Author Topic: Most economical way of shuttling humans to LEO?  (Read 26575 times)

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. 

Quote
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?

Quote

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.

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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.

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