Could a single engine today replace 3 SSMEs?

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willpittenger

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I recently remembered how Boeing tested the 747 and 777 engines. In the case of the 747, they took one of the engine pods off of a B-52 and replaced it with one 747 engine. That engine flew the B-52 by itself. Boeing later did the same with the 777 by installing it on a 747.<br /><br />So that got me wondering about the state of our rocket engine development. Do we have the technology to power the Shuttle with just one engine (plus the SRBs)? I am not talking about actually flying such a design. Just "Could we do it?" Next, how would that engine compare to three normal SSMEs in engine weight, thrust, and capacity for a given amount of fuel? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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lampblack

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Maybe if someone revamped the old F-1 rockets that formed the first stage of the Saturn V?<br /><br />Of course, that'd mean a redesign to take into account present-day materials and construction techniques. And then someone would have to build and staff a new factory. But other than that, it'd be a piece of cake. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>
 
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PistolPete

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Right now, two RS-68 engines, the type used on the Delta IV, could produce the same thrust with slightly less Isp as the current SSMEs. There are also new rocket engines on the drawing boards that could potentially replace all three SSMEs with one engine. <div class="Discussion_UserSignature"> <p> </p><p><em>So, again we are defeated. This victory belongs to the farmers, not us.</em></p><p><strong>-Kambei Shimada from the movie Seven Samurai</strong></p> </div>
 
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vogon13

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Where else would a 1,000,000 + pound thrust LOX/H2 engine be used ??<br /><br /><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>
 
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jimfromnsf

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Short answer, no, single can't be used<br /><br />1. Multiple engines are required for roll control<br /><br />2. Engine out scenerios require more engines<br /><br />3. The B-52 analogy is not applicable. The SSME's size was not constrained by technology, it could have been bigger . It was sized intentionally since multiple engines were a requirement <br /><br />4. As for parameters, it would have to have 3x the thrust of the SSME at the same ISP. It could weigh more than 3x SSME, since there would be weight savings on the orbiter because there would be less ducting.
 
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rfoshaug

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Could a LH2/LOX engine of any thrust be created? Say, an engine 3 or 10 or 20 times as powerful as the SSME with the same ISP? Or would it at some point be so extremely complicated or difficult to create that it would be impractical? <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>
 
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vogon13

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Get out your check book !<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>
 
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scottb50

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Why the facination on a single engine? There is a lot to be said about redundancy.<br /><br />As for more powerful engines I would agree the scale would not be that much of a limitation then it becomes a matter of how many is a optimal number. The Falcon 9 might be a good example, nine engines means a few could quit and it would still reach orbit. The other side is the engines are packed so close together one failing could take out quite a few of the others even though they are running perfectly fine.<br /><br />Maybe the added weight of multiple engines should be converted to protection for fewer bigger engines rather then a bunch of smaller engines. I still think the weakest link is the turbo-pumps, eliminate them and spend their weight on stronger tanks and a pressure feed system. <div class="Discussion_UserSignature"> </div>
 
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qso1

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I'll go for the complicated answer:<br /><br />Yes. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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rfoshaug

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My personal fascination is not for a single large engine, but for several large engines... <img src="/images/icons/wink.gif" /><br /><br />What is better than 3 small engines? 5 large engines.<br /><br />What is better than 5 large engines? 5 even larger ones. <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>
 
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jimfromnsf

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"I still think the weakest link is the turbo-pumps, eliminate them and spend their weight on stronger tanks and a pressure feed system."<br /><br />????<br /><br />And never get. to orbit efficiently. The weight of a turbopump nowhere near the weight of the thicker tanks. Pressure systems are not viable for launch systems
 
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CalliArcale

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Yeah. Turbopumps are a major possible point of failure, but you can't fly a liquid rocket without them. Until somebody develops a revolutionary new replacement for the turbopump (or even just a fundamentally new kind of turbopump), we're stuck with them. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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propforce

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rfoshaug asked:<br /><font color="yellow">Could a LH2/LOX engine of any thrust be created? Say, an engine 3 or 10 or 20 times as powerful as the SSME with the same ISP? Or would it at some point be so extremely complicated or difficult to create that it would be impractical? </font><br /><br />jimfromsf said<br /><font color="yellow">Time and money is all that is needed </font><br /><br /> <br />Well, in all fairness there will be some R&D challenges when you go to a much bigger engine in a size that has not been done before. Rocket engines, with liquid propellant particularly, are complicated devices internally. The SSME turbopumps were blown up many times during its development before they got it "right". Sizing them up represents some unknown challenges, particularly in the turbine section of the turbopump. <br /><br />Another issue is in the main comubstion chamber, particularly with the issue of combustion instability. Large chambers cause acoustic resonance that could induce instability which leads to structural instability, e.g., blown up. It is more of an issue with LOX/ Kerosene and hypergolic type engines than it is with LOX/ LH2 type, but it is still an issue with LOX/LH2 engines. <br /><br />Also the propellant ducts and lines will get nastly huge, esp. the hot gas duct. You may think that's a minor problem, but the whole engine could be dwarfed by the size of these hot gas ducts!!! The new engine may look like the "Michelin Man" or one giant donut. <br /><br />Then there's the issue of thrust vector controling. Engine this size will most likely use hydraulic fluids for its TVC actuations, which is another new development. While I have no doubt that a new larger TVC can actuate the engine for large degree gimbaling, but how about the small and subtle "fine tune" gimbaling? It will challenge the TVC system on the both upper-end and lower-end range of accuracy and that will take some work to get there.<br /><br />Finally there's the ma <div class="Discussion_UserSignature"> </div>
 
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willpittenger

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Thanks for the detailed analysis. So many of the others replied with things like "Who Cares" or "It wouldn't help the shuttle." I never asked if it would be practical. I also never suggested that we use such an engine on the shuttle. In fact, my only goal was to gauge the state of technology. You were the only person to provide an appropiate reply. Thanks again. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>
 
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