An SSTO as "God and Robert Heinlein intended".

[Urwumpe]

Elon also believes he can cut the costs to space to the $100 to $200 per kg range by reusability. Based on his track record I'd say it's a good bet he's probably right.

My local electronics market trades TV sets with "1200" refresh rates. The TV manufacturer sure knows best what his TV set can do and will not try to cheat me with such numbers right? :facepalm:

 

[T.Neo]

There is little debate that a reusable SSTO would have lower operational costs than a TSTO one if it exists. The debate is whether its lower payload would make it worthwhile.

I would say there is much more than little debate. The disadvantages of SSTO- a larger vehicle and more intensive technology, will increase operating as well as development costs.

First, a key problem for reducing the cost of spaceflight is that it can only come from reusability.

That is an extremely simplistic view. There are many ways that launch costs can be reduced, not all include reusability. For example, different schemes for using hardware, different methods of manufacturing, higher manufacturing rates and lower labour costs can all reduce launch costs.

Granted, reusability is likely the only way to get a certain specific type of cost reduction, but it also won't work well in certain scenarios (for example, at a certain flight rate it may be more economic to produce large amounts of hardware and expend it rather than a much smaller amount of hardware and reuse it).

In addition, reusability can backfire and actually increase costs. It has to be implemented correctly both technology wise and logistically.

As I argued before for small SSTO's a large market would be for small privately owned manned SSTO's.

Regardless of the size of this potential market, the disadvantages of SSTO are present for this application too. And perhaps make it particularly unsuited for it (for example, the more advanced engines and higher takeoff weight).

Having seperate stages is not a game-ender. And it isn't limited to "SSTO or TSTO". There are plenty of ways of potentially doing things- for example, a pop-up first stage is one. An air-launched SSTO is another. Both could improve the physical demands to the point at which such a system could be both developmentally and economically viable.

Jon Goff has a series of very interesting blog posts on methodologies for orbital access.

It is only required to marry them together.

One of the main criticisms, if not the primary criticism, of what you have been suggesting in this thread, is that this particular task is far easier said than done. Rocket development is not easy or cheap.

You will have to develop anew a whole lot of components, tweak or re-qualify most if not all existing components... if it gets to the point where it presents only a minor or even negative cost saving, then it obviously doesn't make sense at all.

And then to turn it into a reusable SSTO- for example, adding a TPS, landing and on-orbit hardware, as well as a cabin, is a whole other ballgame.

The most important accomplishment of SpaceX may turn out to be they showed in stark terms that a privately developed spacecraft can be developed for 1/10th the cost of government financed ones.

Yes, but you can assume either;

1. This ~10-fold reduction is universal and applies to any launch vehicle/spacecraft developed in this supposedly more efficient manner. This means that the cheaper solution remains cheaper regardless of whether it is developed by the government or NuSpace.

2. The technology developed determines the cost of development. Arguably SpaceX has been helped in this regard by engine design, stage commonality, extensive testing and small scale experimentation (Falcon 1).

In reality, it is a mix of both: a more efficient contracting structure and development culture, combined with technological decisions that reduce cost. It still puts SSTO at a disadvantage.

Secondly, as mentioned in this thread a large portion of launch costs are because of operational costs due to the large labor costs as run as a government program. For the space shuttle this is literally thousands of people to run it. This has been recognized for a while. A key part of the proposal to cut launch costs for the VentureStar reusable launcher was to cut majorly this required labor force:

A more technologically challenging vehicle can not only require a larger workforce (due to more work needed for turn-around) but a more highly trained workforce as well. Again something that puts SSTO at a disadvantage.

Elon also believes he can cut the costs to space to the $100 to $200 per kg range by reusability. Based on his track record I'd say it's a good bet he's probably right.

What track record? SpaceX may have a good track record at some things, but a pretty poor (or even nonexistant) one at others.

Cutting costs to space down to $200/kg is something that nobody has a track record at (certainly not at achieving such a goal, and I don't believe at attempting it either). SpaceX doesn't even have a track record at keeping its own advertised prices.

 

[RGClark]

My local electronics market trades TV sets with "1200" refresh rates. The TV manufacturer sure knows best what his TV set can do and will not try to cheat me with such numbers right? :facepalm:

I'm not understanding your analogy. Are you saying SpaceX benefits financially by intentionally deceiving people on this issue?
Or are you making some other point?

Bob Clark

 

[Urwumpe]

Are you saying SpaceX benefits financially by intentionally deceiving people on this issue?

Congratulations, you just became aware of marketing. :rofl:

 

[EnDSchultz]

Wow, really? I just read this entire thread. Most of it, anyway (I went through all the pages!). It started early last year and you two are STILL at it? Interesting as it is, I have a nagging suspicion this is going in circles. Please, people, for your own sanity, call a stalemate and put this one to bed.

 

[RGClark]

What track record? SpaceX may have a good track record at some things, but a pretty poor (or even nonexistant) one at others.

I'm talking specifically about Elon Musk's track record. Both with his prior businesses and with SpaceX.
Nobody sent a privately financed rocket to orbit until he did it.
It had long been speculated among insiders that rocket costs were greatly inflated by government financing but he proved the fact by cutting costs by a factor of 10.
If we are finally to make space access routine it's going to take people of guts, insight and of sufficient financing.
Elon has all of those.

Bob Clark

---------- Post added at 02:44 AM ---------- Previous post was at 02:39 AM ----------

Wow, really? I just read this entire thread. Most of it, anyway (I went through all the pages!). It started early last year and you two are STILL at it? Interesting as it is, I have a nagging suspicion this is going in circles. Please, people, for your own sanity, call a stalemate and put this one to bed.

Stay tuned. This is only the tip of the iceberg once you accept what the rocket equation has been saying all along.

Bob Clark

 

[Cras]

Wow, really? I just read this entire thread. Most of it, anyway (I went through all the pages!). It started early last year and you two are STILL at it? Interesting as it is, I have a nagging suspicion this is going in circles. Please, people, for your own sanity, call a stalemate and put this one to bed.

It is how these sort of discussions tend to go around here.

But I wouldn't call it a stalemate. My scorecard shows someone with a lead.

 

[T.Neo]

I'm talking specifically about Elon Musk's track record. Both with his prior businesses and with SpaceX.
Nobody sent a privately financed rocket to orbit until he did it.
It had long been speculated among insiders that rocket costs were greatly inflated by government financing but he proved the fact by cutting costs by a factor of 10.
If we are finally to make space access routine it's going to take people of guts, insight and of sufficient financing.
Elon has all of those.

No track record (and it has already been explained here where the SpaceX track record is lacking) can magically make your venture to lower launch costs down to $100/kg successful. Nobody has a track record relating to that. If it is possible at all, it is extremely challenging.

This is only the tip of the iceberg once you accept what the rocket equation has been saying all along.

Rubbish. The rocket equation is a miniscule fraction of the effort that goes in to making a launch vehicle. Nearly 100% of that effort is actually applying the math technologically.

You can get the rocket equation to do all sorts of nonsense for you that couldn't be done in reality.

RGClark, you never actually bother to answer tough questions (like my SSTO vs TSTO challenge). It seems you pick up on a sort of 'buzzword' (for example, "SSTO can cut costs to $100/kg", "private development can be 1/10th the cost of government development" or soforth) and keep on repeating it (in a manner that harkens the term 'stuck record') whenever someone challenges your claims or asks you to properly substantiate them.

 

[RGClark]

...
You can get the rocket equation to do all sorts of nonsense for you that couldn't be done in reality.

No, it can't. It makes no sense to believe what it says for getting 3-stage to orbit vehicles, and 2-stage to orbit vehicles, then suddenly refuse to believe what it says about getting single stage to orbit vehicles.
The question of turning the mathematics into reality was also raised by Risingfury in the "Elon musk wants to put millions of people on Mars" thread. RisingFury made the point just because the math says you can get as close to light speed as you want doesn't mean you can do it in practice.
The beauty of the rocket equation is that it tells you what you need to do to get that rocket vehicle within the scenario you're considering. For the single stage to orbit vehicle case you need high efficiency engines and lightweight stages. We now have both the high efficiency engines and the lightweight stages. To disregard that would be just like looking at the 2-stage case seeing what the engine requirements are, noting we have engines of those requirements, and seeing what the stage requirements are, noting we have stages with those requirements and then suddenly deciding despite that that it's "impossible" and can't be done.


Bob Clark

 

[T.Neo]

RGClark, I don't believe anyone in this thread is saying that SSTO is a physical impossibility: it is not. It is probably physically possible (as an expendable) with existing technology, too. That isn't the issue.

The issue is the economics. Just because something is physically possible doesn't mean it is economically worth doing. Yes, if you use lightweight tankage and high performance engines, you can get an SSTO... it could work and fly to orbit, but that isn't the issue.

The issue is that SSTO is at a physical disadvantage. To reduce costs, you don't want the bleeding edge. You don't want things like high performance engines.

In your quest to prove that SSTO is not magically impossible, you totally and entirely gloss over the economic aspect. The issue isn't whether you can build an SSTO or not, but rather: if your SSTO costs twice as much as a TSTO design, why bother with the SSTO at all?

 

[Urwumpe]

The main problem that remains to be proven from RGClark: Can a fully reuseable SSTO be in any sense superior to a fully reuseable TSTO? Nobody doubts that the rocket equation permits finding numbers that make a SSTO possible. Most of us simply doubt that:

- You can get the dry mass low enough for building a real expendable one with expendable low-performance engines or
- You can get the engine performance high enough to build a real reusable one with reuseable high-performance engines.

That is the part that RGClark simply ignores. The logic in his argumentation is pretty much like these two alternative paths:

Rocket equation says a certain SSTO configuration is possible ► Something magical happens here ► Launch costs are down to $100 per kg

Or:

Rocket equation says a certain SSTO configuration is possible ► Launch costs are down to $100 per kg because Elon Musk says so.

If I would give Elon Musk the paperwork for a 6000 kg satellite and $60,000 for launching it, do you think he will take the contract and launch it for that price? Maybe together with another satellite in that weight class that he will launch for $6000 per kg on a bigger launcher ("The first one is for free"). But economically, I doubt he could even get the aluminum for building his rockets for that launch price.

Contrary to paper rockets, real rockets are made of real materials, that cost money and need employees and tools that also cost money. all that money goes into the launch costs, together with the R&D effort to get from paper rockets to blueprints. Plus the money for the 200-300 employees that you need for managing your company and keeping contact to your customers and suppliers (You can Kanban rocket production, but you can't rely on standardized supplier networks like car companies already have).

$1000 per kg would already be a major achievement in that economic situation. You would need a pretty cheap launcher with lots of payload, so the overhead does not harm that much.

Just for some fun, I know that the argumentation is really weak and more absurd than realistic economics: if you would try to send your payload with the needed SSTO rocket (An idea less than 1% payload mass fraction) from USA to Europe the cheapest way (in small parts or rolls of sheet metal, container ship, assuming $2000 per TEU), you would already be close to fail if you want to do that with $100 per kg payload (You could transport a scout rocket and its tiny payload actually with that rate, but without any transport tools, like making sure the rocket survives rough seas)

Of course it makes no sense (why should you do that?), but it shows well how cheap $100 per kg for a space transportation service actually is in the real world.

RGClark has done nothing that you don't already get presented in your first semester of aerospace engineering - The case of a SSTO based on the rocket equation and how light it would have to be for having positive payload mass fraction with realistic engines.

You are right, that alone is no reason for 17 pages of arguments.

What annoys me is his Velcro Rocket attitude (Without even bothering using Velcro), of taking existing stages and then do some obscure modifications to them to say: See, it can be done. It is still cheap paper rocketry, but presented like other engineers are just ideologically disoriented, SSTOs censored from engineering or incompetent.

It is like doing just the first 2 hours feasibility study for a new rocket, that will eventually take 5,000,000 man hours to develop (about $1,000,000,000 development costs, that is actually cheap), and claim you did all the important work there.

Maybe this is a bit negative. But the optimistic interpretation of the situation would be: Such launch costs can only be achieved with a revolution in rocketry and in the economics on the ground.

 

[T.Neo]

But economically, I doubt he could even get the aluminum for building his rockets for that launch price.

The justification for the $100-$200/kg launch costs by SpaceX involves reusability; the manufacturing cost of the vehicle is amortised over many flights.

Of course, you also have hardware refurbishment costs, launch operations costs, payload integration costs, etc...

Also, Elon Musk has never actually championed SSTO, at least not seriously. The vehicle that enables his supposed massive cost reductions is a TSTO.

 

[Urwumpe]

Also, Elon Musk has never actually championed SSTO, at least not seriously. The vehicle that enables his supposed massive cost reductions is a TSTO.

And even then, for the moment, SpaceX (not just Musk alone) does do attempts at reuse for the first stages, but give it a much lower priority as performance and costs. Its a capitalist company after all, not the Apollo veteran social club.

 

[Hlynkacg]

The beauty of the rocket equation is that it tells you what you need to do to get that rocket vehicle within the scenario you're considering. For the single stage to orbit vehicle case you need high efficiency engines and lightweight stages. We now have both the high efficiency engines and the lightweight stages. To disregard that would be just like looking at the 2-stage case seeing what the engine requirements are, noting we have engines of those requirements, and seeing what the stage requirements are, noting we have stages with those requirements and then suddenly deciding despite that that it's "impossible" and can't be done.

Is not whether it is mathematically possible, the argument is over whether it is mechanically and economically feasible to do so.

Two factors that you consistantly ignore.

Likewise I thought you wanted to discuss my reservations with your earlier post. Let's discuss them.

 

[RGClark]

I would say there is much more than little debate. The disadvantages of SSTO- a larger vehicle and more intensive technology, will increase operating as well as development costs.

What I am considering as the primary benefit of SSTO's is the use of small, privately owned manned spacecraft to make space access routine. In the example in my prior post if you had the aerospike nozzle on the Falcon 9 first stage then you could lift a Dragon size capsule.
The payload capacity of this reusable SSTO version of the Falcon 9 would be less than a reusable two stage Falcon 9 but you don't want it for lifting large cargo anyway. Both cases would have the operational costs of reusability, but the SSTO version would not have the added purchase costs of the second stage nor its added operational costs.
An extensive discussion of the economic benefits of reusable SSTO's is presented in the book:

Halfway to Anywhere: Achieving America's Destiny In Space.
by G. Harry Stine
http://www.amazon.com/Halfway-Anywhere-Achieving-Americas-Destiny/dp/0871318059

Stine was an engineer who worked on the DC-X program.

Also, I was considering the costs benefits of the SSTO's even if they were only used to lift smaller payloads. However, analysis done by Dietrich Koelle suggests that the development and operational costs of a reusable SSTO will be less than a reusable TSTO even for the case where they lift the same payload:

COST ENGINEERING – THE NEW PARADIGM FOR SPACE LAUNCH VEHICLE DESIGN.
by Dietrich Koelle
Abstract. The paper describes the basic definition and application of ‘Cost Engineering’ which means to design a vehicle system for minimum development cost and/or for minimum operations cost. This is important now and for the future since space transportation has become primarily a commercial business in contrast to the past where it has been mainly a subject of military power and national prestige. Several examples are presented for minimum-cost space launch vehicle configurations, such as increasing vehicle size and/or the use of less efficient rocket engines in order to reduce development and operations cost. Further a cost comparison is presented on single-stage (SSTO)-vehicles vs. two-stage launchers which shows that SSTOs have lower development and operations cost although they are larger, respectively have a higher lift-off mass than two-stage vehicles with the same performance. The design of a space tourism-dedicated launch vehicle is an extreme challenge for a cost-engineered vehicle design in order to achieve cost per seat not higher than $50 000. Finally an outlook is presented on the different options for manned Earth-to-Moon transportation modes and vehicles – another most important application of ‘cost engineering’, taking into account the large cost of such a future venture.
http://faculty.kfupm.edu.sa/AE/hmomar/Air_Launcher_Project/Cost_Engineering.pdf


Bob Clark

 

[Urwumpe]

In the example in my prior post if you had the aerospike nozzle on the Falcon 9 first stage then you could lift a Dragon size capsule.

Really? Where did you hide the evidence for that?

 

[RGClark]

Rocket equation says a certain SSTO configuration is possible ► Launch costs are down to $100 per kg because Elon Musk says so.
If I would give Elon Musk the paperwork for a 6000 kg satellite and $60,000 for launching it, do you think he will take the contract and launch it for that price? Maybe together with another satellite in that weight class that he will launch for $6000 per kg on a bigger launcher ("The first one is for free"). But economically, I doubt he could even get the aluminum for building his rockets for that launch price.

Keep in mind the $100 to $200 per kg number is not arbitrary but is based on estimates by the SpaceX engineers of, for example, their understanding of the reusability of their engines, the most costly part of a rocket. Elon has said the Merlin should be reusable ten's of times.
About your example I think you meant $600,000 to $1,200,000 for that 6,000 kg satellite. But the low cost reusable vehicle does not yet exist. However, I think he would accept that payment now if that launch only had to be within the next 10 to 20 years.
Speaking of economic "bets". Consider this scenario. There have been many cases of people who got in early on an initial public offering and made out big when those companies became successful, such as with Apple, Google, etc.
Let's suppose that if SpaceX succeeded they would patent their reusable $100 per kg design so that no one else could use it or would have to pay license fees to SpaceX to use it, and no other company got in on the reusability paradigm to be able to field their own design for another say 5 years while SpaceX is fielding theirs. But let's say we still don't know whether or not SpaceX will succeed. We just know they said they'll patent their design when they get it and since no company is working on it, it would take a few years to catch up.
Under those conditions, clearly if they succeeded they would get a huge market share. Now let's say tomorrow SpaceX offered an IPO.
Would you buy their stock? Note this is asking a question on how you view the likelihood of them succeeding at this idea. I would, because I consider it likely they will succeed. Also, the other orbital launch companies have shown no dedication to achieving it. So if SpaceX succeeds they will likely be the only ones at least for a few years.


Bob Clark

 

[Urwumpe]

Keep in mind the $100 to $200 per kg number is not arbitrary but is based on estimates by the SpaceX engineers of, for example, their understanding of the reusability of their engines, the most costly part of a rocket. Elon has said the Merlin should be reusable ten's of times.

Estimates of Elon Musk impress me not at all - when he did so, I am impressed. Until that day, I have to assume that all he does is cooking with water like all the others. And is using cheaper, low technology gas generator cycle engines that can have a pretty long run time, but are no magic at all. They still run very hot, need expensive checks after each burn if you for example test them on the ground and can still explode if you mistreat them. Actually all photo and video evidence of the launches, which is the most solid evidence you have from SpaceX, since they keep most of the technical data of their launchers secret (for a reason), show no especially advanced launcher, just a company that applies Russian quality assurance on western technology (which is in case of SpaceX, using the worst of both worlds, since Russian rocket engines are much more advanced as the stuff they build).

Also, if you can reuse your rocket engines 20 times, this does not make the rocket 20 times cheaper. And especially not the launch.

The figure for NASA is like that: They pay 1.6 billion USD for 12 Falcon 9/Dragon flights. That means 133 million per flight. That is in the same range as you pay for a Ariane 5 flight and 50% cheaper than an EELV flight. Worlds apart from the $100 per kg that you advocate by faith.

Each Falcon 9 can haul 9,500 kg into space, this means every flight like that costs $14000 per kg - not even the $6000 that are accepted as low technological risk today. There is no number known about the launch costs without a dragon, and especially no number that is really business as usual.

The estimates by SpaceX for the Falcon 9 without Dragon (not confirmed by any customer contract yet) are 35 million USD. That is $3600/kg - a great number, right in the Russian price range. But not especially cheap.

The lowest estimate by Spacex for the Falcon 9/Heavy is 78 million with 24500 kg payload: $3200 kg. Conservative optimistic estimates from real engineers go to 120 million which is 50% higher, but more realistic, making the Falcon 9/Heavy a whole lot cheaper as the current Ariane 5, with better performance, but that is still a number that has to be achieved first.

Notice something?

What SpaceX promises in their marketing mode, and what they really charge as price, are not the same at all.

If you assume, SpaceX manages to (magically) reduce the costs by 5% every year (a pretty good value, it means it gets cheaper despite inflation), SpaceX would need 137 years to get that low. If spaceX manages to half the cost every year (which is after decades of spaceflight a tiny bit unrealistic), it would take just 4 years.

 

[T.Neo]

They pay 1.6 billion USD for 12 Falcon 9/Dragon flights. That means 133 million per flight.

Which includes both Falcon 9 and the Dragon spacecraft, not just F9 alone.

The estimates by SpaceX for the Falcon 9 without Dragon (not confirmed by any customer contract yet) are 35 million USD.

Not anymore, F9 is now advertised as $54-60 million.

The lowest estimate by Spacex for the Falcon 9/Heavy is 78 million with 24500 kg payload: $3200 kg.

Falcon Heavy is now advertised at $80-125 million.

The prices you have given are previously advertised ones... which shows something else: as SpaceX has gone on, its prices have increased.

If you assume at least, that SpaceX's conduct is relatively respectable, this is pretty clear evidence of one thing: SpaceX is not infallible.

However, analysis done by Dietrich Koelle suggests that the development and operational costs of a reusable SSTO will be less than a reusable TSTO even for the case where they lift the same payload:

The analysis can be flawed if it uses problematic assumptions. For example, if one were to use the exact same technological requirements (for propulsion, structure, TPS, etc) for a TSTO as one were an SSTO, then a higher operating and development costs for the former could indeed make sense.

The key is that a TSTO, not having the same physical requirements as an SSTO, does not need to have the same technological requirements as well. By having more physical leeway in a TSTO design, you can use methods and techniques that are cheaper. And yes, you will have extra recovery/integration costs, and costs for the development of seperate stages... but the less demanding technology overall makes up for it.

And a TSTO need not have as much dissimilarity between the stages as you might imagine. There are lots of solutions that can potentially be employed- including near-identical stages (think shades of bimese/triamese).

In this respect, a TSTO is far more related to a "designing for cost" approach than anything you are suggesting. And it certainly matters when the technology needed for a reusable SSTO is either on the absolute bleeding edge of what is available, or does not even exist (yet).

 

[RGClark]

Which includes both Falcon 9 and the Dragon spacecraft, not just F9 alone.

Not anymore, F9 is now advertised as $54-60 million.

Falcon Heavy is now advertised at $80-125 million.

The prices you have given are previously advertised ones... which shows something else: as SpaceX has gone on, its prices have increased.

But that is for the 53,000 kg launcher, which is about $2,000 per kg, about $1,000 per pound.

Bob Clark

---------- Post added at 12:40 PM ---------- Previous post was at 12:33 PM ----------

...
What SpaceX promises in their marketing mode, and what they really charge as price, are not the same at all.
If you assume, SpaceX manages to (magically) reduce the costs by 5% every year (a pretty good value, it means it gets cheaper despite inflation), SpaceX would need 137 years to get that low. If spaceX manages to half the cost every year (which is after decades of spaceflight a tiny bit unrealistic), it would take just 4 years.

So if SpaceX did offer an IPO tomorrow you would not buy that stock? Even considering that if they succeeded at Elon's avowed dedication to reducing the cost of space to the $100 to $200 per kg range by reusability would mean they would dominate the market?

Bob Clark

---------- Post added at 01:07 PM ---------- Previous post was at 12:40 PM ----------

It seems you pick up on a sort of 'buzzword' (for example, "SSTO can cut costs to $100/kg", "private development can be 1/10th the cost of government development" or soforth) and keep on repeating it (in a manner that harkens the term 'stuck record') whenever someone challenges your claims or asks you to properly substantiate them.

Yes, I am going to keep emphasizing that point about privately financed launchers cutting the cost to space until it sinks in. In fact I was thinking about making it my sig file.

Think about it. You frequently hear about developing a new manned launcher would be a billion dollar project. Say it cost $3 billion by the usual NASA estimates. What that means is that it would only cost $300 million if it were privately financed.

Then any of the large defense contractors could develop their own manned launchers out of their own "pocket change". We could have routine manned space flight if the full implications of what SpaceX accomplished were realized.

Bob Clark