The Next Generation of Human Spaceflight

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rjaypeters
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Postby rjaypeters » Fri Sep 10, 2010 1:01 am

GIThruster: I admire and appreciate your restraint for not ranting. Thank you.

That which makes you groan and wish to spew a thirty-page rant is why I haven't been working for space access for the last ten years. All (okay, maybe most of them) of the good ideas have been thought, studied, debated, conceptualized and roughly costed and where has it gotten us? NASA Constellation/Orion (or whatever they call it - I truly don't care), space shuttle retirement (a good thing in some respects), Back to the Moon, etc.

I sincerely hope Falcons, Blue Origins, Space Ship Twos and all of the entrepreneurs do very well, indeed. I hope the money is good enough that the more speculative ideas can be developed and built. But you started this thread, and I tried to be optimistic along with you.

We wrote together throught the nay-sayers of human spaceflight, largely ignoring them to our mutual benefit. Now we reach an impasse, I've finally told you what I really think and you want to groan. You wanted a notional design for a Titan stay and return mission, I gave you mine. You gave me yours.

Now, we have to do the next most irritating thing in the world; wait for developments:

1. Will the space entrepreneurs succeed well enough to satisfy your first condition in the first post in the thread?
2. Do polywells work? Can we use that power for space applications?
3. Will the space entrepreneurs do better than we expect? FWIW, I'm suspecting Burt Rutan will develop Spaceship Three as a Black Horse variant for TSTO and who knows what after?

[end of rant]

I'm sorry. I am by nature an introvert and run out of things to say until I receive more input. I'll find a more optimistic end quotation for you.
"Aqaba! By Land!" T. E. Lawrence

R. Peters

Betruger
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Postby Betruger » Fri Sep 10, 2010 4:19 am

Rutan may be retiring fairly soon. Not sure if it's only from Scaled or entirely.

GIThruster
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Postby GIThruster » Fri Sep 10, 2010 9:04 am

rjaypeters wrote:1. Will the space entrepreneurs succeed well enough to satisfy your first condition in the first post in the thread?

I think there's no stopping Elon Musk. He shows every ability to succeed at what he's doing and he's doing it out of passion rather than a desire to grow more rich. When the day comes he retires, sell your stock, but until then, I think SpaceX is a great bet.

rjaypeters wrote:2. Do polywells work? Can we use that power for space applications?

If they work we can certainly use them. Question is, "will we?" After all, we're not using fission.

rjaypeters wrote:3. Will the space entrepreneurs do better than we expect? FWIW, I'm suspecting Burt Rutan will develop Spaceship Three as a Black Horse variant for TSTO and who knows what after?

I've been a Rutan fan for more than 25 years, but I just don't see how they're going to reach orbit. Not on rubber tire rocket engines, I can tell you that. They can sell seats for suborbital flight, but that's seriously less than 1/100 the energy needed for orbit and Scaled has never said anything to make me think they had a serious approach for orbit in mind. I know Rutan has said he wants to go to orbit, but he hasn't said how, and that leaves me thinking they'll never get there. Top speed for Spaceship One was Mach 3. ISS moves at almost 10X that. Not getting there on rubber tire engines. . .nosiree.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

rjaypeters
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Postby rjaypeters » Fri Sep 10, 2010 12:27 pm

Scaled Composites to orbit?

GIThruster wrote:...but I just don't see how they're going to reach orbit. Not on rubber tire rocket engines, I can tell you that... ISS moves at almost 10X that. Not getting there on rubber tire engines. . .nosiree.


I'm sure Mr. Rutan and co. know Black Horse requires more energetic propellants, but almost everything we want does. If you like, look here:

http://www.ai.mit.edu/projects/im/magnus/bh/analog.html
"Aqaba! By Land!" T. E. Lawrence

R. Peters

Diogenes
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Postby Diogenes » Fri Sep 10, 2010 3:42 pm

Late in on this discussion, and I haven't read all of the proceeding ideas, but I did want to introduce one point.


There was a recent test of a laser system by the Navy (I think) in which they shot down drone aircraft with a laser. My understanding of the design was that they used an array of solid state laser modules with some sort of beam combiner that preserves coherence. From what I recall reading, they indicated the new method of integrating separate laser modules into one powerful beam is vastly expandable to whatever powers are necessary.

If this is all true, it seems to me that it would make the design of a laser launch system far more practical. Yeah, it's efficiency might suck big time, but with ground based power systems, the lack of efficiency will be more than made up from the losses of having to throw so much reaction mass just to get through the atmosphere. It might be possible to boost through most of the atmosphere using a ground based laser, (or series thereof) and boost outside of atmosphere with a space based laser. Once up to some sort of orbit, a Vasimr engine might be able to produce enough thrust to boost to working orbit within a reasonable amount of time.

Till we get some sort of real "anti-gravity" like device, or till we build the space elevator, this seems like the most reasonable idea i've heard so far.

GIThruster
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Postby GIThruster » Fri Sep 10, 2010 4:33 pm

Diogenes wrote:Late in on this discussion, and I haven't read all of the proceeding ideas, but I did want to introduce one point.


There was a recent test of a laser system by the Navy (I think) in which they shot down drone aircraft with a laser. My understanding of the design was that they used an array of solid state laser modules with some sort of beam combiner that preserves coherence. From what I recall reading, they indicated the new method of integrating separate laser modules into one powerful beam is vastly expandable to whatever powers are necessary.

If this is all true, it seems to me that it would make the design of a laser launch system far more practical. Yeah, it's efficiency might suck big time, but with ground based power systems, the lack of efficiency will be more than made up from the losses of having to throw so much reaction mass just to get through the atmosphere. It might be possible to boost through most of the atmosphere using a ground based laser, (or series thereof) and boost outside of atmosphere with a space based laser. Once up to some sort of orbit, a Vasimr engine might be able to produce enough thrust to boost to working orbit within a reasonable amount of time.

Till we get some sort of real "anti-gravity" like device, or till we build the space elevator, this seems like the most reasonable idea i've heard so far.


Laser launchers require the same reaction mass to be carried aboard. What they don't require is combustible fuels, and the mass of the thruster itself, but they have to carry propellant. Once you understand this, the notion is significantly less attractive. For your hundreds of billions spent in ground based laser systems none of which operate past 50% efficient, you don't get much in return.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

GIThruster
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Postby GIThruster » Fri Sep 10, 2010 4:40 pm

rjaypeters wrote:Scaled Composites to orbit?

GIThruster wrote:...but I just don't see how they're going to reach orbit. Not on rubber tire rocket engines, I can tell you that... ISS moves at almost 10X that. Not getting there on rubber tire engines. . .nosiree.


I'm sure Mr. Rutan and co. know Black Horse requires more energetic propellants, but almost everything we want does. If you like, look here:

http://www.ai.mit.edu/projects/im/magnus/bh/analog.html


Did Rutan express an interest in a Black Horse launch system? I wasn't aware he'd so dabbled.

The trouble I see is that such a system will be much, much more expensive than his sub-orbital system. I don't see how he could sell it. He'd have to use RP-1 or methane (probably the former) and even if he bought the engines from Musk, he'd still have a very expensive launch system. Is there really a market for seats on a spaceship to orbit at $5 million per?
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Diogenes
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Postby Diogenes » Fri Sep 10, 2010 5:38 pm

GIThruster wrote:
Diogenes wrote:Late in on this discussion, and I haven't read all of the proceeding ideas, but I did want to introduce one point.


There was a recent test of a laser system by the Navy (I think) in which they shot down drone aircraft with a laser. My understanding of the design was that they used an array of solid state laser modules with some sort of beam combiner that preserves coherence. From what I recall reading, they indicated the new method of integrating separate laser modules into one powerful beam is vastly expandable to whatever powers are necessary.

If this is all true, it seems to me that it would make the design of a laser launch system far more practical. Yeah, it's efficiency might suck big time, but with ground based power systems, the lack of efficiency will be more than made up from the losses of having to throw so much reaction mass just to get through the atmosphere. It might be possible to boost through most of the atmosphere using a ground based laser, (or series thereof) and boost outside of atmosphere with a space based laser. Once up to some sort of orbit, a Vasimr engine might be able to produce enough thrust to boost to working orbit within a reasonable amount of time.

Till we get some sort of real "anti-gravity" like device, or till we build the space elevator, this seems like the most reasonable idea i've heard so far.


Laser launchers require the same reaction mass to be carried aboard. What they don't require is combustible fuels, and the mass of the thruster itself, but they have to carry propellant. Once you understand this, the notion is significantly less attractive. For your hundreds of billions spent in ground based laser systems none of which operate past 50% efficient, you don't get much in return.


As I mentioned elsewhere, if the pressures and velocities can be increased, the reaction mass can be smaller. Also throwing away the turbopumps and fuel tanks will save a great deal of weight.

The on ground efficiency loss is not terribly important if it can be made up for by it's advantages. Apart from that, it might be possible to provide some sort of scram boost in the atmosphere and reaction mass only beyond.

derg
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Postby derg » Fri Sep 10, 2010 5:46 pm

Am I right in assuming that any non-nuclear feuls can be ruled out for true SSTO (Mach 27?)

GIThruster
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Postby GIThruster » Fri Sep 10, 2010 5:49 pm

derg wrote:Am I right in assuming that any non-nuclear feuls can be ruled out for true SSTO (Mach 27?)


No. X-33/Venturestar could have made SSTO on H2/LOX, had it been approached properly. It's very difficult but the numbers where there that the design would have succeeded if they had built what they had designed.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

rjaypeters
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Postby rjaypeters » Fri Sep 10, 2010 7:32 pm

GIThruster wrote:Did Rutan express an interest in a Black Horse launch system? I wasn't aware he'd so dabbled.

If one reads the acknowledgements of the report one finds Mr. Rutan contributed to the "Black Colt", so one must assume he knows about Black Horse, too.

GIThruster wrote:The trouble I see is that such a system will be much, much more expensive than his sub-orbital system. I don't see how he could sell it. He'd have to use RP-1 or methane (probably the former) and even if he bought the engines from Musk, he'd still have a very expensive launch system. Is there really a market for seats on a spaceship to orbit at $5 million per?

Indeed, Scaled Composites would need help for a Black Horse Variant (BHV), just like they got help with the hybrid rockets for SS1 and SS2. I don't think Scaled Composites has done much supersonic work, but they have gained some experience with SS1 and will gain more with SS2.

Just from reading the 1995 report, neither RP-1 nor methane are best suited for Black Horse.

To whom to sell BHV? Who would be the launch (sorry) customer? Sir Richard Branson of Virgin Galactic, IF SS2 works out well. Sir Richard has a penchant for doing unpredictable things...

The space entrepreneurs know we need to get a toe hold to space access before we can get a foot hold. The chosen toe hold has been (in the case of Virgin Galactic and others) space tourism. The foot hold would be not to offer a measly few minutes of micro-gravity, but hours of micro-gravity and/or a ride to a Bigelow hotel...

Let's quickly look at the elements needed for a BHV: Tanker (also lifter for this variant), orbital vehicle, H2O2+JP-5 rocket & ramjet (optional, but higher performance).

Tanker+Lifter: A higher performance development of the White Knight Two. Is there anyone who builds large, high performance, high gross-weight aircraft better than Scaled Composites?

Orbital Vehicle: A much tougher nut to crack, what with the much higher performance needed than SS2. But the differences are mostly in degree rather than kind. SS2 will need all of the same systems and structures as a BHV orbiter, except for the style of tankage and engine (s).

H2O2+JP-5 engine: Modification of a Russian NK-31 roughly costed, back in the 90s, at a few tens of milliions $US to develop. I'd like to think we are smarter now, but I have been proven wrong about that.

Ramjet (part of the orbiter): I'd delay this development until the non-ramjet BHV was flying. At least, it's not like trying to develop a scramjet.

Sure, BHV isn't a TVS, but it does offer the things, you (I'm looking at you GIThruster) find desirable in launch capacity. Complete lack of ground infrastructure. flexibility of launch parameters (location, azimuth, etc.). I'd think you'd be champing at the bit to build BHV as a stepping stone to TVS. Oh, one more thing...

BHV doesn't any nuclear components to scare the straights.
"Aqaba! By Land!" T. E. Lawrence

R. Peters

GIThruster
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Postby GIThruster » Fri Sep 10, 2010 7:58 pm

rjaypeters wrote:Sure, BHV isn't a TVS, but it does offer the things, you (I'm looking at you GIThruster) find desirable in launch capacity. Complete lack of ground infrastructure. flexibility of launch parameters (location, azimuth, etc.). I'd think you'd be champing at the bit to build BHV as a stepping stone to TVS.


I'd certainly love to see Scaled do as you propose but there are two troubles I see. First is, as a private industry (even if cottage) Virgin needs to pay for what they fly. I'm again wondering about the market. Orbital flight is very expensive and SpaceX is already on the way there. If anyone can fly private citizens to space on a budget, it'll probably be Musk well before Rutan. Just not sure there's a market.

Second thing is there is a serious technical difficulty with orbital flight that Rutan has not faced. His design cannot return from orbit without burning up. It lacks the thermal protection necessary for such a trip.

The shuttlecock design used in Spaceships One and Two is brilliant, but it's not enough to slow the craft returning from orbit. For that, you need to face off squarely against one of the most difficult issues found in spaceflight--hypersonic reentry. The simplest way to cope with this is the capsule method employed by SpaceX. They designed from the start for human spaceflight and Dragon is in many ways much more capable than the Orion capsule. Conversely, Rutan's wings and shuttlecock can't make such a reentry. He'd need to start over from scratch. It's not just a simple issue of adding tiles and even if that approach were viable, he would then no longer have a spacecraft that can be flown every day, nor even every week or month. He'd have another Shuttle problem on his hands.

A third method for handling hypersonic reentery is to carry enough fuel to fire your engines during descent, as with the original Delta Clipper notion. That's very expensive and nothing like economical, and it's never been done before (unless it was a black project and there are lots of reasons to doubt this ever occurred.)

The only other alternative is the X-33 approach: fly the empty tank back, and thereby distribute the thermal loading over such a large surface that one hopes very minimalistic TPS would suffice. Remember too, that X-33/Venturestar were never intended to be manned. The entire spacecraft can therefore be allowed to get much hotter than if people are aboard.

Out of the four, SpaceX's approach is certainly the best tested. They won't have to check thousands of tiles after every capsule recovery. They'll just replace the heat shield in it's entirely. Make enough heat shields and this becomes safe, quick, convenient and relatively economical.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

rjaypeters
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Postby rjaypeters » Fri Sep 10, 2010 9:01 pm

GIThruster wrote:... but there are two troubles I see. First is, as a private industry (even if cottage) Virgin needs to pay for what they fly.

All the entrepreneurs wonder that same question, "If I build it, will they come?" The people we read about in the aerospace press are the ones who answer "Yes, they will" and proceed.

Mr. Musk will get to market before Mr. Rutan/Sir Richard could, but the BHV would be more capable in all the ways you (and especially some paying customers) like. More capable enough to win more customers? Probably yes.

GIThruster wrote:Second thing is there is a serious technical difficulty with orbital flight that Rutan has not faced. His design cannot return from orbit without burning up. It lacks the thermal protection necessary for such a trip.

...The only other alternative is the X-33 approach: fly the empty tank back, and thereby distribute the thermal loading over such a large surface that one hopes very minimalistic TPS would suffice.

A low wing loading approach was selected in the Black Horse study with: "The thermal protection system technology deemed suitable for this application is carbon/silica carbide for the nose cap, DuraTABI for broad areas on the lower surface, and a lightweight blanket insulation for the upper surface."

We have had fifteen years since the Black Horse study, we might be a little better at thermal protection.

Care-free reentry may not be applicable to hypersonic re-entry. But, since I haven't thought about it much either, care-free reentry technology might be adaptable.
"Aqaba! By Land!" T. E. Lawrence

R. Peters

GIThruster
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Postby GIThruster » Fri Sep 10, 2010 9:39 pm

As I said, I'd be thrilled for Rutan to go for it. I've always been impressed with his ingenuity. I don't see a useful distinction between Black Horse and TSTO--seems just whether the craft are connected on the way up and whether you run the motors in the spacecraft are extraneous. The real issue to me is still the TPS. I think they hand-waved this, but if anyone knows better, it would be Rutan ;-)

Market issue is, with tickets for $200,0000@, suborbital flight has a market. Just how many people would be willing to pay $5,000,000 for an orbital flight, or can something like Black Horse substantially reduce this? Sir Richard knew before he paid for his space fleet that he could sell tickets to suborbital space. I don't think Bigelow did the same market research before he purchased his orbital hotel tech.

Black Horse and all the TSTO designs I've seen have another problem too. There's no docking ring. If you're gonna fly to orbit, you want to stay at Bigelow's. But leave it to Rutan for an answer. I wouldn't be surprised if he had the entire craft fold in half to expose a docking ring.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

IntLibber
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Postby IntLibber » Sat Sep 11, 2010 9:17 am

GIThruster wrote:
Diogenes wrote:Late in on this discussion, and I haven't read all of the proceeding ideas, but I did want to introduce one point.


There was a recent test of a laser system by the Navy (I think) in which they shot down drone aircraft with a laser. My understanding of the design was that they used an array of solid state laser modules with some sort of beam combiner that preserves coherence. From what I recall reading, they indicated the new method of integrating separate laser modules into one powerful beam is vastly expandable to whatever powers are necessary.

If this is all true, it seems to me that it would make the design of a laser launch system far more practical. Yeah, it's efficiency might suck big time, but with ground based power systems, the lack of efficiency will be more than made up from the losses of having to throw so much reaction mass just to get through the atmosphere. It might be possible to boost through most of the atmosphere using a ground based laser, (or series thereof) and boost outside of atmosphere with a space based laser. Once up to some sort of orbit, a Vasimr engine might be able to produce enough thrust to boost to working orbit within a reasonable amount of time.

Till we get some sort of real "anti-gravity" like device, or till we build the space elevator, this seems like the most reasonable idea i've heard so far.


Laser launchers require the same reaction mass to be carried aboard. What they don't require is combustible fuels, and the mass of the thruster itself, but they have to carry propellant. Once you understand this, the notion is significantly less attractive. For your hundreds of billions spent in ground based laser systems none of which operate past 50% efficient, you don't get much in return.


THis is not entirely true. The design of the light craft focuses the laser beam to heat air vented through ram air ejector cowlings around the edge. Once above atmosphere, you do need propellant to spray into the focusing cavity, but the mass requirements for that are akin to the second stage of a F9 whereas atmosphere works just fine for the first stage.


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