Author Topic: Most economical way of shuttling humans to LEO?  (Read 26574 times)

Offline msat

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Most economical way of shuttling humans to LEO?
« on: 05/05/2015 05:07 am »
I've been trying to understand what the most economical methods for shuttling people to LEO would be using technology currently available or at least available in the near future. Obviously reusability with minimal refurbishment and prep requirements would go the furthest. Next on the list would probably be simplification of the rocket itself in order to lower the initial cost of the machine (assuming it wasn't absurdly high in the first place, which would negate the benefit of reusability), followed by reduced fuel costs. The first two seem well under way by the likes of SpaceX, and apparently Blue Origin. Maybe they both still have room to simplify? Seems unlikely.

What about fuel costs? From my understanding, LOX is practically dirt cheap. Fuels on the other hand aren't (relative to LOX), with H2 being on the more expensive end as far as common liquids go. Could the price of H2 be reduced using hydrolysis with energy derived from renewable sources (solar, wind, etc), rather than the current (and cheaper) method of extracting it from hydrocarbons? Once the initial investment is paid off, it's mostly the price of water and maintenance that's a recurring cost. How much could that reduce the cost of the fuels?

Once the bottom is reached in terms of fuel costs, what's there left to do? For a given rocket and its ISP, a fixed amount of fuel is required to get a given payload mass to orbit. Assuming all new "standard" rocket engine designs won't increase their ISP relative to their predecessors by a revolutionary amount, that leaves us with changing the rocket itself, or at least its launch profile. The only thing that appears to have any possible potential is air launching, which to date hasn't been done in any meaningful way. There's the notion that "every little bit counts", and while that might be somewhat true if we simply gauge the benefit in terms of slightly reduced fuel usage of the spacecraft, that reduced fuel requirement and associated reduction in spacecraft size does not automatically translate to an overall cost reduction.

For air launching, what's needed is SPEED, and to a lesser extent, altitude. So we know the more velocity and altitude the launching aircraft provides, the less fuel the spacecraft will need to take a given mass to orbit, but at what cost? Development and manufacturing costs for such an aircraft would be extremely high, but if it has high availability and a long life span, those aren't necessarily deal breakers. But what is saved? Assuming it is predominantly an air-breathing vehicle, the necessity of an on-board oxidizer supply is greatly reduced (though not eliminated - I believe any practical high-performance launch craft would need to augment the supply of atmospheric oxygen with its own internal supply), yet we remember that LOX is cheap, but fuel is expensive, and we still need that. Any potential fuel savings would come from the reduction in mass due to not having to carry as much oxidizer as a standard vertical take-off rocket. Whether this savings (if real) translates to any meaningful overall cost reduction is the big question.

Back to vertical launch rockets, where else are there potential savings? Besides the theoretical minimum amount of fuel needed to get a human's mass to orbit, is there a benefit to carrying more people per trip aboard a large rocket since the mass of the support equipment needed doesn't necessarily double along with occupancy (payload spacecraft, life support equipment, etc), among some efficiency gains that apparently come with larger rockets? My guess is that while it might make a difference, the reduction in fuel costs per unit mass lifted would be almost negligible, while the brunt of the savings would come from reduction in number of launches and all the costs associated with them required for taking a given amount of people to LEO. How big of a difference does this make in the real world?

Are we really this constrained until some magical fuel and propulsion system comes along?

Offline ChrisWilson68

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Re: Most economical way of shuttling humans to LEO?
« Reply #1 on: 05/05/2015 05:26 am »
I've been trying to understand what the most economical methods for shuttling people to LEO would be using technology currently available or at least available in the near future.

The problem isn't well-defined because you didn't state the number of people.  The answer is very different for different numbers of people.

Fully-reusable wins when the number of people gets large enough.  As the number of people continues going up, the answer is larger and larger vehicles.  The larger the vehicle, the cheaper it is per person, but the larger the number of people needed to pay the up-front costs.

There are several ways you can do fully-reusable human launch systems.  With current technology, it's very likely going to be a two-stage system that is most efficient for large volumes of people.  It can be done with either vertical landing or winged fly-back boosters, with roughly comparable efficiency.  The same goes for the upper stage and crew compartment (whether part of the upper stage or not).

So, a scaled-up Falcon 9 and Dragon style system is probably roughly as efficient as you're going to get (at least to the nearest order of magnitude).

Of course, that's just with today's technology.  With new technology, that could change.

Offline Burninate

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Re: Most economical way of shuttling humans to LEO?
« Reply #2 on: 05/05/2015 05:32 am »
Propellant (oxidizer and fuel) is extraordinarily cheap.  Hydrogen is noted to be expensive relative to other fuels in that it's expensive to handle, and expensive to design and build tanks to hold reliably, but the raw material remains easy to generate from natural gas.

I think this image is instructive:


Many of the costs associated with space launch are not marginal costs.  It costs roughly the same to employ a range team whether they oversee 1 launch per year or 18 launches per year.  It costs a lot of money to build a proven design and workflow with tools of a certain diameter for a rocket, but not a lot of money to pump out each additional rocket.  When you ramp up production of a rocket, many of the labor-intensive things you're doing to construct individual units can be automated away.  The most complicated rocket is in principle much simpler than, for example, a Toyota, with far fewer moving parts and computer subsystems.  Building a modern automobile in lots of 2-10 units per year would be frightfully expensive, a hundred times more per unit if you amortize R&D of a novel design.  What is different is that rockets are much more hazardous things, which only work at large scales that are inherently expensive to cater to, and there is *far* smaller demand for things shipped to space than there is for Toyotas.

If the world was for some reason to find ourselves with 1000x as many paying customers who want their payloads shipped to space, prices per kilogram would likely come down by 3-10x in the face of mass production techniques and workflow improvements, and a similar number in the face of reusability economics, and possibly even by a similar number in the face of larger, less refined rockets (eg the Sea Dragon or Aquarius).

It would do this *before* we explored spacelaunch based on something other than chemical rockets, which often makes some theoretical sense, but whose development cost is nearly always predicated on what has been up to now, unrealistic projections of customer demand.
« Last Edit: 05/05/2015 05:49 am by Burninate »

Offline hkultala

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Re: Most economical way of shuttling humans to LEO?
« Reply #3 on: 05/05/2015 05:45 am »
First we have to decide that are we talking only about unit costs, can we assume huge number of people and large fixed costs?

Or are we talking about 10 people to orbit/year like now? or something between.




Near-term, only moderate increase in people or orbit/year:

Capsule and rocket for ~30 people would not cost 10 times more than soyuz, it could be launched on falcon heavy, costing only slightly more than sojuz.


Slightly longer-term:

Skylon with personel capsule.


Long-term, huge number of people, huge fixed costs:

Replace first stage with a huge electromagnetic linear accelerator. Requires hundreds of billions, or even trillions to build, but can launch huge number of people cheaply after built.

« Last Edit: 05/05/2015 10:27 am by hkultala »

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #4 on: 05/05/2015 07:15 am »
Thanks for the thoughtful responses.

I suppose I should have specified a hypothetical unlimited demand, and manufacturing techniques as efficient as reasonably possible, so that neither of those are factors (I understand that they can make a big difference). Yet we really can't have one without the other, can we? For example, if the cost of propellants are as low as they could possibly be and engine efficiency is about as reasonably good as we can expect so that the cost of the propellants alone theoretically required to take an average human to orbit is $20k, that would be a far cry from being affordable for most people. This gives us the theoretical minimum pricing for the service. If we could compare such a service to the airline industry, then fuel would consist of 30-40% of operating costs. Now, if we could send people to LEO for under $100k a pop, this isn't an unreasonable expense for a medium-sized business who might have some commercial interest in working in space (say, some sort of mining company), but most of us won't be taking a space vacation. What I'm wondering is if this is as good as we could possibly get in the foreseeable future? What's the chances of reducing the prices to that of half way around the world airfare? Is our only option revolutionary technology?     

Offline Burninate

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Re: Most economical way of shuttling humans to LEO?
« Reply #5 on: 05/05/2015 09:55 am »
There are lots of non-chemical-rocket launch ideas out there, but we're so far from the point where propellant costs represent a substantial portion of launch costs that it's not really worth speculating about yet.

I like the idea of using a 320km long maglev-stabilized hydrogen ram accelerator, with one end 4km below sea level in an underground tunnel, and the other end 6km above sea level on a tall mountain, to propel human cargo at 8km/s muzzle velocity, followed by a scramjet sustainer engine that works out to around 30km altitude, followed by around 2km/s of ammonia laser-thermal rocket stage to orbit.

Great, we've picked a solution!  Now what?

Well, it would cost somewhere between a hundred billion dollars and ten trillion dollars (hard to tell at that level because things go all nonlinear).

We're not going to secure funding to build that solution until we have a payload market 1000x the present size, or possibly larger.  And we'll never get to *that* point without making rockets extremely inexpensive relative to where they are now.
« Last Edit: 05/05/2015 10:06 am by Burninate »

Offline Burninate

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Re: Most economical way of shuttling humans to LEO?
« Reply #6 on: 05/05/2015 09:58 am »
I will note that *bulk goods* that can survive high accelerations, are likely to be the first things we put into space via an impulsive method, and building the much smaller system required to launch those could easily be practical at only 10x to 100x the present payload market size.  Humans are likely to be the last.

Offline Robotbeat

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Re: Most economical way of shuttling humans to LEO?
« Reply #7 on: 05/05/2015 04:22 pm »
Single-stage suborbital launch to a rotovator? (This deals with the reentry velocity, too, since it can also be used to slow down the stage before reentry.)

Dual-stage rapid reusable assisted by electric jets?

Lots of ideas out there. But you probably are looking at a similar number of passengers per flight as typical for airliner traffic here.
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Offline RonM

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Re: Most economical way of shuttling humans to LEO?
« Reply #8 on: 05/05/2015 04:35 pm »
Thanks for the thoughtful responses.

I suppose I should have specified a hypothetical unlimited demand, and manufacturing techniques as efficient as reasonably possible, so that neither of those are factors (I understand that they can make a big difference). Yet we really can't have one without the other, can we? For example, if the cost of propellants are as low as they could possibly be and engine efficiency is about as reasonably good as we can expect so that the cost of the propellants alone theoretically required to take an average human to orbit is $20k, that would be a far cry from being affordable for most people. This gives us the theoretical minimum pricing for the service. If we could compare such a service to the airline industry, then fuel would consist of 30-40% of operating costs. Now, if we could send people to LEO for under $100k a pop, this isn't an unreasonable expense for a medium-sized business who might have some commercial interest in working in space (say, some sort of mining company), but most of us won't be taking a space vacation. What I'm wondering is if this is as good as we could possibly get in the foreseeable future? What's the chances of reducing the prices to that of half way around the world airfare? Is our only option revolutionary technology?   

It takes a specific amount of energy to get to orbit. As you point out there are limits to how cheap chemical rockets can get. Without science fiction style technologies, getting to orbit will always be far more expensive than air travel.

Offline nadreck

Re: Most economical way of shuttling humans to LEO?
« Reply #9 on: 05/05/2015 05:06 pm »
Thanks for the thoughtful responses.

I suppose I should have specified a hypothetical unlimited demand, and manufacturing techniques as efficient as reasonably possible, so that neither of those are factors (I understand that they can make a big difference). Yet we really can't have one without the other, can we? For example, if the cost of propellants are as low as they could possibly be and engine efficiency is about as reasonably good as we can expect so that the cost of the propellants alone theoretically required to take an average human to orbit is $20k, that would be a far cry from being affordable for most people. This gives us the theoretical minimum pricing for the service. If we could compare such a service to the airline industry, then fuel would consist of 30-40% of operating costs. Now, if we could send people to LEO for under $100k a pop, this isn't an unreasonable expense for a medium-sized business who might have some commercial interest in working in space (say, some sort of mining company), but most of us won't be taking a space vacation. What I'm wondering is if this is as good as we could possibly get in the foreseeable future? What's the chances of reducing the prices to that of half way around the world airfare? Is our only option revolutionary technology?   

It takes a specific amount of energy to get to orbit. As you point out there are limits to how cheap chemical rockets can get. Without science fiction style technologies, getting to orbit will always be far more expensive than air travel.

Yes but if you could get down to the same ratios of other costs to fuel costs that airlines have(30% is fuel the rest is amortization of vehicle, maintenance, airport fees, salaries, etc) you could still sell a seat in a Dragon or CST100 style craft for $100,000 - $200,000 and cargo to LEO at about $30 - $50 kg. More importantly a different vehicle on top of an F9 or FH could have more passengers for the same total weight and potentially bring that price under $30,000.  At those prices there would be serious demand.  However we won't see that even with the BFR when it comes to pass. These vehicles will have a much rougher life than an airliner that can average 7-10 hrs a day in the air (allowing for all the maintenance down time) over a 15 year life (what amortization is usually based on). So real, practical limits will probably be 100 flights with major overhauls every 10 flights (actually maybe more for first stages and less for 2nds).  So amortization will in fact equal all the other costs just about doubling the numbers above. That is still a huge discount to current pricing and would stimulate demand.
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Offline Coastal Ron

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Re: Most economical way of shuttling humans to LEO?
« Reply #10 on: 05/05/2015 05:17 pm »
I've been trying to understand what the most economical methods for shuttling people to LEO would be using technology currently available or at least available in the near future.

This is too broad, and just based on your statement above we're really only talking about vehicles that are already in operation (i.e. Soyuz) or are in active development now (i.e. CST-100 and Dragon 2).

How many people do you want to carry per trip, and how many trips per year do you require?

A good amount of pricing information already exists by the way.  For instance, Soyuz flights to the ISS are being sold to NASA for around $70M/seat for two passengers (assuming the Russian pilot is not part of the deliverables), which is the high end of the spectrum, whereas the low end is when Elon Musk said they would be offering rides to LEO for as low as $20M/seat assuming 7 passengers (the Dragon 2 is automated).

So $20-70M/seat to LEO is your answer.

If the volume climbs the prices should fall, but until reusability of the launch vehicle happens the prices wouldn't fall too much.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #11 on: 05/05/2015 10:55 pm »

This is too broad, and just based on your statement above we're really only talking about vehicles that are already in operation (i.e. Soyuz) or are in active development now (i.e. CST-100 and Dragon 2).

How many people do you want to carry per trip, and how many trips per year do you require?

A good amount of pricing information already exists by the way.  For instance, Soyuz flights to the ISS are being sold to NASA for around $70M/seat for two passengers (assuming the Russian pilot is not part of the deliverables), which is the high end of the spectrum, whereas the low end is when Elon Musk said they would be offering rides to LEO for as low as $20M/seat assuming 7 passengers (the Dragon 2 is automated).

So $20-70M/seat to LEO is your answer.

If the volume climbs the prices should fall, but until reusability of the launch vehicle happens the prices wouldn't fall too much.


I meant with current knowledge and manufacturing capabilities, or in the not distant future, and not some pipe dream tech that would require a $10000000000000000000 investment. Nor did I mean currently flying machines, which I had hoped I made clear since we already know the prices of those, and they're not in the spirit of this thread.

Passengers per trip is also irrelevant if for instance a 1 passenger rocket can take a person to orbit for $100 instead of one that could take 1,000 people at $1,000,000 per seat.

As I said in my initial post, reusability will likely go the furthest in reducing overall launch costs, but my actual question was where else are there potentially massive savings to be made? Is there any possibility that we can see fuel consist of 30-40% of launch costs like we do with the airlines?

Offline Coastal Ron

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Re: Most economical way of shuttling humans to LEO?
« Reply #12 on: 05/06/2015 05:21 am »
...Nor did I mean currently flying machines, which I had hoped I made clear since we already know the prices of those, and they're not in the spirit of this thread.

You were not clear about that.

Quote
Passengers per trip is also irrelevant if for instance a 1 passenger rocket can take a person to orbit for $100 instead of one that could take 1,000 people at $1,000,000 per seat.

I'm not the only one that has stated your question is too broad.  How can comparisons be made if you don't have anything to compare against?  How will you know whether proposed solutions are better than current ones unless you can compare them to current solutions?

You obviously are asking this question because you have a specific usage in mind, so just state it.
« Last Edit: 05/06/2015 04:05 pm by Coastal Ron »
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #13 on: 05/06/2015 06:23 am »
There must be a point where an increase in demand can no longer reduce costs, and in fact might actually increase them (supply issues related to limited resources). I doubt air travel costs would go down with an increase in passengers, even if the airlines purchased more planes. So what about space launches? I doubt it would require millions of passengers per year to reach the bottom.




You were not clear about that.

Fair enough. Hopefully it's clear now

Quote
I'm not the only one that has stated your question is too broad.  How can comparisons be made if you don't have anything to compare against?  How will you know whether proposed solutions are better than current ones unless you can compare them to current solutions?

You obviously are asking this question because you have a specific usage in mind, so just state it.

It may be broad, but purposely so, as I don't want to unnecessarily limit the discussion. The stated aim is getting passengers to LEO as cheaply as possible, which I thought I clearly stated. I don't believe there's much sense in making comparisons to current and past human rated launch vehicles as cost effectiveness has not been a driving factor in any meaningful sense.

Offline rklaehn

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Re: Most economical way of shuttling humans to LEO?
« Reply #14 on: 05/06/2015 07:11 am »
Single-stage suborbital launch to a rotovator? (This deals with the reentry velocity, too, since it can also be used to slow down the stage before reentry.)

Dual-stage rapid reusable assisted by electric jets?

Lots of ideas out there. But you probably are looking at a similar number of passengers per flight as typical for airliner traffic here.

I think it is way premature to select a winner. But if I had to bet, single stage to tether would also be my favorite.

A rotating tether (rotovator) with 4km/s tip velocity is well within what is possible even without anything super exotic like carbon nanotubes. And a stage with 5km/s delta-V would have a huge payload mass fraction and could be made very robust. It would never have to survive a full orbital reentry.

A rotovator in LEO would also throw you directly into a highly elliptic earth orbit, which is much more useful than LEO.

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #15 on: 05/06/2015 08:13 am »
I've been trying to understand what the most economical methods for shuttling people to LEO would be using technology currently available or at least available in the near future. Obviously reusability with minimal refurbishment and prep requirements would go the furthest. Next on the list would probably be simplification of the rocket itself in order to lower the initial cost of the machine (assuming it wasn't absurdly high in the first place, which would negate the benefit of reusability), followed by reduced fuel costs. The first two seem well under way by the likes of SpaceX, and apparently Blue Origin. Maybe they both still have room to simplify? Seems unlikely.
You need to make better use of the search function on this site.

This topic has been discussed many times before.  :(

The classic problem is simply that you build a vehicle the size of a Boeing jet, with a ground staff about 10x (to 100x)  that needed to service a Boeing jet and then throw it away after 1 flight.

As Bono and Gatland pointed out in "Frontiers of Space" in 1969 the energy requirement to get to LEO is about the same as that for a round trip between London and Sydney. Yet such round trip tickets don't cost $m and are widely affordable.

To do what you want you have to build a system which spreads the non recurring engineering costs as widely as possible. Current systems only spread those costs to their direct customers because they operate on the single builder/operator model.

No other transport system in the world does this. Airbus does not own an airline (though it legally could in Europe), shipyards don't container ships and truck makers don't run shipping companies.

The vehicles they make are sold to operators. This means they only have to worry about building the vehicles at a price customers will buy them at.

Likewise the operators don't have to worry about being able to design an RLV, just find enough customers on a regular basis to meet their finance payments. That means you can have many more operators than builders and that means costs shared over a much larger user base.

Unfortunately while the only known LVs that work looks like a re-purposed ICBM it's likely to remain that way with a single builder/single operator model.   :(

Your other problem is getting the money.

Historically all RLV's sacrifice payload for reusability. The question a funder will ask is how much will you lose over an ELV the same size (Musk estimated 30-50% for a semi reusable design). So (the funder will say) "I'm being asked to put up a shed load of cash for something that's 1/2 as "good" (in payload terms) as what customers can already get in the market?

Why should I bother?

So far only 1 design is offering to deliver an equal payload to an equivalent sized ELV to orbit.

When you include all the issues you discover this is a very tough problem.
« Last Edit: 05/06/2015 08:19 am by john smith 19 »
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Offline R7

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Re: Most economical way of shuttling humans to LEO?
« Reply #16 on: 05/06/2015 09:16 am »
Historically all RLV's sacrifice payload for reusability. The question a funder will ask is how much will you lose over an ELV the same size (Musk estimated 30-50% for a semi reusable design). So (the funder will say) "I'm being asked to put up a shed load of cash for something that's 1/2 as "good" (in payload terms) as what customers can already get in the market?

Why should I bother?

This pondering is only valid for funding F9->F9r type conversion. For a clean-sheet design the investor should research the market for optimum payload size for the customers and fund RLV delivering that capability.

If you counter-argue with "but an ELV of that new size could also deliver double payload" then either the market research didn't get it right (market for higher payloads exists, RLV sized too small) or you are arguing using imaginary market (there are no real payloads for that size).
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Offline Jim

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Re: Most economical way of shuttling humans to LEO?
« Reply #17 on: 05/06/2015 02:08 pm »

Unfortunately while the only known LVs that work looks like a re-purposed ICBM it's likely to remain that way with a single builder/single operator model.   :(


Resusability vs expendable are completely independent of the owner vs operator conop.

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #18 on: 05/06/2015 03:40 pm »
Resusability vs expendable are completely independent of the owner vs operator conop.
Should be.

Are not.
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Offline Jim

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Re: Most economical way of shuttling humans to LEO?
« Reply #19 on: 05/06/2015 04:07 pm »
Resusability vs expendable are completely independent of the owner vs operator conop.
Should be.


Why?   There is no reason that the manufacturer of reusable launch vehicles can't be the operator.  There isn't enough business to support multiple operators and despite cost reductions, there still might not be that much of an increase in business to warrant it.

Also, there is no reason that a manufacturer of ELV can't sell them to operators.

It has nothing to do with expendable or reusable.

I don't buy this thinking that there is an ICBM mentality in ELV contractors.
« Last Edit: 05/06/2015 04:15 pm by Jim »

Offline notsorandom

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Re: Most economical way of shuttling humans to LEO?
« Reply #20 on: 05/06/2015 06:16 pm »
Scale is an important thing to consider when talking about economics. The most people who have ever been launch to orbit at once was 8, though the Shuttle could have carried a passenger compartment in cargo bay and increased this amount. The mythical MCT may carry a hundred or so. What may be a ridiculously expensive way to launch a handful of people may become cheaper than rockets when the number of people increases beyond a certain point. If you want to move thousands of people non-rocket solutions are going to start entering the trade space.

The king of all near term realistically build-able non-chemical methods of space access is good old Project Orion style nuclear pulse propulsion. There are a number of problems with it but none of them are technological, unlike space elevators needing impossibly strong fibers. A ground launched ship would not be cheap at all but it could move a city into orbit. The price per person becomes very cheap. As strong as the ship would be it could also land and be reused. If the Falcon looks impressive descending firing its rocket imagine how one of these would look decelerating using nuclear bombs!

I am not seriously advocating Project Orion. Though wouldn't a single stage to Saturn ship be pretty cool? Focusing in on the lowest cost per person without constraining the total number of people launch or time frame can result in some pretty out there ideas. Not like that is a bad thing.

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #21 on: 05/06/2015 11:24 pm »
It would seem to me that separating manufacturers from operators would be antithetical to maximum cost reduction, assuming all other factors being equal. The major benefit separation provides for the manufacturer is being to weather  a storm in poor performing market segments (it's the operator that gets hit the worst). But then again, a 5-10% price-per-seat difference is unlikely to result in a make-or-break situation, unless there's some fierce competition. 

Offline Coastal Ron

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Re: Most economical way of shuttling humans to LEO?
« Reply #22 on: 05/06/2015 11:38 pm »
It may be broad, but purposely so, as I don't want to unnecessarily limit the discussion. The stated aim is getting passengers to LEO as cheaply as possible, which I thought I clearly stated.

How should that be measured?

Cost for a single human?  A group of 4 humans?  A group of 100 humans?  They may all have different solutions.

How will you know when the best solution has been found?
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #23 on: 05/07/2015 03:02 am »

How should that be measured?

It should be measured based on how broadly affordable it is to commercial entities and the general public. 

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Cost for a single human?  A group of 4 humans?  A group of 100 humans?  They may all have different solutions.

How will you know when the best solution has been found?

That's in essence the question. What are the different (but practical) solutions? The metric is cost per seat. I believe demand would be plenty if pricing is sufficiently low and there's space/lunar stations to accommodate the passengers. I understand that in those cases, the cost of transportation to LEO is only a chunk of the overall cost, but it would still represent a significant chunk.

I think in the history of engineering, there has never been a "best" solution, only the most practical given the body of knowledge and capabilities of that time. Given that, we should still be able to distinguish between a good solution and a bad one. Throwing away complex rockets is an example of an obviously bad solution to the question at hand.

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #24 on: 05/07/2015 05:56 am »
Does a larger passenger capacity necessarily make it more economical?

It would seem there's a few benefits to using smaller reusable launchers (we'll stick with talking about the first stage for now). The smaller size simplifies aspects like ground handling, while also making automated NDT of the structure more practical. They're also cheaper to produce and maintain due to less materials needed for the structure and less/smaller engines, and with sufficient demand, can benefit from economies of scale as they could be manufactured on an assembly line. The smaller size also allows for a more efficient structure such as the balloon-type of the original Atlas, which (correct me if I'm wrong) wouldn't scale well to a larger rocket, thus cheaper and more robust (read: heavier) engines could be used.

In many ways, both in the short and long term, three 2-passenger scooters is more economical than one big 6-passenger SUV, even when 6 people are being transported at all times.

Offline The Amazing Catstronaut

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Re: Most economical way of shuttling humans to LEO?
« Reply #25 on: 05/07/2015 07:53 am »
Does a larger passenger capacity necessarily make it more economical?

It would seem there's a few benefits to using smaller reusable launchers (we'll stick with talking about the first stage for now). The smaller size simplifies aspects like ground handling....
...In many ways, both in the short and long term, three 2-passenger scooters is more economical than one big 6-passenger SUV, even when 6 people are being transported at all times.

Ground handling for very large LVs is something that is entirely manageable. As mentioned up thread, a Falcon Heavy sized LV can bring a significant amount of crew up into orbit by itself. Remember, humanity already has significant prior experience with handling Falcon Heavy (or larger) sized launchers.

Nearly any crew mission to LEO is going to benefit from a crew capacity as close as possible to the station that the mission is intended to dock with, for multiple reasons. Imagine if the Soyuz was the size of a mercury capsule and could only lift one crew member at a time - the ISS would have to cope with multiple docking events, using up significant amounts of time, manpower and propellant to do so. The cost effectiveness of the station would drop dramatically.

It is telling that all of the orbital crew vehicles currently under construction in the USA have crew capacities approaching that of the shuttle - better to have something that can launch more people than you need, than less.
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Offline R7

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Re: Most economical way of shuttling humans to LEO?
« Reply #26 on: 05/07/2015 08:02 am »
I think in the history of engineering, there has never been a "best" solution, only the most practical given the body of knowledge and capabilities of that time. Given that, we should still be able to distinguish between a good solution and a bad one. Throwing away complex rockets is an example of an obviously bad solution to the question at hand.

It is not obvious if the market does not support flight rates required for RLVs to be more economical.
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Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #27 on: 05/07/2015 10:00 am »
@The Amazing Catstronaut

I didn't mean to imply that handling large rockets is impossible by any stretch, but I still think it's fair to say that smaller rockets are overall easier and pose some additional benefits due to their small size for the reasons I gave.

You do bring up a good point about docking and the associated logistics. These are the kinds of discussions I appreciate being brought up. Just to be clear though, I don't actually have trips to the ISS in mind. If anything, it would be some sort of commercial space station(s). Granted, that doesn't alleviate the issue entirely, but it would be a slightly different scenario.

At any rate, I agree that launching a larger crew would be more desirable, but I'm more interested in the reducing costs aspect. So if for example, launching a crew of 2 is substantially cheaper per seat than any other option then that's what I want to know. 

@R7

In the current state of things, I think you're right. There's nothing in LEO for the general public to go to, and I'm  including the ISS. But we know BA is interested in building orbital hotels, and that business would certainly benefit from cheap launch prices. But then again, there would be at least some sort of customer base for LEO flights with no actual in-space destination. After all, people seem willing to pay good money just for a several minute suborbital jaunt.

The intent of this thread isn't about slashing costs of launches today, but what might realistically be possible without seemingly far-fetched technology in the near-term given a sufficient and sustainable customer base. Then hopefully demand continues to increase to the point where very large investments can be made in more advanced technologies to cut costs further.
« Last Edit: 05/07/2015 10:02 am by msat »

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #28 on: 05/07/2015 10:08 am »
It would seem to me that separating manufacturers from operators would be antithetical to maximum cost reduction, assuming all other factors being equal.
You might like to check you understand the difference between cost (what it costs me to make something) and price (what I'm going to charge you to buy it).

The sole builder/operator business model guarantees a monopoly on the product. Either you pay me what I charge or you don't buy it.

As a customer I don't want "cost reduction" I want price  reduction, as in I want a lower $/lb to orbit and I want that at a sensible scale, at a scale I can use, not have to sign up another 5 or 6 satellites to ride share with me, to get that (still mythical) "Less than a $100/lb if you use all the 53 tonnes of payload (and we can launch at least 4 times a year)".
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The major benefit separation provides for the manufacturer is being to weather  a storm in poor performing market segments (it's the operator that gets hit the worst). But then again, a 5-10% price-per-seat difference is unlikely to result in a make-or-break situation, unless there's some fierce competition.
That's one of the benefits.

You should look at the history of the ULA merger. Both partners used the sole builder/sole operator model.

Downturn in the commercialmarket and they both run to the USG saying "Only a merger can save us."

You might like to look at what happened to the prices charged by the (newly formed) ULA from then on.

Monopolies never give lower consumer prices.  :(

Why?   There is no reason that the manufacturer of reusable launch vehicles can't be the operator.  There isn't enough business to support multiple operators and despite cost reductions, there still might not be that much of an increase in business to warrant it.
You have it backwards.

Every RLV proposal I've seen (with one exception) expects the builder to be the sole operator. That means the "operator" carries both their operating expenses for the vehicle and the total development cost of the vehicle, not just what it cost to build the one (or more) that it operates.
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Also, there is no reason that a manufacturer of ELV can't sell them to operators.
While every payload needs a coupled loads analysis to ensure it won't be shaken to bits (or shake the LV to bits) the link between "operator" and "manufacturer" will remain so close as for them to be virtually indistinguishable, outside of accountancy. The closest I've seen is Soyuz launching out of Kourou under Arianespace.
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It has nothing to do with expendable or reusable.

I don't buy this thinking that there is an ICBM mentality in ELV contractors.

So you're saying with enough money a customer could go to ULA, buy a Delta or Atlas and (assuming they have the launch pad) launch it?
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Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #29 on: 05/07/2015 10:48 am »
Of course technically speaking the most economical way to do it is the Soyuz.

All development costs paid by the former USSR and current Russian governments.

Most operation costs paid by them as well.

Total cost $70m a seat Vs $X Bn to develop a new RLV with it's cost to be absorbed through Y # of passengers x Z number of flights.

Do you perhaps begin to see that you're asking the wrong question.  :(
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Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #30 on: 05/07/2015 10:49 am »
Does a larger passenger capacity necessarily make it more economical?
Depends where you're getting the money from.
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It would seem there's a few benefits to using smaller reusable launchers (we'll stick with talking about the first stage for now).
Then you're not talking about an RLV at all. You're talking about a semi reusable system. In which case the costs will converge (fairly quickly) on the cost of the upper stage and cost of refurbishment.
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The smaller size also allows for a more efficient structure such as the balloon-type of the original Atlas, which (correct me if I'm wrong) wouldn't scale well to a larger rocket, thus cheaper and more robust (read: heavier) engines could be used.
Perhaps you should look at the size of the original Atlas. it was quite big. The tanks were Convairs solution to the fairly poor engines available then. The tradeoff in 1st stage is something like a weight gain of 6-13 units causes a drop in payload of 1 unit. For the upper stage it's roughly 1 to 1.
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In many ways, both in the short and long term, three 2-passenger scooters is more economical than one big 6-passenger SUV, even when 6 people are being transported at all times.
Depends what you want to do with it. If you're driving profile includes a coast-to-coast trip once a month and you can only have either the SUV or the scooter, the SUV might look pretty good.


That's in essence the question. What are the different (but practical) solutions? The metric is cost per seat. I believe demand would be plenty if pricing is sufficiently low and there's space/lunar stations to accommodate the passengers. I understand that in those cases, the cost of transportation to LEO is only a chunk of the overall cost, but it would still represent a significant chunk.
You've got a chicken and egg situation. What's the incentive for the operator to put somewhere in LEO for humans to go in the first place.  :(

Cost wise so far we've seen people pay somewhere in the $10-20m range for some days on the ISS. BTW that also required an 18month stay in Russia for training.

Virgin Galactic demonstrated there is a market for space tourism. So as a price point if $250k gets you 15 mins of sub orbital let's say $1m for a day in space?

BTW Musk said the F9 propellant bill is about $120k. so if you can run your operation at 3x that ($260K) you can offer a price people can pay and still make a major profit.

Now the bad news. The average aerospace worker cost (all benefits included) was also around $120k (when a report on Space Shuttle costs was prepared prior to the start of DC-X programme). It's obviously gone up since.

You appear to have some kind of architecture you've been thinking about and want to discuss. Why don't you tell us what you think is the right way to do things?
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Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #31 on: 05/07/2015 01:39 pm »

You might like to check you understand the difference between cost (what it costs me to make something) and price (what I'm going to charge you to buy it).

I'd argue that you're being pedantic as it's probably safe to assume most people know what I'm referring to, but be that as it may, I'll try to use the appropriate terms from here on.

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Then you're not talking about an RLV at all. You're talking about a semi reusable system. In which case the costs will converge (fairly quickly) on the cost of the upper stage and cost of refurbishment.
I wasn't trying to imply that the first stage wouldn't be reusable, but rather that it was irrelevant to discuss in that comment.

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Perhaps you should look at the size of the original Atlas. it was quite big. The tanks were Convairs solution to the fairly poor engines available then. The tradeoff in 1st stage is something like a weight gain of 6-13 units causes a drop in payload of 1 unit. For the upper stage it's roughly 1 to 1.

It may not be the smallest launcher in the world now, but it was significantly smaller than the Soyuz1 and sufficient enough to get project Mercury astronauts into orbit. My point was that an efficient structure lends itself well to cheap and robust engines with only mediocre performance (by today's standards). Could an Atlas-like balloon structure be scaled up? Seems unlikely. So that makes smaller launchers an interesting proposition for the stated goals.

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You've got a chicken and egg situation. What's the incentive for the operator to put somewhere in LEO for humans to go in the first place.  :(

True. But no one or no thing is going anywhere if the price is too high.

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Virgin Galactic demonstrated there is a market for space tourism. So as a price point if $250k gets you 15 mins of sub orbital let's say $1m for a day in space?

Indeed there's some apparent market. How sustainable it is would be anyone's guess. I'm sure I'm not the only one who would like to see access be available to even those who don't so much money that it's bursting through the floor of the bank's vault.

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BTW Musk said the F9 propellant bill is about $120k. so if you can run your operation at 3x that ($260K) you can offer a price people can pay and still make a major profit.


That may have been for the Falcon1? F9 figures are around $200k. Still, divide that by 7 (or realistically 5 if we count 2 as being flight crew) and your figure perhaps becomes even more tenable. This would be extraordinary, but why not try to go even cheaper?


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You appear to have some kind of architecture you've been thinking about and want to discuss. Why don't you tell us what you think is the right way to do things?

Is this a reference to my other thread? If so, then how they fit in with reducing costs and ideally pricing, I have no idea. Not sure if they're even tenable. As for knowing the "right way" to do things, I don't have the answer to that either, or else I'd be swimming in my pool of money like Scrooge McDuck if I did. I just find the topic of cost effectiveness fascinating, including things non space related. The purpose of this thread is an intellectual experiment to bounce ideas around. I'm not trying to rally up the troops to build the $1 rocket in my back yard :)

Offline notsorandom

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Re: Most economical way of shuttling humans to LEO?
« Reply #32 on: 05/07/2015 02:14 pm »
Smaller RLVs as oposed to bigger ones is a trade that makes sense when the total amount of payload and funding is constrained. RLVs need to fly a lot. They have higher development costs which will make each individual flight pricey unless amortized over many flights. Also for the same liftoff mass of an expendable they lift much less payload. There becomes a point where expendables just can't get any bigger and can't fly often enough to compete with an RLV.

However this point lies well beyond the mass requirements for the most lift intensive missions that might be reasonably undertaken in the near future. A Mars missions for example may take around 600mt in LEO give or take a hundred. Assuming that there will be one launched every opportunity it will take 3 Saturn V class launches a year or 6 total. The general consensus is that an RLV needs to fly 10-15 times a year to break even. So to make economic sense they need to be smaller so they can fly more often.

I'm really simplifying things here but let's assume that the total yearly non-Mars lift needs are about double that so that there is a need to launch around 600mt a year. The Mars folks are going to want to the most payload per launch they can get as to reduce on orbit assembly. Augustine said at least about 70mt. So lets say about 20mt like the biggest rockets today and make the Mars mission just have to work around it. A successful RLV is going to have competitors, both RLVs and expendables so the whole amount will be divided up. In this scenario an RLV that has managed to grab half the market share is flying 15 times a year and half if the Mars mission gets canceled. So that is where the HLV vs small RLV debate comes from.

Elon Musk on the other hand isn't looking to send a few people to Mars but a lot. A small RLV is not going to to accomplish that, it can't fly often enough. An expendable HLV could fly quickly enough but not at a price point that enables his plans. As the needed mass in orbit increases the trend is going to favor a reusable HLV more and more.  Especially as the Mars mass becomes so much that the commercial, NASA, and DoD needs become a small fraction of the total yearly LEO needs.

Offline Jim

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Re: Most economical way of shuttling humans to LEO?
« Reply #33 on: 05/07/2015 03:51 pm »

While every payload needs a coupled loads analysis to ensure it won't be shaken to bits (or shake the LV to bits) the link between "operator" and "manufacturer" will remain so close as for them to be virtually indistinguishable, outside of accountancy.


And same thing applies to RLV's

Offline edkyle99

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Re: Most economical way of shuttling humans to LEO?
« Reply #34 on: 05/07/2015 04:07 pm »
I don't buy this thinking that there is an ICBM mentality in ELV contractors.
I agree.  The last U.S. ICBM development effort was, when, during the 1980s with MX?  Most of the contractors involved don't even exist today, at least not in their 1980's Cold War era form.

 - Ed Kyle
« Last Edit: 05/07/2015 04:08 pm by edkyle99 »

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #35 on: 05/07/2015 05:33 pm »
For some desired payloads, even the biggest LV isn't sufficient. But when it comes to transporting people, the option is there send them up individually. That's a relatively light payload. I can imagine cases where sending up a large number of passengers all at once would be desirable, but that doesn't have to be true in all cases.

Offline RanulfC

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Re: Most economical way of shuttling humans to LEO?
« Reply #36 on: 05/07/2015 06:40 pm »
It would seem to me that separating manufacturers from operators would be antithetical to maximum cost reduction, assuming all other factors being equal. The major benefit separation provides for the manufacturer is being to weather  a storm in poor performing market segments (it's the operator that gets hit the worst). But then again, a 5-10% price-per-seat difference is unlikely to result in a make-or-break situation, unless there's some fierce competition. 

Starting off with my usual mantra; Spacecraft are not aircraft and vice versa!

During the commercial aircraft ramp up several aircraft companies started out operating or involved in operating airlines but this quickly became counter productive as they could make MORE money by selling aircraft to other operators rather than being restricted to only the "airlines" they were involved with. This actually ended up biting Boeing in the keester when they introduced the Model 247 (http://en.wikipedia.org/wiki/Boeing_247) which was so popular they couldn't actually produce enough aircraft to satisfy demand which opened the door to Douglas with their DC-1.

But we're still along way from being anywhere near that model with space launch, unless of course "something" changes the equations :)

One thing that I think gets overlooked a bit in this thread is the exact premise: "People" to "LEO"

Flight rate in this case is pretty much paramount. Never mind the "actual" market we're assuming there is one for the moment and the question is basically what makes that cheaper and I think it would be very hard to argue large numbers of passengers and few flights would work in those circumstances so you want MORE flights even if the number of passengers is fewer.

Hence turn-around time and reusability are both high priorities with minimum up-front cost and overall operations costs as low as you can get them. Which is pretty much the opposite of the current situation.

Randy
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Offline RanulfC

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Re: Most economical way of shuttling humans to LEO?
« Reply #37 on: 05/07/2015 07:01 pm »
I don't buy this thinking that there is an ICBM mentality in ELV contractors.
I agree.  The last U.S. ICBM development effort was, when, during the 1980s with MX?  Most of the contractors involved don't even exist today, at least not in their 1980's Cold War era form.

 - Ed Kyle

ICBMs are VERY different than ELVs because the missions are quite different. This idea is that there is a "hold-over" from artillery as a basis for rocketry which is true only in a very limited and narrow way. Most current LVs were "developed" from early missiles and ICBMs but the divergence was quite a while ago and the truth is that ELVs have, under the current missions/market/assumptions, been more economical than RLVs. This MAY change when RLVs are flying but will definitely change if the market/flight rate increases enough.

As a note, "most" of the contractors who had actual ICBM experience were gone by the mid-70s and the few left are handling "legacy" systems using mostly the same equipment and techniques used for the original productions in the mid-1960s. The exact problem is there is almost no commonality between LVs and ICBMs therefore no one working on one finds applicability or market share with the other. (Using "de-commissioned" ICBMs as LV is a very limited utility and ONLY is "economical" as long as those "de-commissioned ICBMs" are available for use. Once you have to "buy" them the cost skyrockets and is no longer viable) Hence almost no incentive to "do" both for any manufacturer.

Pretty much the main "sticking" point of fielding a new ICBM is that it would require a significant cost to design and build the new infrastructure to design and build and field the new weapons system. Almost none of the "LV" makers have the capability of producing a new ICBM and the one manufacturer that possibly could (ATK) doesn't have the needed facilities. (And before someone asks there are issues with using segmented solids for an ICBM, the military has looked at the option and rejected it)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #38 on: 05/08/2015 06:10 am »

Starting off with my usual mantra; Spacecraft are not aircraft and vice versa!

During the commercial aircraft ramp up several aircraft companies started out operating or involved in operating airlines but this quickly became counter productive as they could make MORE money by selling aircraft to other operators rather than being restricted to only the "airlines" they were involved with. This actually ended up biting Boeing in the keester when they introduced the Model 247 (http://en.wikipedia.org/wiki/Boeing_247) which was so popular they couldn't actually produce enough aircraft to satisfy demand which opened the door to Douglas with their DC-1.

The difference is that there already was a thriving airline industry with numerous operators. It's hard to compare the space launch industry with the old airline industry in that regard. There was an immediate practical use for quickly flying people and cargo from point A to B.

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But we're still along way from being anywhere near that model with space launch, unless of course "something" changes the equations :)

Hah. It'll probably need more than something; I'll need a lot of things.

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One thing that I think gets overlooked a bit in this thread is the exact premise: "People" to "LEO"

Thanks for the observation. The very specific topic of this thread does indeed seem to get overlooked. What works for a billion dollar 50,000lbs satellite doesn't necessarily lend itself to getting people to LEO as cheaply as possible.

Quote
Flight rate in this case is pretty much paramount. Never mind the "actual" market we're assuming there is one for the moment and the question is basically what makes that cheaper and I think it would be very hard to argue large numbers of passengers and few flights would work in those circumstances so you want MORE flights even if the number of passengers is fewer.

Hence turn-around time and reusability are both high priorities with minimum up-front cost and overall operations costs as low as you can get them. Which is pretty much the opposite of the current situation.


This is what I'm leaning towards. There seems be various potential economical benefits towards going this route, even if the rocket isn't the most efficient in terms of getting a given mass to orbit with the least amount of propellant. Besides the lower costs associated with development and manufacturing of smaller and simpler rockets, having a relatively large supply of them also minimizes the chances of downtime from low availability. I'm still not sure how air launching plays into this. With a steady stream of launches, perhaps even the minuscule reduction in delta V requirements common air launches provide become economically attractive. 

Offline pmcaerospacefreighter

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Re: Most economical way of shuttling humans to LEO?
« Reply #39 on: 05/08/2015 01:37 pm »
I think modular, mass produced self-contained thrusters that can be clustered together in multiple stages should be the way to go. Also, having many of them on a vehicle reduces the risk of mission failure.
Surely not the most efficient way in use of materials, but if production and quality control can be automated it would decrease the cost tremendously.


Before you think I'm some genius, I wasn't the first with this idea :)
http://www.astronautix.com/lvs/otrag.htm
« Last Edit: 05/08/2015 01:44 pm by pmcaerospacefreighter »

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #40 on: 05/08/2015 05:05 pm »
I think modular, mass produced self-contained thrusters that can be clustered together in multiple stages should be the way to go. Also, having many of them on a vehicle reduces the risk of mission failure.
Surely not the most efficient way in use of materials, but if production and quality control can be automated it would decrease the cost tremendously.


Before you think I'm some genius, I wasn't the first with this idea :)
http://www.astronautix.com/lvs/otrag.htm

Haha! I was thinking of OTRAG the whole time as I was reading you post, just to find that link at the end. A while back, I read some long and well researched article on the whole history of it. Well, it was a pretty hard read because it was in german and I had to use google translate (which leaves a lot to be desired). Basically, it had a lot of severe technical issues inherent in the design, and the author doubted that it could ever work - at least not as planned.

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #41 on: 05/09/2015 11:44 am »
I've been trying to understand what the most economical methods for shuttling people to LEO would be using technology currently available or at least available in the near future. Obviously reusability with minimal refurbishment and prep requirements would go the furthest. Next on the list would probably be simplification of the rocket itself in order to lower the initial cost of the machine (assuming it wasn't absurdly high in the first place, which would negate the benefit of reusability), followed by reduced fuel costs. The first two seem well under way by the likes of SpaceX, and apparently Blue Origin. Maybe they both still have room to simplify? Seems unlikely.

The real lowest cost way to shuttle people to orbit will be found when there is
a) Multiple ways to do it.
b) Multiple vendors of those systems, ideally supply multiple operators of those systems
c) No restriction on which vendor you use.

IOW when there is real competition both in technology and in vendor and a real market in the service.

The launch industry is not the commercial aviation industry but there was a period around (roughly 1945-1960) when mfgs offered large piston engine, turbo prop, turbojet and (low and high bypass) turbo fan aircraft. The "Britania" was an interesting point. A turbo prop nearly as fast as contemporary jets but the propellers looked old fashioned. On paper a winning design, IRL not so much.

As experience was gained in operations, maintenance and noise levels this shrank to turbo fans for large passenger aircraft. Likewise for long haul the consensus became bigger-is-better. AFAIK turbjets for commercial aviation were dying by 1970 with dropping permitted noise levels and dead by 1980 with fuel efficiency issues.

High bypass turbo fans were the "best man" and they won.

Nothing like that has happened in space launch. NASA are sort-of trying to start a market for human launch to the ISS but until that becomes "we need X seats this year. How many (and when) can you provide them and at what price?" and NASA buys the cheapest this will not produce a "winner" either.  :(

It's much like the propellant depot distributed lift architecture. No market, no incentive to develop a  better vehicle.
« Last Edit: 05/09/2015 11:46 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Jim

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Re: Most economical way of shuttling humans to LEO?
« Reply #42 on: 05/09/2015 12:17 pm »

The real lowest cost way to shuttle people to orbit will be found when there is
a) Multiple ways to do it.
b) Multiple vendors of those systems, ideally supply multiple operators of those systems
c) No restriction on which vendor you use.


There first has to be a good reason for people to go into space before that happens

Offline Borklund

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Re: Most economical way of shuttling humans to LEO?
« Reply #43 on: 05/09/2015 11:55 pm »
There first has to be a good reason for people to go into space before that happens
There are plenty of good reasons for people to go into space, just not ones you agree with.

Offline Jim

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Re: Most economical way of shuttling humans to LEO?
« Reply #44 on: 05/10/2015 01:37 am »

There are plenty of good reasons for people to go into space, just not ones you agree with.

Quite wrong.  There are few to none good reasons that are economical viable, which is needed to make it sustainable.

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #45 on: 05/10/2015 02:13 am »
Hopefully it's just a matter of time with the pieces slowly falling in place. What with SpaceX and BO focusing on reusability, while Bigelow works on inflatable habitats, all of which reduce costs relative to current options by orders of magnitude. These are very good starts.

Offline KelvinZero

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Re: Most economical way of shuttling humans to LEO?
« Reply #46 on: 05/10/2015 04:20 am »
Im hopeful too.

For a thread like this I would just avoid the discussion of motivation.

The question only becomes interesting to me if we assume a largish number of people sent. Otherwise it may simply look much like today.. possibly like F9R but that is hardly proven.

Assuming a largish number of people I think F9R is the best bet. Maybe it won't work but it is ahead of the pack and you are getting into faith based territory if you go further afield than that.

If F9R works but the upper stage proves impractical to recover, my pet idea is to combine upper stage and crew into a single vehicle that probably has to be a lifting body instead of a capsule now. You are probably abandoning any launch escape system. I have also heard it stated that capsules to not scale to such large sizes as lifting bodies. I don't know if that is true.

(edit) I just wanted to agree with john smith 19:
The best way of FINDING the most economical method would have been to have multiple launch providers and compete them. I wish we had kept three candidates to the ISS. You might specifically have a rule that forces you to drop the third one occasionally and fund something else.
« Last Edit: 05/10/2015 04:23 am by KelvinZero »

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #47 on: 05/10/2015 05:40 am »
@KelvinZero

Full LV reusability (except possibly some interstage hardware) would certainly be beneficial. Having the upper stage be integrated with the payload seems like the most likely configuration, but as you point out, an escape system becomes a tricky, if not impossible proposition.

Instead of a lifting body design, I've been thinking of a sort of underbody structure  that contains the heat shield attached to the cylindrical upper stage. Instead of using using a lifting body, it would use a retractable rotor system on the opposite side similar to what NASA experimented with in the 60s (except it would be stowed parallel to the length of the body and deployed perpendicular to it). I believe that would save weight over a lifting body design, and lower touch-down speeds to ideally 0. This could also be applied to just the 2nd stage, while retaining a passenger capsule as to maintain an escape system.

Offline Patchouli

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Re: Most economical way of shuttling humans to LEO?
« Reply #48 on: 05/10/2015 06:49 am »
The most economical way to shuffle a lot of people to orbit near term probably would be a large lifting body about the size of the HL-42 carrying about 20 passengers riding on an EELV heavy class LV.
The cheapest probably would be Falcon Heavy.
Farther term a HTOL SSTO like Skylon that can carry 30 passengers at a time.
« Last Edit: 05/10/2015 07:04 am by Patchouli »

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #49 on: 05/10/2015 07:58 am »

The real lowest cost way to shuttle people to orbit will be found when there is
a) Multiple ways to do it.
b) Multiple vendors of those systems, ideally supply multiple operators of those systems
c) No restriction on which vendor you use.


There first has to be a good reason for people to go into space before that happens
Exactly.

In Marketing they teach that people have "wants" and "needs"

Whatever you feel about Virgin Galactic and XCOR's programmes they have demonstrated there are people who want to go into "space" and would probably like to go to orbit if the price is right.

But there are very few people who need to go into space, or rather that someone else IE their employer needs them to go into space.

Until that changes this discussion is somewhat redundant.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline QuantumG

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Re: Most economical way of shuttling humans to LEO?
« Reply #50 on: 05/10/2015 09:57 am »
Needs are just wants felt more immediately - probably Mises.
Human spaceflight is basically just LARPing now.

Offline RanulfC

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Re: Most economical way of shuttling humans to LEO?
« Reply #51 on: 05/11/2015 04:06 pm »
There first has to be a good reason for people to go into space before that happens
There are plenty of good reasons for people to go into space, just not ones you agree with.

There are plenty of good reasons for people to go into space, just not ones you agree with.

Quite wrong.  There are few to none good reasons that are economical viable, which is needed to make it sustainable.

Folks, the thread ASSUMES there IS a "good reason" for getting people into LEO in numbers, it is in fact the usual "chicken/egg" issue in fact at the moment but we're assuming the need is there.

Needs are just wants felt more immediately - probably Mises.

"Technically" needs are not optional where as wants are. Marketing is all about turning "wants" into "needs" despite the fact the two are very different. It's all about the spin :)

JS is right that there are people who "want" to go into space but very few that "need" to and the thread assumes that this paradigm has changed. Lets stick with that take then :)

Back to the OP again, there is really a need to define some parameters on the "market" to be able to define the "best" method. For example, if your yearly "market" is 100 people to orbit (very early projections for a LEO tourism market with a much lower but still pretty high price) then having a vehicle capable of putting more than about 9 people per month is a waste. Further if your market consists of 100 people a month (very difficult to justify at this point) but they are divided between several destinations (say 4, 25 passengers each) then having a vehicle capable of putting 100 people per flight into orbit is not a good solution.

Couple of technical points:
"Capsule" sizing: Greatly depends on how you define "capsule" really. I've known people who have made a good argument that something like the Phoenix or ROMBUS was technically a "capsule" and they had pretty significant passenger and cargo abilities. I think the main drawback is if you are limited to parachutes as a landing system which does not allow large scale growth due to sizing and landing velocity limits. (This is NOT strictly a "capsule" issue as the Russians found out when researching the MTKVP (https://falsesteps.wordpress.com/2012/10/06/mtkvp-glushkos-opening-gambit/) lifting body spacecraft)

Air-Launch criteria: Speed is foremost as noted but altitude actually comes in last as Angle-of-Attack (AoA) above the local horizon plays a major part in the equation and is why most Air Launch proposals you see have LVs with attached wings and stabilizer structures so that they can perform their own pull-up maneuver to a higher AoA than horizontal during launch. (The downside, or failing of this method is that its heavy due to the needed wing area and requires a seriously structurally robust LV which is ALSO very heavy)

There are ways around this such as the AirLaunch LLC lanyard-and-trapeze system or giving the carrier aircraft more capability to use either on-board or LV engines to pull the entire vehicle up into a higher AoA prior to separation as suggested in the CROSSBOW study.
(http://thehuwaldtfamily.org/jtrl/research/Space/LaunchVehicles/AirLaunch/AirLaunchToOrbit-ALTO-Crossbow-concept,MSFC.pdf)
Or even using a "platform" such as proposed for the SwiftLaunch LV concept. (http://mae.engr.ucdavis.edu/faculty/sarigul/aiaa2001-4619.pdf)

Another is using some type of "Launch Assist Platform" such as a jet-powered LAP to lift the rocket stages (usually at least two) to a medium altitude but at higher speed and AoA than a "normal" carrier aircraft. Savings usually come from the LAP being less costly than a custom built carrier aircraft due to "minimal" design and long-life and rapid turn around time compared to the rocket stages. (Your rocket stages are going to be your highest maintenance and operational "time" constraint systems for a long time) You don't get any "synergy" from being able to use you "carrier aircraft" for other uses this way but it is assumed your flight rate is high enough you don't NEED additional uses.
(The LAP has the drawback that it does not scale up well beyond a certain size, for example it would probably work up to Falcon-9/EELV class but not to FH size LVs. This 'works' for the LAP system as it is expected to have a much higher turn-around and launch rate, but again the rocket stages will end up being the driver here)

Propellant costs as a "driver" factor in space launch: Propellant costs for space launch are not going to be a factor enough to warrant making them a major driver for launch vehicle design even under an assumed model as per this thread. SOME issues will be traded (Liquid Hydrogen versus Liquid Methane for example) but for the most part the considerations of commonality of parts and production costs will rank higher.

Example again would be the F9 where both stages use kerolox. The F9 would do much better with a higher energy propellant upper stage such as cryogenic propane (which would fit into the current tanks), liquid methane (requires a tank stretch) or liquid hydrogen (SERIOUS up-sized tanks required) and it would allow higher mass margins, (probably enough to allow reuse even from GTO/GEO) but at the time the design was frozen none of them "traded" well considering the requirement of common tankage and new engine development. (Which makes me think that they didn't think of cryo-propane but that's actually quite common I've found out :) ) Liquid methane will end up costing a bit less than liquid hydrogen both for equipment and the propellant itself but overall technology costs are about the same over time. With a MUCH higher flight rate this might change but in most respects it will greatly depend on the more "common" market factors rather than something reflecting user-costs. (IE: Liquid Methane/Hydrogen cost more to ship currently than does hydrocarbon {including NON-Liquid/gaseous} fuel simply because the infrastructure is already in place)

Randy
« Last Edit: 05/11/2015 04:08 pm by RanulfC »
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #52 on: 05/11/2015 06:24 pm »
Folks, the thread ASSUMES there IS a "good reason" for getting people into LEO in numbers, it is in fact the usual "chicken/egg" issue in fact at the moment but we're assuming the need is there.
Quote
Back to the OP again, there is really a need to define some parameters on the "market" to be able to define the "best" method. For example, if your yearly "market" is 100 people to orbit (very early projections for a LEO tourism market with a much lower but still pretty high price) then having a vehicle capable of putting more than about 9 people per month is a waste. Further if your market consists of 100 people a month (very difficult to justify at this point) but they are divided between several destinations (say 4, 25 passengers each) then having a vehicle capable of putting 100 people per flight into orbit is not a good solution.
This is a key point. What is the "shape" of the market?
« Last Edit: 05/12/2015 10:12 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #53 on: 05/11/2015 08:02 pm »
Thanks Randy for thought-provoking response and keeping to the topic of the OP.

I must admit that it is a bit silly to consider practical, near-term solutions to a hypothetical situation which is unlikely to come to fruition any time soon. And at any rate, any "practical" solutions depend on so many factors, with at least a handful of them brought up in this thread already. I think that makes the topic that much more interesting. 

What I'm still not entirely convinced of is that a larger LV capable of carrying more passengers is more efficient overall than smaller ones, even if there's enough passengers to justify its size. Though I admit the issue brought up earlier in this thread with docking so many spacecraft to a space station is one of the best arguments against it.

I'm going to further argue in favor of smaller & cheaper LVs, and while I know it's a stretch to apply the following to this topic, I still want to entertain this thought:

The Rutan Quickie was marketed as a 1-place $4,000 (1979, so ~$13k now) aircraft, capable of around 100MPG with an 18hp engine (could probably do better with a more efficient modern engine, especially diesel). According to the following blog post (https://blogs.law.harvard.edu/philg/2007/03/19/airbus-a380-more-fuel-efficient-than-a-toyota-prius/), a loaded, all economy seating A380 with 850 passengers gets similar fuel economy. It would require 850 Quickies to carry the same amount of passengers as a single A380, but it would do so at a price of roughly $11M, compared to the ~$430M for the A380. Granted, the A380 is a far more capable aircraft all around (except its runway requirements, heh). Now, it wouldn't be practical to replace all airliners with quickies, if for no other reason than the sheer amount would congest the runways (but in terms of space access, we're so far away from having that problem). But lets just say we could, mass manufacturing would bring the unit as well as parts cost down further, so we'd get even more passenger transport capabilities for the money. Maintenance could be standardized and tasks such as structures inspection could probably be largely automated (imagine an automatic car-wash, but with X-rays and sophisticated data processing software, etc.), which are things you can't do when you only have a few thousand (MASSIVE) units spread around the globe. Ok, that's enough of the apples to carrots to pork chops comparison.


The more I think about it, the more I like the jet-powered LAP concept. As you point out, it should be much simpler (and thus cheaper) to develop than a specially designed aircraft. Even if we could use an existing aircraft, the performance would be much lower than what is possible for a LAP. For one, the speed and altitude could be greatly increased over the flight regime jet engines are typically suited for via LOX/water injection (perhaps around Space Shuttle staging velocity and altitude?). The simpler structure should also make aerodynamic heating more easily managed than a full-on airplane of comparable performance.
 

As for the market size, I guess it's not fair to say "unlimited", while at the same time using current-day figures is boring for the sake of discussion. One of the big points I was trying to make is how to reduce costs to the point where the pricing enables a larger customer base (even if the customers are wealthy by most standards) over current options. Lets just say the market is big enough to justify the development costs of RLVs. Realistically speaking, SpaceX is in the best position as they have one LV which they could use for passengers, cagro, and satellite payloads, thus spreading the NRE for the core rocket tech as much as possible. But that doesn't make a fun discussion, does it?

Offline SoulWager

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Re: Most economical way of shuttling humans to LEO?
« Reply #54 on: 05/12/2015 03:38 am »
Reusable rockets are a big step forward, but if you're talking about millions of people, you probably should look into developing a launch loop, or some other inertially supported structure.
« Last Edit: 05/12/2015 03:39 am by SoulWager »

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #55 on: 05/12/2015 10:57 am »

The Rutan Quickie was marketed as a 1-place $4,000 (1979, so ~$13k now) aircraft, capable of around 100MPG with an 18hp engine (could probably do better with a more efficient modern engine, especially diesel). According to the following blog post (https://blogs.law.harvard.edu/philg/2007/03/19/airbus-a380-more-fuel-efficient-than-a-toyota-prius/), a loaded, all economy seating A380 with 850 passengers gets similar fuel economy. It would require 850 Quickies to carry the same amount of passengers as a single A380, but it would do so at a price of roughly $11M, compared to the ~$430M for the A380. Granted, the A380 is a far more capable aircraft all around (except its runway requirements, heh). Now, it wouldn't be practical to replace all airliners with quickies, if for no other reason than the sheer amount would congest the runways (but in terms of space access, we're so far away from having that problem). But lets just say we could, mass manufacturing would bring the unit as well as parts cost down further, so we'd get even more passenger transport capabilities for the money. Maintenance could be standardized and tasks such as structures inspection could probably be largely automated (imagine an automatic car-wash, but with X-rays and sophisticated data processing software, etc.), which are things you can't do when you only have a few thousand (MASSIVE) units spread around the globe. Ok, that's enough of the apples to carrots to pork chops comparison.

Your just missing a couple of small details in your comparison.

The A380 has about 5x the speed and between 10x and 15x the range of Quickie.

In the launch area there is only one acceptable speed (orbital). The size of the vehicle is then set by the payload and an allowance for losses (which are quite substantial and  well worth trying to reduce).

In any given market there is a sweet spot for the size of single package you can deliver with any given delivery system.

On the one hand you're saying "What's the smallest you can make it?" and on the other you're saying "What's the most economical you can build?"

Smallest and simplest is easy.

It's a 1 person capsule with a replaceable heat shield on a TSTO ELV. It's completely automated and there are no controls. The capsule carries the GNC for the rocket. It has limited cross range from the launch site and adequate endurance to get the passenger to and from their destination. Out side of that range it's an emergency and you come down where you come down and wait for S & R. The training to use is minimal.

It's almost a 1 person subway car. How much training do you need to use one of those?

But I'll note that the ISS was built with the Shuttle, which may explain why the CTS competition require passenger carriage in line with the Shuttle, rather a Soyuz.

If you've got the passenger volume to justify the expense then you're looking at something more than 1 person per launch. You can probably justify the use of a person to control the vehicle (partly). You could have more cross range or build it so that it can land at an airport (ideally in a state that allows it's self ferry back to base).  You'll probably want either more cross range or > 24 hr endurance so the launch site comes back under its orbital track without requiring enormously high cross range.

BTW one interesting calculation you can do on a spreadsheet is to run the rocket equation with different levels of Isp and partial delta V's and losses to orbit.

High Isp (relative to a rocket) means you have a structure which is much heavier than any known rocket, but only air breathers give 1000's of seconds of Isp. Once your breathing air winged lift lets you lift mass 3x take off thrust, although the Launch Assist Platform with afterburning and inlet fluid (either LOX or water) injection can give you a (relatively) simple 1st stage structure with high thrust at ground level and maximum payload (exactly  where you need it) while sustaining acceleration up to maybe M4 without exotic technology like SCRamjets.

The improvement on the available mass fraction for structure is quite remarkable.

MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline RanulfC

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Re: Most economical way of shuttling humans to LEO?
« Reply #56 on: 05/12/2015 02:54 pm »
This is a key point. What is the "shape" of the market?

Kidney shaped? Maybe oval with ill-defined edges? :)

Seriously a number would help msat :)

As for the market size, I guess it's not fair to say "unlimited", while at the same time using current-day figures is boring for the sake of discussion. One of the big points I was trying to make is how to reduce costs to the point where the pricing enables a larger customer base (even if the customers are wealthy by most standards) over current options. Lets just say the market is big enough to justify the development costs of RLVs. Realistically speaking, SpaceX is in the best position as they have one LV which they could use for passengers, cagro, and satellite payloads, thus spreading the NRE for the core rocket tech as much as possible. But that doesn't make a fun discussion, does it?

SpaceX and CST100 are both 7 "people" as payload, call one of them a "pilot" and round down that's 6. Currently they can't launch but every couple of months and there's only one "destination" which is the ISS.

So we could "assume" a scenario based on 8 people per month, 96 a year but that 'technically' wouldn't even strain the system we have assuming we get a third provider. I also don't think it would help lower costs all that much. Anyone have suggestions for a "conservative" number?

Thanks Randy for thought-provoking response and keeping to the topic of the OP.

I live to annoy... er that is help, really it's help. Annoying is just a side benefit :)

Quote
I must admit that it is a bit silly to consider practical, near-term solutions to a hypothetical situation which is unlikely to come to fruition any time soon. And at any rate, any "practical" solutions depend on so many factors, with at least a handful of them brought up in this thread already. I think that makes the topic that much more interesting.

Your on the NSF-forums, "speculation" is a way of life around here :)
However your correct we DO have to define the problem and parameters if we're going to keep going which is what I'd like to see happen. 

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What I'm still not entirely convinced of is that a larger LV capable of carrying more passengers is more efficient overall than smaller ones, even if there's enough passengers to justify its size. Though I admit the issue brought up earlier in this thread with docking so many spacecraft to a space station is one of the best arguments against it.

I'm going to further argue in favor of smaller & cheaper LVs, and while I know it's a stretch to apply the following to this topic, I still want to entertain this thought:

(Going to snip the rest of this to saver some space)

Your "Quickie" analogy breaks down hard, even before the issues of range and speed: How many passengers on an A380 can fly a "Quickie" let alone the A380 they are on? So as JS19 points out you have to have an automated flight systems which would NOT be cheap nor easy to install in a "Quickie" and you'd have to (in the example) build, test, install, and test 850 of them.

Mass production and all that but really 850 fully automated "Quickie's" is a really bad analogy in the first place. Lets talk a bit more relevant one:
7 Falcon-1s versus 1 Falcon-9 with Crew-Dragon.

Using the numbers from the following site (for reference ONLY people :) ):
http://www.spacelaunchreport.com/falcon.html

F-1e would put 1mT (1000kg/2205lb) so lets "assume" for a moment that we could make a single person, automated spacecraft reentry vehicle AND fit a person and some "supplies" inside it and launch it on the F-1e. The cost to do so quoted on the above site is $9.1 million dollars. SpaceX quotes a Falcon-9 launch at $61.2 million, so at its most basic the Falcon-1 option costs at least $63.7 million while the single Falcon-9 only costs $61.2 million. F9 is $2.5 million less than multiple F1es. (And this is before the added costs of developing and building the automated one-person capsules for the F1e)

Now you can still argue that multiple "smaller" launches more often does in fact make more economic sense in some cases and it does. But in general I don't see it being economical for personnel launch without some sort of "infrastructure system" in place (such as the suggested launch loop or skyhook/rotovator, etc) where you are transferring people constantly. Even then I doubt single person vehicles will be cost effective.
(Of course someone WILL argue differently and one such person is Danni Eder who originally came up with the jet-LAP assisted launch concept at Boeing who has a google book he's working on here: http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods
http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods/Human_Transport
Where he argues the case for single person transports)

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The more I think about it, the more I like the jet-powered LAP concept. As you point out, it should be much simpler (and thus cheaper) to develop than a specially designed aircraft. Even if we could use an existing aircraft, the performance would be much lower than what is possible for a LAP. For one, the speed and altitude could be greatly increased over the flight regime jet engines are typically suited for via LOX/water injection (perhaps around Space Shuttle staging velocity and altitude?). The simpler structure should also make aerodynamic heating more easily managed than a full-on airplane of comparable performance.

If you haven't yet I'd recommend taking a read of these threads:
http://forum.nasaspaceflight.com/index.php?topic=29160.0
http://forum.nasaspaceflight.com/index.php?topic=26680.0;all
http://forum.nasaspaceflight.com/index.php?topic=25095.0;all

And I'll jump on the most "obvious" flaw before anyone else does: If your rocket stages are your main turn around driver then having a stage that you CAN actually turn around faster doesn't help you. ... Unless you have multiple rocket stage sets waiting for launch that is :)

(some snippage)
You could have more cross range or build it so that it can land at an airport (ideally in a state that allows it's self ferry back to base).  You'll probably want either more cross range or > 24 hr endurance so the launch site comes back under its orbital track without requiring enormously high cross range.

BTW one interesting calculation you can do on a spreadsheet is to run the rocket equation with different levels of Isp and partial delta V's and losses to orbit.

High Isp (relative to a rocket) means you have a structure which is much heavier than any known rocket, but only air breathers give 1000's of seconds of Isp. Once your breathing air winged lift lets you lift mass 3x take off thrust, although the Launch Assist Platform with afterburning and inlet fluid (either LOX or water) injection can give you a (relatively) simple 1st stage structure with high thrust at ground level and maximum payload (exactly  where you need it) while sustaining acceleration up to maybe M4 without exotic technology like SCRamjets.

The improvement on the available mass fraction for structure is quite remarkable.

One thing I've noted from reading numerous studies on horizontal vs vertical take off (other than the huge amount of pre-assumed conclusions and bias' attached to both methods :) ) is that if you drop some assumptions such as high cross-range without power, requirements for wings sized for horizontal take off under full load, and numerous other "aircraft" based assumptions, spacecraft (as opposed to aircraft) benefit more often from vertical rather than horizontal take off and "rocket-like" operations. This however has to take in things like engine cycles and thrust-to-weight because an engine that (for example) makes its own LOX in flight has to fly quite a different trajectory than one that constantly accelerates to SCramjet speed and beyond. Further a Jet-LAP assisted TSTO rocket REALLY works better when launched as a rocket than an aircraft even though the aircraft has the advantage of cruising to an "open-spot" in the weather if need be, matching ground track of an orbital object and some other advantages.

Multi-stage, (and actually according to the "experts" Single-Stage as long as your willing to use things like Liquid Air Collection, {LACE} and SCramjets which I'm not :) ) air-breathing seems to benefit from smaller payload sizes and vertical take off over horizontal and the use of existing carrier aircraft. But the devil is fully and really embedded in the "details" and you have to do some serious trades to compare those details as well as define them.

For what we're talking about its pretty even between a modified 747 air-launch, ground launched jet-LAP assisted, (both of which give you a higher margin for reusability on your rocket stages) and a "simple" F9-like TSTO with somewhat lower payload and margins depending on the recovery method chosen.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #57 on: 05/12/2015 03:40 pm »

Your just missing a couple of small details in your comparison.

Well, I did mention that it's quite a stretch to compare them :)

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On the one hand you're saying "What's the smallest you can make it?" and on the other you're saying "What's the most economical you can build?"

All I'm saying is that a rocket capable of carrying more people may not necessarily be more efficient or economical than a smaller one, and that there may be legitimate benefits to smaller and simpler. That said, I don't think an ELV could ever be made simple enough to be so cheap as to undercut a high-availability RLV.

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High Isp (relative to a rocket) means you have a structure which is much heavier than any known rocket

How do you figure? I don't see why that would inherently be the case.


(ooh.. new response by randy. I'll get to it later)

Offline john smith 19

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Re: Most economical way of shuttling humans to LEO?
« Reply #58 on: 05/12/2015 10:21 pm »
How do you figure? I don't see why that would inherently be the case.
That was poorly expressed.

What I meant was the lowered delta V (even if the 2nd stage carries all of the losses" mean you can have a much higher empty weight, due to the much higher Isp of an air breathing stage, closer to the Virgin Global Challenger for example, rather than the few % of a rocket stage. 

This opens up the possibility for a horizontal winged take off.

One small data point. The heaviest Mercury capsule was 3000 lb. 1364 Kg.

Cutting the mass of a single person capsule by 25%, even after 1/2 century is a pretty big ask. Apparently the system was all built inside the pilots pressure vessel and not packaged into LRU's to save weight (Gemini sacrificed mass and put most of them outside the PV in separate packages).

Mercury had no computer but a complex set of relays implementing the emergency abort system. it also had quite a lot of displays and a joy stick for the pilot to operate.

A "hands off" system would probably dump all that in favour of a computer in a box, a load of interfaces (in another box) to handle the I/O, an IMU (doing the GNC for the whole ELV) and a smallish flat panel to let you know what's happening (but not really control anything).

Battery technology has also advanced considerably, driven by laptop, phone and EV needs. Likewise in the early 60's discrete transistor (and valve  :) ) radios were the norm. A modern non fully integrated design (not actually custom, just leveraging parts from the mobile radio, sat TV and mobile phone industries and modern SMT packaging) would deliver equal capability in a much smaller package.

Enough to cut 300Kg off the total mass?   Possibly, but doubtful when you factor in the enhanced functionality IE putting the ELV GNC in the capsule so you can keep it.
« Last Edit: 05/12/2015 10:26 pm by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #59 on: 05/12/2015 11:46 pm »


Seriously a number would help msat :)

I really don't know. How sustainable are these suborbital services, and what kind of frequency will they be flying with? Maybe those can give us some figures to work with.

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SpaceX and CST100 are both 7 "people" as payload, call one of them a "pilot" and round down that's 6. Currently they can't launch but every couple of months and there's only one "destination" which is the ISS.

So we could "assume" a scenario based on 8 people per month, 96 a year but that 'technically' wouldn't even strain the system we have assuming we get a third provider. I also don't think it would help lower costs all that much. Anyone have suggestions for a "conservative" number?

Well, there doesn't have to be a destination for space "tourism", but Dragon V2 wouldn't offer much of a view given its tiny hatch window. That doesn't preclude SpaceX, or a partner from rolling out their own space stations (BA comes to mind). But this still remains a chicken<->egg scenario which won't change unless someone is willing to take a lot of risks and invest (luckily some are). Maybe some major high-end hotel chains would like the prestige of having a space hotel, particularly the very first one?

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Your on the NSF-forums, "speculation" is a way of life around here :)
However your correct we DO have to define the problem and parameters if we're going to keep going which is what I'd like to see happen. 

Well then, I feel right at home! Everyone is free to throw in their thoughts and see what sticks, preferably as long as it keeps with the spirit of the OP.

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Your "Quickie" analogy breaks down hard, even before the issues of range and speed: How many passengers on an A380 can fly a "Quickie" let alone the A380 they are on? So as JS19 points out you have to have an automated flight systems which would NOT be cheap nor easy to install in a "Quickie" and you'd have to (in the example) build, test, install, and test 850 of them.

I didn't specify the piloting as I felt it was somewhat besides the point. The vast majority of LV/spacecraft have been fully or highly automated. I think you looked too far into the details of quickie flight controls, but I'd argue that it's not as far fetched of an idea as you seem to indicate.

Quote
Lets talk a bit more relevant one:
7 Falcon-1s versus 1 Falcon-9 with Crew-Dragon.

Using the numbers from the following site (for reference ONLY people :) ):
http://www.spacelaunchreport.com/falcon.html

F-1e would put 1mT (1000kg/2205lb) so lets "assume" for a moment that we could make a single person, automated spacecraft reentry vehicle AND fit a person and some "supplies" inside it and launch it on the F-1e. The cost to do so quoted on the above site is $9.1 million dollars. SpaceX quotes a Falcon-9 launch at $61.2 million, so at its most basic the Falcon-1 option costs at least $63.7 million while the single Falcon-9 only costs $61.2 million. F9 is $2.5 million less than multiple F1es. (And this is before the added costs of developing and building the automated one-person capsules for the F1e)

Now you can still argue that multiple "smaller" launches more often does in fact make more economic sense in some cases and it does. But in general I don't see it being economical for personnel launch without some sort of "infrastructure system" in place (such as the suggested launch loop or skyhook/rotovator, etc) where you are transferring people constantly. Even then I doubt single person vehicles will be cost effective.
(Of course someone WILL argue differently and one such person is Danni Eder who originally came up with the jet-LAP assisted launch concept at Boeing who has a google book he's working on here: http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods
http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods/Human_Transport
Where he argues the case for single person transports)

But how would the F1 price fair if its design allowed for more automated manufacturing? Particularly when the lesser amount of big rockets wouldn't allow for it.  Going by passenger capacity, were're at a ratio of 7:1 (or 6:1 if we really need a pilot). With the costs per passenger between the F1 and F9 being so close to one another, it's really hard to know which was the scales would tip as it's dependent on so many factor.

Thanks for the links. Looks like good stuff!

Quote

If you haven't yet I'd recommend taking a read of these threads:
http://forum.nasaspaceflight.com/index.php?topic=29160.0
http://forum.nasaspaceflight.com/index.php?topic=26680.0;all
http://forum.nasaspaceflight.com/index.php?topic=25095.0;all

And I'll jump on the most "obvious" flaw before anyone else does: If your rocket stages are your main turn around driver then having a stage that you CAN actually turn around faster doesn't help you. ... Unless you have multiple rocket stage sets waiting for launch that is :)

I'll check out these links soon. Thanks.

If you have numerous RLVs, then I think it's fair to say you could pipeline your operation so you're not waiting on any single unit to be refurbed/prepped before your next scheduled launch. That maximizes your launch availability.

Offline RanulfC

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Re: Most economical way of shuttling humans to LEO?
« Reply #60 on: 05/13/2015 08:42 pm »
Seriously a number would help msat :)

I really don't know. How sustainable are these suborbital services, and what kind of frequency will they be flying with? Maybe those can give us some figures to work with.

I don't think those will help either, specifically its about as much of a "possible" rather than actual market as orbital travel is :)

The main question is what kind of traffic is needed to support multiple providers? "Technically" the ISS resupply and crew exchange is that with 3 people and several cargo flights per year, but its not really a commercial market at the moment. We could assume some multiple of "6" passengers per month, with each "provider" carrying a load ever other month which would be a fantastic number compared to current rates. But if you look at it that's only four flights per year per carrier not counting any "cargo" or other payload flights. Suggestions?

Well, there doesn't have to be a destination for space "tourism", but Dragon V2 wouldn't offer much of a view given its tiny hatch window. That doesn't preclude SpaceX, or a partner from rolling out their own space stations (BA comes to mind). But this still remains a chicken<->egg scenario which won't change unless someone is willing to take a lot of risks and invest (luckily some are). Maybe some major high-end hotel chains would like the prestige of having a space hotel, particularly the very first one?

Actually the studies say that having a "destination" and not going up for simply a couple of orbits and return is the more "desired" tourism route. Going around the Earth a couple of times is seen as little better than a shorter (and cheaper) suborbital trip and all things being equal (reusability, turn around time and other factors wise) you get more throughput with less technical and engineering issues with the latter than the former.

(Seriously, IMHO most suborbital companies are going about it the wrong way because they are actually all trying for "orbital" capability eventually. Suborbital Class-1 {straight up and back down} would be better served by a combination jet/rocket powered single-stage VTVL vehicle using MIPCC-modified surplus F100s and a simple robust set of H2O2/kerosene rockets similar to the RL40 {http://www.hydrogen-peroxide.us/history-US-Reaction-Motors/AIAA-2001-3838_History_of_RMI_Super_Performance_90_Percent_H2O2-Kerosene_LR-40_RE-pitch.pdf} which was as easy to maintain as a standard jet engine of the time. Up and down 20 passengers per hour 10 hours a day...)

Hilton, (not Bigelow who keeps telling everyone he has NO ambition to develop space hotels but would rather "rent-space" to government or commercial operations, which is a very different thing) has said that once he felt that the technology and access issues were resolved to his satisfaction he's be willing to put up a space hotel. Similarly there was a Japanese company that made similar statements before the second financial collapse. What most people don't realize is the amount of support infrastructure and personnel that are required to "service" the high end tourism market which is NOT represented by any current "space-tourist" who are by and large much more willing to put up with fewer (or none mostly) amenities. A good figure of merit is about 4 "service" people per tourist in an enclosed environment system, and that's a very minimum number with the "average" being about three times that when you consider dedicated maintenance and "behind-the-scenes" service personnel.

One thing I never see anyone really considering is that each "paying passenger" to a space station is never just paying for THEIR seat but for everyone that will be going in support with them and all the cargo and support for their stay :)

Quote
I didn't specify the piloting as I felt it was somewhat besides the point. The vast majority of LV/spacecraft have been fully or highly automated. I think you looked too far into the details of quickie flight controls, but I'd argue that it's not as far fetched of an idea as you seem to indicate.

The Quickie is actually a good example with mostly simply flight controls however it takes some skill to fly properly and there isn't much room (by design) for automation :) As most pilot will tell you "flying" is easy (as long as nothing goes wrong and the weather is good) taking off can be tricky and landing is a bear. In the capsule example all that would be computer and ground controlled so it would in fact be "easier" than flying a plane, but most smart designers NEVER design for things to go "right" all the time :)
Quote
Quote
Lets talk a bit more relevant one:
7 Falcon-1s versus 1 Falcon-9 with Crew-Dragon.

Using the numbers from the following site (for reference ONLY people :) ):
http://www.spacelaunchreport.com/falcon.html

F-1e would put 1mT (1000kg/2205lb) so lets "assume" for a moment that we could make a single person, automated spacecraft reentry vehicle AND fit a person and some "supplies" inside it and launch it on the F-1e. The cost to do so quoted on the above site is $9.1 million dollars. SpaceX quotes a Falcon-9 launch at $61.2 million, so at its most basic the Falcon-1 option costs at least $63.7 million while the single Falcon-9 only costs $61.2 million. F9 is $2.5 million less than multiple F1es. (And this is before the added costs of developing and building the automated one-person capsules for the F1e)

Now you can still argue that multiple "smaller" launches more often does in fact make more economic sense in some cases and it does. But in general I don't see it being economical for personnel launch without some sort of "infrastructure system" in place (such as the suggested launch loop or skyhook/rotovator, etc) where you are transferring people constantly. Even then I doubt single person vehicles will be cost effective.
(Of course someone WILL argue differently and one such person is Danni Eder who originally came up with the jet-LAP assisted launch concept at Boeing who has a google book he's working on here: http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods
http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods/Human_Transport
Where he argues the case for single person transports)

But how would the F1 price fair if its design allowed for more automated manufacturing? Particularly when the lesser amount of big rockets wouldn't allow for it.

Both F1 and F9 are pretty automated at this point. F1's manufacturing was a 'scale-run' of what they do for the F9 so the price difference would be negligible.
Quote
Going by passenger capacity, were're at a ratio of 7:1 (or 6:1 if we really need a pilot). With the costs per passenger between the F1 and F9 being so close to one another, it's really hard to know which was the scales would tip as it's dependent on so many factor.

No that's why I pointed it out. Launching multiple F1s requires multiple pads, multiple launch crews as well and support equipment so the price is going to be higher as a basic factor. The reason that multiple smaller load to orbit "works" with systems like gun-launch, launch-loop, etc is the basic cost of the "launch" is lower per launch than that of a "standard" rocket launch at least in theory. Theory tends to break down in places like the orbital services end of things due to varied delivery and attitude changes introduced by a "static" launch system though.

Quote
Thanks for the links. Looks like good stuff!

Welcome :)
Quote
Quote
If you haven't yet I'd recommend taking a read of these threads:
http://forum.nasaspaceflight.com/index.php?topic=29160.0
http://forum.nasaspaceflight.com/index.php?topic=26680.0;all
http://forum.nasaspaceflight.com/index.php?topic=25095.0;all

And I'll jump on the most "obvious" flaw before anyone else does: If your rocket stages are your main turn around driver then having a stage that you CAN actually turn around faster doesn't help you. ... Unless you have multiple rocket stage sets waiting for launch that is :)

I'll check out these links soon. Thanks.

If you have numerous RLVs, then I think it's fair to say you could pipeline your operation so you're not waiting on any single unit to be refurbed/prepped before your next scheduled launch. That maximizes your launch availability.

Your still going to have "choke-points" but your correct that a properly designed system will minimize those if possible :) In the cited case you only need a few jet-LAPS but enough rocket stages to keep up the launch rate while others are being turned. Pretty much the whole idea for a LAP is to allow enough margin for robust reusability in the LV stages.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #61 on: 05/16/2015 09:03 pm »


I don't think those will help either, specifically its about as much of a "possible" rather than actual market as orbital travel is :)

The main question is what kind of traffic is needed to support multiple providers? "Technically" the ISS resupply and crew exchange is that with 3 people and several cargo flights per year, but its not really a commercial market at the moment. We could assume some multiple of "6" passengers per month, with each "provider" carrying a load ever other month which would be a fantastic number compared to current rates. But if you look at it that's only four flights per year per carrier not counting any "cargo" or other payload flights. Suggestions?

The ISS figures are pretty much useless. One flight a month even on a fully RLV won't do much for making access as cheap as possible, would it?

Really, what I had in mind when I started this thread was getting people to LEO to board space stations and interplanetary shuttles and the like. In which case, earth->LEO transit would only be a fraction of the overall cost. And in the event such infrastructure existed in any large-ish scale, I guess there's probably better methods of getting to LEO than using rockets.

Quote
Actually the studies say that having a "destination" and not going up for simply a couple of orbits and return is the more "desired" tourism route. Going around the Earth a couple of times is seen as little better than a shorter (and cheaper) suborbital trip and all things being equal (reusability, turn around time and other factors wise) you get more throughput with less technical and engineering issues with the latter than the former.

Well, sure. But that doesn't mean there wouldn't be a market for destination-less orbital flights. Particularly true if the price of access could come anywhere close to the range upcoming suborbital services are targeting.

Quote
(Seriously, IMHO most suborbital companies are going about it the wrong way because they are actually all trying for "orbital" capability eventually. Suborbital Class-1 {straight up and back down} would be better served by a combination jet/rocket powered single-stage VTVL vehicle using MIPCC-modified surplus F100s and a simple robust set of H2O2/kerosene rockets similar to the RL40 {http://www.hydrogen-peroxide.us/history-US-Reaction-Motors/AIAA-2001-3838_History_of_RMI_Super_Performance_90_Percent_H2O2-Kerosene_LR-40_RE-pitch.pdf} which was as easy to maintain as a standard jet engine of the time. Up and down 20 passengers per hour 10 hours a day...)

I somewhat agree in terms of current suborbital designs being all wrong, but my craft would look a bit different than yours  8)

I'd probably go with a jet-powered HTOL therefore capable of zoom climbs and then use decomposed N2O (and maybe water) for jet oxidizer supply above a certain altitude. I find H2O2 pretty scary. You might be thinking self-pressurized N2O is scary too (which it is) but you can have a small pump and a decomposition chamber and thus pressurize the N2O with the resulting oxygen and nitrogen, instead of the much less stable gaseous N2O.

Quote
Hilton, (not Bigelow who keeps telling everyone he has NO ambition to develop space hotels but would rather "rent-space" to government or commercial operations, which is a very different thing) has said that once he felt that the technology and access issues were resolved to his satisfaction he's be willing to put up a space hotel. Similarly there was a Japanese company that made similar statements before the second financial collapse. What most people don't realize is the amount of support infrastructure and personnel that are required to "service" the high end tourism market which is NOT represented by any current "space-tourist" who are by and large much more willing to put up with fewer (or none mostly) amenities. A good figure of merit is about 4 "service" people per tourist in an enclosed environment system, and that's a very minimum number with the "average" being about three times that when you consider dedicated maintenance and "behind-the-scenes" service personnel.

I vaguely recall hearing Hilton make that comment. As far as the kinds of service and amenities the rich would expect, my guess is that with those requirements, most rich people couldn't afford it. If potential tourists can't get over the fact that space accommodations imply minimalist living, then their won't be much space tourism at all.

Quote
One thing I never see anyone really considering is that each "paying passenger" to a space station is never just paying for THEIR seat but for everyone that will be going in support with them and all the cargo and support for their stay :)

I wonder how staff costs relate to all other costs. I'd also assume that in-space staff would stay there for a longer duration than the tourists. Shuttling all the staff with each customer would not be very economical.


Quote

The Quickie is actually a good example with mostly simply flight controls however it takes some skill to fly properly and there isn't much room (by design) for automation :) As most pilot will tell you "flying" is easy (as long as nothing goes wrong and the weather is good) taking off can be tricky and landing is a bear. In the capsule example all that would be computer and ground controlled so it would in fact be "easier" than flying a plane, but most smart designers NEVER design for things to go "right" all the time :)

Apparently you never seen this: http://www.popsci.com/xavion-ipad-app-can-make-emergency-airplane-landing-autopilot

:)

The amount of compute power and sensor integration in a typical smart phone is more than enough to control an airplane from taxi to touchdown.


Quote
Both F1 and F9 are pretty automated at this point. F1's manufacturing was a 'scale-run' of what they do for the F9 so the price difference would be negligible.

Maybe so. I suppose there must be an upper limit where this holds true? Maybe the F9 (and by extension, the heavy) is near the upper end?



Quote
Launching multiple F1s requires multiple pads, multiple launch crews as well and support equipment so the price is going to be higher as a basic factor. The reason that multiple smaller load to orbit "works" with systems like gun-launch, launch-loop, etc is the basic cost of the "launch" is lower per launch than that of a "standard" rocket launch at least in theory. Theory tends to break down in places like the orbital services end of things due to varied delivery and attitude changes introduced by a "static" launch system though.

Does it require multiple pads? That would really only be true if a larger vehicle has enough launches to keep them largely utilized. But if a larger LV makes use of a pad once a month, vs several times a month for a smaller LV, then I don't see how it would be necessary. As for crew and support equipment, well, you're likely going o be paying a crew regardless. I don't see many skilled workers/technicians willing to take an hourly paid job that only requires maybe a few days of work per month. 

Quote
Your still going to have "choke-points" but your correct that a properly designed system will minimize those if possible :) In the cited case you only need a few jet-LAPS but enough rocket stages to keep up the launch rate while others are being turned. Pretty much the whole idea for a LAP is to allow enough margin for robust reusability in the LV stages.

Randy

That's the way I see it too. Sounds like a reasonable solution.

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #62 on: 05/17/2015 08:35 pm »
As usual, I should have done the most basic of calculations before opening my big mouth and supporting some kind of position.  :-[


Lets say a hypothetical single passenger Falcon1 RLV cost $10M to purchase, an a 6 passenger F9 RLV $60M. Assuming a fixed seat price between the two, the F1 would get paid off with 6X fewer passengers than the F9, but both would be paid off within an equal number of flights. After that, each F9 results in 6X the revenues per launch. If each RLV is suitable for 20 flights, then while both give us identical returns relative to our original investment, the overall payback is greater for the F9 obviously. A premature loss of vehicle results in a greater absolute financial loss for the larger LV, but for the same number of passengers served, the odds are against the rocket that requires more flights.

So what about infrastructure requirements? A larger vehicle requires a larger and more expensive pad and support equipment, but a smaller vehicle with a greater number of launches can more easily over-saturate the support infrastructure.

This is such a tight rope scenario where either method can easily tip the scale in its favor but never by much. Are there really any worthwhile benefits to be had from the increased production of a smaller complete unit necessary to math the capabilities of a larger unit, especially when we factor in the larger burden associated with a greater number of launches? Probably not. Any potential savings from an increased production (but not productivity) rate become more and more negligible (assuming a manufacturer would be willing to cut their per-unit profits in the first place).

A smaller vehicle is only favorable to a larger one if the demand is low, but still sufficient for mass production, leading to a quicker RoI for the production equipment and tooling. Otherwise it's just a wash.

Therefore, it seems that the only real savings can be had from a more efficient (in terms of energy usage) or simpler (cheaper) RLV relative to one of equal of equal capability (payload).
« Last Edit: 05/17/2015 08:36 pm by msat »

Offline Patchouli

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Re: Most economical way of shuttling humans to LEO?
« Reply #63 on: 05/17/2015 09:11 pm »
The larger vehicle is going to be more mass efficient as a lot of things such as docking hardware and avionics are won't increase much in mass over the small vehicle.
MMOD protection and insulation will benefit from the square cube law.
« Last Edit: 05/17/2015 09:17 pm by Patchouli »

Offline Robotbeat

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Re: Most economical way of shuttling humans to LEO?
« Reply #64 on: 05/18/2015 02:47 am »
The larger vehicle is going to be more mass efficient as a lot of things such as docking hardware and avionics are won't increase much in mass over the small vehicle.
MMOD protection and insulation will benefit from the square cube law.
There are a heck of a lot of things which scale worse when you get larger. For instance, past a certain point, rocket engines get heavier faster than their their thrust increases (i.e T/W gets worse). There are some basic physics reasons for this.

http://spacecraft.ssl.umd.edu/akins_laws.html
"8. In nature, the optimum is almost always in the middle somewhere. Distrust assertions that the optimum is at an extreme point."
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Offline scienceguy

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Re: Most economical way of shuttling humans to LEO?
« Reply #65 on: 05/18/2015 05:06 am »
a space elevator is coming, people. Just be patient.
e^(pi*i) = -1

Offline msat

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Re: Most economical way of shuttling humans to LEO?
« Reply #66 on: 05/18/2015 05:44 am »
a space elevator is coming, people. Just be patient.

I'll take the stairs!

Offline Darkseraph

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Re: Most economical way of shuttling humans to LEO?
« Reply #67 on: 05/18/2015 05:51 am »
a space elevator is coming, people. Just be patient.

What is the music like in a Space Elevator? Will they loop they same jingle for all 2 weeks?
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." R.P.Feynman

Offline hkultala

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Re: Most economical way of shuttling humans to LEO?
« Reply #68 on: 05/18/2015 06:00 am »
a space elevator is coming, people. Just be patient.

Space elevator cannot get anybody into LEO.

Offline R7

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Re: Most economical way of shuttling humans to LEO?
« Reply #69 on: 05/18/2015 06:29 am »
Space elevator cannot get anybody into LEO.

Step out at the right floor and you are in a transfer orbit to desired perigee and need a lot less dv to circularize. The bold would aerobrake. Inclination restricted though as all the megastructure assisted space aspirations tend to be.
AD·ASTRA·ASTRORVM·GRATIA

Offline QuantumG

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Re: Most economical way of shuttling humans to LEO?
« Reply #70 on: 05/18/2015 06:30 am »
Plus the van Allen belts will fry you.
Human spaceflight is basically just LARPing now.

Offline deltaV

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Re: Most economical way of shuttling humans to LEO?
« Reply #71 on: 05/18/2015 04:00 pm »
Plus the van Allen belts will fry you.
This thread's about the most economical way, not the safest way.   ;)

Offline RanulfC

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Re: Most economical way of shuttling humans to LEO?
« Reply #72 on: 05/18/2015 05:37 pm »
Plus the van Allen belts will fry you.
This thread's about the most economical way, not the safest way.   ;)

Killing your passengers is not conducive to high passenger throughput and tends to be a dis-incentive to continued use by said passengers :)

Space Elevators would be most effective with cargo rather than passengers, but while active and passible shielding would allow passengers to "ride-the-rails" as it were its a toss-up if the time factor would be offset by the supposed cost savings. Ships and trains are much more cost effective and efficient than airplanes but the majority of "passengers" (destination to destination not tourists enjoying the ride) go by plane despite the cost. "Tethers" are probably a more near-term (and faster) technology for minimizing the LV delta-v versus fixed cost but its another toss up if those fixed costs are viable without significant incentives (outside investment) over improved, reusable LVs straight to LEO.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Most economical way of shuttling humans to LEO?
« Reply #73 on: 05/18/2015 06:47 pm »
The ISS figures are pretty much useless. One flight a month even on a fully RLV won't do much for making access as cheap as possible, would it?

Probably not, but then again its a FAR higher rate than we currently have :)

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Really, what I had in mind when I started this thread was getting people to LEO to board space stations and interplanetary shuttles and the like. In which case, earth->LEO transit would only be a fraction of the overall cost. And in the event such infrastructure existed in any large-ish scale, I guess there's probably better methods of getting to LEO than using rockets.

That would be on the order of an more "standard" transportation model where your "terminal" is a LEO destination and getting there in your car or a bus is the main method. However that "assumes" a multiple use vehicle type (car or bus which runs routes/missions OTHER than getting to the "terminal/LEO") which isn't the case.

Your LEO transport is only going to be a 'fraction' once it gets common enough to have several flights an hour let alone a day and we've yet to get it to the point of once a month.

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Well, sure. But that doesn't mean there wouldn't be a market for destination-less orbital flights. Particularly true if the price of access could come anywhere close to the range upcoming suborbital services are targeting.

Actually no. Once your "price point" for orbit reaches a certain point (such as those suggested for suborbital flight) then it makes even less sense to offer "non-destination" flights. Remember that all the suborbital "flights" offer what amounts to a vacation package (if not included IN a vacation package such as XCOR's arrangement) as part of the "flight" cost. The incentive for "just" an orbital flight drops rapidly once the price decreases because (its assumed) that such low cost of access would allow destinations to be offered and if they are then you have little incentive for "just" flying for a couple of orbits and then returning.

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I somewhat agree in terms of current suborbital designs being all wrong, but my craft would look a bit different than yours  8)

I'd probably go with a jet-powered HTOL therefore capable of zoom climbs and then use decomposed N2O (and maybe water) for jet oxidizer supply above a certain altitude. I find H2O2 pretty scary. You might be thinking self-pressurized N2O is scary too (which it is) but you can have a small pump and a decomposition chamber and thus pressurize the N2O with the resulting oxygen and nitrogen, instead of the much less stable gaseous N2O.

We've had a couple of thread on the fears over H2O2 and frankly the stuff is pretty benign IF you treat it with respect. The British had a highly successful H2O2 program and the usual example of the Germans need to take into account hey were loosing a war at the time, used hastily designed and constructed rockets and STILL managed an operational program that had a pretty decent success rate. American "issues" with H2O2 are mostly inherited from early "experts" who significantly didn't like the stuff to the point where they willfully sabotaged development in order to deflect official interest and funding away from it. And despite all that we successfully used it in a series of high performance vehicles with high success.

The main reason to go with VTVL (or VTHL) over HTOL is in fact the studies have shown that Vertical Take Off (rocket-like) is a bigger "draw" and more entertaining than HTOL. People "expect" it of rockets or spaceships and "airplane" style take offs are not seen as being the "proper" mode for a "rocket" to use. (Where as "technically" it might make sense in this case its all about the PR :) )

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I vaguely recall hearing Hilton make that comment. As far as the kinds of service and amenities the rich would expect, my guess is that with those requirements, most rich people couldn't afford it. If potential tourists can't get over the fact that space accommodations imply minimalist living, then their won't be much space tourism at all.

Talk to some folks who work hotel/motel services and admin you will find that "expectation" is a major driver no matter what the cost. You can get away with minimum services in a small, niche market but not in any significant market with large turn around. Automation helps a lot but you're going to need a minimum number of people per "paying passenger/tourist" in any case and they are going to be doing double and triple duty till the price drops enough.

And you are NEVER going to have a significant "passenger/tourist" to orbit traffic as long as you have to go to Russia for a year and "train" to be an astronaut. Here the sub-orbitals have it right in that making the "training" part of the "experience" is one thing but having it be a minimum as possible is another significant factor. (Under your proposed model you don't even want that. It's like "training" to fly on an airplane as a passenger, you simply don't as the traffic is too high for it)

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I wonder how staff costs relate to all other costs. I'd also assume that in-space staff would stay there for a longer duration than the tourists. Shuttling all the staff with each customer would not be very economical.

No "staff" would stay for as long as possible but the "passenger" is still paying for all the supplies and equipment that staff needs to support their stay. So even if you don't ride up with the staff you ride up with your meals and life support cargo :) But there's a question of how long the "staff" can stay to consider as well. LEO is not so much of a problem, up to a year is possible as we've shown. I suspect it would average about 6 months with "two-week" stays by "guests" for an average of 6 turn-arounds.

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Apparently you never seen this: http://www.popsci.com/xavion-ipad-app-can-make-emergency-airplane-landing-autopilot

:)

The amount of compute power and sensor integration in a typical smart phone is more than enough to control an airplane from taxi to touchdown.

Hadn't seen that one but yes I'm aware of how much automation is possible but hadn't seen this one. (And I'm not surprised that it is based on X-Plane since this has become the basis for most commercial flight sim software now :) )

And no it isn't "taxi-to-touch-down" capable yet and the article states that, an actual pilot is needed still which was my point. Further that example is still pretty benign as an engine failure in clear weather is not all that serious.

It's good and in fact we HAVE had fully autonomous flight from taxi-to-landing with drones but they have a much more sophisticated and costly sensor and computational power on-board for the very reason they are expected to operate in anything BUT "benign" environments and weather.

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Does it require multiple pads? That would really only be true if a larger vehicle has enough launches to keep them largely utilized. But if a larger LV makes use of a pad once a month, vs several times a month for a smaller LV, then I don't see how it would be necessary. As for crew and support equipment, well, you're likely going o be paying a crew regardless. I don't see many skilled workers/technicians willing to take an hourly paid job that only requires maybe a few days of work per month.

The pads have to be repaired and serviced between launches, this would reduce your flight rate to that amount of time. Multiple pads removes that factor. The workers/techs may not mind but the people paying the bills might, and usually do :) You want to work them as much as possible for the pay so a higher flight rate is good but multiple launch pads might not be since you would have to have them work sequentially or have multiple crews both of which have issues over the long run versus payload throughput. You really want as many launches as possible sure, but you also want as much payload per launch as possible to spread the costs.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

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