proposal for a partly reusable ,SD CEV+payload delivery

Page 2 - Seeking answers about space? Join the Space community: the premier source of space exploration, innovation, and astronomy news, chronicling (and celebrating) humanity's ongoing expansion across the final frontier.
Toggle sidebar Toggle sidebar
Status
Not open for further replies.
P

propforce

Guest
<blockquote><font class="small">In reply to:</font><hr /><p><br />" how much propellant do you need to "fly" this back to launch site? " <br /><br />Since most launches will occur eastward over a sea, may I propose this environmentally friendly first stage sail-back method. <p><hr /></p></p></blockquote><br /><br />I am wiping tears off my eyes as I read this.... <div class="Discussion_UserSignature"> </div>
 
F

frodo1008

Guest
It is really nice of you to make this effort. However, it is completely unecessary, as the current single stick SRB launch concept IS completely reuseable as far as the first stage goes (and the second and further stages are going to be the same anyway). The SRB's on the current system are picked up by special ship and reused. There would be no reason to change this system at all.<br /><br />Look, for many years I to have wanted to see a fully reueable two stage to orbit (and in my own case NO SRB's) fly-back type of system. However, for almost exactly the same reasons as when the original shuttle was designed, it just IS NOT going to happen! Get over it! I had to. <br /><br />Congress is going to limit the amount of funding that NASA gets to build the next system, so what we think should be, is NOT going to be. What Mike Griffen wants to do however, is the next best thing. He wants to use as much of the current shuttle system as possible to reduce development costs to a minimum. This is not an engineering decision, it IS a funding decision. Something that engineers have always had to contend with. Scientists can generally afford to be dreamers, but the people who have to put those dreams into practical motion (the engineers, accountants, and even manufaturing types, and Quality Assurance people [ where I was for most of my career]) have to almost always compromise! I am sorry, but that is the way life IS!<br /><br />NOw, what Mike Griffen and NASA are attempting to do (and I think that are going about it the right way here) is to break the current shuttle up into its main two jobs. One is to carry astronauts (not ordinary people at this time. in the future that will be the job of people like Burt Rutan and Virgin Galactic) into LEO and even beyond. The single stick SRB concept with a capsule may not be very pretty, but it will do the job far more economically than anything else at the present time. Even this is going to take billions in design and develo
 
L

lunatio_gordin

Guest
"KSC AHOY!"<br />"ARR!"<br />Genius! <img src="/images/icons/tongue.gif" /><br />
 
M

mrmorris

Guest
<font color="yellow">"...should shame the congress..."</font><br /><br />WHOA!!!!! I finally understand why you and I seem to have such problems finding any common ground whatsoever. You obviously are from a parallel universe of some sort where things are very different from this one. In this particular parallel, politicians of any stripe have their 'shame' gland surgically removed before running for public office. I think it's in the bylaws somewhere.
 
S

spacefire

Guest
<font color="yellow">Do you have any new super technologies in mind that would allow new systems? That is eleminate requirements to live and operate in space? <br />Are they proven in space flight? <br />Certified for flight? </font><br /><br />I don't understand what you're asking from me, and I'd rather not post based on what I assumed you asked...<br /><br /><br /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
 
S

spacefire

Guest
I have refined my design a bit:the second stage I chose is a Centaur 1.<br />I assumed the payload we want to put in LEO will weigh 30,000lb. Calculated 2nd stage delta V will be about 3000m/s.<br />For the first stage I assumed-a rather conservative approach IMO- that the weight will be:1/2 SRB+1/2ET+1/2 Orbiter.<br />Delta V I got, discounting drag, is 5900m/s.<br />Adding the DeltaVs , it gives a total delta V of 8900m/s which is greater than the delta V required to atain LEO of 8600m/s.<br />I used this tool to calculate delta Vs for each stage:<br />http://www.strout.net/info/science/delta-v/intro.html<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
 
F

frodo1008

Guest
I don't quite think that you understand. When we were creating the fantastic SSME's, two things were "Gods". One was performance (and the SSME IS the highest performing rocket engine ever built), and the other was weight, take off weight (which also related to performance) and get a real big pat on the back!! Expense meant nothing, whatever the cost, performance and weight were to be used as design criteria. This meant many of the more expensive manufacturing methods were to be used (not dilliberatly pf course, just because we needed a very high performing and light engine). welding instead of bolting together, grinding to very high tolerances instead of much cheaper lathe work (caused by turbo pumps that turned over at some 30,000+ rpm for higher performance). <br /><br />Now, there is a completely different criteria, COST is now God, and if some performance and weight has to be sacrificed to get lower cost , then so be it! The ENTIRE RS68 costs less than just the turbo pumps of the SSME! Style and looks have NEVER been a criteria. I mean you can have beautiful vehicles like the Naboo Transport in Star Wars in the movies, but in reality nobody cares as long as the craft will do the job safely, reliably, and inexpensively!! At this time this is what CATS is all about.<br /><br />So if NASA has to go back to 40 years to capsule designs to get astronauts into space quickly, safely, reliably, and inexpensively, then that is the way it IS going to be done!!<br /><br />Now, if you refer to Burt Rutan and his designs, I think I can say that he will be designing a non-capsule design. He is going to be taking non-astronaut people into sub orbital orbit. These are people who are going to be paying a lot of money for this. They are going to want at least two things, comfort, and a very good view! These things can't be had with a capsule type of design! <br /><br />He is going to be building at Mojave a much larger carrying aircraft alled Eve that can haul a larger sub or
 
C

cuddlyrocket

Guest
Throwing away <i>cheaper versions</i> of the SSME (as they don't have to have all the expensive equipement required to make them reusable).<br /><br />And the SRBs will be reusable, as now.<br /><br />And even with throwing away the SSMEs etc, it will still be cheaper - and that's the design criterion.
 
F

frodo1008

Guest
For awhile at least the older models that have been already paid for could be used. That is the nine already on the current orbiters, and all the spares currently in stores. IF the shuttle C is the first configuration to be used (which would use the same three SSME's per flight)there would quite probably be enough of the older models for a least six flights.<br /><br />At one time Boeing was interested in some kind of special pod to actually bring back the engines alone to Earth to be reused. I don't know exactly how practical this would have been, but it is certainly a possibility.<br />Then the engines could even retain their reusability, it would take some pretty sophisicated cost studies to see which method would be least expensive in the long run!<br /><br /> Even if the newer engines are to be straight throw-away expendibles, they could drop all reuseability and they would NOT have to be man rated. <br /><br />I also know that back in the 1990's Rocketdyne had a very large program going on reducing the cost of the SSME for even the fully reuseable man-rated engines. One of the problems that would NOT be a block in drastically reducing the final costs of these otherwise great engines would be the need to recertify any changes made, as they would not be man-rated. This was one of the problems with making even small changes to the original engines. It takes a LOT of expensive testing to recertify these engines. So without these requirements these engines could indeed be brought down in cost greatly. It might even be possible to build the entire three engine cluster for only the price of one original engine. <br /><br />Then there is the relatively new factor of Rocketdyne being owned by United Technologies, which also ownes Pratt & Whitney. I would think that they would possibly like to establish a good working relationship with NASA by making these new engines as inexpensive as possible!
 
M

mrmorris

Guest
Two interesting articles comparing the RS-68 to the SSME here and here. A couple of the more interesting quotes:<br /><br /><i>"The RD-68 design has a totally different philosophy compared to the space shuttle main engine (SSME) which was designed to be performance driven. The SSME doesn’t have an extra ounce of weight on it. With this RD-68 rocket engine, there is alot of performance margin because of the use of oxygen/hydrogen propellants and that gives a lot of extra performance that can then trade away for simple manufacturing techniques. "</i><br /><br /><i>"Compared to the SSME, development time for the RS-68 was cut in half, the number of parts was reduced by 80 percent, the hand-touched labor reduced by 92 percent and non-recurring costs were cut by a factor of five. "</i>
 
F

frodo1008

Guest
Agreed. The RS68 engines would be just as good, if not better. However, this would be good for only material to LEO only as the RS68's were never man-rated.<br /><br />So I would guess that NASA is aiming at using the man-rated SSME as the main engines for the second stage of the capsule launch system to take human beings to LEO. Another choice that I have seen is the J2S engine. The only problem here is that while the J2's themselves were used for the engines(5) of the second stage of the Saturn V (and I believe that the third stage had a single J2, also), and were therefore man-rated in themselves. I do not know if the J2S would be considered too much of a design change from the original engines to have to go through all the extensive testing that would then be required to man-rate it?<br /><br />If, you know then I would also like to know. Thanks for any information you could give. Or perhaps we should see if shuttle_guy or propforce would know.
 
F

frodo1008

Guest
You are correct. The SSME has the highest ISP of any chemical rocket ever built for production.<br /><br />We did try to use the only chemical combination higher in potectial ISP than liquid oxygen/liquid hydrogen. In the 1960's Rocketdyne had an experimantal engine that was tested up at Santa Su. Its propellent combination was liquid oxygen and liquid flourine! The only problem was that not only is liquid flourine highly toxic, but it is very unstable. Light alone was enough to set it to burning or exploding!! <br /><br />So until some form of nuclear or electric rockets are built the higest practical ISP is quite probably going to be the magnificent (but expensive) SSME's!!
 
S

spacefire

Guest
I doubt any of today's rockets accelerate at 10g, or spews enough toxic material to make it past the life support of a spacecraft, so...wouldn't the presence of an escape tower eliminate the need for this man-rating process?<br />btw doing a search in google for man-rating pointed me to another thread here where NajaB explained the process, but the explanation was more for the shuttle.<br /> <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
 
M

mrmorris

Guest
<font color="yellow">"Agreed. The RS68 engines would be just as good, if not better. "</font><br /><br />I don't really know what you're agreeing with... I just posted two links comparing the RS-68 to the SSMEs. I didn't actually make any statements to <b>be</b> agreed with. Just providing data... <img src="/images/icons/smile.gif" /> SG has pointed out the problems with 'replacing' the SSMEs with RS-68s too many times for me to even consider that particular suggestion without providing any rationalization. <br /><br />The J2S is interesting, though. It's half the weight of the SSME (and half the thrust) whereas the RS-68 is twice the weight of the SSME and only about 150% of the thrust. ISP still low compared to the SSME and the sea-level ISP <b>really</b> bites if astronautix has that correct.<br /><br />I'd wonder about the feasibility of RS-68s on the first stage of a given HLV, where the thruster mass is a tiny fraction of vehicle GLOW, and J2-S for upper stage(s). Of course, if anything is going to be recoverable -- it'd be the first stage -- which means you might as well use SSMEs and get the ISP bonus.<br /><br />SSME:<br />Thrust(vac): 2,278.00 kN. <br />Isp: 453 sec. <br />Isp (sea level): 363 sec. <br />Mass Engine: 3,177 kg. <br /><br />RS-68:<br />Thrust(vac): 3,312.00 kN. <br />Isp: 420 sec. <br />Isp (sea level): 365 sec.<br />Mass Engine: 6,597 kg. <br /><br />J2-S:<br />Thrust(vac): 1,187.00 kN. <br />Isp: 426 sec. <br />Isp (sea level): 200 sec. <br />Mass Engine: 1,400 kg.
 
P

propforce

Guest
<blockquote><font class="small">In reply to:</font><hr /><p> <i>"The RD-68 design has a totally different philosophy compared to the space shuttle main engine (SSME) which was designed to be performance driven. The SSME doesn’t have an extra ounce of weight on it. With this RD-68 rocket engine, there is alot of performance margin because of the use of oxygen/hydrogen propellants and that gives a lot of extra performance that can then trade away for simple manufacturing techniques. " <br /><br />"Compared to the SSME, development time for the RS-68 was cut in half, the number of parts was reduced by 80 percent, the hand-touched labor reduced by 92 percent and non-recurring costs were cut by a factor of five. "</i> <p><hr /></p></p></blockquote><br /><br />I would advise someone to inform the referenced website to check their spelling as misspelling RS-68 as *RD-68*, changing an American (specifically Rocketdyne) engine designation to a Russian engine designation, can be embarrassing.<br /><br />Rocketdyne incorporated many new manufacturing & design technologies gained since SSME was first developed over 30 years ago and incorporated them into the RS-68. Rocketdyne has wanted to incorporated many of these technologies into their next generation engines, and changing the SSME was too costly. Some key ones are using an integrated casting part instead of many individual machined parts, such as on the turbopump components and the main combustion chamber, and the channel wall cooling loop instead of individual cooling tube on the SSME.<br /><br />But to be fair, the RS-68 is a much simpler engine than the SSME being a gas generator cycle than a high performing staged combustion cycle. It has only one gas generator, 2 pumps where as the SSME has 2 preburners and 4 pumps. This makes the control on the SSME very difficult and needed be very precise.<br /><br />The RS-68 was designed using the Cost As Independable Variable (CAIV) process, meaning the cost drives the design and operation o <div class="Discussion_UserSignature"> </div>
 
P

propforce

Guest
<blockquote><font class="small">In reply to:</font><hr /><p>So I would guess that NASA is aiming at using the man-rated SSME as the main engines for the second stage of the capsule launch system to take human beings to LEO. Another choice that I have seen is the J2S engine. The only problem here is that while the J2's themselves were used for the engines(5) of the second stage of the Saturn V (and I believe that the third stage had a single J2, also), and were therefore man-rated in themselves. I do not know if the J2S would be considered too much of a design change from the original engines to have to go through all the extensive testing that would then be required to man-rate it? <p><hr /></p></p></blockquote><br /><br />The SSME, as it is designed today, would not qualify as a 2nd stage engine. It would need to go through a design change and qualification testing in order to satisfy the requirements as a 2nd stage engine.<br /><br />The SSME has no *re-start* capability which is essential for a 2nd stage engine. After the first burn and engine shutdown, there're water moistures left in both preburners as well as the turbine passages and injectors. These water moistures needed to be purged, preferrably by warm gaseous helium, in order to avoid ice build-up and block passages. The SSME did not design for this requirement as it was meant to be a *one-burn* engine on the STS.<br /><br />The J-2S was designed and qualified, but was never launched on the Saturn V. I do believe they had six J-2S engines stored at NASA MSFC, all sealed up and ready to go. They took one out and use some of its components for the X-33 aerospike engine, so there should still have 5 left. <div class="Discussion_UserSignature"> </div>
 
Status
Not open for further replies.

TRENDING THREADS

Latest posts

Share this page

COMPANY
RESOURCES
FOLLOW
Top Bottom