luke strawwalker
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Here's an interesting study from the early 90's, of a shuttle replacement design for a small lifting body crew transport using the Titan IV for a launch vehicle. It was called the "Personnel Launch System" (PLS). This basic concept is still around today, over 20 years later, having come back around in the "Orbital Space Plane" design of the early 2000's (just before the Columbia accident changed the space program markedly) which was designed to be launched on an EELV heavy variant (eliminating some of the nastier catastrophic launch vehicle failure modes of the Titan IV, which is all the designers had available to put it on back in 91 when this study was done). The idea is currently in vogue as the "Dreamchaser" vehicle, being designed by a commercial company to fly on the Atlas V rocket.
The study itself is almost 300 pages, but a good portion of that is also devoted to management issues and other such minutea that has little interest or bearing on spacemodeling. The vehicle itself has the outer mold line of the Soviet BOR-15 lifting body vehicle they experimented with in the early-mid 80's. It would have been interesting to see the alternative vehicle designs that were competing against it and weren't chosen. I bet there were some interesting concepts... Too bad that NASA chose to waste ANOTHER decade on SSTO concepts for things like the X-33/Venturestar program, etc. rather than simply going for a cheaper, more easily maintainable and quicker turnaround "airliner" type spaceplane (which is the ONLY way a reusable spaceplane makes economic sense), launched by a (preferably low cost) expendable booster... which interestingly enough was one of the early proposals for a preliminary shuttle design-- a 'cheap to build, fly, and maintain' orbiter lofted by a low cost design expendable booster rocket (see the recent NASA Study Summary I did on Tech Influences on Shuttle Design for more information). IF NASA had developed something like this, maybe partnering up with the Air Force to gain access to the Delta IV Heavy or Atlas V Heavy, (which was designed but never built) and had NASA paid for manrating their preferred version of the EELV heavy to lift this small spaceplane, we wouldn't be in the position we find ourselves in now... Shuttle could have been phased out in the mid-late 90's and replaced with this orbital spaceplane crew ferry vehicle and EELV's used to launch space station components for ISS.
This vehicle wasn't wedded to the Titan IV, either... it probably would have relied on Titan IV early on (unless it was phased in in the mid-late 90's, by which time the EELV's could have been ready for it, and had they been manrated from the get-go, it would have been much cheaper and more effective to do it in the original design phase). There is also obtuse mentions of the "ALS" launcher, which was a last-gasp attempt at a shuttle derived concept for an "HLV" (heavier payloads than shuttle, but not in the range of a "true" HLV like Ares V or SLS-- maybe 50 tons or so to LEO) which grew out of the "NLS" (National Launch System) studies that had been going on since shortly after the Challenger explosion... which designed a shuttle-derived launcher designed for payload launches or lofting a small top-mounted crew capsule or follow-on spaceplane to orbit using various proposed designs of rocket boosters based on existing shuttle elements-- SRB's, the 27.5 foot diameter ET turned into a core stage, SSME or STME (disposable shuttle engines, basically) engines, in various combinations from SRB augmented liquid boosters (not unlike SLS today) to innovative six SSME/STME engined 1.5 stage all-liquid boosters like a huge hydrogen powered modern version of the original Atlas, dropping a ring of 4 SSME's halfway through flight and continuing to orbit on a central pair of SSME's on the core... NLS started in earnest in the wake of Challenger when it was thought by some, early on, that shuttle might be retired due to the loss of the crew. NLS morphed into ALS when NASA was trying to get the Air Force interested in a joint replacement/shuttle augmenting HLV to operate beside or instead of the shuttle. After it became clear that the shuttle program would continue and return to flight, NLS morphed into ALS, the "Advanced Launch System" which was more tailored specifically to Air Force needs, and as such, competed against what would soon become the EELV's. The Air Force had their eye on eventually replacing the Titan IV, because its launch and operations costs were very expensive, on par with shuttle (which was a TERRIBLY expensive vehicle!) The Air Force had a definite bad taste in their mouth from their collaboration with NASA on the shuttle, and didn't look to want to repeat that mistake again, so ALS got essentially no traction in the DOD because of its close ties with the shuttle program, which was NASA's baby by this point since DOD had pretty much backed out of shuttle by this point and had thrown full efforts behind Titan IV. It was rather sad because some of the ALS designs were quite innovative and had they been developed, we again would be in a MUCH better position now at shuttle retirement than we presently are, because the ALS vehicles would have been ideal for modification into manned space launchers... (and essentially that's what SLS is... the old NLS parading in new clothing, trotted out once again after 25 years as "something new"). Had ALS/NLS been developed, we'd at least have a core vehicle ready to fly or modify to fly manned...
At any rate, the Air Force politely said "no" and brushed NASA off, ALS died quietly and within a couple years, the Air Force got their Titan IV replacements into development, the Atlas V and Delta IV common core EELV's, ditching the expensive SRM's altogether, leaving NASA the only one flying the big segmented solids anymore (though of a different design, which is part of the reason they were so expensive for both the Air Force and NASA in the first place). The rest is history...
SO, here's the report... "Dreamchaser" and "OSP" ala 1991... Enjoy!
OL JR
View attachment NASA Study Summary- Personnel Launch System Final Report.txt
The study itself is almost 300 pages, but a good portion of that is also devoted to management issues and other such minutea that has little interest or bearing on spacemodeling. The vehicle itself has the outer mold line of the Soviet BOR-15 lifting body vehicle they experimented with in the early-mid 80's. It would have been interesting to see the alternative vehicle designs that were competing against it and weren't chosen. I bet there were some interesting concepts... Too bad that NASA chose to waste ANOTHER decade on SSTO concepts for things like the X-33/Venturestar program, etc. rather than simply going for a cheaper, more easily maintainable and quicker turnaround "airliner" type spaceplane (which is the ONLY way a reusable spaceplane makes economic sense), launched by a (preferably low cost) expendable booster... which interestingly enough was one of the early proposals for a preliminary shuttle design-- a 'cheap to build, fly, and maintain' orbiter lofted by a low cost design expendable booster rocket (see the recent NASA Study Summary I did on Tech Influences on Shuttle Design for more information). IF NASA had developed something like this, maybe partnering up with the Air Force to gain access to the Delta IV Heavy or Atlas V Heavy, (which was designed but never built) and had NASA paid for manrating their preferred version of the EELV heavy to lift this small spaceplane, we wouldn't be in the position we find ourselves in now... Shuttle could have been phased out in the mid-late 90's and replaced with this orbital spaceplane crew ferry vehicle and EELV's used to launch space station components for ISS.
This vehicle wasn't wedded to the Titan IV, either... it probably would have relied on Titan IV early on (unless it was phased in in the mid-late 90's, by which time the EELV's could have been ready for it, and had they been manrated from the get-go, it would have been much cheaper and more effective to do it in the original design phase). There is also obtuse mentions of the "ALS" launcher, which was a last-gasp attempt at a shuttle derived concept for an "HLV" (heavier payloads than shuttle, but not in the range of a "true" HLV like Ares V or SLS-- maybe 50 tons or so to LEO) which grew out of the "NLS" (National Launch System) studies that had been going on since shortly after the Challenger explosion... which designed a shuttle-derived launcher designed for payload launches or lofting a small top-mounted crew capsule or follow-on spaceplane to orbit using various proposed designs of rocket boosters based on existing shuttle elements-- SRB's, the 27.5 foot diameter ET turned into a core stage, SSME or STME (disposable shuttle engines, basically) engines, in various combinations from SRB augmented liquid boosters (not unlike SLS today) to innovative six SSME/STME engined 1.5 stage all-liquid boosters like a huge hydrogen powered modern version of the original Atlas, dropping a ring of 4 SSME's halfway through flight and continuing to orbit on a central pair of SSME's on the core... NLS started in earnest in the wake of Challenger when it was thought by some, early on, that shuttle might be retired due to the loss of the crew. NLS morphed into ALS when NASA was trying to get the Air Force interested in a joint replacement/shuttle augmenting HLV to operate beside or instead of the shuttle. After it became clear that the shuttle program would continue and return to flight, NLS morphed into ALS, the "Advanced Launch System" which was more tailored specifically to Air Force needs, and as such, competed against what would soon become the EELV's. The Air Force had their eye on eventually replacing the Titan IV, because its launch and operations costs were very expensive, on par with shuttle (which was a TERRIBLY expensive vehicle!) The Air Force had a definite bad taste in their mouth from their collaboration with NASA on the shuttle, and didn't look to want to repeat that mistake again, so ALS got essentially no traction in the DOD because of its close ties with the shuttle program, which was NASA's baby by this point since DOD had pretty much backed out of shuttle by this point and had thrown full efforts behind Titan IV. It was rather sad because some of the ALS designs were quite innovative and had they been developed, we again would be in a MUCH better position now at shuttle retirement than we presently are, because the ALS vehicles would have been ideal for modification into manned space launchers... (and essentially that's what SLS is... the old NLS parading in new clothing, trotted out once again after 25 years as "something new"). Had ALS/NLS been developed, we'd at least have a core vehicle ready to fly or modify to fly manned...
At any rate, the Air Force politely said "no" and brushed NASA off, ALS died quietly and within a couple years, the Air Force got their Titan IV replacements into development, the Atlas V and Delta IV common core EELV's, ditching the expensive SRM's altogether, leaving NASA the only one flying the big segmented solids anymore (though of a different design, which is part of the reason they were so expensive for both the Air Force and NASA in the first place). The rest is history...
SO, here's the report... "Dreamchaser" and "OSP" ala 1991... Enjoy!
OL JR
View attachment NASA Study Summary- Personnel Launch System Final Report.txt