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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)

#91

Post by Qwertious »

tsimionescu wrote: post #81
SCM-Enthusiast wrote: post #52

Earlier quoted context omitted.

it was always the "Right approach" and everyone knew that there was nothing in the laws of physics that prohibits this. But you are writing that as if it's still be solved. No one has ever had a fully reusable orbital rocket.. still to this day. Althought starships got a shot.

It should be noted that reusable rockets are fundamentally less cargo per trip than non-reusable ones, since the reusable rockets have to carry extra fuel for re-entry. The sweetspot of having enough mass to orbit so that this reduced capacity is still worth it is not at all easy to reach. In general, if rocket building costs could really be reduced to almost nothing, reusable rockets would be useless. The only case…

Even if building rockets can be cheap, not all rockets/use-cases can be solved cheaply.

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

#92

Post by Self-Perfection »

contrarian1234 wrote: post #73

“then the frontier would open as the great railway to orbit supplanted the first generation wagon trains“ Except the frontier had fertile lands and vast potential. It was not a cold barren emptiness. You could also make access to Antarctica cheap and affordable at scale. It wouldn't suddenly make it economically sensible to go there I'm skeptical there is a huge amount of pent up demand that is just itching for lower…

I hope there might be some manufacturing process that will greatly benefit from microgravity. Maybe 3d printing of artificial organs for transplantation? Something that needs undisturbed crystallization?

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

#93

Post by dotnet00 »

looofooo wrote: post #87
dotnet00 wrote: post #70

Earlier quoted context omitted.

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 On…

Another JWST would have cost 1 Billion, so it is more than an Order of magnitude less.

That number isn't really convincing coming from the project that was initially expected to cost $1B and over time ballooned to $10B.

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

#94

Post by tsimionescu »

jessriedel wrote: post #89
tsimionescu wrote: post #80

Earlier quoted context omitted.

If you were to limit tourism to those fit enough to be allowed anywhere near a space launch, do you still think you'd reach that number? Not to mention, space tourism being an eighth of the total tourism market is obviously insane. The total tourism market is gigantic, space tourism would do wonderfully if it it were 0.01% of it (so, 8 billion or so? Probably not enough to warrant an assembly-line approach).

> If you were to limit tourism to those fit enough to be allowed anywhere near a space launch, do you still think you'd reach that number? Yes. The majority of the population can handle 3Gs. John Glenn was 77. > Not to mention, space tourism being an eighth of the total tourism market is obviously insane. I don't think space tourism becoming an eighth of total tourism is insane. I'd guess the fraction of tourism doll…

> John Glenn was 77.

He was in exceptionally good health.

> I don't think space tourism becoming an eighth of total tourism is insane. I'd guess the fraction of tourism dollars that are spent on travel reached by plane is a lot higher, maybe about a third or half.

The cost of a plane ticket is typically less than, say, a quarter of the total spending on a holiday (including hotel, food, attractions, souvenirs). Also, people go to certain destinations to spend time there, they don't go for the plane ride - which is all space tourism can be.

Just think about the number of civilian airports in the world, and compare to the number of locations where rockets can be launched from. There'll be more money to make in taking people to see the rocket launches than in actually putting tourists on rockets, I can guarantee that.

The only way space tourism might catch a break is if a space plane is ever actually successfully designed. That gets rid of many of the problems of rockets. But even then, it's a once in a lifetime experience, not something people would do every year like actual tourism.

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

#95

Post by cma »

bryanlarsen wrote: post #78
LeifCarrotson wrote: post #67

Earlier quoted context omitted.

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.

Airliners with extended range tanks are much less efficient than normal airliners, since they both decrease capacity and increase consumption. That's the range where Starship becomes competitive, basically trans-Pacific or further.

I estimate to hit the 2028 in active passenger service timeframe they would have probably have needed at least thousands of flights by now demonstrating safety with a perfect track record.

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

#96

Post by jessriedel »

tsimionescu wrote: post #94
jessriedel wrote: post #89

Earlier quoted context omitted.

> If you were to limit tourism to those fit enough to be allowed anywhere near a space launch, do you still think you'd reach that number? Yes. The majority of the population can handle 3Gs. John Glenn was 77. > Not to mention, space tourism being an eighth of the total tourism market is obviously insane. I don't think space tourism becoming an eighth of total tourism is insane. I'd guess the fraction of tourism doll…

> John Glenn was 77. He was in exceptionally good health. > I don't think space tourism becoming an eighth of total tourism is insane. I'd guess the fraction of tourism dollars that are spent on travel reached by plane is a lot higher, maybe about a third or half. The cost of a plane ticket is typically less than, say, a quarter of the total spending on a holiday (including hotel, food, attractions, souvenirs). Also,…

> He was in exceptionally good health.

Yes, but he was nevertheless more fragile than the majority of the overall population (all ages), which was the original concern you raised.

> The cost of a plane ticket is typically less than, say, a quarter of the total spending on a holiday (including hotel, food, attractions, souvenirs).

Agreed for LEO flights, but (1) I don't see why that difference matters much and (2) the cost breakdown of Mars tourism will similar to international travel now, i.e., 5-30% spent on transportation, and the rest spent on location.

> The only way space tourism might catch a break is if a space plane is ever actually successfully designed.

I don't really see why a space plane would be make a big difference here. Are you thinking of cost or the physical rigors? Space planes still require ~3 gees on launch (unless you're talking about something really exotic like JP Aerospace's Airship to Orbit").

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

#97

Post by tsimionescu »

jessriedel wrote: post #96
tsimionescu wrote: post #94

Earlier quoted context omitted.

> John Glenn was 77. He was in exceptionally good health. > I don't think space tourism becoming an eighth of total tourism is insane. I'd guess the fraction of tourism dollars that are spent on travel reached by plane is a lot higher, maybe about a third or half. The cost of a plane ticket is typically less than, say, a quarter of the total spending on a holiday (including hotel, food, attractions, souvenirs). Also,…

> He was in exceptionally good health. Yes, but he was nevertheless more fragile than the majority of the overall population (all ages), which was the original concern you raised. > The cost of a plane ticket is typically less than, say, a quarter of the total spending on a holiday (including hotel, food, attractions, souvenirs). Agreed for LEO flights, but (1) I don't see why that difference matters much and (2) the…

Mars tourism makes no sense, as there will be nothing whatsoever on Mars that you could even see for the next hundred years or more. An actual colony on Mars is way beyond our current technology, despite what some "futurologists" claim.

And even IF a colony on Mars is ever created, the amount of tourism it could ever imaginably sustain would be tiny compared to, say, New York or Tokyo or Paris - and neither of those, nor even all three together, are 1/8 of global tourism. Not to mention, a colony on Mars would just be tunnels in a desert (except it's a very very cold and highly radioactive dessert). Only a tiny handful of people would even be conceivably interested in spending months on a cramped rocket to visit it.

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

#98

Post by paulus_magnus2 »

Unfortunately this was published a few revisions too early IMHO. And a couple of peer reviews but the exploration itself is a nice try.

Due to nonlinearity of the rocket equation some assumptions are really really really off [a] [b]. V2 only has 2500m/s deltaV [5] and the launch vehicle's delta-v needed to achieve low Earth orbit starts around 9.4 km/s [6] (the actual delta-v is typically 1.5–2.0 km/s more for atmospheric drag and gravity drag). [7] Therefore V2 only deliveres (2500/9400)^2 (7% or 1/14 of the needed kinetic energy)

Trouble is we only get to convert 1-4% of the launch mass into payload in LEO with chemical engines. And that's for large rockets with economies of scale.

Sputnik (rocket) Mass: 267,000 kg Payload to LEO 500kg [3]

The smallest orbital rocket is the Japanese SS-520 with the following characteristics: It can launch 3 kg to orbit in 4.4 minutes. It's a modified sounding rocket with three solid-propellant steps. It's only 9.54 m long, 0.52 m dia., and has a mass of 2.6T @ liftoff [google]. The SS-520 rocket cost less than $5 million [google]

Bolting a 2nd stage on top of V2 was tried in [2] programme and with both stages at ~0.7 reliability things only work half the time. Not commercially viable.

Is there a market for small & cheap rockets? [8] What about dual purpose ? W54 "Davy Crockett" Atomic Projectile was the smallest nuke designed to maintain fission and could be carried around in a backpack! The final weapon was 10.862 inches (275.9 mm) in diameter, 15.716 inches (399.2 mm) in length and 50.9 pounds (23.1 kg). I guess this could be worked with. With the current risk of global war everyone should be mass producing a small launcher. However this way we still only get 1cubesat into orbit per $1m, not what the autor aimed at.

To get below $1000/kg into orbit we will need a bigger boat. And that's what SpaceX is doing.

(sorry to not have these in the nice order)

[8] https://space.stackexchange.com/questions/36261/why-isnt-the...

[a] assume that our bigger, more complicated (two-stage), and higher tech (LH2/LOX instead of Ethanol/LOX), launcher costs ten times as much as the V2

[b] If our mass produced LH2/LOX launcher equals the performance of the Delta 6925 by placing 3900 kg in LEO, the cost to LEO is US$333/kg; if we achieve better throw-weight, this figure goes down accordingly. If we build the thing so cheap, dumb, and heavy that its payload is only 1000 kg--one metric ton--the cost rises to US$1300/kg, which is still a factor of ten lower than the comparable cost to LEO for Ariane, Atlas, Delta, and Titan.

[1] So yes, a stripped-down stretch-tank engine-augmented two-stage V2-derived rocket, massing 351 tons as opposed to the 12.5 tons in the original, would be able to reach orbit*. :)

[2] https://en.m.wikipedia.org/wiki/RTV-G-4_Bumper

[3] https://en.wikipedia.org/wiki/Sputnik_(rocket)

[1] https://www.quora.com/If-boosters-were-strapped-on-the-V2-ro...

[5] https://space.stackexchange.com/questions/59879/how-much-del... [6] https://en.wikipedia.org/wiki/Low_Earth_orbit [7] https://en.wikipedia.org/wiki/Specific_orbital_energy

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

#99

Post by SCM-Enthusiast »

tsimionescu wrote: post #81
SCM-Enthusiast wrote: post #52

Earlier quoted context omitted.

it was always the "Right approach" and everyone knew that there was nothing in the laws of physics that prohibits this. But you are writing that as if it's still be solved. No one has ever had a fully reusable orbital rocket.. still to this day. Althought starships got a shot.

It should be noted that reusable rockets are fundamentally less cargo per trip than non-reusable ones, since the reusable rockets have to carry extra fuel for re-entry. The sweetspot of having enough mass to orbit so that this reduced capacity is still worth it is not at all easy to reach. In general, if rocket building costs could really be reduced to almost nothing, reusable rockets would be useless. The only case…

or if you can reduce the total cost of the payload.

That's what blue orgin is doing with the blue ring concept. Take avionics, data telemetry, battery's, and solar panels out of the design and let the customer focus on what end goal they are trying to achieve. I think blue ring is a very good business innovation as well.

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