SSME

[ambrous]

How many Space Shuttle Main Engines have been produced and or flown. I know that it must be less than 114x3. But I also guess that there are more than just 3 per orbiter.

 

[vogon13]

Shuttleguy probably has a good count.<br /><br />3 were lost on Challenger and 3 more on Columbia. Of course, a few were zorched during developement, and I don't know how strict the division was between development and flight hardware.<br /><br />I don't know if any have been written off during refurbishment.<br /><br />I wouldn't be surprised if some have been cannibalized for parts.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[ambrous]

Wow, that is amazing that there are only 20 some SSME's. This is even more incredible when you think that there were 65 flown F-1's not including test engines for only 13 flights.<br />Thanks S_G

 

[propforce]

Hey SG,<br /><br />Off topic here. Where can I find the latest requirements info on CEV size & mass requirements?<br /><br />Also, is the requirements for Lunar mission or Mars mission? I'd like to find one for Mars but would settle for Lunar <<no pun intended />> <img src="/images/icons/cool.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[edkyle98]

I don't have an exact count, but Jenkin's Space Shuttle lists 45 flight engines used during the first 100 missions, an average of 6.7 flights per engine. An additional dozen or so SSMEs would have been used for development testing. <br /><br />Since then, NASA has put (or is putting) 15 new Block IIA SSMEs (12 flight units, 3 development units for use on the Mississippi test stands) into service. <br /><br />The last SSME (maybe ever) is either in production now, or has been recently completed. These final 15 or so SSMEs should be the only ones in active service today. <br /><br /> - Ed Kyle

 

[edkyle98]

"This is even more incredible when you think that there were 65 flown F-1's not including test engines for only 13 flights. "<br /><br />I don't have the total F-1 count handy, but I've read that each Saturn V was delivered with a "kit" of six F-1 engines (one to serve as a spare). There would also have been six engines for the T-Bird, six each for the two completed, but not flown S-IC stages, and a number of development test units. Altogether, probably more than 100 F-1 engines were built.<br /><br /> - Ed Kyle

 

[frodo1008]

The SSME was designed to be re-useable, therefore the overall shuttle program does not require that many of them. This made the SSME's much more expensive than throw-away engines, but as you can see they (NASA) did not need mearly as many of them because of this. So the over all cost was quite reasonable under the circumstances.<br /><br />The Saturn engines were not re-useable, and therefore a lot more of them were needed!

 

[henryhallam]

I think the F1s were pretty reusable already and could have been made more so without much effort. (reference).<br /><br />The reason the SSME costs so much is partly because few were/are built, but also because it is a VERY high performance engine (thrust, weight, Isp) with extremely fine manufacturing tolerances as well as a high development cost. The F1 developed more thrust but the SSME is really in a whole new league in terms of Isp and system complexity.

 

[john_316]

Not to get off topic here but if someone where to design a new smaller orbiter with say 1 or 2 SSME (If feasable) would NASA sell those motors to a private firm?<br /><br />Has anyone did a design (space vehicle) manned or unmanned with only 1 or 2 SSME's for a mini-shuttle or cargo lifter other than the CLV?<br /><br />I was just wondering if anyone did and if a smaller shuttle would be about the size of a Delta Heavy stack for comparison...<br /><br /><br /><img src="/images/icons/smile.gif" /><br />

 

[frodo1008]

Actually if you bring back almost any liquid rocket engine, and it has not been damaged by its use, it could be reused. But you are correct in that it was weight and performance that governed cost in the case of the SSME. I don't at this time see it being re-designed in any way, so when the shuttles are retired so will the wonderful (I worked on these engines for some 20 years of my own career) but too costly SSME's.<br /><br />When the RS68 was being designed for Boeing's entry into the EELV designs it was (realiability and therefore quality assurance are ALWAYS number one, if not then you don't have any business in the rocket engine business!) designed with lower performance and higher weight, but this was a natural exchange for far lower cost! I think the entire RS68 engine costs just about the same as just the turbopumps for the SSME!<br /><br />Cost has rightfully become the chief aim of getting into space, so I see where the RS68 engines are now going to be NASA's choice for the CALV. These engines will neither need to be reuseable nor man-rated. <br /><br />They also have the advantage over the SSME of being far more powerful engines. At 665 K thrust you could use only three such engines instead of five (400 k) thrust SSME's. However, I suspect that NASA is going to use four such angines, thus giving the CALV at least 500 k thrust more than a vehicle powered by five re-designed SSME's!<br /><br />I also heard a rumor from some friends (I am retired) at Rocketdyne that an upgrade to 1,000 k was being considered for the RS68. We shall see....

 

[nacnud]

Some imagesshow 5 RS-68s

 

[shoogerbrugge]

<blockquote><font class="small">In reply to:</font><hr /><p>The SSME was designed to be re-useable, therefore the overall shuttle program does not require that many of them. This made the SSME's much more expensive than throw-away engines, but as you can see they (NASA) did not need mearly as many of them because of this. So the over all cost was quite reasonable under the circumstances. <p><hr /></p></p></blockquote><br /><br />Not having the numbers by hand, isn't there something missing in your equation. What about the overhaul, inspection and refitting required after each firing of the engines. Those costs add up at each mission and are quite labour intensive.