for years until SpaceX already was well underway. It was fortuitous but unplanned, not a factor in the original vision of the company when it was founded.

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.

Sure, they might have guessed the scale or ramp-up wrong, I would still argue there is quite a few more launches now happening than there would be without Space X jump-starting the whole thing.

Still, not being fully dependent on that certainly helps. :)

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

#63

Post by m4rtink »

flashback2199 wrote: post #26
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.)

Just as 100k jet airplane flights per day would have been unimaginable in the ~50s when the jet airliner industry started, I actually can imagine a near future where many more than 10k rockets per day are launched, if the industry has it's way and succeeds in reducing costs dramatically.

At such scale it would be a different (and in some cases potentially much more dangerous :D) technology - huge hydrolox SSTOs, launch loops, rotovators, nuclear lightbulb SSTOs, maybe even orbital elevators.

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

#64

Post by m4rtink »

bryanlarsen wrote: post #56
pi-e-sigma wrote: post #50

Earlier quoted context omitted.

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.

It gains efficiency compared with an airplane by spending most its trajectory outside of atmosphere with no air resistance.

There are also other benefits - avoiding weather along the route, taking a straight road where an airplane needs to take a longer route for political or safety reasons, etc.

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

#65

Post by pi-e-sigma »

bryanlarsen wrote: post #59
pi-e-sigma wrote: post #57

Earlier quoted context omitted.

No it does not, because thanks to atmosphere wings on an airplane generate lift. And they do it more efficient than any kind of engine known to the mankind

Yes, an airplane can climb much more efficiently than a rocket. So on a 300km flight where all it is doing is climbing and descending it's way more efficient than a rocket. But for a 10,000km flight the airplane expends almost all of its fuel coasting rather than climbing. Luckily we don't have to rely on assertions. If I'm wrong, there should be an obvious error in my math (which is trivial) or facts (which is on Wi…

You think an airplane doesn't need lift when in a level flight? :) Thanks to the atmosphere an airplane doesn't need to carry its own oxidizer, either. I'll leave to you to check how much oxidizer a Falcon rocket needs to carry for every ton of fuel.

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

#66

Post by bryanlarsen »

pi-e-sigma wrote: post #65
bryanlarsen wrote: post #59

Earlier quoted context omitted.

Yes, an airplane can climb much more efficiently than a rocket. So on a 300km flight where all it is doing is climbing and descending it's way more efficient than a rocket. But for a 10,000km flight the airplane expends almost all of its fuel coasting rather than climbing. Luckily we don't have to rely on assertions. If I'm wrong, there should be an obvious error in my math (which is trivial) or facts (which is on Wi…

You think an airplane doesn't need lift when in a level flight? :) Thanks to the atmosphere an airplane doesn't need to carry its own oxidizer, either. I'll leave to you to check how much oxidizer a Falcon rocket needs to carry for every ton of fuel.

We don't have to wait long to prove you wrong. Starship using just ~1200t of Methane and 150t of payload capacity will fly East (the long way) from Texas to Hawaii in 90 minutes. That's 8x as much payload 3x as far as a 787 can do with its 100t of fuel.

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

#67

Post by LeifCarrotson »

bryanlarsen wrote: post #56
pi-e-sigma wrote: post #50

Earlier quoted context omitted.

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.

It gains efficiency compared with an airplane by spending most its trajectory outside of atmosphere with no air resistance.

That's more efficient if most of your trips require you to go 90% of the way around the planet (maybe?). Or for sure if you coast twenty times around the planet.

But half the circumference of earth is not that far.

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

#68

Post by dotnet00 »

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?

They're running out of money and can't really get the kind of money needed to continue on the rocket R&D, so they're trying to stick to their satellite components business to stay alive until they can attract funding.

Plus, they're kind of at a bad point and time in the market as small launch is not as lucrative as they hoped but moving up to medium lift is a big hurdle. So far, SpaceX is the only 'new space' launch company to have managed it, with all other competitors in development hell.

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

#69

Post by dotnet00 »

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.

I think most people familiar with space stuff, even ardent Musk supporters, don't really see that panning out. Even putting aside the pollution, there are too many logistical issues when it comes to spreading out all those launch sites and resupplying them.

The rocket transport service they're working on with the DoD is the only thing that we might see demonstrated by then but not really used since there aren't many things so valuable as to need it. That too only because the DoD will probably be willing to pay for the Starship to be scrapped after landing, as unless they build up the infrastructure to fuel and launch the rocket, it's stuck there.

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

#70

Post by dotnet00 »

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.

That only works when you're doing something like Starlink or Starship's development, where losing some prototypes is fine. However, that's not how JWST was designed, so losing many prototypes of it would be very costly. If JWST were designed with the consideration that it'd be mass produced, it would not be the JWST we know today and instead would be a completely different design (a rough comparison can be between OneWeb's more standard delicate satellite design and deployment procedure vs SpaceX's heavily optimized stack of less delicate satellites just drifted into orbit).

Most space companies are still doing their prototyping in the JWST style, so losing those prototypes is costly.

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