RS68 confirmed for CaLV

propforce · May 22, 2006

In reply to: -------------------------------------------------------------------------------- The CaLV with RS-68's, five segment SRBs and J2X has a payload of about 18,000 pounds less than a Saturn Five. -------------------------------------------------------------------------------- Why is that? It's sure going to have quite a bit more thrust and (almost certainly) be heavier on the pad than Saturn V, so why won't it carry a heavier payload than the ol' kerosene rocket? Isp, my friend, is why. Isp is equivalent to your car's miles per gallon (mpg). It is defined as pound of thrust per (lbm/sec) of propellant flow rate. In this case, SRB simply does not have the Isp of LOX/RP that powers the F-1 engines. <div class="Discussion_UserSignature"> </div>

rocketwatcher2001 · May 22, 2006

OK, dumb question..... I understand that the boosters have to be there to support the rocket on the pad, but they don't have to be solids, do they? RP-1/Lox gives better ISP, why aren't we developing liquid boosters? <div class="Discussion_UserSignature"> </div>

nacnud · May 22, 2006

Money. A booster just needs to get the core to a certain stageing higth and velocity, I think it's cheaper to do that with solid boosters than liquid ones. Solids may have lower ISP but you can make up the difference by building them bigger. You can't do that with the core stage because it won't make orbit. Rdit: Speling

rocketwatcher2001 · May 22, 2006

Plus, you have to admit, solids do look really cool. And they sure light up the sky at night. I'm going to really miss the Space Shuttle, but if we replace it with this bad boy, it won't be quite so bad. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

barrykirk · May 22, 2006

Why is that everyone is saying that LOX/RP-1 is so expensive? Maybe if one looks at a single use. But solids are much more expensive to refurb and re-use than LOX/RP-1.

nacnud · May 22, 2006

I hope we do get some more night launches before the end of the program, especialy now that they can capture them in HD <img src="/images/icons/smile.gif" /> I think a CaLV launch is going to be spectacular, apparently the thrust of that is near C39 noise limits!

rocketwatcher2001 · May 22, 2006

I think a CaLV launch is going to be spectacular, apparently the thrust of that is near C39 noise limits! I knew I moved to Titusville for a reason. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> </div>

nacnud · May 22, 2006

Maybe if one looks at a single use. But solids are much more expensive to refurb and re-use than LOX/RP-1. What LOX/PR-1 engines have been reused in flight vehicels and how do you get the boosters back? I think that possible ways to lower refurb costs would be a monolithic SRB that is refurbished at the launch site, closely followed by a liquid fly back booster. The problem is the developent costs of the fly back bit of the booster and that high flight rates are needed to get back the investment in reuseable systems.

propforce · May 22, 2006

OK, dumb question..... No such thing. Only dumb answers <img src="/images/icons/smile.gif" /> I understand that the boosters have to be there to support the rocket on the pad, but they don't have to be solids, do they? You're correct. A rocket booster does not have to use solid propellants, as in the SRB. It can use LOX/RP, such as in the case of Saturn and Atlas. It can also use LOX/LH2, such as in the case of Delta IV. It can also use hypergolics (NTO/UDMH), such as in the case of Titan IV as well as the Chinese Long March, but not desirable due to their toxicity and not environmental friendly. RP-1/Lox gives better ISP, why aren't we developing liquid boosters? Well... this is where technical and business intersect with the NASA politics. Mike Griffen, before he became the NASA adminstrator, was a co-lead on a NASA exploration study where he advocated the use of existing Shuttle SRB to send CEV to space. But now, he is reportedly upset with ATK, the maker of Shuttle SRB, as they've raised to cost of qualifying a new 5 segment SRB from $1 Billion to $3 Billions, a jump of 300% in less than 6 months after the ESAS released their report recommending the use of SRB for the CLV (crew launch vehicle). Many of the so-called "Shuttle-Derived" for CLV and CaLV have moved to "EELV-derived" in less than 6 months of ESAS's published reports, that drew lots of criticisms of its study as factually not correct. Some EELV contractors complained that the ESAS study team did not consult with the EELV "experts", which ESAS claimed they have. Politics aside, one would have to question why build the CLV at all, when the EELVs are clearly cheaper and already exist to launch the CEV to the ISS. Second; the 5-segment SRB can be easily replaced by the 'stretch' version (larger tan <div class="Discussion_UserSignature"> </div>

propforce · May 22, 2006

A booster just needs to get the core to a certain stageing higth and velocity, I think it's cheaper to do that with solid boosters than liquid ones. Solids may have lower ISP but you can make up the difference by building them bigger I don't think it's necessary cheaper to use the SRB than a liquid booster, especially considering in this case a $3 billion price tag in qualifying the 5-segment SRB. If you make another bigger SRB, that's another qualification cost. Everytime you make a different size, chances are you'll make a different grain for different thrust profile, you'll have to pay another $B qualification cost. Here's another point, if the CLV use the 5-segment SRB, it needs a lift-off thrust of 3.5M lbf. Whereas if one replaces the SRB with the Atlas first stage CCB with a 20% bigger tanks and 2 RD-180, it only needs 1.7M lbf, nearly half of the thrust required for the SRB. Resaon is simple, higher Isp reduces amount of propellant required to get to a certain altitude. <div class="Discussion_UserSignature"> </div>

rocketwatcher2001 · May 22, 2006

Thanks, prop. <div class="Discussion_UserSignature"> </div>

nacnud · May 22, 2006

True, the cost thing is the current NASA explanation but if you don't belive NASAs figures... I do like the idea of Atlas derived booster with a shuttle/delta core and a shuttle/apollo 2nd stage/EDS. Something old, something new something borrowed, something blue <img src="/images/icons/smile.gif" />

scottb50 · May 22, 2006

First I have no intention of putting the engine in sea water. With a TSTO the first stage would flyback to a landing at the launch site. Using an extendable nozzle would allow greater thrust once the SRB's burned out, allowing both higher altitude and speed from the first stage that would add capability to the upper stage. The extention could be a simple ablative coated section, retracted against the engine for initial operation and pushed out over the normal nozzle when needed. By optimized I assume you mean it is not perfect for either surface performance or flight performance. A simple extension could be quite productive, especially on a re-usable vehicle. <div class="Discussion_UserSignature"> </div>

strandedonearth · May 22, 2006

"OK, dumb question..... No such thing. Only dumb answers " Actually, there are 2 types of dumb questions. Questions that don't get asked and questions you don't want to know the answer to. Not that either of those apply here. This morphing of Shuttle-derived into EELV-derived reminds me of that morphing English into German joke over in Free Space. But hey, whatever gets men on the Moon.

frodo1008 · May 23, 2006

A Three BILLION dollar developement cost for going to the five segment SRB? Absolutely NOT! Some time ago Rocketdyne stated that they should be able to start up the F1A again (including modern improvements) for some $2 billion or even less. I am equally certain that Boeing could upgrade the Common Booster Core manufacturing line to produce a Common Booster Core for either a single (or possibly even two) such F1's and still keep the total costs to the same range. We could then get rid of the solids entirely! For one thing solids are inherently less safe than liquids (you can't hot fire a solid and then use the same solid for your actual launch vehicle, but it is a common practice for liquid engines), this advantage alone wipes out any safety advantage of the simplicity of solids! I too would be angry if I were Griffin! What ATK has done is to increase the cost to such a level as to totally wipe out any savings for using the shuttle derived hardware! They have killed their own golden goose here, such stupidity should NOT be rewarded! Although knowing the power of the Utah congress people, it would still quite probably end up being used anyway! If I were Girffin I think I would simply state that such an increase would make the entire CEV/CALV program too expensive, and threaten to resign! Then hopefully the rest of congress could step up and give the man a free hand to do his job! I am NOT angry with NASA over this. What I am angry with is a single politically supported contractor gouging both NASA and the American taxpayer! Or at the very least gouging well beyond even the norm for such contractors! If something isn't done about this, then perhaps those negativists on this forum that want NASA disolved might just be correct. Perhaps it would even be best to just depend on pure profit making private industry after all! Grrrrrrrr!!!!!!!

john_316 · May 23, 2006

What I dont get is they already tested a 5 Segment SRB not too long ago. So how does that go from 1 billion to 2 billion dollars? Sounds like a rip off to me. I think they should axe ATK and the 5 segment SRB and continue with a 4 segment SRB and continue just to procure them as with they did STS and only for the CaLV. I think they should move CEV to ATLAS-5 and DELTA Heavy and pull the plug on ATK. Then again we could always go look for a foreign solid rocket booster maker too. Though I don't like that approach. <img src="/images/icons/smile.gif" />

tap_sa · May 23, 2006

"What LOX/PR-1 engines have been reused in flight vehicels and how do you get the boosters back?" RD-170 was supposed to be but USSR flopped before Energia flights got into full gear. You get the liquid boosters back the same way as SRBs, with parachutes. IMO pressure fed design would be great for liquid (strap-on) booster. It would nearly match the simplicity/reliability of SRB, be cheaper to construct than turbopumped engine with delicate light weight tank, it would be very sturdy to survive the landing impact easily, and clear benefit over SRB is that after plunging into sea it would float like a cork. SRB is just a reaction chamber so it gets flooded, the liquid booster closes propellant valves after operation so no water would enter the tanks. Btw regarding liquid engines and salt water; I don't see why brief splash into ocean would render pressure fed reaction chamber useless when that does not happen to SRB either. Perhaps the engine could be run very fuel rich at the end of it's flight to cover the RC with thick soot. I reckon that would provide protection against the salt water. Then dip the engine to vat of detergent during refurb.

mattblack · May 23, 2006

Here's a summary of the EELV vs Shuttle-derived argument over at NasaSpaceflight.com that I participated in. This is my new post there that quotes some other posters, with rebuttals/approvals from me: ***************************************** On many levels, I think the 5-Segment CLV is a brilliant design, bold in it’s simplicity and exciting in its potential performance. I have no doubt whatsoever that it would work pretty much as advertised. It’s re-usability, sheer power and commonality with the CaLV (first version) makes it an attractive proposition for a family of vehicles, the way the Saturn 1B and Saturn V shared the same upper stages and their engines. Also, after the Soyuz, the Shuttle SRB has more data and more statistics on safe human flight than any other launcher. **But there are some sobering thoughts and things to ponder. In earlier posts, Jim said: />>The five segment SRM was not a flight configuration. Other than having 5 segments, it will not be the same as what will be used for ESAS. The core configuration will be different, the nozzle, and other things. The test had nothing to do with what will fly.<< Of course it will have something to do with how it will fly!! The fact they’ve actually tested the thing means it’s already halfway to flight, as much or more so than a 2x RD-180 Atlas Phase 2. Changing the propellant back to PBAN will save money and make it easier to man-rate. />>Jim: I am going to take the opposite point of view. When would we have landed on the moon if it wasn't for John C. Houbolt? He had the stones to go against the larger than life icon of the US spaceprogram, Werhner Von Braun. Who ended up right? If I think parts of the ESAS is wrong, then I want to change it.<< The Houbolt comparison is a good one, though not entirely applicable in that the EELV vs SRB argument, which is more to do with money/schedule/risk than achieving a mass-fract <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

tap_sa · May 23, 2006

"I think the choice of SRB/CLV has far, far more to do with the data, or at least the data as Nasa perceives it "/safety_wrapper>

propforce · May 23, 2006

"I think the choice of SRB/CLV has far, far more to do with the data, or at least the data as Nasa perceives it " Having work with MSFC last few years on the NGLT project, I am convinced that some, not all, of their people are not capable to use judgement on data anymore. Case in point, they rated existing engines with much lower reliability rating than engines that are just on paper and not even exist yet! Why? Simple, when an engine is on paper, the contractor can claim it has 99.999% reliability "prediction". On the other hand, something like the SSME that's been flown over 100 times has a "field reliability" far less. In the case of SDLV vs. EELV, I can just imagine the same people evaluated that 'existing' launch vehicles such as the EELV are inherently less reliable than something that's never been flown such as the CLV. It was a sad day at NASA when these geniuses can not make practical judgement on "data", and make big decisions based on "garbage in - garbage out" number crunching. <div class="Discussion_UserSignature"> </div>

edkyle98 · May 23, 2006

"For one thing solids are inherently less safe than liquids (you can't hot fire a solid and then use the same solid for your actual launch vehicle, but it is a common practice for liquid engines), this advantage alone wipes out any safety advantage of the simplicity of solids! " The flight record shows that big solids have been more reliable than liquid booster stages. The combined space shuttle, Titan 3-4 series results show that three of the 474 big solid motors flown failed (a 0.69% failure rate), while six of the 237 core liquid vehicle sets suffered failures (a 2.5% failure rate). (An additional eight upper stage failures marred the Titan program). Not all liquid vehicle failures would be survivable. There is risk any time you have to "punch out". If liquids fail more often than solids, they will expose crews to more aborts, and thus more risk. - Ed Kyle

propforce · May 23, 2006

The flight record shows that big solids have been more reliable than liquid booster stages. One certainly can not argue with flight record, however; I think the solids require more "touch labor" in the pre-launch processing, e.g., stacking/ assembly/ checkouts, than liquids. All these translate into more time and people which increases the launch operational cost. The liquid engines are certainly more complex, especially with cryogenic fluids and lots of moving parts. The benefit is that they can be checkout at the pad, powered up and abort if needed, whereas the SRB can not. <div class="Discussion_UserSignature"> </div>

frodo1008 · May 23, 2006

The failure rate for Rocketdynes RS27A Delta II Engine is zero. The solids for the Delta II have failed on occasion, however, even with this NASA uses the Delta II for almost all of its Mars and smaller deep space probes as it is quite probably the most reliable rocket launch system in existance, and they really don't want to lose the mission just at its start! The SSME's have NEVER caused either mission failure, nor lost us any astronauts. True there have been aborts, but these have just shown that it is indeed possible to start and stop these magnificent (and absolutly cutting edge engines) in seconds, this kind of control is NOT available with the solids however! Remember Challenger? ATK has done a very good job of using Statistical Process Control to ensure that the performance of the four segment SRB's have been safe ever since Challenger. And I congradulate them on it. However, it still remains that you can (and Rocketdyne does) make a Green Run(s) on liquid engines. These are total test runs that ensure the engines work safely. Then THE VERY SAME ENGINES are used on the actual flight vehicle! I believe the Russians do the same thing with their liquid engines, and their record is also very good! It is true that at the kinds of temperatures and pressures that such large liquid engines run at, even pre testing can not always stop a disaster, but this also holds true for large solids! But once again, the solid manufacturer MUST make sure that the flight engines are EXACATLY the same as the test engines. And they have to do this without the benifit of being able to use the same engines as the test engines. Do you begin to now understand my point? It is kind of like your car engine in a new car, I am certain that the engine is given a running test before it is sold (If nothing else if you don't insist on taking the car for a test spin yourself, then you are an idiot!). Automobile engines are also l

radarredux · May 23, 2006

> Here's a summary of the EELV vs Shuttle-derived argument over at NasaSpaceflight.com/i> Thanks! Although, I think I am just as undecided as ever. By the way, Jeffrey Bell has posted an article/op-ed piece on this debate: The VSE Booster Switch http://www.spacedaily.com/reports/The_VSE_Booster_Switch.html

propforce · May 23, 2006

Well... let me stir the pot a bit, adding to MattBlak's summary. The folks at Lockheed complained that, they were submitting publication papers for the Space 2005 conference, outline how the Atlas V is safer and cheaper than the proposed CLV/ CaLV. Mike Griffin and Scott Horowitz were reportedly very upset about these upcoming papers, so they called the Lockheed VP in charge of Atlas (and reportedly did likewise to the Boeing VP) and told them to pull those papers. NASA wanted the contractors to "fall back in line" otherwise there would be consequences. Someone then e-mailed to Chris Bergen, editor of Nasaspaceflight.com, those papers and he published them in the L2 section <img src="/images/icons/cool.gif" />. <div class="Discussion_UserSignature"> </div>

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