A very solid future?

[dwightlooi]

I am just wondering... how feasible is it to build a launch system around the Shuttle's SRB. By using 3 to five segments and clustering the boosters (singly, in threes and in sevens), we can theoretically launch up to 120 tons. Pretty much the same concept as with the Delta IV CBCs, except that the common booster core is the SRB and we have the added flexibility of using 3, 4 or 5 segments. The SRBs should undercut the EELVs in terms of common booster costs.<br />

 

[rybanis]

I would pay money to hear the NASA TV voice guy have to say "super fatty" on TV. <div class="Discussion_UserSignature"> </div>

 

[le3119]

Very nice designs! We really need that "fatty" to get things going on the Moon. Maybe a private interest could try these.

 

[mikejz]

check out: http://www.astronautix.com/lvfam/sls.htm

 

[spacefire]

no launches in January <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[propforce]

Very nice. <br /><br />May I suggest swapping out the RS-68 for SSME on your heavy lift version? This will add another 61 MT additional payload to your current vehicle without adding more propellant. <br /><br />You have relatively high T/W for both stages, may need to throttle back quite a bit as much as 50% in one case. I'd imagine that would be difficult to do with current SRB or the new 5-segment SRB? <div class="Discussion_UserSignature"> </div>

 

[dwightlooi]

Considering that it is believed in the early 1980s that 12 Shuttle flights a year would have put out about the same amount of environmental polutants a year as a large coal fired powerplant of that era. I know that environmental standards for powerplants have improved over the last 20 years, but I think we can live with one or two 1980 grade coal powerplant just for the sake of space exploration.

 

[john_316]

you do make a good point...<br /><br />why not use solids for practical commercial launches? If it is cheaper then why not go for it....<br /><br />I understand that chemical means is favored for controllable stages but the first stages doesnt always need to be set that way especially when the the rocket may only be cargo not crew...<br /><br /><img src="/images/icons/smile.gif" /><br />

 

[ozspace]

"I would pay money to hear the NASA TV voice guy have to say "super fatty" on TV. "<br /><br />I have now read this a few times and I laugh out loud each time! Go super fatty!

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>why not use solids for practical commercial launches? If it is cheaper then why not go for it.... <p><hr /></p></p></blockquote><br /><br />Probably not bad for cargo only launches. <div class="Discussion_UserSignature"> </div>

 

[john_316]

A 4 segment SRB with a twin J-2S upperstage for cargo is a good cargo variant for the ISS. <br /><br />Of course this questions why bother allow companies such as Kissler to build the K-1 and for cargo launches. If the K-1 can deliver a cheaper cost at relatively same cost per pound than its a win either way. As the advancement in systems is continued and not kept the same for decades.<br /><br />A 4 or 5 Segment SRB with either the single RS-24 or twin J-2S is envisioned for crew.<br /><br />But what I see is this; it will be this way for the CEV and that allows a 20 to 30 ton CEV which can be almost twice the size or half the weight of Apollo CM/SM with todays technologies.<br /><br />If solids are this reliable for first stage assent then why didn't Boeing and LM go this route for the EELV using SRM's where advantageous and create 2 stage rockets? Or would this be too time consuming and work consuming to configure and build?<br /><br /><img src="/images/icons/smile.gif" /><br /><br />

 

[dwightlooi]

Well I think it is two fold...<br /><br />(1) Firstly, neither Boeing nor LM is in the SRB business. So, they will then to prefer something that they can readily make in house.<br /><br />(2) The EELVs are called EELVs because they are supposed to be "evolved" from the earlier members of the Delta and Atlas vehicles. This means, for the most parts, the reuse of the weak Centaur (RL10 based) upperstages. The RL10 is a 10 ton thrust class engine. Had a solid booster have been used as the first stage, a much larger second stage would have been necessary and at least a J2 class engine (90 ton thrust) and a 40-60 ton upper stage would have been needed for the 8 to 12 ton payload the Delta and Atlas boosters lift. The Delta IV and Atlas V systems have the 1st stage do most of the work. The Delta IV medium for example burns the 1st stage for 250 secs and ignite the 2nd stage at 100km altitude. The Shuttle burns out its SRBs at 35km altitude at 124 secs.<br /><br />If the EELVs have gone with a solid booster, their 1st stage would probably have to be outsourced to Thiokol, Alliant or someone else heavily in the solid business. They will also have to use a big upper stage and a big upper stage engine which will have nothing to do with the Atlas IV or Delta II/III family. These both makes the business case for the them weak and the term "Evolved Expendable Launch Vehicle" an oxymoron. <br /><br />IMHO, an SLS type launch vehicle family may have been the end result of the now defunct SLI but it doesn't flow into the EELV game plan very well.

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>If solids are this reliable for first stage assent then why didn't Boeing and LM go this route for the EELV using SRM's where advantageous and create 2 stage rockets? Or would this be too time consuming and work consuming to configure and build? <br /><p><hr /></p></p></blockquote><br /><br />ATK, the SRB manufacturer, was in the running for EELV contract during phase 1 and proposed what basically the SDLV configuration, e.g., SRB first stage and a cryo 2nd stage. But they were eliminated from competition by the Air Force.<br /><br />Both Boeing and Lockheed use SRM/SRB as 'strap-on' for the booster stage in their EELV configurations.<br /><br />SRM/SRB have good reliability number simply because they have very few moving parts. Safety people, however; don't like them for obvious reasons. <br /><br />The main advantage for 'super-heavy-lift' here is obviously that, Shuttle class SRB already exist, whereas one would have to redesign/ remanufacture F-1A class liquid engines without going to the Russian RD-171.<br /><br />Now as to using SRB as the main first stage, there are some disadvantages I can think of. The first, of course, being safety during stacking and checkouts of vehicle. The precautions and hazardous nature require more time and procedure involved. I don't have the data but someone may have on the timeline in stacking the 4-segment RSRM in the VAB and see how long does that take?<br /><br />Second, the SRB imposes a higher vibration load (and maybe acoustic load as well) onto the fairing and the electronics onboard the vehicle. The entire SRB is, in effect, acting as an acoustic cavity during burn which transmit the vibration load onto the 2nd stage electronics. This may require beefier structures on 2nd stage, fairing and electronic boxes. Whereas a liquid stage contributes a fairy benign vibration loads.<br /><br />Therefore heavier fairing and structures may eat into the payload performance, which one would n <div class="Discussion_UserSignature"> </div>

 

[najab]

><i>One thing no one has address here, as well as for the SDLV thread(s), is how to make SSME and/or RS-68 a 're-startable' engine in flight? This is no easy task and may require a major re-design of the engine.</i><p>The SSME is, theoretically, air restartable, there aren't any one-shot components or anything like that, and as we all know, there's little difference between theory and practice. In theory.</p>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>The SSME is, theoretically, air restartable, there aren't any one-shot components or anything like that, and as we all know, there's little difference between theory and practice. In theory. <p><hr /></p></p></blockquote><br /><br />Actually no.<br /><br />I want to distinguish between "start" and "restart", in case there is a misunderstanding.<br /><br />After an engine operation, there are water moistures trapped in pre-burners, turbines, and main injector manifolds which turn to ice and block flow passages. To remove these moistures and to avoid ice formation so to get the engine ready for re-start, warm gas purging for hours are required which, neither the time or warm gaseous helium source are readily available in flight.<br /> <div class="Discussion_UserSignature"> </div>

 

[tap_sa]

Interesting, does expander cycle engines suffer this same problem or is the kind of automatic gaseous hydrogen purge enough? And how did Saturn V/J-2 work, did it do the burn-coast-burn or burn all the way up to initial orbit?

 

[drwayne]

It burned all the way to orbit, and then did restarts after that, including some long burns after the CM had retrieved the LM and moved off....<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>does expander cycle engines suffer this same problem or is the kind of automatic gaseous hydrogen purge enough?<p><hr /></p></p></blockquote><br /><br />No, the expander cycle engines such as the RL10 do not suffer the same problem because there's no pre-burner or gas generator.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>And how did Saturn V/J-2 work, did it do the burn-coast-burn or burn all the way up to initial orbit? <p><hr /></p></p></blockquote><br /><br />The J-2 solved this problem with lots of helium purging. It was design with several purge control valves and check valves in order to purge the gas generator and thrust chamber injectors, before engine start and after engine shutdown. It also has a single gas generator only, therefore easier to purge.<br /><br />Shuttle_Guy may remember this from his S-IIB and/or S-IVB days <img src="/images/icons/laugh.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[radarredux]

My biggest concern with the ATK solutions is that Ron Dittemore is now President of the company. I did not like the way he came out in public after Columbia saying "we did everything we could have done" or "there was nothing we could have done to change the situation."<br /><br />IMHO, he holds a lot of responsibility for the Columbia tragedy, and he is rewarded by becoming President of one of the shuttle suppliers (probably for a lot higher salary). And now he will probably be rewarded again by by having his company become an even greater supplier for the new VSE.<br /><br />Kill seven people and get a financial windfall. Grrrr.

 

[najab]

Note the last part of what I said: there's no difference between theory and practice - in theory.<br /><br />That's my way of saying that while in the "big picture" it looks like it can be done, the details will be the dickens to work out.

 

[dwightlooi]

IMHO, the preferred choice for the upperstage engine in an SRB derived launch vehicle is an expander cycle engine. They are simpler -- hence safer -- than gas generators or staged combustion designs. They are inherently receptive restarts and airborne ignition. Thrust to weight will be inferior to pump fed designs for the most parts, but they are not horribly heavy and impractical by any means.<br /><br />If NASA wants to do a 18-25 ton SRB based CEV launcher, I think they should look beyond J2 derivatives. The best choice, in my opinion, is a large expander cycle engine like the 300,000 lbs RLX coupled with a 80-120 ton upper stage. I think it will be worthwhile to spend the additional dollars to finish the RLX and to certify it for manned space flight. This will be a very flexible, extremely useful engine to have around for any future space venture -- manned or unmanned, commercial or government funded.

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>Note the last part of what I said: there's no difference between theory and practice - in theory. <br /><br />That's my way of saying that while in the "big picture" it looks like it can be done, the details will be the dickens to work out. <p><hr /></p></p></blockquote><br /><br />Sorry I misread that <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>