Which engine for the SRB launcher's upper stage

[spacefire]

<font color="yellow"><br />Perhaps we sould just wait until space-x launches the first Falcon I successfully, before we have them taking us to Mars!!</font><br /><br />show some faith ,Frodo, rocket science is supposed to be fun <img src="/images/icons/smile.gif" /><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>

 

[gunsandrockets]

the Space/X advantage<br /><br />I for one am not proclaiming some childlike faith in Space/X to conquer the universe, nor proclaiming NASA and the big aerospace companies are devils. But Space/X is progressing faster than frodo realizes for reasons that SpaceX may have some advantages over the big aerospace companies.<br /><br />I'ts hard to believe but I have read (unfortuneatly I don't remember where) that Elon Musk has only spent $80 million dollars so far on the Space/X company! And despite that pitifully small expenditure two Falcon I rockets are sitting on launch pads waiting to be launched. With costs that low it's no wonder SpaceX is already fabricating the Falcon V rocket in it's factory. SpaceX isn't waiting nor does it have to wait for the complete success of the Falcon I rocket before proceeding with the Falcon V.<br /><br />Possibly the reason SpaceX is able to achieve this remarkable performance is due to several factors it can take advantage of that the large aerospace giants can not. The SpaceX company is focused, it is only going to do one thing, try to create cheap access to space. Plus Musk is willing to finance such a risky enterprise. SpaceX also could equip itself with the latest methods and technology that is available in the market, plus snap up whatever trained talent is out there just wasting away in the shrinking aerospace market. There is no dead weight of a huge management bureaucracy, large capital investments, easily spooked investors or contractor specifications to weigh SpaceX down.<br /><br />In a way Elon Musk is able to take advantage of the huge mountain of experience, technology and talent just sitting out there to be exploited. He is standing on the shoulders of giants. By combining solid engineering with solid business practices SpaceX may succeed where many other previous small companies crashed and burned. Luck doesn't hurt either, and so far SpaceX has been lucky.

 

[spacefire]

not to mention they are planning to reuse the first stage, which AFAIK hasn't been attempted on a liquid fuel launcher until now, <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[dwightlooi]

<i>"If you put something that is say 100,000 kg on it, not only will the payload rating be small, the G-load expereinced will be in the neighborhood of 15Gs."<br /><br />You're overestimating the G-load here, probably by not taking the SRB's empty mass (86 tonnes) into account. Assuming a near-burnout thrust of 1400 tonnes (it's likely less), upper stage plus payload mass of 100 tonnes results in 7.5 G. For 150 tons, it's 6 G, for 200 tonnes, 4.9 G.<br /><br />Also, I don't think the upper stage's thrust must necessarily be the same or more than stage-plus-payload mass. For instance, the Ariane 5G still weights around 150 tonnes after booster separation, with a thrust of 113 tonnes.<br /><br />Therefore, at the low end, a 120 tonnes stage with a single J-2S might be feasible. Incidentially, that's a Saturn V third stage. Payload is of course modest, maybe 12 to 14 tonnes to an ISS orbit.</i><br /><br />Yes, you are right! I forgot to account for the 86.6 tons of empty mass in the SRB. This almost halved my mass figures and practically doubled the accelerative load. And thanks for the SRB thrust profile chart!<br /><br />It will seem that - not accounting for the sharp fall off in thrust during the last few seconds - peak accelerative load at SRB burnout will be rather gentle. 3.9 Gs if you do not take into account gravity. If you do, then it is between 4.9Gs (vertical flight) and 3.99Gs (horizontal flight) -- I am sure the vehicle won't be flying straight up or level at this point so I'll just estimate it at 4.5Gs.

 

[john_316]

Not to do a point counter point to everyones post but I think either the 4 segmented SRB with SSME + CEV(CM/SM) or the 5 segmented SRB with SSME + CEV (CM/SM) or heck even a Aeroplane liftingbody would be suffice for the project.<br /><br />1. SRB + SSME Already in production.<br /><br />2. J2S needs tooled and manufacturing/remanufacturing facility unless the J2 always had an Area-51 facility just in case.<br /><br />3. While we are on the idea of SRB CEV I am surprised the USAF hasnt about reviving Dynasoar into a Dynasoar-II project with SRB idea.<br /><br />4. The time to build and certify it will be less with off the shelf components.<br /><br />5. Either way they need it soon if they already havent started building them in the interest of national security.<br /><br /><img src="/images/icons/smile.gif" /><br />

 

[tap_sa]

<font color="yellow">"2. J2S needs tooled and manufacturing/remanufacturing facility unless the J2 always had an Area-51 facility just in case. "</font><br /><br />The XRS-2200 aerospike engine that was supposed to propel X-33 is based on J-2S technology. Since the aerospike was actually built and tested, it's tooling might help a lot in doing a conventional bell-version.

 

[dwightlooi]

Maybe, but an aerospike, radial or linear, isn't really needed for an upperstage engine. The only reason for an aerospike is to obtain a better overall nozzle performance. They do carry a weight penalty by being heavier than bell nozzles. The problem with conventional bell nozzles is that those designed for low altitudes will under expand in vacuum and vacuum optimised nozzles will seriously overexpand at lift off. Usually, bell nozzles are a compromise. However, since the liquid engine on the SRB derived booster is going to be an upper stage engine it can simply be a vacuum nozzled engine. By the time the SRB separates (50-70km altitude) there is very little penalty from using a nozzle designed for vacuum since whatever thin atmosphere that is left won't exert much pressure on the plume.

 

[tap_sa]

I repeat; "Since the aerospike was actually built and tested, it's tooling might help a lot in doing <b>a conventional bell-version.</b>". For instance, the aerospike engine might have turbopumps that fit in the bell engine as is.

 

[tempel1]

Dear friends <br />Go here please:<br />http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=117 <br />” The spacecraft's VELOCITY RELATIVE TO THE SUN is at about 26 kilometers per second (about 59,250 miles per hour). Cassini is now more than 9 million kilometers (almost 6 million miles) from Earth”. <br /><br />Since our probe is launched from the earth, it has already a velocity of 65,000 miles per hour (earth's velocity). <br /><br />Why have NASA engineers steered Cassini on this trajectory? <br /> http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=h_cassini_trajectory_02.gif&cap=The <br /><br />Instead of increasing Cassini's velocity they have slowed down it at 59,250 miles per hour. <br /><br />NASA engineers think the earth is the center of our solar system and don't consider earth's velocity. <br /><br />In this wrong way Cassini has travelled for 2 200 000 000 miles to meet Saturn. <br /><br />Cassini would have been able to fly along a straight line travelling for less than 1 000 000 000 miles. <br /><br />65,000 miles per hour (earth velocity) + 36,000 miles per hour (spacecraft's velocity) = 101,000 miles per hour <br /><br />1 000 000 000 miles : 365 days : 24 hours : 101,000 miles per hour = 1.13 years <br /><br />If NASA engineers considered the earth's velocity, Cassini could meet Saturn in one year! <br />

 

[john_316]

Looking at the information on the RS-24, RS-68, and J-2S which all are built by Rocketdyne either way they have a win win situation. I can see why people will favor one over the other in space application.<br /><br />The RS-68 being 3 times the mass of the RS-24 or the J-2S would however deliver more thrust and allow more weight to lifted.<br /><br />I think the RS-24 has to become a new disposable rocket engine or twin J-2S's will power the upperstage.<br /><br />RS-24 (SSME)<br /><br /><img src="/images/icons/smile.gif" /><br />

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>Do you believe that, if given the funding and the job, Rocketdyne or P&W can get the RLX engine finished by 2010? <p><hr /></p></p></blockquote><br /><br />Yes. <div class="Discussion_UserSignature"> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>The initial thrust of an SRB is 1,500,000 kg. This is a little more than it was in the early launches. <p><hr /></p></p></blockquote><br /><br />S_G,<br /><br />Do you know when did the RSRM change it's sea level thrust? The open literature still shows its sea level thrust at 2.65M lbf (1,202 kg lbf). Somewhere it moved up to 3.31M lbf....<br /> <div class="Discussion_UserSignature"> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>Given that we do not know the weight of the CEV, might a non LH2 Engine suffice?" <p><hr /></p></p></blockquote><br /><br />Big impact of Isp on 2nd or 3rd stage engines. <br /><br />For example, if replacing upper stage (EDS) SSME with a RS-27A, one would increase a GLOW of over 1.5M lbm. What's worse, the 2 Shuttle SRB may have trouble of lifting off all that mass !<br /><br />For comparison, if replace the SSME with J-2S (Ivac = 426 sec), the weight increase is less than 165K lbm.<br /> <br />EDIT: This is based on the SDV ILC-1 in-line cargo vehicle version with a payload of 245,858 lbm to 220 nmi circular @28.5. The J-2S Isp number is based on a relatively low nozzle area ratio, which I'd suspect this would change to a high area ratio for SDV.<br /><br />Conclusion: you would want to use H2 engines if at all possible. <div class="Discussion_UserSignature"> </div>

 

[propforce]

OK thanks. <div class="Discussion_UserSignature"> </div>

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>"That is not going to work for an upper stage that will light 180 sec into the flight " <br /><br />The first stage burn out (SRB) is at 122 seconds, which makes it even a worse candidate. <p><hr /></p></p></blockquote><br /><br />HA HA HA .... I just got the joke !!! <br /><br />LMAO !!! <div class="Discussion_UserSignature"> </div>