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A solution for all Ares-I problems: the J-2Y engine
Over a year ago in my 5-segments SRB article I've expressed several doubts about the 5-segments SRB real power, safety and costs, then, a few months ago, many (never refuted) rumors seemed confirm there are problems due to an "underpowered" Ares-I and/or an "overweighted" Orion.
Before the Ares-I contracts assignation, that problems would be solved in two ways: developing a more powerful Ares-I (as suggested in many articles here) and/or cut the Orion's mass, as suggested (also) in this article and in two other articles about a lighter Orion and an underside-LAS.
But, in a few weeks (between june and august) NASA has put a TOMBSTONE on all alternative ESAS rockets (as explained in this ghostNASA article) then, now all problems to match the Ares-I power with the Orion weight can/must be solved (only) cutting the Orion's mass.
That's what I've thought just a week ago, however, all problems are made to be solved, so, thinking again about the Ares-I/Orion problems, I've found a "third way" to solve it, WITHOUT CHANGE THEIR MAIN DESIGN SPECS.
Since great part of the lower-than-necessary Ares-I power seems due to the 2nd stage J-2X engine, the (SMART) solution I suggest is to develop a "super J-2X" (that I've called "J-2Y") with the SAME (J-2 derived) design but a +20% RESIZED DIMENSION to have 352,800 lbs. of thrust vs. the (too low) J-2X 294,000 lbs. thrust (of course, this is just an example, since the J-2X can be resized more or less than suggested here, following the Ares-I needs) also, this "resized" engine, could be very very useful to develop a close-to-specs AresV that (as new "rumors" say) seems have less power than necessary (in its current design) allowing to carry to LEO a payload 13 mT lower than planned.
You know that the early ESAS plan's Ares-I was designed around a standard 4-segments SRB (that I still consider the BEST choice vs. the 5-segments version!) for the first stage and an "air-started" version of the SSME for the second stage, both changed last year to the current 5-segments SRB first stage and the J-2X as second stage engine, since the production of the SSME will end after the Shuttles retirement and (seems) also due to "problems" to modify the SSME to be "air-started".
The SSME is heavy (about 3.2 MT) and expensive ($60M each) engine, but it is READY AVAILABLE now (while the J-2X will need 6+ years to fly) man-rated and with a 350+ times successful launch rate, also, the SSME has a powerful 408,568 lbf sea level thrust and a 512,114 lbf vacuum thrust.
The J-2X (derived from the 80+ times successful SaturnV J-2) has the advantages of a lower (2.4 mT) mass, a lower ($12M each) expected cost, a simpler design (with less parts) and the air/vacuum-start 4+ times restart capabilities built in from scratch, but the J-2X needs 6+ years to fly with an R&D price of over $1.2 billion that boosts the costs of each J-2X used in the next 20 years (including the shared R&D costs) to over $60M ...the same price of an SSME...
However, the 6+ years to have a J-2X ready to fly give the advantage that, since its design is now in the early stages (maybe, its just a CAD-software file...) the dimensions and thrust specs of the J-2X could be CHANGED now just using the "resize all" command of the CAD software... :) ...so, the bigger, better and +20% powerful "J-2Y" could be designed quickly and without need any additional funds!!!
I do believe that the J-2X design CAN be (quickly) changed NOW (to develop the more powerful J-2Y) since the engine is in the early stages, but, if that change will be impossible or, simply, they don't want to do it, there is a second (fast, easy and cheap) option to increase the 2nd stage thrust and allow the Ares-I power to match the Orion's weight: add two+ (smaller) RL10B-2 engines to the main J-2X.
Two RL10B-2 (that's the DeltaIV second stage engine and four of them will be the LSAM descent-stage engines) may increase the Ares-I 2nd stage total thrust to 344,400 lbs. (294,000 + 24,750 + 24,750 lbf) or (about) 17% more than a J-2X.
Then, thanks to these new and brilliant ideas.. :) ..the NASA engineers will have (at least) SEVEN different choices to design a BETTER Ares-I able to match (and launch!) the Orion:
a) develop the powerful "J-2Y" for the second stage with the 5-segments SRB as first stage,
b) add two+ RL10B-2 to the standard J-2X 2nd stage engine with the 5-segments SRB as first stage,
c) develop a (much more powerful) SSME-class "J-2Y" to be used with a standard (ready available, man-rated, reliable and cheap) 4-segments SRB as first stage,
d) add four RL10B-2 to the standard J-2X second stage engine with the standard 4-segments SRB as first stage,
e) resize the Orion (and its SM/LAS) from a 5 m. (never used) "six seats" to a (more rational) 4.5 m. "four seats" model (since ALL orbital and moon missions will have only THREE or FOUR astronauts aboard!) to be launched with a 4-segments-SRB/J-2X Ares-I,
g) use five+ SSME-class "J-2Y" to build an upgraded and MAN-RATED AresV able to carry the full moon mission's hardware with a single (SaturnV-style) launch.
I still think that, use the (ready available, man-rated, reliable and cheap) 4-segments SRB in ALL rockets (one for the Ares-I and three for the Ares-V) ALWAYS is the BEST CHOICE, while, the (early...) $1.8 billion that NASA has already promised to ATK (to develop the 5-segments SRB and build five test-units of the new booster) could be "converted" to buy 40 standard (expendable) SRBs.
September 6 - 2007
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Copyright © 2007 Gaetano Marano - All rights reserved - base images used for the drawings are © NASA and Boeing