Boeing and Space-X win NASA contracts for manned spaceflight

[K. A. Pital]

An SSTO spaceplane is going to run into some of the same problems of safe engine reusability as a reusable rocket stage.

Not quite. Plane engines do not undergo the stress of either hard landing or water damage that much. But even so they are quite a problem in and of themselves.

Yeah, that's why they are doing soft landings with the Falcon 9Rs out in the Atlantic.

Did you even read what I wrote? They do not have a plan for the second stage at all. The first stage plan is fuzzy at best. They do not have a solution for payload loss (other than 'we'll just have a powerful rocket', well gee thanks).

We don't even know how much that would cost, but you seem wedded to the idea of Horizontal Take-off/Horizontal Landing (HTHL), and I doubt I can convince you otherwise. I wonder why no one else is trying it seriously? Could it be the structural problems are just too nasty?

Am I saying it is possible? No. I am saying that is a breakthrough technology. I would say that a fully reusable rocket is also a breakthrough, but I have the very same doubts about its feasibility. No amount of Musk-talk can convince me - and given that people approached reusable rockets before and abandoned the idea entirely due to payload loss and damage issues, I would only believe it when I see it. Same goes for spaceplanes, but development in that area is still ongoing. The concept itself is not that crazy, it is the engine design requirements that are an issue.

The current payload cost (per SpaceX documents) for a Falcon Heavy launch (which they are booking for) is $2200 per kilogram. The target cost for your beloved Skylon (which doesn't even have the full prototype engines running yet - although I don't see any show stoppers) is 1430£ per kilogram, or about $2300. That is for an expendable Falcon Heavy, not a reusable one.

Like I said: a cheaper reusable rocket is a cheaper rocket and perhaps it does solve many issues, but can it be called a breakthrough? Proton launch costs per kilo are only twice higher than the yet-to-be-achieved 'target cost' of the SpaceX rocket which doesn't yet exist. That is a rocket developed in the 1960s. Impressed? I am not.

Also, for the record, there was a reusablitlity study in the 1960s that showed that if you can recover a liquid stage with the engine and most of the tankage intact, you can have a refurbishment at less than 10% of the cost of a new rocket.

Yup. Right. I mean, let's talk about a 1960s study instead of the way more recent experiences of people who had a chance to go that way for decades, but consciously decided against it.

[Sky Captain]

Given that Space X already have showed the ability to consistently control first stages through reentry till soft touchdown on ocean surface recovery of the first stage is not that far off. Placing a barge in right spot and have first stage land on it isn't that difficult compared to stuff they already have done to bring the first stage back. Ultimate goal is to land stages back at the launch site, but that will come with severe payload penaltie because of extra fuel needed and range safet issues.
Reusing the second stage may or may not be cost effective, but second stage containing only one engine is much cheaper than first stage with 9 engines so even if only first stage can be reused cost effectively it still is a big win.

Neat thing about Space X approach towards reusability is every first stage they launch is also their reusability testbed, they can afford to crash stages, see what part failed and make an improvement on next stage until they get it right while still making money with launch. A company developing a spaceplane could never afford to crash their super expensive prototypes one after another and remain profitable.

[K. A. Pital]

Good lord, did you even read what I said about landing boosters on water? It is not good for the engines.

[Simon_Jester]

An SSTO spaceplane is going to run into some of the same problems of safe engine reusability as a reusable rocket stage.

Not quite. Plane engines do not undergo the stress of either hard landing or water damage that much. But even so they are quite a problem in and of themselves.

Since the plan for Falcon, such as it is, appears to involve landing on a barge, this may be less of an issue than you make it out to be.

Like I said: a cheaper reusable rocket is a cheaper rocket and perhaps it does solve many issues, but can it be called a breakthrough? Proton launch costs per kilo are only twice higher than the yet-to-be-achieved 'target cost' of the SpaceX rocket which doesn't yet exist. That is a rocket developed in the 1960s. Impressed? I am not.

Since Proton represents a rocket where all costs other than "manufacture the rocket as efficiently as we know how" have long since been dealt with, I would expect Proton's cost per kilogram to LEO to be about as low as that of any rocket that now exists.

Any technology that halves the cost per kilo compared to such a reliable workhorse is going to be a breakthrough, if only by being the thing that finally replaces Proton.

Remember: the first car was really only about twice as fast as a good horse. This does not mean the automobile didn't represent a substantial jump in technology.

On an unrelated note, if Skylon and Reusable Falcon 9 are expected to have the same cost per kilo to LEO... clearly it cannot be the case that one of them is a revolutionary breakthrough while the other isn't.

Also, for the record, there was a reusablitlity study in the 1960s that showed that if you can recover a liquid stage with the engine and most of the tankage intact, you can have a refurbishment at less than 10% of the cost of a new rocket.

Yup. Right. I mean, let's talk about a 1960s study instead of the way more recent experiences of people who had a chance to go that way for decades, but consciously decided against it.

So, what was the fault in the study?

[TimothyC]

Not quite. Plane engines do not undergo the stress of either hard landing or water damage that much. But even so they are quite a problem in and of themselves.

Bird ingestion. I'd really like to see how well the Skylon engines do when we shoot a large frozen turkey at them. It can't be good, not with the complex pre-cooler. And yes, if you want it to operate like an aeroplane, it must be able to eat small numbers of (potentially large) birds without breaking.

Did you even read what I wrote? They do not have a plan for the second stage at all. The first stage plan is fuzzy at best. They do not have a solution for payload loss (other than 'we'll just have a powerful rocket', well gee thanks).

I admit, the second stage recovery plan is still at the power point level, but the first stage is most certainly not fuzzy at all. They are doing controlled water landings, which is part of the long term plan (or have you missed their plan to land on solid ground with legs)

Am I saying it is possible? No. I am saying that is a breakthrough technology. I would say that a fully reusable rocket is also a breakthrough, but I have the very same doubts about its feasibility. No amount of Musk-talk can convince me - and given that people approached reusable rockets before and abandoned the idea entirely due to payload loss and damage issues, I would only believe it when I see it. Same goes for spaceplanes, but development in that area is still ongoing. The concept itself is not that crazy, it is the engine design requirements that are an issue.

Politics and up-front cost have been the bane of the US space program for decades. What Musk has done was he developed the Falcon 1 independent of government funds, then got the contract to deliver to the station, using that money to fund the Falcon 9 development. It worked. Now that he has a medium capacity launch system, he's using the profits he gets to fund development of the features he needs to re-use the rockets. Yes, the Falcon 9R Dev1 exploded, but that was a part of his R&D program, and problems are to be expected. The risk averse nature of space development has only slowed progress, and better that a development rocket explode than one with payload.

Like I said: a cheaper reusable rocket is a cheaper rocket and perhaps it does solve many issues, but can it be called a breakthrough? Proton launch costs per kilo are only twice higher than the yet-to-be-achieved 'target cost' of the SpaceX rocket which doesn't yet exist. That is a rocket developed in the 1960s. Impressed? I am not.

Well, I doubt that the Proton has any margin for lower costs (without destroying payloads at an even higher rate), or the mighty soviet space-industrial complex would have squeezed it out years ago. The Falcon 9 was designed from the start to be the basis of a reusable launch system, and as such has room to improve.

Yup. Right. I mean, let's talk about a 1960s study instead of the way more recent experiences of people who had a chance to go that way for decades, but consciously decided against it.

Clearly politics (NASA), and lack of funding (NASA and CNES) had Nothing to do with it. I suggest you read up on the history of the Delta Clipper rocket. You should love it. It was SSTO, fully reusable, but it did take off and land on it's tail, so it isn't your perfect launcher. Also, CNES is one of the two companies involved in the Ariane V, a direct competitor to the Falcon series of rockets, so clearly they are an impartial observer. No conflict of interest here!

Good lord, did you even read what I said about landing boosters on water? It is not good for the engines.

Oh, I was so hoping you would bring this up.

I'd like to bring your attention to the Rocketdyne H-1. The H-1 was an evolutionary development of engines use in earlier rockets (Thor and Jupiter), but much simpler (the H-1 had on the order of 1/10th the parts count of the earlier S-3D engine). Now, in the early 1960s, after the Saturn C-1 (which became the Saturn I) was selected, there was a NASA evaluation done on recoverability of the S-I and S-1B stages. The idea was to make minor changes to the rocket after every launch with the eventual goal of making the launching stage recoverable. This did not happen mostly because the Staturn IB was dropped in favor of the Space Shuttle, but in 1962, the engines were given immersion tests.

I'll quote the NTRS PDF

Figure 9. H – 1 Engine, Half -Submerged.
Figure 10. Spraying H- 1 Engine after Recovery.
The purpose of this test program was to better define the effects of salt water immersion on the H-1 engine. Because of the various recovery schemes proposed for SATURN booster recovery, it was essential that hardware such as an H-1 engine be immersed in salt water and the results investigated to better evaluate the economics of booster recovery (wet versus dry recovery systems). The salt water immersion tests, reconditioning, and subsequent full duration static firings of the H-1 engine provided valuable information reflecting the feasibility of re-using large boosters after exposure to salt water.

The test program scheduled a series of three immersion tests with subsequent hot firing in the test stand. The first test was performed with known preservative measures, the second with less preservation, and the third and final test with no preservation methods applied. The salt water immersion was performed at Port Canaveral, Florida, and the dismantling, checking of components, assembly, and hot firing at the MSFC, Huntsville, Alabama.

The general test procedures were as follows:
1. First test – March, 1961. H-1 engine was:
a. Prepared and static fired.
b. Immersed in salt water to a depth of 10 feet for 2 hours, and half -submerged for 2 hours.
c. Purged. Preservations were applied.
d. Stored for 2 weeks.
e. Dismantled, inspected, cleaned, damaged parts were replaced, and engine was assembled.
f. Hot fired for short duration and full duration (150 seconds).

2. Second test – June, 1961:
a. Immersed H-1 engine to a depth of 10 feet for 1 hour, half submerged for 3 hours, and on the surface for 3 hours.
b. Waited 12 hours before purging, and applying minimum
preservatives.
c. Upon arrival at the MSFC, engine was dismantled, inspected, cleaned, damaged parts were replaced, and engine was assembled
d. Hot-fired for short duration and full duration.

3. Third test immersion in August, 1961; hot fired in March, 1962.
a. Dropped H-1 engine into water to simulate water entry conditions, immersed it, held it half-submerged, and on the surface for a total of 9 hours.
b, Engine washed with fresh water; – no preservative compounds were used.
c. Upop arrival at the MSFC, engine was dismantled, inspected, partially cleaned, ind left in storage.
d. Six months later the engine was assembled and hot-fired for short duration and full duration.

In order to establish an approximate cost factor, a log was kept of the procedures, reconditioning manhours, materials, and an itemized list of replaced engine parts. The cost to recover and recondition the H- 1 engine was approximately 5 per cent of the cost of a new one.

Clearly we can't have engines that take being in salt water.



Ever.

On an unrelated note, if Skylon and Reusable Falcon 9 are expected to have the same cost per kilo to LEO... clearly it cannot be the case that one of them is a revolutionary breakthrough while the other isn't.

Just a note, It's Skylon and the expendable version of Falcon Heavy that have the same cost to LEO, not the reusable Falcon 9 or Falcon Heavy. SpaceX really has done a number on launch costs. We have costs for Falcon Heavy because SpaceX is selling launches. Much better than the "We're still working on the full scale prototype engine" status for Reaction Engines.

[Irbis]

Space elevators need physics breakthrough.

No. See my post again. You can replace strength of the material with kinetic energy of transmission stream in structure going either directly upwards or, if you want something more conservative, forming loop 80 km above the ground. Neither design requires anything more than steel or carbon fiber. And they promise performance far superior to rockets in every single possible field, and that after being very conservative and multiplying/dividing as necessary every single target figure by 10.

And before you go 'long tunnel with superconducting magnets at the base is infeasible', we already have the technology. See Large Hadron Collider - 27 kilometres in circumference, capable of directing magnetic fields with micrometer precision, and it works. We already built something far more capable than a base loop would need.

Then, there is the problem of pollutants and greenhouse gases. Each rocket puts tens of thousands of tons of the stuff in the atmosphere. Active support structures just need single nuclear power plant.

Rehash or not, true SSTO will drop costs of launch to low orbit to hundreds of dollars per kilo, making at orbital assembly feasible.

But that's the thing, loop design promises cutting it to 3$/kg. Three. Even if they are off by order of magnitude, you can still put a hundred kilograms in orbit for a single kilogram put there by even most fantastically optimistic rocket designs.

Building ships on orbit? For the cost of Apollo Program, with loop you can put together manned mission to Jupiter and back. Or build base on the Moon. You don't have to bother with cutting corners and minimalistic goals.

Hell, you can even do that much touted 'space tourism' thing. 10.000$ (and 9/10 of that is pure profit) for a week on orbital station sure as hell sounds more affordable than rockets and 250.000$ just in cost of transporting your body to orbit.

[Simon_Jester]

And before you go 'long tunnel with superconducting magnets at the base is infeasible', we already have the technology. See Large Hadron Collider - 27 kilometres in circumference, capable of directing magnetic fields with micrometer precision, and it works. We already built something far more capable than a base loop would need.

Er, what would the long tunnel be doing again?

[Grumman]

And before you go 'long tunnel with superconducting magnets at the base is infeasible', we already have the technology. See Large Hadron Collider - 27 kilometres in circumference, capable of directing magnetic fields with micrometer precision, and it works. We already built something far more capable than a base loop would need.

Aren't we talking about a system that must contain a hundred thousand times more energy than the LHC - 10 GJ vs 1.5 PJ?

[Sky Captain]

Good lord, did you even read what I said about landing boosters on water? It is not good for the engines.

Goal is to land on a barge and later do full return to launch site. I don't see a problem with salt water immersion here. If landing fails and stage goes overboard it is writeoff anyway salt water or not. Current water landings are only to test reentry and braking maneuvers.

But that's the thing, loop design promises cutting it to 3$/kg. Three. Even if they are off by order of magnitude, you can still put a hundred kilograms in orbit for a single kilogram put there by even most fantastically optimistic rocket designs.

Problem with this sort of launch systems is huge up front cost and you need to use it as hard as possible to amortize the enormous investment over as much payload mass as possible. Essentially you need decades long large scale space program demanding thousands of tons payload per year to make such investment worthwhile.

[TimothyC]

But that's the thing, loop design promises cutting it to 3$/kg. Three. Even if they are off by order of magnitude, you can still put a hundred kilograms in orbit for a single kilogram put there by even most fantastically optimistic rocket designs.

Problem with this sort of launch systems is huge up front cost and you need to use it as hard as possible to amortize the enormous investment over as much payload mass as possible. Essentially you need decades long large scale space program demanding thousands of tons payload per year to make such investment worthwhile.

Uhm, while you are correct, I'm not the one backing the loop ideas. I favor fully reusable TSTO systems, or if needed, partially reusable ones (there are designs existing for Big Dumb Boosters that get payload into orbit for about $100 a pound).

[Beowulf]

Good lord, did you even read what I said about landing boosters on water? It is not good for the engines.

They're not intending to land on water. They're testing water landings right now for range safety reasons. If they can get it to land on the water at zero velocity and a specific point reliably, they can also land it on a concrete pad on land. That's why they have landing legs. And they're doing one stage at a time, because it's easier and cheaper to do it that way. Once they can get the first stage to be landing reliably, they'll start working on the second stage.

[Irbis]

Problem with this sort of launch systems is huge up front cost and you need to use it as hard as possible to amortize the enormous investment over as much payload mass as possible. Essentially you need decades long large scale space program demanding thousands of tons payload per year to make such investment worthwhile.

Yes, it does. But so what? You can make same argument over 1 lane dirt road and 12 lane concrete highway - yet we still build highways instead of arguing it's better to spend the cash on paying for delays and repairs incurred on dirt road.

Decades long? Once we have it, all sorts of industries and profits open up, pretty much immediately. We need to mine Helium-3 on the Moon? Done. Chromium/Vanadium/Gold/Platinum asteroid deposits in asteroid belt? Sure. Space tourism? Why not? Even manned mission become much safer because instead of thin wall you can put tanks full of water as shielding.

And it's not so huge - 20 billion $. Let's multiply by 10x to assume for any optimism and budget overruns and it's still what, 6-8 weeks of US military spending alone?

Er, what would the long tunnel be doing again?

*sigh* read the link perchaps? You need 4 km ring at the base to redirect the stream of pellets up after they complete one trip - that's how you go around the requirement of having nanotube tether, by replacing material strength with kinetic energy. It's even plainly visible on both illustrations.

Aren't we talking about a system that must contain a hundred thousand times more energy than the LHC - 10 GJ vs 1.5 PJ?

That's like saying a car is safer than railroad network of united states - because energy of one ton going 65 mph is smaller than million tons of rail cars. Yes, it's bigger, but over far bigger area.

[Grumman]

Aren't we talking about a system that must contain a hundred thousand times more energy than the LHC - 10 GJ vs 1.5 PJ?

That's like saying a car is safer than railroad network of united states - because energy of one ton going 65 mph is smaller than million tons of rail cars. Yes, it's bigger, but over far bigger area.

A space loop that had the same energy density as the LHC would cover half the United States. It's big, but it's not that big.

[Simon_Jester]

Problem with this sort of launch systems is huge up front cost and you need to use it as hard as possible to amortize the enormous investment over as much payload mass as possible. Essentially you need decades long large scale space program demanding thousands of tons payload per year to make such investment worthwhile.

Yes, it does. But so what? You can make same argument over 1 lane dirt road and 12 lane concrete highway - yet we still build highways instead of arguing it's better to spend the cash on paying for delays and repairs incurred on dirt road.

But we don't build highways to nowhere- we build them to places where there is already a well-defined destination and an immediate demand.

Towns that are now connected by twelve lane highways were invariably connected by four lane highways first, and usually be graveled roads before that, and dirt tracks before those.

And it's not so huge - 20 billion $. Let's multiply by 10x to assume for any optimism and budget overruns and it's still what, 6-8 weeks of US military spending alone?

More like five months. The catch is that while twenty billion (or two hundred) isn't a lot compared to the entire spending of a national economy, or even to the largest agencies of a major national government... it's a lot to spend on a single infrastructure project.

So there's an understandable degree of caution involved, especially when it's an infrastructure project that could spontaneously break down explosively. Which is not a problem for a bridge or highway, for instance.

Er, what would the long tunnel be doing again?

*sigh* read the link perchaps? You need 4 km ring at the base to redirect the stream of pellets up after they complete one trip - that's how you go around the requirement of having nanotube tether, by replacing material strength with kinetic energy. It's even plainly visible on both illustrations.

Ah. Sorry. I was thinking of "launch loops" and you were talking about "space fountains."

The problem I foresee from that is, yes, that you are exerting much larger forces with your superconducting magnets. And the consequences of a mechanical failure are far worse than with the LHC- which has had such failures.

Basically, a space fountain involves having countless hypervelocity bullets ricocheting around; it is hopefully a stable closed system, but the fundamental concept makes a hash out of any traditional concept of public safety and failure-tolerant design.

Aren't we talking about a system that must contain a hundred thousand times more energy than the LHC - 10 GJ vs 1.5 PJ?

That's like saying a car is safer than railroad network of united states - because energy of one ton going 65 mph is smaller than million tons of rail cars. Yes, it's bigger, but over far bigger area.

If the magnets fail, all 1.5 petajoules of energy (roughly 250 kilotons of TNT) are going to be released within a fairly small area sooner or later.

Of course, what I'm really interested in here is the 'top deflector.' How exactly is that supposed to work?

[Sky Captain]

If built on remote island there wouldn't be much public safety hazards in case of failure, just countless billions of $ going up in smoke.

But we don't build highways to nowhere- we build them to places where there is already a well-defined destination and an immediate demand.

Towns that are now connected by twelve lane highways were invariably connected by four lane highways first, and usually be graveled roads before that, and dirt tracks before those.

Yeah that is the problem, essentially you need large sustained space program going to make such huge infrastructure project worthwhile. In a situation where spaceplanes and reusable rockets fly like airliners and surface - orbit - surface traffic is projected to only increase in the future there would be economical incentive to build such system.
Currently reusable rockets and later spaceplanes is best bet to reduce launch prices to more affordable levels.