Gemini: We can rebuild it, we have the technology

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killium

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Just a quick question, if we change the avionics, the computer, the fuel cell, the number of seat etc....... what is left from the original thing ? Where do we save ?<br /><br />Am i wrong to think that testing is the major part of the cost ? This craft with all these new things would have to be tested very toroughly, i doubt we would save anything by re-using the Gemini <img src="/images/icons/frown.gif" /><br /><br /><br /> <div class="Discussion_UserSignature"> </div>
 
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yurkin

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If you are going to extend it to fit five people then doesn’t it make sense for it to re-enter on its belly as opposed to its back. Like the Russian Clipper or Lockheed’s OSP design. Also by doing this you can make the whole craft re-usable not just perhaps the crew section.<br /><br />But I can’t argue that for simplicity it hard to beat the basic capsule configuration. ESA did some work with a scaled up capsule design for five people during the nineties. It sounds like what you guys are describing except it was only supposed to be a CRV.<br />
 
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mrmorris

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<font color="yellow">"...what is left from the original thing ?"</font><br /><br />From everything I've been looking at -- very little except the basic capsule concept will be left. <br /><br />The US space program has really only had four manned orbital space programs (unless I'm having a really bad day and am missing one -- s'possible): Mercury, Gemini, Apollo, and the shuttle. Mercury was essentially a prelude to Gemini (the Gemini capsule started as the Mercury Mark II) -- leaving us with three 'concepts' in spacecraft design. Of those three, the Gemini did the most with the least. The Apollo return module was much heavier (even accounting for an additional person), and the shape would be much more difficult to work into a controlled landing (i.e. paraglider).<br /><br />I have <b>not</b> been a closet Gemini fan for years. When I saw this concept (specifically a modern Gemini on a Falcon V) posted on the X-Prize board, I took some time to read the Gemini specs on a whim. What I saw was interesting -- the Falcon V could easily lift the original 1960's tech capsule, with a few hundred kg to spare. My original thought was that using composites and modern electronics for the capsule *might* shave enough weight to allow an increase in size sufficient to squeeze in three more people.<br /><br />Instead, as I've dug deeper and deeper into researching the Gemini (I've spent <b>way</b> too much time on this mental exercise) -- it's becoming more and more obvious that the potential of a modern Gemini-style capsule is much greater than I originally thought. As I stated earlier -- the original was very obviously mass-limied, as opposed to volume-limited. There was wasted space in all three capsules. The Adapter and Equipment modules had the most, but the unpressurized bays for electronics in the RM were also fairly open (I presume due to heat-dissapation issues). The placement of high-volume (but critical) supplies in the EM (water, oxygen and power) meant t
 
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mrmorris

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<font color="yellow">"If you are going to extend it to fit five people then doesn’t it make sense for it to re-enter on its belly as opposed to its back. "</font><br /><br />Again -- you missed part of the thread. <img src="/images/icons/smile.gif" /><br /><br />We've been bandying about resurrecting the original Gemini idea -- namely using a paraglider controlled landing. The craft is bottom-first only until the parasail is deployed -- then makes a controlled landing. The X-38 development and testing of this concept should rectify the original Gemini problems (i.e. they couldn't get the parasail to reliably deploy) <br /><br />In some ways -- this is the best of all worlds. The re-entry is vastly simplified with the teardrop shape bottom-first entry, there's no mass lost to 'lifting body' elements, but it still allows for a controlled landing.
 
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yurkin

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Well I'm convinced.<br />Lets go build one or two. <img src="/images/icons/smile.gif" />
 
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scottb50

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I would think the best way would be to combine the three Gemini sections into a single vehicle, basically the same dimensions as the entire Gemini package, except a single structure. The dynamics would be basically the same and the entire ship would be re-usable if a TPS type heatshield is used. The volume would allow more payload space, as you have said, there was a lot of lost space in the Gemini.<br /><br />Take the parachute out of the top and add a docking adapter, compatible with ISS, or whatever, and house the parasail in a longitudinal housing down the length of the vehicle. This would open up a lot of volume for more people or cargo.<br /><br />The main reason for starting with the Gemini, or a similar design, is the relatively benign, and proven, re-entry dynamics, sort of like the SS1, it assumes the position without much crew, or computer interaction. Soyus offers the same benefits, but scaling up the design has problems, a sphere is ideal, but a Gemini type capsule can be made longer much simpler than a sphere being made bigger.<br /><br />I would also think if a high enough performance orbital maneuvering stage is used, a vehicle of this size could be launched from a bigger version of the White Knight, eliminating expendable boosters. Specifically the restartable second stage of a Delta, would be a good starting point. <div class="Discussion_UserSignature"> </div>
 
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mrmorris

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<font color="yellow">"The dynamics would be basically the same and the entire ship would be re-usable if a TPS type heatshield is used."</font><br /><br />You're still going to have to poke holes through your heatshield. Also -- reading through the familiarization manuals -- I determined that I had made an incorrect assumption based on the Astronautix data (added to my own preconceptions). There is no such thing as a 'main engine' on the capsule. Astronautix gives a set of stats:<br /><br /><i>Main Engine: 120 kg. Main Engine Propellants: N2O4/MMH. Main Engine Propellants: 322 kg. Main Engine Isp: 273 sec.</i><br /><br />Which I took to mean that there was a 120kg engine on the EM used for maneuvering. Nope. Apparently that's just all the weights of the RCS thrusters combined. What this means in terms of a 2-module capsule is that the Adapter Module (I'd prefer to call it the De-orbit Module, DM) would consist of a ring of aluminum, some trusses, and about eight small SRBs. Very little is lost by allowing this to burn up, or saved by bringing it back to earth.<br /><br />In any event -- it becomes an engineering question. If the heat shield will still work with eight holes through it -- the SRBs can be on the capsule side of it. I'll graciously allow the company that builds this capsule to make the in/out decision. <img src="/images/icons/smile.gif" /><br /><br /><br /><font color="yellow">"Take the parachute out of the top and add a docking adapter, compatible with ISS, or whatever, and house the parasail in a longitudinal housing down the length of the vehicle."</font><br /><br />Yes -- I've thought of that rearrangement. The potential locations for the docking mechanism all have pros and cons. I like the idea of one that goes through the heat shield least. I'm torn between one in the nose and one at the top. I really liked the lines of the Multi-Role Recovery Capsule designed by British Aerospace Ltd. (picture below) -- but I can find no data
 
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scottb50

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<<You're still going to have to poke holes through your heatshield.>><br /><br />No I would keep the heatshield a single piece. As you say it would probably be better to have an expendable de-orbit engine, or engines, these could be in a module that attaches to the bottom of the capsule, nesting the heatshield in the top and attaching to the main body above the heatshield.<br /><br />Another option would be putting the docking port on the side, or top as you say, and mounting the de-orbit engines on the nose, you could also mount aft firing thrusters to this part eliminating any attachments to the aft section at all. The biggest problem would be exposure of the docking port and aft facing thrusters during re-entry. One advantage to this would be allowing stowage of the parafoil in the nose rather than down the center. This configuration would allow maximum internal capacity. <br /><br />There is also a third option. Where I see the most problem is getting from an initial orbit to the ISS or a similar facility and back to the atmosphere. If all you have to orbit is the capsule then a small launcher would be appropriate, add an upper stage and the weight increases drastically.<br /><br /> I have long talked about using a Tug that would solve both of the problems. A capsule could be put in a minimal orbit, picked up by a Tug and taken to a higher orbit relatively simply, de-orbit could be done in a similar way, the Tug providing the de-orbit burn then separating and returning to a higher orbit for refueling and re-use. I would think the same launcher could be used for both as well as putting propellant in orbit for Tug use. This would keep the capsule extremely light, allowing maximum capacity and reduce costs further by increasing the flight rate, the more launchers built the cheaper they become. <div class="Discussion_UserSignature"> </div>
 
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mrmorris

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<font color="yellow">"There is also a third option. Where I see the most problem is getting from an initial orbit to the ISS or a similar facility and back to the atmosphere."</font><br /><br />I'm still hoping to direct this capsule towards a company developing it to win Bigelow's prize. A space tug just isn't happening for that.<br /><br />Anyway -- the upper stage of the Falcon V has the oomph to get the capsule to an ISS-compatible orbit.<br /><br />However -- there *is* a fourth option. The RCS could actually be an RCS/OMS like the shuttle's. Add three or four nacelles to the bottom of the capsule. Each nacelle would contain a large manuvering thruster facing rearward and three smaller thrusters to the front and both sides. It could use either hydrazine as the shuttle does currently, or possibly LOX/Ethanol (long considered as an upgrade for the shuttle).<br /><br />I don't think the aerodynamics of the capsule would be seriously impacted by the nacelles (although I could easily be mistaken). It would, however, lose the launch abort function of the SRBs. The OMS engines won't be able to provide the same 'swift-kick-in-the-pants' as eight SRBs.
 
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najab

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><i>I don't think the aerodynamics of the capsule would be seriously impacted by the nacelles (although I could easily be mistaken). It would, however, lose the launch abort function of the SRBs. The OMS engines won't be able to provide the same 'swift-kick-in-the-pants' as eight SRBs.</i><p>I think that a launch shroud could be designed which would totally eliminate the aerodynamic effects of such an arrangement. However, in my opinion, this would be a poor design choice since you lose the ability to use the RCS as an abort motor - this is a double penalty since you would then have to add additional mass and complexity to the system with the addition of a separate launch escape system. Also, the small additional delta-v provided by the OMS system wouldn't really allow for significant orbital manouvering and probably wouldn't be worth the increased mass.<p>If you want to add an additional 1000kg to the liftoff mass it is probably better to add it as first stage propellant than as plumbing, propellant, OMS engines and a launch escape system.</p></p>
 
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mrmorris

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<font color="yellow">"However, in my opinion, this would be a poor design choice..."</font><br /><br />Ayup. I prefer the SRB/expendable AM myself. The only reason I even mentioned the possibility of an OMS/RCS is for 100% reusability of the capsule (a dubious 'advantage' at best), and because in looking around for a modern equivalent for the RCS system, I found that Aerojet made the OMS/RCS system for the shuttle. I'm having trouble finding hydrazine thrusters that meet the isp shown on Astronautix for the Gemini -- much less beat it. The RCS thrusters show an isp of about 273-288 on Astronautix (depending on which module being referred to). However -- most modern hydrazine thrusters that I've found while Googleing show an isp of around 225-240. Astronautix shows an isp for Endeavor's RCS/OMS system of 316. I figure it's the most advanced RCS system in use today -- and so Aerojet would be a good candidate for supplying this subsystem for the Gemini-X3.<br /><br />BTW -- from now on (assuming I remember) I'm going to start referring to the 'modern' Gemini as Gemini-X3. Reading the history -- Gemini got its name from the fact that it carried two people. Since I'm hoping the modern one will carry six, I figure Gemini-X3 makes a good name. Of course if I can manage to trim enough weight and locate enough volume -- it might end up being the Gemini-X4 or even the Gemini-X5 (not that there's currently any <b>reason</b> to send ten people into orbit... but one can hope). <img src="/images/icons/smile.gif" /><br />
 
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scottb50

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I think the starting point is the basic configuration of the Gemini capsule, from there the number of seats and cargo volume can vary as needed. It wouldn't cost that much more for a six seat version as a ten seat version when the only difference is physical size. The key is the basic configuration that has proven ideal for a stable re-entry without crew interaction.<br /><br />As for the thrusters I would think if the need exists whatever you want could be made available. I also think using hydrozine, from a storage and transfer point alone would make it a very poor choice. There are many more benign propellant combinations available, LOX and LH would be a better, and proven, choice, and have a much higher ISP, requiring less and reducing launch weight. <br /><br />I've been thinking along the lines of a mechanically rotating system. Aft facing for launch, swivel forward for re-entry and point as needed for orbital corrections. Two thrusters in each pod for redundancy, four on the aft circumference, above the heat shield, and four forward would be needed, identical, they would allow quick change capability and total failure of one or more could be compensated for by a combination of the others. Aft facing for ascent would be aerodynamic and forward facing during re-entry would provide heat shielding. <br /><br />For launch escape, from an expendable booster, it would make sense to use a system similar to Mercury and Soyus, pull the capsule away and use the existing parafoil for return and landing. Recovery of an unused escape motor could also be possible with a fairly small chute, if it is fired after having separated from the capsule to reduce landing weight, though the tradeoff may not be that important, the mass of the parachute being the main factor.<br /><br />I still think my Tug idea would have merit, especially for a project such as Bigelows. If you use a re-usable upper stage to launch the initial capsules, or construction materials, then keep it in Space, at y <div class="Discussion_UserSignature"> </div>
 
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mikejz

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I have been reading this thread with great interest—the idea seems to be to put a Gemini capsule on top of a Falcon V. I have to say however that no has discussed what could be used from the 2nd stage. (esp with regard to the EM) For example, it seems easier to add or up rate the RCS on the 2nd stage and change it over to Lox/LH2 (if we are still using fuel cells and not solar) and simply fly it as a combo 2nd stage/EM. It could also be used for the retro-burn (if there is a weight advantage to a using an escape tower). You stand to lose a few hundred pounds by combining computer and power systems into one, plus you could not need to worry about a separation system between the 2nd stage and the capsule.
 
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mrmorris

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<font color="yellow">"I have to say however that no has discussed what could be used from the 2nd stage. (esp with regard to the EM)"</font><br /><br />You lost me at 'Hello'.<br /><br />I assume you mean use the second stage of the Falcon V. Since it's essentially a fuel tank and engine -- and will be pretty much out of fuel by the time it has placed the capsule into the proper orbit -- I don't know what you mean it should be used *for*.<br /><br /><br /><font color="yellow">"For example, it seems easier to add or up rate the RCS on the 2nd stage and change it over to Lox/LH2 (if we are still using fuel cells and not solar) and simply fly it as a combo 2nd stage/EM."</font><br /><br />Still lost. LOX/LH2 is not a normal RCS combination. Hydrazine, of course, it the most common. I've seen LOX/Ethanol suggested for thrusters, but not LH2. I assume the connection with the fuel cell is that the FC Oxygen/Hydrogen reactant tanks could be shared with the RCS system. I don't think the FC Hydrogen is stored cryogenically though. Besides that -- I've pretty much decided that fuel cells (even modern ones) don't make sense for a spacecraft as envisioned. They only come into their own for extended missions. Batteries will be sufficient for this purpose, and will require considerably less mass and volume for the power levels required.<br /><br /><br /><font color="yellow">"It could also be used for the retro-burn (if there is a weight advantage to a using an escape tower). You stand to lose a few hundred pounds by combining computer and power systems into one, plus you could not need to worry about a separation system between the 2nd stage and the capsule."</font><br /><br />By the time the DO burn is required -- the 2nd stage will be out of fuel. I don't understand the statement about the computer and power systems. Finally -- the 2nd stage will have to be jettisoned before re-entry unles you are planning both for it to have heat-shielding and beco
 
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mrmorris

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Question for NajaB or shuttleguy (dunno if SG is even reading this thread) about the shuttle avionics. I've been looking for an updated avionics system for Gemini-X3. Ideally it'd be great to <b>start</b> with something like the shuttle's MEDS/'Glass Cockpit' upgrade. Keeping with the COTS mindset, I've been looking for integrated avioncs suites. <br /><br />I expect the answer to my question will consist largely of 'it depends', but I was wondering if avionics systems designed for airplanes/helicopters could be modified to work for this. I read <b>somewhere</b> (that I can no longer find) that the X-38 has a glass cockpit and that it used primarily COTS equipment. Unfortunately -- I can't determine who supplied it. <br /><br />I found three suites that are designed to be customized to fit a variety of aircraft (the Primus in particular seems to be very flexible):<br /><br />Honyewell's Primus Elite<br />Rockwell's Pro-Line 21<br />Garmin's G1000
 
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najab

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><i>I expect the answer to my question will consist largely of 'it depends', but I was wondering if avionics systems designed for airplanes/helicopters could be modified to work for this.</i><p>Yes, once you have someone to develop and test the software, the hardware wouldn't much care whether it is used in space or in the atmosphere.</p>
 
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scottb50

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I would think a Collins system with RLG's would work great. They have been used for years on airliners and business jets.<br />That part of it should be very simple, reliable and light weight.<br /><br />The software shouldn't be a major problem either, existing programming using GPS references would probably work as is. <br /><br /> <div class="Discussion_UserSignature"> </div>
 
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scottb50

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I hate to see this thread die so soon. An updated version of a proven manned design that could be launched by an existing, commercially available, cheap, rocket is a great idea. If the basic Vehicle itself could be expanded, and upgraded, to allow more passengers or payload capabilities. If an existing, or soon to be available, Falcon rocket can launch a vehicle of the size and mass of an original Gemini, then it would be the way to go and would lead to bigger rockets and and more capable orbiters and, eventually colonization of LEO. It's a start anyway, better than has been done since Apollo days. The sooner there are even bigger Falcons, or better Falcons, the better.<br /><br />We have to start building an infrastructure and expand the demand to be in orbit, that will lower costs and lead to expansion through increased demand. First we have to get there. <br /><br />We already know we can exist and work there, as well as build an infrastructure, it's been proven with MIR, ISS, Soyus and Gemini. It's has been proven we can exist on other Worlds, at least the Moon, Mars, Venus, an Asteroid and soon Titan.<br /><br />It's just like building any Hotel, It costs a lot of money. But, if it wasn't profitable, why do we have so many places like Las Vegas and Disney Land that make so much money? <br /><br />The only way to start is to start. LEO bases would allow gradual expansion beyond LEO, once access itself became manageable, if they also served as entertainment estalishments they would easily pay their own way. <div class="Discussion_UserSignature"> </div>
 
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mrmorris

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<font color="yellow">"I hate to see this thread die so soon. </font><br /><br />I'm not planning on letting it hit the trash bin yet. I'm just getting deeper into specifics -- trying to find out in more detail the masses and volumes of the various Gemini elements were, what modern equivalents would supplant them and how much would be saved in both areas. <br /><br />I have found two documents that go into significant detail the masses of various elements and systems. I just need to transfer all of this to an Excel spreadsheet -- fill in the specs for modern equivalents where I can find them. I've also made a quick scale diagram of the Gemini capsule using a CAD program, and played around with rearranging the various elements required for Gemini-X3. I still believe that capsule with the same exterior dimensions of the original Gemini can accomodate six people. <br /><br />It will definitely be a short-duration craft, using batteries instead of fuel cells, and having no onboard water supplies or waste disposal (somebody break out the 'Depends'). However -- the weight should actually be fairly close to that of the original Gemini... around 4000-4500 kg.
 
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mrmorris

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Woo Hoo. Bigelow finally released the rules to the Americas Space Prize. The Gemini-X3 on a FalconV (at least as envisioned) can easily handle the primary requirements. I don't know about turnaround times -- obviously no one can until the FalconV actually exists.<br /><br />The most important thing (to me at least) about the announcement today was the price he's willing to pay for flights to his station. Essentially he's set the contract value at $33.3 million per flight. With the FalconV projected to launch at ~$16 million, we're left with $17 million and change to cover costs of the Gemini-X3 per flight and allow for profit. With everything except the de-orbit SRBs getting re-used -- this would *seem* to be reasonable. Too many unknowns.<br />
 
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najab

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Yeah, that sounds reasonable - even if the America's Space Prize rules aren't.
 
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mrmorris

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<font color="yellow">"...even if the America's Space Prize rules aren't. "</font><br /><br />Yep. I've said before (although I don't think on this thread) -- the only way I see someone having any chance of taking this prize is through some variant of what's suggested here. Namely -- a firm building *just* a spacecraft and using someone else's booster. No way both the spacecraft and booster tech are going to be developed (from scratch) by the same company by 2010. It's <b>possible</b> that SpaceX could do both -- since they've already started on the V. However -- I think that's simply stretching their resources too thin.
 
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yree

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cool<br />The Little Hercules launchers<br />By Kevin ,J waldroup<br />Little Hercules Tourist<br />The Medium Lift Hercules, or Little Hercules is a solid rocket booster with a second stage hydrogen fueled J2 class rocket engine that can launch 40,000 pounds into low Earth orbit. It will able to launch the new NASA spaceship I call "Clementine".<br />The Little Hercules will launch government spacecraft and will also launch private based craft that will launch tourist into low Earth orbit. The spacecraft will be based on what was called back in the 70's Big Gemini. The big Gemini can launch 10 tourist instead of the Soyuz 3, or the Shenzhou which can carry 4 space tourist. The Big Gemini will use a paraglider that can be guided to an airport and landed on a runway.<br /><br />The Little Hercules will use Russian spacecraft like the Soyus and the Kliper while we wait for the Big Gemini to be built. It will probably take tourist to Bigelow’s inflatable space hotels, or the International Space Station, or an external tank built space hotel.<br /><br />Improved Little Hercules<br /><br />The class A or basic Little Hercules design have 2 stages. A solid Rocket Booster, that is fully reusable, the chemical 2nd stage is non-reusable. The basic package will be used to launch the Clementine into low Earth orbit. This basic design will also be used to launch tourist into orbit.<br /><br />The class B will add 4 strap on chemical rockets that are similar to the Long March rockets used by the Chinese. We will have to use a cleaner fuel because the United States is judged by a different standard, environmentally. With the 4 strap on boosters will be increased from 40,000 lbs to approximately 48,000 to 50,000 lbs. The class C is basically a Little Hercules with 2 solid rocket boosters attached. It will be able to lift approximately 60,000 lbs. Into low Earth orbit.<br />The improved Little Hercules used a 5 segment solid rocket booster with an improved chemical upper stage. This should incre
 
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odysseus145

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Has anybody seen the Vanguard team's entry for the xprize. I believe it was the only entry designed to be fully orbital. Does anybody think they have a chance at this new competion? <br /><br />Official Website <div class="Discussion_UserSignature"> </div>
 
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mrmorris

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<b>Focus</b> please. The thread is about Gemini and a modified version thereof. I'd really like to avoid tangents.
 
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