Solids really are rough rides. Hybrids don't seem much better (SS1 had both rough and smooth rides, so there's something designers don't understand, yet) but at least they can be throttled.
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The Indian GSLV comes to mind, and I’m sure there’s others.<br /><br />My concern with the SRB as a manned LV is that it would mean a redesign of the rockets body. It was designed to be strapped to the side of the shuttle not fly with the weight mounted directly above it. The hard points have to be changed. The stresses all need to be recalculated and the body modified. It will need a more robust guidance and control system since I assume that the shuttle main engines do that work now. Basically it’s a whole new rocket just with the same solid fuel. It will need to be extensively tested before putting manned mission can use it. Even the fuel will have to be redesigned to fire at less thrust for longer. <br />The EELVs are pretty much ready to go in the state that they are in.
I think since the SRBs are bolted to the ET, which is then bolted to the Shuttle, probably dampens some of the vibrations caused by the burn. So much thrust! Watch the SRBs accelerate at the end of a Challenger video...they were really moving before the Range Officer destroyed them. <div class="Discussion_UserSignature"> </div>
Will this new Atlas be manufactured in Colorado or Huntsville? I thought that they were phasing out the Atlas program and going with straight Delta from now on *is so confused* ... or at least just sticking with one and manufacturing it at the Boeing plant. But I can't imagine they'd get rid of Delta, as it's one of the best boosters and is completely American as opposed to Atlas which has Russian engines -- and you know how the government gets 
Saturn V class...<br /><br />http://www.astronautix.com/lvs/atlhase3.htm<br /><br />Atlas family and development...<br /><br />http://www.astronautix.com/lvfam/atlas.htm<br /><br />My favorite growth version of Atlas V...<br /><br />http://www.astronautix.com/lvs/atlhase2.htm<br /><br />"Orbital launch vehicle. Family: Atlas. Country: USA. Status: Design.<br /><br /> Proposed growth variant of the heavy-lift version of the Atlas V launch vehicle with three parallel 5-m-diameter wide-body Common Core Boosters (CCB), each with 1 or 2 RD-180 engines; a 5-m-diameter new Lox/LH2 stage with 2 or 4 engines with a total thrust of 180,000 kgf; and a 5 m diameter payload fairing.<br /><br />Manufacturer: Convair. Payload: 29,000 kg. to a: earth escape trajectory. Liftoff Thrust: 2,340,000 kgf. Total Mass: 1,800,000 kg. Core Diameter: 5.00 m. Total Length: 63.00 m. Span: 15.00 m. "
"I thought that they were phasing out the Atlas program and going with straight Delta from now on"<br /><br />No. Both the Delta IV and Atlas V will continue.<br /><br />http://www.globalsecurity.org/space/systems/eelv.htm<br /><br />"On 04 March 2005 the Air Force announced plans to allow Boeing to bid on new rocket contracts after a two-year suspension. Boeing was disciplined after the Air Force discovered the company stole documents from competitor Lockheed Martin. The Air Force wants more companies to compete for upcoming contracts and said Boeing has improved its practice of ethics since the incident.<br /><br />On 07 April 2005 it was announced that the Air Force will evenly split 24 satellite launch contracts between Lockheed Martin and Boeing under Buy Three. The government opted to split the launches, which may be worth $100 million each, to keep both companies healthy: It wants to make sure one company is always available to launch satellites.<br /><br />Buy 3 probably won't be awarded until 2006, which would probably mean they wouldn't start launching till '08. There will be a significant number of launches acquired. It will probably be for a two or three-year period." <br /> <br /><br /><br /><br />
<font color="yellow">It will need a more robust guidance and control system since I assume that the shuttle main engines do that work now. </font><br /><br />I'm not saying you are wrong, just wondering how that can be. The SRB nozzles have gimbaling capability of 8 degrees while the SSMEs go 10.5. With their enormous thrust the lateral vector is 459271 pounds for one SRB while all three SSMEs with their larger range of motion can only muster 202014. <br /><br />I guess one way to have the orbiter do the steering would be just to not use the solids to do it, but I think they could overwhelm the steering capacity of the orbiter. <div class="Discussion_UserSignature"> </div>
"If NASA needs a booster in the 100 MT class, then Shuttle-derived is probably the way to go. But if the architecture only calls for, say, 60 MT, then the story may be different. "<br /><br />Northrop Grumman argues that a 55t HLV is all that is needed and more cost effective than anything heavier.<br /><br />"CE&R Initial Concept Overview<br /><br /> 13 September 2004 <br />CE&R Intial Forum <br />Washington, D.C."<br /><br /> On page 6 of the report they say "Early trades show affordability of intermediate launchers", "130t launcher unaffordable in early development, no cost benefit over 55t class", "reliance on existing LVs unaffordabe post-2016 due to launch rates", and "55t class cheaper than reliance on current vehicles."<br /><br />Page 6 has a graph of estimated costs over time using three different options, one line using 30t launcher, one line using a 55t launcher and a third line using a 130t launcher.<br /><br />The costs for the 55t launcher are barely higher than the 30t launcher, until 2016 when the costs for the 30t launcher zoom much higher. The 130t launcher cost zooms much higher than the other launchers by 2008, the gap peaking by 2013, and finally reaches parity with the 55t launcher in 2015 after which the 130t launcher has only a slight cost advantage.
><i>The grain does not have to be changed if the upperstage and the payload weigh about 400,000 pounds. </i><p>You know, every time you write that I think - "That's got to be a misprint 200 tons?!" - then I realise that the SRB does have an ignition thrust of a measly little 3 1/3 million pounds. <img src="/images/icons/smile.gif" /></p>
Utilizing SRB thrust vector control during their burn time saves hydrazine for the shuttle APU system, which is also used during re-entry. The little 70,000 rpm turbine in the APU can develop 100+ horsepower if needed, but just like everything else in the world, running at higher load depletes fuel faster.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
><i>Northrop Grumman argues that a 55t HLV is all that is needed and more cost effective than anything heavier.</i><p>This is a false dicotomy, since it assumes that <b>only</b> a 55t or 100t launcher is available. It is much more likely that both will be in existance and that either can be used as appropriate.</p>
<font color="yellow">It is much more likely that both will be in existance and that either can be used as appropriate. </font><br /><br />Really? I thought this whole debate was about which heavy lift vehicle design (i.e. beyond the current heavy EELVs) was going to be selected. Do you think that NASA will opt for both a Shuttle-derived and an enlarged EELV-derived system? Personally, I think that would be great, since I like both systems.
><i>Do you think that NASA will opt for both a Shuttle-derived and an enlarged EELV-derived system?</i><p>No, I don't see NASA funding both. But the EELV heavies (heavy singular?) are already up to ~30 tons, the changes required to get them up to nearly 50 ton lift capacity aren't beyond what Boeing/Lockmart might do on their own if they see a demand (think Space Solar Power and/or space hotels) or what DoD might fund if BMD goes ahead. It would take hundreds of millions (rather than billions) to uprate Delta to lift 45 tons.</p>
The science of rocketry died along with Werner Von Braun. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
The Russians have built many wonderful rocket engines since then.<br /><br />Perhaps you mean more globally, as in a vision for space exploration?<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything." Admiral Jackie Fisher</p> </div>
perhaps I mean that the Atlas is a 50 year old ICBM <br /><br />but maybe we are indeed approaching the limits of chemical rockets and all we can muster are minor improvements to existing designs. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
<br /><br />but maybe we are indeed approaching the limits of chemical rockets and all we can muster are minor improvements to existing designs. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>In terms of combustion processes/fuels, we have been at a stagnation point for some years. There are improvements that can be made in ISP, but they generally involve adding nasty stuff like Flourine which add significant danger to the process. <br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything." Admiral Jackie Fisher</p> </div>
I wonder if production and operating costs are at a similar minimum or if they can still be dramatically brought down... (perhaps without a very high flight rate which of course would bring down costs but is unrealistic in the near term)
I'm wondering how hard it would be to change an Atlas from an RD-180 over to a RD-170 or 173...which serve as the parent of the 180. Both those engines are slightly higher thurst than an F-1.
<font color="yellow">"...wonder if production and operating costs are at a similar minimum..."</font><br /><br />Elon doesn't think so. Without increasing ISP, there are several ways I can see to reduce cost/pound to orbit for a given rocket.<br /><br />Reduce booster mass.<br />- More use of composites & lightweight alloys in booster main structure & tanks.<br />- Use of newer/smaller/less power hungry electronics (besides the direct mass reduction -- there's secondary reductions in wiring, batteries, and packaging/support related to the electronics)<br />- Advances in rocket engines -- reduced components -- better alloys, etc.<br /><br />Reduce costs related to launch:<br />- Lower range fees (e.g. SeaLaunch)<br />- Lower insurance rates (heckifIknow how)<br />- Reduced launch team requirements (e.g. more automation, health-monitoring sensors & remote telemetry ala Spacex)<br />- Reduced timeframe between booster arrival at range and launch.<br /><br />Reduce costs related to production:<br />- Higher launch rates<br />- More automation in factory -- lower manpower requirements.<br />- Modular systems & common parts between booster classes.<br />- Shorter lead times on booster orders (i.e. move closer to 'just-in-time' inventory)<br /><br />... I'm sure that I'm missing some goodies.<br /><br />SpaceX is pursuing most of these cost reductions. I don't know enough about the EELV production/operations to state definitively whether they are pursuing many of these. From what I have *heard*, they are pursuing only a small fraction of this list.
what happened to the linear aerospike concept? has it become a no no because of the problems with the X33? which I understand were not engine related, but pertained to the fuel tank <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
Something that I have wondered about is the cost of fuel especially liquid hydrogen compared to kerosene. Once you start having a lot of launches and the cost of hardware drops at what point does this become significant?<br /><br />I remember that liquid nitrogen was about the cost of beer and liquid helium was about the cost of spirits but I'm not sure about the costs of liquid hydrogen and kerosene.<br /><br />Note I'm assuming liquid oxygen is unsurpassable as an oxidiser on both cost and effectiveness.<br />
<font color="yellow">"Something that I have wondered about is the cost of fuel"</font><br /><br />I listened to Elon's interview on The Space Show last week. He was asked about the cost of fuel and he laughed it off. Said it was about $30K. He referred to it as 'an accounting error'.
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