Coaxial Staged Rocket

[rogers_buck]

This came up in another thread, and I thought it deserved a conversation of its own. The idea in question is "coaxial staging". Basically, stages arrayed as hot dog buns on a hot dog. When the bun burns out, the dog takes off.<br /><br />Here's an example:<br /><br />The first stage is a hollow cylinder made from tightly coiled oxidizer and fuel tanks that are wound like a spring around the second stage in the center line. The tanks could be a couple of meters accross and would resemble a barber pole. The exterior would be sprayed with foam. The second stage nestled inside wouldn't need any insulation. <br /><br />Arrayed around the base of the outter barber-polish 1st stage would be engines controlled in the same fashion as the N1 for steering. That is to say they would be throttled instead of gimbled. <br /><br />_/[]_----- top payload mounted to centerline stage 2 <br />/o||o <br />O|_|O ---- fuel spiral tank (stage 1) <br />O|_|O---- oxidizer spiral tank (stage 1) <br />O|_|O <br />O|_|O <br />O[_]O <br />O[X]------turbo pumps & control <br />^^^^<br />1221 - stage of depicted nozzle<br /><br />When the first stage burns out it is released and slides off the second centerline stage which then ignites when free. <br /><br />I like this, because it seems like it would produce an incredibly powerfull rocket in a dense package with scant wastage. If you were really cleaver, you could perhaps use a single turbo pump to feed both the first and second stage engines. <br /><br /><br /><br /><br /><br /> <br />

 

[vogon13]

Check out the original staging scheme for the Atlas missle. Also recall, in the 60's, an entire Atlas (less 2 booster engines) was orbited! Practically an SSTO vehicle.<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>

 

[drwayne]

The Atlas was called a "stage and a half vehicle".<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[vogon13]

Was that the one with the recording of Eisenhower broadcasting greetings in it? <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>

 

[vogon13]

Hellish payload.<br /><br /><img src="/images/icons/wink.gif" /><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>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>When the bun burns out, the dog takes off. <p><hr /></p></p></blockquote><br /><br />Technically, that would mean the "dog" would be called the second stage. Titan IV-B actually wasn't all that far from what you're suggesting. Its twin solid rocket boosters were all that lifted it off the pad; the core stage was airlit.<br /><br />BTW, one other way to get rid of insulation is to change propellants. The Titan also did not require insulation, as it used Aerozine-50 and nitrogen tetroxide, a highly corrosive but hypergolic combination ideal for use in things like ICBMs. It's not as efficient as cryogenics, however.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Arrayed around the base of the outter barber-polish 1st stage would be engines controlled in the same fashion as the N1 for steering. That is to say they would be throttled instead of gimbled.<p><hr /></p></p></blockquote><br /><br />If you can get it to work, it is a truly brilliant means of controlling the vehicle. It requires a high degree of precision in the engineering, however, which is part of the reason the N1s failed. (Not to rag on the Soviets or anything, but it really was a concept ahead of its time.) It should give you a much more efficient vehicle, as you won't be eating up payload mass with heavy and complicated gimbaling systems. Your software will also have to be excellent, and this is something that has also come a long way since the early 70s. A NASA project recently developed a fly-by-wire system that can be retrofitted into commercial airliners to allow them to make a completely controlled landing entirely with differential thrust (intended to help in situations where the airliner loses use of its control surfaces somehow). So the technology is probably ready for this now. <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>

 

[drwayne]

"A NASA project recently developed a fly-by-wire system that can be retrofitted into commercial airliners to allow them to make a completely controlled landing entirely with differential thrust (intended to help in situations where the airliner loses use of its control surfaces somehow). "<br /><br />Fascinating - the Sioux City scenario...<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[vogon13]

Let's not forget Capt. Bryce McCormick in the Windsor incident!<br /><br />And undoubtedly, many air crews in WWII.<br /><br />Sallllllute! <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>

 

[CalliArcale]

Yep; differential thrust is nothing new. Heck, you can buy a cheapie R/C airplane that uses nothing more than that for control. (It's cheaper than adding servos for control surfaces.) But in a big airliner, it takes a lot of skill and is still pretty dicey. Getting a computer to do it is a lot trickier. The team that came up with this fly-by-wire system can get the plane down as gently as if it were a normal landing with all the control surfaces working! And it can be done by somebody with very little experience. It's pretty neat software, basically coming out of the old anti-porpoising systems that were so heavily influenced by the early Shuttle research. (For a time, the Space Shuttle was the biggest fly-by-wire system around, and certainly it's one of the most unwieldy, so it tends to show problems more easily. Enterprise almost crashed due to a problem with the fly-by-wire system, but the fixes proved valuable for everybody contemplating a fly-by-wire design.) <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>

 

[igorsboss]

<font color="yellow">Was that the one with the recording of Eisenhower broadcasting greetings in it?</font><br /><br />Yeah, but what Ike had to say was really Heavy.

 

[rogers_buck]

N1 had also featured the closed system turbo-pumps that blew away the TRW guys. They doubted the russians claims as to engine efficiency and were astonished when they got one in house and saw what it could do. In that system the turbo pump is powered inline with the engine by an over rich oxygen mixture and more fuel is injected downstream. The other engines of the day and even today dump that turbo pump exhaust wasting energy. The new Delta has engines that evolved from this technology.<br /><br />What would be a nice trick is if one turbo pump could feed all the active engines. That turbo pump could be mounted in the central core and would switch to the active set of engines. That would be a tough engineering job to avoid cavitation and over pressures but if you could do it the engines would be incredibly light weight. <br /><br />Another interesting aspect of the coaxial configuration is that you can have outter stages that are fuel/oxidizer only. When depleated those just strip off.<br /><br />I wonder if you could "wind" a stage right on the pad? Imagine that the 2-meter tank was somewhat flexible at STP (like a rubber hose). Wind the thing around and when you put the cryos in it you get the rigidity and strength you need. Water is as hard as rock on Titan sort of thing. Coil them up and glue them right on the pad, spray them with foam, and then fill them up.

 

[vogon13]

<img src="/images/icons/wink.gif" /><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>

 

[semiliterate]

Not exactly your idea, but look up the Douglas ROMBUS concept. Central core with 8 coaxial reusable hydrogen drop tanks. It was also to have 36 engines.

 

[rogers_buck]

Pretty cool. Here's some links:<br /><br />http://www.abo.fi/~mlindroo/SpaceLVs/Slides/sld009.htm<br />http://www.abo.fi/~mlindroo/SpaceLVs/Slides/sld010.htm<br /><br />Thanks.