<p>Link.....</p><p>Draft RFP (PDF)....</p><p><font size="2"><font face="Arial"><strong>PRESS RELEASE</strong></font></font></p><p><font size="2"><font face="Arial"><strong>Date Released:</strong> Tuesday, November 25, 2008<br />Source: </font></font><font face="Arial" size="2">NASA Exploration Systems Mission Directorate</font></p><p align="left"><font face="geneva,arial,verdana" size="-1">WASHINGTON -- NASA has released a draft request for proposals, or RFP, regarding Phase I of its Ares V launch vehicle. The rocket will perform heavy lift and cargo functions as part of the next generation of spacecraft that will return humans to the moon. Phase I will define operational concepts, develop requirements, and refine design concepts for the Ares V. </font></p><p align="left"><font face="geneva,arial,verdana" size="-1">This document is a draft of the final version of the RFP for Phase I, expected in January 2009. By responding to this draft RFP, potential offerors can provide input on the requirements, small business goals and contract structure. The industry input received will be combined with NASA's expertise for potential inclusion in the final version of the RFP for Phase I, which will ask for bids on five Ares V work packages. </font></p><p align="left"><font face="geneva,arial,verdana" size="-1">A pre-solicitation conference is scheduled for Dec. 3, 2008, at NASA's Marshall Space Flight Center in Huntsville, Ala. The conference is designed for information sharing about the Ares V Phase I for potential offerors. </font></p><p align="left"><font face="geneva,arial,verdana" size="-1">For a copy of the draft RFP for Phase I, designated NNM09274026R, and more information about the conference, visit: </font></p><p align="left"><font face="geneva,arial,verdana" size="-1">http://prod.nais.nasa.gov/cgi-bin/eps/sol.cgi?acqid=131145#Draft%20Document </font></p> <div class="Discussion_UserSignature"> </div>
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Ares V thought experiment
The Ares V sure has evolved :lol: since the first ESAS report. From 5 x SSME core engines to 6 X RS68, from an 8.4m diameter core stage to 10m diameter, from 5-segment SRB to '5.5'-segment. Yet supposedly the performance of the Ares V is never quite good enough despite it's continued growth. One thing is clear, despite the original claims that Ares V would be a cost-saving derivation of Space Shuttle hardware, the reality is Ares V is a clean sheet design.
So in the spirit of improving the Ares V design as a clean sheet enterprise, I think it would be interesting to look at some of the basic assumptions of the Ares V. What changes could be made to improve the current design of the Ares V? What if instead of the pattern Ares V has followed so far of ever greater 1st stage and SRB growth, we grew the other stages instead?
In short, I propose a 10m diameter core 1st stage with 5 x RS-68a engines, only 4-segment SRB, a 10m diameter 2nd stage with 2 to 4 J-2S engines, and a greatly enlarged 'drop stage' for the Altair lander with 2 to 4 RL-10b. (The increased similarity with the Saturn V configuration is notable
) I'll try to explain my reasoning in what follows.
Despite roughly similar dimensions, the Ares V was always supposed to land much more cargo on the moon than the old Saturn V could. But that is mostly a function of the use of high-performance LH2/LOX on the Altair lander descent stage compared to the Apollo use of lower performance hypergolics.
In fact increasing the performance of the 'top end' of a launch vehicle is an easier way to increase payload than enlarging overall size. That's why the Saturn V had such a greater payload than the Soviet N-1 despite the N-1's greater power. The Saturn V used LH2/LOX propellant on it's 2nd and 3rd stages, whereas all four of the N-1 stages used Kerosene/LOX.
One proposal to increase Ares V performance was to add a third stage, but this was dropped for various reasons including a maximum height restriction to fit the VAB. But if you consider the Altair descent stage as a third stage interesting possibilities open up. Which I why I think it's important to consider the Altair as an integral part when considering design changes to the Ares V. Instead of just 2 LH2/LOX stages (plus 2 SRB), when you include the Altair the Ares V really has 3 LH2/LOX stages. I think resizing and repurposing all three of these liquid-propellant stages of the Ares V could improve the payload of the overall system.
Another odd aspect of the current Ares V design is the thermal management of the EDS and the Altair descent stage. The partially empty EDS must loiter in LEO for days while waiting to rendezvous with the Orion spacecraft. Meanwhile the EDS is baking in the sun and boiling off some precious propellent. But the Altair is even worse. The current configuration shows a maze of multiple small tanks which bake and boil for days longer than the EDS. :shock:
Adding the TLI burn to the job of the Altair descent stage as I propose would greatly increase it's size, but it would still be much smaller than the current EDS of the Ares V. That would enable reduced engine mass, reduced sun exposure, reduce mass needed for insulation, and therefore reduce deadweight for the TLI.
Off course such a larger descent stage requires it function as a 'drop stage' (better known as a crasher stage) for the job of lunar landing, but that's a feature not a bug. The design size of the current descent stage is already problematic for lunar landing and surface ops. Plus a simply shaped 'drop stage' would prevent propellant boil off much better than the forest of tanks in the current design of the descent stage.
The Ares V sure has evolved :lol: since the first ESAS report. From 5 x SSME core engines to 6 X RS68, from an 8.4m diameter core stage to 10m diameter, from 5-segment SRB to '5.5'-segment. Yet supposedly the performance of the Ares V is never quite good enough despite it's continued growth. One thing is clear, despite the original claims that Ares V would be a cost-saving derivation of Space Shuttle hardware, the reality is Ares V is a clean sheet design.
So in the spirit of improving the Ares V design as a clean sheet enterprise, I think it would be interesting to look at some of the basic assumptions of the Ares V. What changes could be made to improve the current design of the Ares V? What if instead of the pattern Ares V has followed so far of ever greater 1st stage and SRB growth, we grew the other stages instead?
In short, I propose a 10m diameter core 1st stage with 5 x RS-68a engines, only 4-segment SRB, a 10m diameter 2nd stage with 2 to 4 J-2S engines, and a greatly enlarged 'drop stage' for the Altair lander with 2 to 4 RL-10b. (The increased similarity with the Saturn V configuration is notable
) I'll try to explain my reasoning in what follows. Despite roughly similar dimensions, the Ares V was always supposed to land much more cargo on the moon than the old Saturn V could. But that is mostly a function of the use of high-performance LH2/LOX on the Altair lander descent stage compared to the Apollo use of lower performance hypergolics.
In fact increasing the performance of the 'top end' of a launch vehicle is an easier way to increase payload than enlarging overall size. That's why the Saturn V had such a greater payload than the Soviet N-1 despite the N-1's greater power. The Saturn V used LH2/LOX propellant on it's 2nd and 3rd stages, whereas all four of the N-1 stages used Kerosene/LOX.
One proposal to increase Ares V performance was to add a third stage, but this was dropped for various reasons including a maximum height restriction to fit the VAB. But if you consider the Altair descent stage as a third stage interesting possibilities open up. Which I why I think it's important to consider the Altair as an integral part when considering design changes to the Ares V. Instead of just 2 LH2/LOX stages (plus 2 SRB), when you include the Altair the Ares V really has 3 LH2/LOX stages. I think resizing and repurposing all three of these liquid-propellant stages of the Ares V could improve the payload of the overall system.
Another odd aspect of the current Ares V design is the thermal management of the EDS and the Altair descent stage. The partially empty EDS must loiter in LEO for days while waiting to rendezvous with the Orion spacecraft. Meanwhile the EDS is baking in the sun and boiling off some precious propellent. But the Altair is even worse. The current configuration shows a maze of multiple small tanks which bake and boil for days longer than the EDS. :shock:
Adding the TLI burn to the job of the Altair descent stage as I propose would greatly increase it's size, but it would still be much smaller than the current EDS of the Ares V. That would enable reduced engine mass, reduced sun exposure, reduce mass needed for insulation, and therefore reduce deadweight for the TLI.
Off course such a larger descent stage requires it function as a 'drop stage' (better known as a crasher stage) for the job of lunar landing, but that's a feature not a bug. The design size of the current descent stage is already problematic for lunar landing and surface ops. Plus a simply shaped 'drop stage' would prevent propellant boil off much better than the forest of tanks in the current design of the descent stage.
Probably not worth updating until the administrations review of the program is finished, and hearings haven't even started yet. Hell...they just got around to appointing a new NASA administrator & his assistant last week.
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