Re: NASA's grand plan to revive human exploration...

[aftercolumbia]

> Senior Space Writer<br /> /> SPACE.com<br /> /> Wed Oct 5, 1:00 PM ET<br />...<br /> /> For the most part, editorial pundits have not been easy on NASA's<br /> /> newly announced strategy.<br /><br />I can see why later on in this post. A lot of "editorial pundits" are ex-NASA, ex-prime or nuts like me who crunch numbers just for the heck of it...and know NASA technoganda when it is this obvious.<br /><br />I'm posting this in the technology forum because most of what I have to say is technological discussion.<br /><br /> /> Putting those barbs aside, the NASA vision as unveiled last month by<br /> /> NASA chief, Michael Griffin, is starting to undergo <br /> /> technical critique.<br /><br /> /> "I think Griffin's team has come up with a truly workable solution<br /> /> that really does make sense," said Jerry Grey, Director, Science and<br /> /> Technology Policy for the American Institute of Aeronautics and<br /> /> Astronautics (AIAA). Grey is also Visiting Professor of Aerospace<br /> /> Engineering at Princeton University.<br /><br />I've seen some rather impressive stuff come out of AIAA (including a paper on the Microcosm MCD launch vehicle series.) Given these credentials, some of the stuff to follow in this article is rather surprising.<br /><br /> /> "Certainly there will be technical issues," Grey told SPACE.com, "but<br /> /> in view of the current concerns over shuttle and station, the ever-<br /> /> present budget constraints, the political issues, and the lofty long-<br /> /> term goals -- which are indeed the right ones -- it would be hard to<br /> /> find a better approach."<br /><br />As it concerns the overall mission architecture, I tend to agree with his assessment of the VSE (Vision for Space Exploration)...however...The technological choices are very expensive, and not very robust. An SSME takes almost 2 years and $20 million dollars to make...it has 5 turbopumps in a device, when stripped to its essential minimums, requires none...it has over a

 

[drwayne]

This topic area is more of a general technology area.<br /><br />More of the folks who would be interested in this (and related material) frequent the missions and launches section.<br /><br />Welcome to the forum by the way. We have a number of propulsion people here, I am a plumie myself. <img src="/images/icons/smile.gif" /><br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[drwayne]

I moved this thread from technology<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[frodo1008]

If this is supposed to be a technical thread, the perhaps somebody needs to go back to school. Just one example:<br /><br /><font color="yellow">” ...it has 5 turbopumps in a device, when stripped to its essential minimums, requires none...it has over a hundred thousand shaft horsepower when the final goal is thrust, rather than horsepower. The mission launch vehicle uses at least six, the CLV, one...all of which are thrown into the sea after a few minutes!”</font><br /><br />As shuttle-guy also pointed out there are four, not five turbopumps in a single SSME. Just for general information they are: the low pressure oxidizer (liquid oxygen) pump, the low pressure fuel (liquid hydrogen) pump. The high pressure oxidizer pump, and the high pressure fuel pump. There are no other pumps.<br /><br />Now the statement about the engine requiring no turbopumps is so totally incorrect as to be almost humorous! The only way that you could get the kind of flow of propellants through the engine and burning them out the nozzle would be to pressurize the fuel and oxidizer tank to thousands of pounds per square inch! The exit pressure of the high pressure turbopumps is something on the order of 9,000 lbs per square inch! How thick do you think the walls of the propellant tanks would have to be to get this kind of pressure? Such tanks would then have to weigh in at so high a weight that even four of the SRB’s would not be able to lift the resultant vehicle! <br /><br />Turbopumps with the kind of capability to produce this kind of pressure require the kind of horsepower that these pumps have. The SSME’s themselves are rated by thrust NOT horsepower. Although if you wished I would guess that the actual horsepower rating of a single SSME would be in the millions of horsepower!<br /><br />Now whether or not the new super heavy lift vehicle design will actually dump the expensive SSME’s into the drink is questionable at best. A number of years ago Boeing was working on variou

 

[aftercolumbia]

"The SSME only has 4 turbo pumps..."<br /><br />I was counting the LOX boost pump which inclreases the pressure to the preburners to something like 4600psi from the HPOT discharge...it's small, but significant.<br /><br />"The Challenger SRB were sent thrust termination commands..."<br /><br />The cancellation of the thrust termination system was part of the revision between Vehicles 4 and 5 in, IIRC, late 1972 sometime after Phase C/D started. Those were destruct commands. The RH SRB's IIP (Instantaneous Impact Point) hit a yellow line, the RSO had no choice. By this point the LSCs for the ET had been separated from the CRDs as a side-effect of the break-up. The ETs destruct LSCs were later recovered intact, while they were still being considered as a potential cause of the accident.<br /><br />"...fins to move the Center of Pressure aft."<br /><br />Not necessarily, digital control systems make up for these problems, which is why the fins were removed from the original MSC-040C launch vehicle as it moved from the drawing board to reality (MSC-040C was the MSC in house concept drawn up in August-September 1971 and eventually accepted as the difinitive Space Shuttle.)<br />

 

[aftercolumbia]

I've read fhree editions of Dennis Jenkins (the Aerograph, 1, and 3 ed; currently "The History of the National Space Transportation System; the first 100 missions.") It might as well be called the "Space Shuttle Bible" because it has a heck of a lot of information in it...including info on the PDS sensors that delayed STS-114 from May to July. I have not yet verified that it has any errors it hasn't admitted to. I'm pretty sure that little LOX boost pump is for real.<br /><br />"Now the statement about the engine require no turbopumps is so totally incorrect as to be almost humorous!"<br /><br />I'm not laughing, even though your ignorance of pressure-fed technology (as was mine about this time last year) could be described with the same vocabulary. As I recall, the discharge pressure of the HPFT is about 4200psi, leading to a 3000psi chamber pressure or thereabouts.<br /><br />The SRBs bear the entire pressure (and the ignition transient, a force to be reckoned with) along their entire lengths, and they are not uselessly heavy. I've hunted all over for the SRB's Pc, but can't find it...whatever it is, it is held in by 0.125in steel and is certainly not as high as 9000psi. If the SRBs can bear that sort of pressure, so can a pressure-fed booster.<br /><br />"The SSMEs themselves are rated by thrust NOT horsepower."<br /><br />Absolutely true, but the turbopumps are rated by displacements, revolutions, torques, and horsepower...they don't produce thrust.<br /><br />"Now whether or not the new super heavy lift vehicle design will actually dump the expensive SSME's into the drink is questionable at best."<br /><br />Not any more...they are going into the drink, trust me. The recovery pod for the SSMEs was on an SDV named Ares, which was designed by David Baker in support of the study he shared with Robert Zubrin called Mars Direct in early 1990, just after SEI's reputation collapsed in the halls of Congress (this is in Zubrin and Robert Wagner's 1997 Freedom Press title, "The

 

[frodo1008]

As to pressure, the SRB's and the SSME's are not quite the same thing. If pure liquid engines could indeed use only pressure fed systems they would already be doing so as such systems would indeed be much less complex than turbopumps. However, this is not the case, so it would seem to me that turbopumps are indeed needed. Not only does every small, medium, and large liquid engined rocket built by the US have turbopumps, but so does every other such rocket built by every other country! You couldn't use turbopumps with solids under any circumstances now could you? <br /><br />By the way I also have and have read Jenkins book, I also have an older copy of Suttons book "Rocket Propulsion Elements" wihich is the bible of rocket engiines.<br /><br />I am sorry, but I just don't see a pressure fed system of any kind being able to empty out the volumn of the external tank through the three SSMS's through the full 8.5 minutes of their running time! Evidently neither does anyone else who deals with such systems.<br /><br />I think the extra pump you are referring to is the lox preburner, which can be referred to as a pump. But it definitly is not a turbopump. It is more like another small injector. <br /><br />I would be the first to agree that if the SSME's are NOT going to be recovered, that some other engines should be used. My own choice for this would then be the excellent RS68 which powers the Delta IV. Not only are these engines of a higher thrust that the SSME's. You could have all five such engines as planned for the booster of the SHLV for the price of only one SSME! When the RS68 was designed and built "Cost" was the goal. Unlike when the SSME was designed where "performance" and "Weight" were the goals. So if you were going to remove the reusabilty, and variable thrust, and man rated capability of the SSME's, then why use them at all? I say this, and I think the SSME is the finest rocket engine ever built, but becuase of this it is NOT inexpensive!

 

[dobbins]

I can think of one reason to use the SSMEs on an ELV, to expend the ones that NASA has on hand after the Shuttles are retired. An engine that is already paid for is cheaper than buying a new one. I would rather see the left over SSMEs make one final flight and wind up on the bottom of the Atlantic than have them become expensive yard ornaments in front of NASA centers. Now buying new SSMEs is a whole different story, then it makes far more sense (and cents) to go with the more affordable RS68.<br />

 

[tap_sa]

<font color="yellow">" Not only does every small, medium, and large liquid engined rocket built by the US have turbopumps"</font><br /><br />This isn't exactly the case. There isn't fully pressure fed liquid booster (yet) that has reached orbit, but there has been numerous designs and several has been tested to some extent. <br /><br />There's the grand old man Robert Truax who tested launching pressure fed rocket from sea (also the father of Sea Dragon behemoth). <br /><br />Andrew Beal of Beal Aerospace testfired 810,000lbf pressure fed engine aimed for his heavy lift. Unfortunately he folded soon after that but the choice of pump technology had little to do with that. <br /><br />Microcosm has been busy developing cheap pressure fed boosters doing couple suborbital test flights.<br /><br />t/Space CVX booster is supposed to be fully pressurefed. It's larger version of AirLaunch LLC's Quick-Reach that has already been ground testfired for DARPA.<br /><br />If all deities smile upon us we shall 'soon' see first pressure fed upper stage reach orbit, in the form of succesful Falcon-1 launch.<br />

 

[dobbins]

"There are currently only 11 SSMEs"<br /><br />Does that include the three that are in each shuttle? These can be removed before they are hauled off to be displays somewhere.<br />

 

[propforce]

<i>"...The SSME starting from space will want a much larger nozzle to achieve good expansion, and a higher oxidizer to fuel ratio, closer to stoichiometric, than is currently run. This will result in higher chamber temperatures, the main challenge. The Isp will probably be in the range of 475seconds against the standard SSME's 452 seconds vacuum Isp, and the RL-10B2's 462 seconds...."</i><br /><br />A few points<br />1) A SSME can have a higher Isp in space only if you're willing to swap out the existing nozzle to a bigger one. You can keep the chamber pressure and propellant mixture ratio the same.<br /><br />2) However; your statement about changing the oxidizer-to-fuel ratio (MR) closer to stoichiometric will result in a higher Isp is false. Actually the optimal MR for the best Isp is around MR of 5.5 and it gets progressively worst if you go either direction, fuel rich or lean. Therefore in this case, burning a little cooler and drop the MR from 6.0 to 5.5 would increase Isp, but then the eninge has to be re-qualified which is expensive.<br /><br />3) Going back to point #1. For the Heavy version of SDLV, the SSME will start on the ground, not space. So your point is moot. Any bigger nozzle on the ground would cause flow separation which will literally tear the nozzle apart due to the violent shaking of pressure waves. <div class="Discussion_UserSignature"> </div>

 

[propforce]

<i>"...I would be the first to agree that if the SSME's are NOT going to be recovered, that some other engines should be used. My own choice for this would then be the excellent RS68 which powers the Delta IV. Not only are these engines of a higher thrust that the SSME's. You could have all five such engines as planned for the booster of the SHLV for the price of only one SSME!..."</i><br /><br />I hope those at NASA MSFC would listen to you.<br /><br />Throw away 5 SSME per launch at $40M per engine = $200M, plus 2 SRB at $40M each, plus 2 J-2S+ at $XXM each, plus all the tanks, electronics, little Joe escape rocket... then plus all the man-power. <br /><br />This is will be $1 billion per launch before soon !! <div class="Discussion_UserSignature"> </div>

 

[gaetanomarano]

<font color="yellow">I don't understand why MANY want to dismantle the Shuttles "as soon as possible" or (best) TO-DAY!<br /><br />I don't understand why the Shuttle can't be used WITHOUT crew (after conversion) for 100+ cargo flights as explained here www.gaetanomarano.it/spaceShuttle/spaceshuttle.html and here http://uplink.space.com/showflat.php?Cat=&Board=missions&Number=345521&page=0&view=collapsed&sb=5&o=7&fpart=16&vc=1<br /><br />I don't understand why so much people are so much "excited" about the new-old-looking CEV-SDLV-Lunar program!<br /><br />The image www.gaetanomarano.it/spaceShuttle/CEVpollo13.jpg synthetize WHAT (I think) may happen in 2025 if the "CEVpollo" will be REALLY made...</font><br /><br />[ this image can be freely distributed and published, but without changes ]<br /><br /><br />

 

[henryhallam]

Please don't cross-post irrelevant things to every thread in the forum, keep it where it's appropriate.

 

[gaetanomarano]

I think my post is appropriate with the new "grand (or poor?) plan" argument... (rebuild the Apollo for NASA is like rebuild the Mustang for USAF)

 

[henryhallam]

Regardless, it is almost always bad "netiquette" to post the same thing in more than one location - even if you do think it is relevant to both.

 

[dobbins]

"I don't understand why MANY want to dismantle the Shuttles"<br /><br />Because it's a deeply flawed design that could only be corrected by starting over with a clean sheet of paper.<br /><br />"I don't understand why the Shuttle can't be used WITHOUT crew"<br /><br />Because it would still cost more money to launch than an ELV making it a waste of money.<br /><br />"I don't understand why so much people are so much "excited" about the new-old-looking CEV-SDLV-Lunar program"<br /><br />Because that "Apollo" shape is the best engineering solution to the problem of a spaceship returning from deep space. Just because a wheel on a modern car is round doesn't mean it's "covered wagon technology". It means a round shape is the best engineering solution to the problem of designing a wheel. Nobody designs cars with square wheels just to have something new and different.<br /><br />

 

[gaetanomarano]

ok, remove it if possible

 

[gaetanomarano]

"...is the best engineering solution to the problem of a spaceship returning from deep space..."<br /><br />I agree about "from deep space" but not to go in orbit and come back to earth.<br /><br />NASA has done 40 years of studies, projects and experiments about the "Space Airplane", it is not a good choice to come back to Mercury!<br /><br />It is like change a good idea (round wheels) with a bad idea (square wheels).

 

[barrykirk]

Why is a capsule such a bad idea. The biggest problem with it is that you can't return a lot of mass from orbit with it.<br /><br />And if you did, I'm sure it might be possible to design a return capsule for just that purpose.<br /><br />The guys at SpaceX are claiming that they can fully recover both their upper and lower stages. I'll reserve judgement on the re-usabilibity of the upper stages until I see more details on it.<br /><br />But it's the lower stages that are expensive.<br /><br />And it's the lower stages that are easy to reuse, even with a capsule design.

 

[drwayne]

I mumble about space infrastructure from time to time, but it appears to me that to do a range of things in space, to a range of places, will demand a variety of vehicles, from motorcycles to sports cars to 18 wheelers.<br /><br />But hey, I was just strained to work with my wife and put up a ceiling fan, so what do I know.... <img src="/images/icons/frown.gif" /><br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[dobbins]

A Capsule provides the largest interior volume for the area that has to have thermal protection. That is a function of basic geometry and something that no engineering can change.<br /><br />Some people are assuming that a capsule can't be reused because they weren't during the Apollo program. As a matter of fact one capsule was reused during the Gemini program. The unmanned capsule from the Gemini II test flight was reused by the Air Force as a test for it's MOL program before it was canceled. There is no fundamental reason capsules can't be reused.<br /><br />Some people object to capsules having a ballistic reentry instead of a controlled glide. The original plans for Gemini called for it to use a paraglider instead of a parachute and to land airplane style like the X-15 on skids. This approach was dropped because of time constraints. NASA needed Gemini to fly before Apollo. There is no reason why the paraglider system can't be looked into instead of parachutes for the CEV. It would give the advantages of a winged craft without the large weight and thermal protection disadvantages of a space plane approach.<br /><br />

 

[frodo1008]

Nobody on these boards has been a bigger supporter of NASA and its projects than I have been. But, I must admit to a certain amount of concern over the new plans for going back to to moon. What I get from these plans, is that for some $104 billion in developement money, and some $2 billion per trip, we are going to send 4 people instead of 2 to the moon to stay up to 14 days. So for the entire manned protion of the present NASA budget we can have 4 people on the moon for at most some 45 days. That is three trips for $6 billion dollars! And many on these boards think that building and operating the ISS is far too expensive!<br /><br />I am very sorry it just dosen't add up very well! If we are going to go back to the moon in any meaningful way we need to build up the necessary support infrastructure between the Earth and the moon so that many people can stay and actually work on the moon 100% of the time! Exploring the moon is indeed important, but it is not nearly as important as EXPLOITING the moons mineral resourses for the building up of the infrastucture to go further out into the solar system!! I know that this may take more time, and possibly just as much money as flag planting cerimonies, but in the long run it will be far more profitable and sustainable!!<br /><br />I am afraid that like the shuttle NASA is being forced to compromise once again for political reasons, and it is going to be just as negative in the long run!

 

[dobbins]

NASA is not United Airlines. It's job isn't to transport people to the Moon. NASA does not and will not have a bottomless Apollo budget for the foreseeable future. They do not and will not have the funds do more than explore, to find out where those minerals you want to mine are located. You can't just start mining for Gold or Iron at any random location on Earth, you have to find out the best place to dig first. That is what the return to the Moon is about.<br /><br />Lets send up some explorers while we have a chance and find the best place to put a lunar base, before we start worrying about building one and talking Delta Airlines into having service going there. One step at a time.<br /><br />

 

[dobbins]

Frodo1008,<br /><br />One other thing, there are a couple of problems that need to be taken care of if you want to exploit the Moon's resources, ones that don't require a single rocket to be launched.<br /><br />The first is the 1967 space treaty that bans territorial claims on the Moon. The USA and Russia are partys to this treaty. It needs to be amended to allow for claims. No corporation is going to pay the costs of setting up a lunar mining operation if they don't have the assurances of ownership of the property. That requires a system of law, which requires some sort of sovereignty be established. We need to get the Chinese on board for this too.<br /><br />The second is the Moon treaty of 1979, the UN's attempt to seize control of space on behalf of the can not and will not nations. No space fairing nation is a party to this abomination, but the new treaty needs to contain a clause expressly denouncing the UN Moon treaty and it's socialistic claims that space is the common heritage of all mankind. No private corporation is going to invest in a lunar mining operation if they have to fork most of the profits over to the bums at the UN that didn't put up one dime towards developing space.<br /><br />