Oh boy, been there, done that: http://forum.nasaspaceflight.com/index.php?topic=3307I think the end result was that you could, but you'd probably simultaneously shrink the upper stage to better balance the dV...Simon
Quoteedkyle99 - 18/7/2006 4:58 PMOne alternative ESAS option, for example, called for the development of only one, "mid-size" launch vehicle (90-100 tonnes to LEO). The study found that a lunar mission performed with two such launchers would cost less than the current "1.5 Launch" mission. - Ed KyleThat option has me curious.Pure hypothetical: Two 4-seg SRB's plus three 500,000lb thrust engines (Shuttle) today is enough to launch 116mT to ISS.Replace the three SSME's with two RS-68's and you'd get very similar performance, but you can do so in a simpler in-line arrangement, and spend less cash.The Payload would require an OMS system to performa the final circularisation burn, but the ol' space tug idea would seem to suit that role nicely. The two Shuttle's OMS Pods mass a total of about 20mT, including the integral RCS systems, so my guess would be you could launch 100mT of useful payload on each flight.NASA wouldn't need to pay for 5-segs (yet, although they'd be nice as an upgrade later), wouldn't need to plan extensive changes to the MLP's or Pad Structures and could retain much of the current infrastructure for both SRB's and ET processing.Depending on it's expected LOC figures, it might be a realistic, less costly and quicker system to get operational.Ross.
edkyle99 - 18/7/2006 4:58 PMOne alternative ESAS option, for example, called for the development of only one, "mid-size" launch vehicle (90-100 tonnes to LEO). The study found that a lunar mission performed with two such launchers would cost less than the current "1.5 Launch" mission. - Ed Kyle
But that's why I started the thread oh so long ago; if you use the current upper stage, you don't energetically need a full three cores. Rather, to match the dV and thrust of the RSRM-V, you can take a Delta IV core, stretch the tanks a few meters and add an extra engine. It's essentially a new vehicle, but no more delta than RSRM vs RSRM-V...Simon
Quote from: simonbp on 07/22/2008 06:00 pmBut that's why I started the thread oh so long ago; if you use the current upper stage, you don't energetically need a full three cores. Rather, to match the dV and thrust of the RSRM-V, you can take a Delta IV core, stretch the tanks a few meters and add an extra engine. It's essentially a new vehicle, but no more delta than RSRM vs RSRM-V...Simon A Delta IV CBC-based first stage would have to be stretched nearly 30%, or by about 10 meters, to carry enough propellant for this job, as near as I can tell. When JAXA was confronted with this problem (H-IIA to H-IIB), it decided to go with a fatter tank. - Ed Kyle
It might look something like this. - Ed Kyle
The Ares 1B idea is so sensible it almost hurts... A bit like Atlas V Phase 2, only with all-American engines. It could even be a way for NASA to save face if (when?) Ares 1 T.O. and payload issues become insurmountable: By using "off-the-shelf" engines and tooling, but keeping the original Ares 1 J-2X powered upper stage to avoid scrapping all the Stage and J-2X contracts, work done and money spent.
Does anyone here know if the solid rockets used for ICBM's are segmented? I ask because they are, as far as i know, extremely reliable LV's.)
IIRC, the upper stage currently provides something like 80% of the delta V; if you reduce that to closer to 60%, the GLOW should go down. Indeed, you might be able to get the upper stage light enough to not need that that second J-2X. Presumably this could be done by shortening the stage by taking out the cylindrical part of the LOX tank and scaling the LH2 tank accordingly...The "Ares IB" name is good; it has good connotations both historically and in relation to being a "better Ares I"...Simon
Now I'm wondering what a 2xRS68 first stage would be able to do with an even smaller upper stage optimized for EELV-type GTO/GEO missions. - Ed Kyle
How about if we take that Ares 1B, add two RSRMs and forget the upper stage? That way the solids and two RS-68s can be ground lit and... Oh. Wait a minute. That's...