I lost my entire friggin' post again...
...fortunately this time, I had the foresight to copy and paste it into Wordpad before hitting "Submit"
Here's a basic rundown of Sprint versions throughout its history since STS-107, not counting if it tracked under anyone who might have followed it up. All sport being able to land on land and have a nose docking port. Aside from the first, all feature closing nose docking doors, hypergolic propulsion module with main power from descent module batteries, a flyable parasol and airbag cushioned landing. The most recent versions, "Sprint" without "Delta" feature big changes, I'll mention as I get there.
Soyuz-on-SeaLaunch: A brief feasibility study on launching Soyuz on Sea Launch, thus allowing it to reach any inclination from its site on the equator for rescue missions. Sea Launch has _lots_ of extra shitzpah, so the integration team would have a lot of mass to play with.
Delta Sprint/Fregat: This is the one I worked most on, trying to get a 5500kg spacecraft and Fregat on the Delta 7920. This failed utterly as it was too heavy.
Delta Sprint/Standard: This was launched directly off the Delta II, and is much smaller than the Fregat version (4950 vs. 5500kg, and 3.0m diameter vs. 3.5m), but still designed for three crew in a similar arrangement to the original.
Delta Sprint II: This was the forward look to planetary, i.e. Mars Direct, etc. with Delta IV as the chosen launch vehicle. This one came in 4 flavors:
Delta Sprint II 4l: Low energy orbit, four crew, 4m diameter, Delta IV-M, meant for Outbound crew transfer. (Outbound is a tether pathfinder station for Mars Direct tether mode, launched via Delta IV-H or Atlas 552.)
Delta Sprint II 4p: Low energy orbit ascent, high energy return. Modified from 4l with tougher thermal protection. Delta IV-M4.2
Delta Sprint II 6l: Low energy orbit, six crew, 4m diameter, Delta IV-M4.2 Longer than 4l and 4p, this one is designed for a bigger crew.
Delta Sprint II 6p: Low energy orbit ascent, high energy return. Six crew, launched on a Delta IV-M4.2, or potentially a Delta IV-M4.4 (not an official version.)
Sprint: This is the current model, most changed since discovering
www.dunnspace.com and "LEO On The Cheap." This version, utilizing the low cost 12000kg low energy capacity of the latest iteration of ISTS, my big pressure-fed three stage booster. It features the Delta Sprint II 4p descent module with a much larger service module. The Service Module Main Thrusters of previous Sprint's used nitrogren tetroxide/hydrazine, while the attitude thrusters used hydrazine monopropellant from a separate supply that could be linked to the main engine supply via a crossfeed valve. The current system uses four main thrusters (as opposed to two) and monopropellant hydrazine in several tanks (probably 4) to run both the main thrusters and attitude control. The propulsion system has grown similarly to Mars orbiters, with MGS utilizing bipropellant main engine with monopropellant secondary thrusters fed from the same hydrazine supply, while MRO uses six main thrusters in an all monopropellant system designed to be practically bulletproof (i.e. able to tolerate the failure of any thuster.) Sprint has also added a cylindrical solar array to wrap around the service module, thus providing the ability to stick around longer, and potential independence from station/mission power supplies upon which Sprint serves as return descent module or lifeboat.
Sprint II: The 5m diameter version of Sprint, mass about 13,500kg launched on a slightly bigger version of ISTS:
ISTS: International Space Transportation System. This project has gone through considerably more topsy-turviness than the Sprint Program.
Bluestar: An 8000kg satellite capacity Ashford-type reusable spaceplane (see
http://www.bristolspaceplanes.com for a summary on David Ashford's original concepts.) This turned out to be ludicrously optimistic of what is feasible in the modern aerospace environment (much like the Phase A/B Shuttle.)
Greystar: An even bigger and more ludicrously optimisitic 40,000kg capacity two stage Ashford-type spaceplane that barely works even in the fictional INSEA universe.
Cyanstar: An 8000kg satellite capacity partially reusable system using a two stage single use booster launched from a very large supersonic aircraft. Summarizing QuickReach II for CXV sounds similar: 5000kg...subsonic aircraft.
Greenstar: The 40000kg version of Cyanstar.
ISTS-M: The "big dumb booster" of the family. 1st stage intended as 5m diameter 500 tonne LOX/RP-1 building blocks with one, three, and five block versions. 1 block version studied so far can launch 12000 to 13500kg to LEO depending on the third stage. Five block version can probably launch about 55 tonnes, but I havn't crunched it yet. Five-block will probably airstart the core stage as well. This single block version, with the -M dropped, is what I refer to now when I say "ISTS". Estimated at a construction cost of $100/kg of dry hardware including acceptance testing and integration to the pad, it is intended to be constructed at a submarine yard and barged to the horizontal integration facility at the launch site, where it is assembled with upper stages and mated with the pre-encapsulated payload. Two days before launch, the vehicle, loaded with satellite hypergolics and all vehicle ordnance, is rolled out to the pad and erected for fuelling and launch the next day.
ISTS-M II: As above but with a piggyback parachute module added to the first stage building blocks. By enabling an angled nose-first splashdown in the ocean with the stucture reinforced by some 300psi of residual pressure, the first stage is recovered, towed back to the launch site where the 525psi hydroburst acceptance test is repeated after the stage is refurbished. In this manner, the first stage can be reused probably about 12 times. The core block of the 5 block version can't be recovered as it winds up going too fast to survive the thermal loading of the descent.
ISTS-M III 'TFS': With recovery proven by ISTS II, it becomes worthwhile to use turbopump engines in the first stage. The 350psi operating pressure of the stage becomes the head-suppression pressure for a 3000psi class first stage engine using staged combustion (such engines exist: RD-170, RD-180, RD-190, and SSME.) The high tank pressure eliminates the need for low pressure turbopumps like those of the SSME. The stage is stretched by the addition of length to the LOX tank barrel section, accomodating the new engine's higher mixture ratio. The second stage (still pressure-fed) is stretched in both fuel and oxidizer tanks, taking it out of balance for optimized payload/GLOW performance. This is done to slow the new pump-fed building block stages down so that they land in the same recovery zones as ISTS II, and also to prevent burnout accellerations from becoming intolerably high for payloads. The 5 block core will be a high expansion serial edition of the ISTS I version with fewer engines and will certainly airstart for ISTS III.
ISTS reserves the right to be "smart" in the third and fourth stages as up here, the aerospace-grade optimization (hydrogen fuel and isogrid waffles milled from fancy age-hardened aluminum-lithium billet) might still be worthwhile from a cost perspective...however that is not likely. The ISTS 4th stage, however, will probably wind up being a GN2 pressurized hypergolic like the Delta II second stage, or a vapor pressurized H2O2/C3H8 non-toxic hypergolic, in either case restartable, and fuelled in the horizontal integration facility. The 3 and 5 block versions might be large enough to warrant hydrogen fuelled, pump fed fourth stages for heavy high energy missions (twice the mass of Phobos and Cassini, possibly Mars Direct supply drops.)
ISTS Freezerburn: Enough ISTS I building blocks are stacked on a special pad (probably 12) to launch something really big, like Skylab, Apollo or Mars Direct (~120 tonnes LEO, 45 tonnes GTO equivalent.) The name comes from an INSEA concoction of about this time last year, which uses similar building block stages of 1000 tonnes each to launch 250 tonne space hotels.
ISTS dial-a-booster:
First digit: number of 1st stage blocks
Second digit: Type of first stage block (1, original single use pressure-fed, 2, reusable pressure-fed, 3 reusable tank fed.)
Third digit: Type of second stage (1, original pressure-fed short, 2, original pressure-fed long, 3, single engine version of 1st stage pressure-fed building block.)
Fourth digit: Type of third stage (haven't nailed down what the options should be yet, suggestions welcome. Currently have in mind a 4m and 5m version, single maneuver stages. The fairing integrates with the third stage.)
Fifth digit: Type of fourth stage (haven't nailed down options yet, except 0, no fourth stage; fourth stage needed only for high energy or multiple maneuver missions.)
ISTS guidance is in a toroidal module located at the top of the third stage with two interface rings, one above, and one below, either (but not both) of which can be made seperable. In this manner, the vehicle can be easily modified to include guidance with the fourth stage in a four-stage vehicle, while leaving it behind while the payload separates from a three stage vehicle. If the same module is used for 4m and 5m fourth stages, the 4m version will constrain the dimensions, leading to a rather interesting looking "puckered butt" for the 5m version. The engine nozzle would peek out the middle of the module.
I hope I've given you something to think about
