<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It will never float. It will sink. It would need huge floatation devices. <br />Posted by Cygnus_X_1</DIV></p><p> </p><p>Does 4,000-5,000 lbs. of polyurathane foam on the 2nd stage, qualify as a huge floatation device? <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>"I am quite dense." I believe that you've commited an offense here. I take that as a personal attack. In the spirit of this heated debate, I will let this one slide. However, if you do it again, I will complain to the moderators, and you will be suspended, or banned. <br />Posted by kyle_baron</DIV><br /><br />I agree; however, he ain't wrong. You seem to be dedicated to ignore all existing physics of launch vehicles. An being darn snarky about it. The concept you are suggesting is just plain unrealistic and silly. There is minimal benefit, and many much larger negatives to the approach you suggest. You seem to be offended that these unrealistic pluses to your approach are being pointed out.</p><p>You've had far better ideas that were worth defending. This is not one of them.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> The concept you are suggesting is just plain unrealistic and silly. There is minimal benefit,</DIV></p><p> </p><p>It's not so silly any more. We've just uncovered a "huge flotation device" already built into the rocket, by arguing amongst ourselves. Who knows what we'll uncover next. And as far as minimal benefit, I would argue, that taking the mass of a rocket, making it nearly weightless, and applying 2.8 million lbs. of thrust, would cause an additional acceleration that could be used for additional payload, or orbital velocity.</p><p> </p><p> Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> You seem to be offended that these unrealistic pluses to your approach are being pointed out.</DIV></p><p> </p><p>Not at all. I consider them challenges. You may call the idea silly or nutty, but when someone is name calling, that goes over the line.</p><p> </p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You've had far better ideas that were worth defending. This is not one of them. <br />Posted by MeteorWayne</DIV></p><p> </p><p>That's your opinion. I think it's one of my better ideas, that flies in the face of "business as usual" or "the status quo".</p><p> </p><p><br /><br /> </p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>.... I think it's one of my better ideas, that flies in the face of "business as usual" or "the status quo". <br />Posted by kyle_baron</DIV></p><p>Perhaps, but if you proposed this notion in a freshman physics class you would fail, for all the reasons that have been ponted out.<br /></p> <div class="Discussion_UserSignature"> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>...The water spout effect is a significant load on the nozzle and has to be taken care of via engineered design features or else you have a failure.The disadvantages of a submerged ignition event include a very loud noise, pieces flying all over the place at high velocity, and an annoying lack of control of the thrust vector. Posted by DrRocket</DIV></p><p>Thanks for that! I needed it. 
The image of a rocket igniting under water and rapidly achieving negative flight potential made me bust a few stitches. </p> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>
The image of a rocket igniting under water and rapidly achieving negative flight potential made me bust a few stitches. </p> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div><p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Does 4,000-5,000 lbs. of polyurathane foam on the 2nd stage, qualify as a huge floatation device? <br /> Posted by kyle_baron</DIV></p><p>no, not compared to the 2 million lb or so vehicle. That is insignificant, only a couple of percent. Hardly would make a difference </p>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> It's not so silly any more. We've just uncovered a "huge flotation device" already built into the rocket, by arguing amongst ourselves. Who knows what we'll uncover next. And as far as minimal benefit, I would argue, that taking the mass of a rocket, making it nearly weightless, and applying 2.8 million lbs. of thrust, would cause an additional acceleration that could be used for additional payload, or orbital velocity. Not at all. I consider them challenges. You may call the idea silly or nutty, but when someone is name calling, that goes over the line. That's your opinion. I think it's one of my better ideas, that flies in the face of "business as usual" or "the status quo". <br /> Posted by kyle_baron</DIV></p><p> Incorrect, it is an insignificant flotation device but that does matter. Again, it is not "weightless" Floating in water is not weightless. There is no advantage of a floating booster. It still has the same mass, (it is not lighter)</p><p> It can't be a "better" idea because it is non viable. It can't happen. You lack the basic education to see that it is. </p>
<p>Kyle... Come on, seriously. You've got a professional who has probably spent a good chunk of his life working on rockets giving you a little insight into the physics of it all. He provides you a glimpse of his credentials on what he's worked on and your first response is:</p><p>"Maybe that's part of the problem, when you're conditioned to see things one way."</p><p>You then follow it up by saying he is "hiding information" as if he is trying to decieve you. A few posts later, after he refers to your idea as "nutty" (and having shown why it is nutty), you respond with:</p><p>"OK, why don't you take a break, and not focus on these aspects (if it's too dificult for you). I really don't care what you might think of my "theoretical idea"."</p><p>Why wouldn't you focus on the catastrophic events before the rocket even starts to significantly move? The fact that you refuse to accept a professional's opinions by demeaning said opinions with smart alec comments is nothing more than you being thickheaded and stubborn (aka dense). That is not an aspersion on your character or name calling (aka ad hominem). You are the one who set the tone. </p><p>DrRocket was doing nothing more than giving his professional insight. </p><p>YOU attack his education and credentials by saying he is 'conditioned'. YOU question his intentions by blaming him for "hiding information". YOU question his mentality "(if it's too dificult [sic] for you)." Then YOU cast aside his professional opinions by saying "I really don't care what you might think". YOU question his work ethics by suggesting "professionals "have to be told" what to design."</p><p>Do you see how immature and grating your debating tactics are? This is a rather familiar tactic for you when someone provides evidence or opinions that are not your own.</p><p>Sorry for injecting myself into the thread and offering a rant that doesn't advance the topic at hand.</p><p><br /> <img src="http://sitelife.space.com/ver1.0/Content/images/store/6/1/d697b6c4-1f91-41ea-81b9-24b03ce2a9f2.Medium.gif" alt="" /><br /> </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Incorrect, it is an insignificant flotation device but that does matter. Again, it is not "weightless" Floating in water is not weightless. There is no advantage of a floating booster. It still has the same mass, (it is not lighter) It can't be a "better" idea because it is non viable. It can't happen. You lack the basic education to see that it is. <br /> Posted by Cygnus_2112</DIV></p><p>While I agree it is a crazy idea I could see something like the way submarines launch missles from canisters. If you put the rocket in a canister with floatation devices and compressed gas canisters it could be sunk to a specific depth and the floatation devices inflated, once the canister pops above the surface the rocket would be ignited. The initial acceleration upward would be useful and he tanks for the floataion devices could be reused. The only way it could work is with the rocket igniting after leaving the water though, because even a few feet of water would be a lot worse then hundreds of feet of air.</p><p>A cannister able to contain an Ares and sink it to say 2,000 feet would have to be pretty substantial, but if it popped out of the water and immediately ignites it might work. </p> <div class="Discussion_UserSignature"> </div>
<p>If you want to get some initial speed for the booster before firing the motor(s), I'd prefer a hydraulic or gas based spring system which would bounce it upwards a second or two before the engines are ignited. Depending how the system is designed it could lift the rocket pretty high and pretty fast if you like. However what kind of reliability/safety aspect it arises for example launch abort cases or crew evacuation, it is a totally different story...</p><p>If you really want to launch under water you probably need a huge compressed airflow to make a "bubble" under the engines. Also as earlier said the friction of water is much higher than air. That's why I'm suggesting "spring" system like air craft carries are using to launch fighters (at least the same principle).</p> <div class="Discussion_UserSignature"> </div>
<p>[<br /><br />QUOTE]While I agree it is a crazy idea I could see something like the way submarines launch missles from canisters. If you put the rocket in a canister with floatation devices and compressed gas canisters it could be sunk to a specific depth and the floatation devices inflated, once the canister pops above the surface the rocket would be ignited. The initial acceleration upward would be useful and he tanks for the floataion devices could be reused. The only way it could work is with the rocket igniting after leaving the water though, because even a few feet of water would be a lot worse then hundreds of feet of air.A cannister able to contain an Ares and sink it to say 2,000 feet would have to be pretty substantial, but if it popped out of the water and immediately ignites it might work. <br />Posted by scottb50[/QUOTE]</p><p>What gives SLBMs (submarine launched ballistic missiles) the initial boost is not buoyancy but rather a gas generator (basically a rocket motor grain) in the launch tube that propels the missile upwards and in a bubble. The rocket motor is not ignited until after it clears the surface. It is never "floating". Even then the initial velocity from the gas generator is essentially spent at ignition. The only point is to clear the water so that the motor can ignite without blowing up.</p><p>A canister that could take the pressure of substantial depth would be quite heavy -- like a submarine hull. Unless you somehow get a very high velocity as it erupts from the water, there is no significant performance benefit. And you won't get significant velocity. Even an emergency surface of a submarine is of modest speed compared to what you are looking for in a rocket. All that such a scheme would be is a very complex, very expensive and very inefficient initial stage for the the vehicle. Let's say you got an extra 60 mph (88 fps) out of this scheme. That would be a lot for a hull moving through the water, and you would actually get much less -- you will hit terminal velocity very quickly when rising through water under nothing more than bouyancy. That would be very little performance increase, and you have obtained it a great cost, and much increased risk of a launch failure. Why bother ? There are many simpler ways to do that. And even if you could ignite the motor underwater, that scheme would be a net loser because of the huge losses from water resistance. You would gain a tiny amount from the bouyant forces and lose a huge amount to fluid drag.</p><p>There are so many problems with this idea that anyone looking at it will miss a few. On the scale of dumb ideas this is one of the dumbest. The bottom line is that the best you could hope for is a gain in energy equal to the height above water level to which the missile (the aft end of the missile) would go under the influence of buoyancy alone. And that height is going to be negative. And then the motor ignites and the whole shebang blows up. Or suppose you somehow manage to get this behemoth clear of the water, then the water come rusing back into the void below and creates a water eruption (like when a kid does a cannonball) that eruption will impact on the aft end of the motor and the nozzle, and without some serious engineering will overload the nozzle or the thrust vector actuation system in another failure mode -- and this is not a hypothetical, it has been done.</p><p>><img src="http://sitelife.space.com/ver1.0/Content/images/store/9/14/99d41d24-854d-48c1-9e7e-3ac6af23aa27.Medium.bmp" alt="" /></p> <div class="Discussion_UserSignature"> </div>
<p>And here is what it looks like when a big motor is overpressurized at ignition.<br /><img src="http://sitelife.space.com/ver1.0/Content/images/store/11/9/db63caee-7a51-4710-a9cc-f5eb13d7595c.Medium.jpg" alt="" /></p> <div class="Discussion_UserSignature"> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>What gives SLBMs (submarine launched ballistic missiles) the initial boost is not buoyancy but rather a gas generator (basically a rocket motor grain) in the launch tube that propels the missile upwards and in a bubble. The rocket motor is not ignited until after it clears the surface. It is never "floating". Even then the initial velocity from the gas generator is essentially spent at ignition. The only point is to clear the water so that the motor can ignite without blowing up.A canister that could take the pressure of substantial depth would be quite heavy -- like a submarine hull. Unless you somehow get a very high velocity as it erupts from the water, there is no significant performance benefit. And you won't get significant velocity. Even an emergency surface of a submarine is of modest speed compared to what you are looking for in a rocket. All that such a scheme would be is a very complex, very expensive and very inefficient initial stage for the the vehicle. Let's say you got an extra 60 mph (88 fps) out of this scheme. That would be a lot for a hull moving through the water, and you would actually get much less -- you will hit terminal velocity very quickly when rising through water under nothing more than bouyancy. That would be very little performance increase, and you have obtained it a great cost, and much increased risk of a launch failure. Why bother ? There are many simpler ways to do that. And even if you could ignite the motor underwater, that scheme would be a net loser because of the huge losses from water resistance. You would gain a tiny amount from the bouyant forces and lose a huge amount to fluid drag.There are so many problems with this idea that anyone looking at it will miss a few. On the scale of dumb ideas this is one of the dumbest. The bottom line is that the best you could hope for is a gain in energy equal to the height above water level to which the missile (the aft end of the missile) would go under the influence of buoyancy alone. And that height is going to be negative. And then the motor ignites and the whole shebang blows up. Or suppose you somehow manage to get this behemoth clear of the water, then the water come rusing back into the void below and creates a water eruption (like when a kid does a cannonball) that eruption will impact on the aft end of the motor and the nozzle, and without some serious engineering will overload the nozzle or the thrust vector actuation system in another failure mode -- and this is not a hypothetical, it has been done.> <br /> Posted by DrRocket</DIV></p><p>Probably right. What I was implying was a rapid rise from the depth using rapidly inflated balloons. Tethered to the canister they could attain enough velocity to throw the entire structure high enough out of the water that when the engines ignite it would be high enough to not be affected. Sort of a slingshot effect, a very rapid ascent with release of the canister as it comes out of the water. A gas generator to inflate the balloons would start the ascent and if sufficiently big enough the assembly would attain enough energy to fling the canister out of the water.</p><p>I don't see it being of much use, because, as you say, to handle the pressures at the needed depths the canister would be pretty heavy, though I doubt as heavy as the Shuttle launch platform. The velocity gain would be neglible also, but the simplicity might outweigh the negatives. </p> <div class="Discussion_UserSignature"> </div>
Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Probably right. What I was implying was a rapid rise from the depth using rapidly inflated balloons. Tethered to the canister they could attain enough velocity to throw the entire structure high enough out of the water that when the engines ignite it would be high enough to not be affected. Sort of a slingshot effect, a very rapid ascent with release of the canister as it comes out of the water. A gas generator to inflate the balloons would start the ascent and if sufficiently big enough the assembly would attain enough energy to fling the canister out of the water.I don't see it being of much use, because, as you say, to handle the pressures at the needed depths the canister would be pretty heavy, though I doubt as heavy as the Shuttle launch platform. The velocity gain would be neglible also, but the simplicity might outweigh the negatives. <br />Posted by scottb50</DIV><br /><br />But you can build a such slingshot without submerging into water... A "little" hydraulics or similar gas based thingys will do the trick without water. And probably they are much more effective and simplier as well. Like aircraft carriers are slingshotting the fighters away their decks. <div class="Discussion_UserSignature"> </div>
<p><font size="1">(quote):..."and is filled with with a substance which has the density of a pencil eraser "</font></p><p><font size="1">Guess what, I took what anyone can regard as an ordinary pencil eraser, put it in a glass of water and it promptly sunk. I've seen Richard Feynman place 'O' ring rubber in a glass of chilled water - it did not float.</font></p><p><font size="1">I've been an observer of this forum for a while now, I've seen the good, the bad and the absolute gems, stuff contibuted by the unseen hands that actually build, maintain and fly these super machines. No superlatives are good enough for those things that we are privileged to watch from afar, and when a professional decides to give his two cents worth, listen!</font></p><p><font size="1">Sometimes, it's worth getting up from the computer and start playing with bits of rubber, like Mr Feynman, and from there, start to draw your conclusions. I guess the next step in this experiment is to invest in some model rockets and start launching them from tubs of water. They may not blow (large saftey margin - public liability, small surface area to thrust ratio etc), and then you can quatitively define - by observing launcher apex - whether a submerged launch is "value for money", which is THE bottom line in launchers.</font></p><p> </p> <div class="Discussion_UserSignature"> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>But you can build a such slingshot without submerging into water... A "little" hydraulics or similar gas based thingys will do the trick without water. And probably they are much more effective and simplier as well. Like aircraft carriers are slingshotting the fighters away their decks. <br />Posted by Zipi</DIV></p><p>Things like that have been evaluated in the past. Pegasus launches from an aircraft. Some versions of standard missile have a very short duration first stage/booster charge. Electric rail launchers have been considered.</p><p>But all of these things are equivalent to adding another initial stage. In most cases it turns out to be more practical to add that stage or to just make the first stage a bit bigger. Pegasus might appear to be the exception, but really is not. Pegasus was conceived from the beginning as an air-launched vehicle and the aircraft provides some flexibility in launch location as well as some initial velocity and height for the rocket stages. The aircraft is actually commonly referred as stage 0. Ares is a bit big for an air launch approach.</p><p>The bottom line is delta V. Anything that can provide additional delta V will improve performance. But the means of acquiring that additional performance must be compatible with the overall vehicle design. The vehicle must be capable of taking the loads that provide the performance.</p><p>Generally speaking if you need more performance, the way to get it is to design a vehicle that provides that performance in the first place. If you need to upgrade performance, the next place to look is in reduction in inert weight. After that you look to getting greater Isp from the rocket. There are two things that could be done to Ares SRBs in those areas. Once is to replace the steel cases with graphite-epoxy composite cases. That would require some additional design and qualification work, but it can be done, and the materials and design techniques are readily available. The other is to replace the existing propellant, and older PBAN, formulation with a more modern HTPB formulation to get a bit more Isp. I don't know if this would increase perfromance enough, but it would provide a mesurable increase in payload capability. Engineers with the details of the mission requirements and with the details of the overall vehicle design could readily determine if these changes would be sufficient. A composite case, called the FWC, was designed and ready when the Challenger disaster occurred. A second design was conceived but never funded prior to the constructin of the ISS, and HTPB propellant was evaluated at that same time. Both were evaluated in terms of the 4-segment SRBs of the shuttle, but the adaptation to a 5-segment design would be the same as what was done for the existing design. None of this, of course, comes without additional development costs or schedule impacts.<br /></p> <div class="Discussion_UserSignature"> </div>
<p> </p><p>The whole thing sounds completely impractical. Even if you were able to successfully get a fully loaded rocket to the bottom of the ocean, even if you were able to get the rocket motor to operate while submerged and under a significant amount of pressure, both of which would be extraordinarily expensive and difficult to achieve assuming it's even possible with our current technological capability, at the end of the day what advantage are you even gaining? You would use rocket fuel to get up to the surface of the water so your tank would already be partially consumed and you've only manage to get yourself back to sea level. Add in the drag of the water, and how much speed advantage do you think you could possibly gain? The entire thing is just absurd.</p><p>If you're going to go out of your way to launch from a highly unusual & inherently dangerous environment, why not instead build a launch pad on top of Mt. Everest? Of course that too would be outrageously expensive and completely impractical, but at least you would get an actual advantage of 29,000+ feet!</p><p> </p> <div class="Discussion_UserSignature"> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> The whole thing sounds completely impractical. Even if you were able to successfully get a fully loaded rocket to the bottom of the ocean, even if you were able to get the rocket motor to operate while submerged and under a significant amount of pressure, both of which would be extraordinarily expensive and difficult to achieve assuming it's even possible with our current technological capability, at the end of the day what advantage are you even gaining? You would use rocket fuel to get up to the surface of the water so your tank would already be partially consumed and you've only manage to get yourself back to sea level. Add in the drag of the water, and how much speed advantage do you think you could possibly gain? The entire thing is just absurd.</DIV></p><p> </p><p>Hmmmmm......I could be very sarcastic here, but I've decided to restrain myself:</p><p> </p><p>http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29</p><p> </p><p>The <strong>Sea Dragon</strong> was a 1962 design study for a fully reusable two-stage sea-launched rocket. The project was led by Robert Truax while working at Aerojet, one of a number of designs he created that were to be launched by floating the rocket in the ocean. </p><p>Truax's basic idea was to produce a low-cost heavy launcher. To lower the cost of operation, the rocket itself was launched from the ocean, requiring little in the way of support systems. A large ballast tank system attached to the bottom of the first-stage engine bell was used to "hoist" the rocket vertical for launch.</p><p> </p><p>http://www.astronautix.com/lvs/searagon.htm</p><p> </p><p>The launch vehicle would be fuelled with RP-1 kerosene in port, then towed horizontally to a launch point in the open ocean. It would then be filled with cryogenic liquid oxygen and hydrogen from tankers or produced by electrolysis of sea water by a nuclear aircraft carrier (such as the CVN Enterprise in the painting). After fuelling, the tanks at the launcher base would be flooded, and the vehicle would reach a vertical position in the open ocean. Launch would follow. The concept was proven with tests of the earlier Sea Bee and Sea Horse vehicles</p><p> </p><p>http://www.astronautix.com/lvs/seabee.htm</p><p> </p><p>Seabee was a brief proof of principle program to validate the sea-launch concept for Sea Dragon. A surplus Aerobee rocket was modified so that it could be fired underwater. The rocket worked properly the first time in restrained mode. Later tests were made with various approaches to readying the unit for repeat firings. This proved to be so simple that the cost of turn-around was found to be about 7% of the cost of a new unit.</p><p> </p><p>http://www.astronautix.com/lvs/seahorse.htm</p><p> </p><p>The engine was first fired several meters above the water, then lowered and fired in successive steps until reaching a considerable depth. Firing from underwater posed no problems, and there was substantial noise attenuation. In actual operation, it was planned to tow the missile to its launch site, flood attached compartments so that the missile rode vertically in the water, and then fire it.</p><p><br /><br /> </p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Hmmmmm......I could be very sarcastic here, but I've decided to restrain myself: http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29The Sea Dragon was a 1962 design study for a fully reusable two-stage sea-launched rocket. The project was led by Robert Truax while working at Aerojet, one of a number of designs he created that were to be launched by floating the rocket in the ocean. Truax's basic idea was to produce a low-cost heavy launcher. To lower the cost of operation, the rocket itself was launched from the ocean, requiring little in the way of support systems. A large ballast tank system attached to the bottom of the first-stage engine bell was used to "hoist" the rocket vertical for launch. http://www.astronautix.com/lvs/searagon.htmThe launch vehicle would be fuelled with RP-1 kerosene in port, then towed horizontally to a launch point in the open ocean. It would then be filled with cryogenic liquid oxygen and hydrogen from tankers or produced by electrolysis of sea water by a nuclear aircraft carrier (such as the CVN Enterprise in the painting). After fuelling, the tanks at the launcher base would be flooded, and the vehicle would reach a vertical position in the open ocean. Launch would follow. The concept was proven with tests of the earlier Sea Bee and Sea Horse vehicles http://www.astronautix.com/lvs/seabee.htmSeabee was a brief proof of principle program to validate the sea-launch concept for Sea Dragon. A surplus Aerobee rocket was modified so that it could be fired underwater. The rocket worked properly the first time in restrained mode. Later tests were made with various approaches to readying the unit for repeat firings. This proved to be so simple that the cost of turn-around was found to be about 7% of the cost of a new unit. http://www.astronautix.com/lvs/seahorse.htmThe engine was first fired several meters above the water, then lowered and fired in successive steps until reaching a considerable depth. Firing from underwater posed no problems, and there was substantial noise attenuation. In actual operation, it was planned to tow the missile to its launch site, flood attached compartments so that the missile rode vertically in the water, and then fire it. <br />Posted by kyle_baron</DIV></p><p>In the summer of 1962, I was working for R.C.Truax at Aerojet's Advanced Development Dept. I was running calculations on first stage boosters of 20, 40, 60, 80 and 100 MILLION LB THRUST Sea Dragon 1st stages! We were also working on designs that utilized self-pressurizing boosters, utilizing hypergolic propellants that were liquid under their own vapor pressures. All you had to do was open the valves at the bottom of the tanks, the liquid boiled at the top of the liquid column, pressurizing and feeding the propellants. Pressures could be increased by either cooling the propellant prior to loading, or heating the tanks. (For the Aerobee proof-of-concept vehicle, they wrapped the tanks in an electric blanket! Worked like a charm! Of course, ISP went to h--l, and combustion chamber pressure had to be lower than the tank pressure plus the pressure drop across the injector head. Which didn't give you much leaway. So far as ISP was concerned, who cared...with a 100M LB thrust 1st stage? Anyhow, it was a lot of fun for a college kid.</p><p>Ad Luna! Ad Ares! Ad Astra!<br /></p>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Hmmmmm......I could be very sarcastic here, but I've decided to restrain myself: http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29The Sea Dragon was a 1962 design study for a fully reusable two-stage sea-launched rocket. The project was led by Robert Truax while working at Aerojet, one of a number of designs he created that were to be launched by floating the rocket in the ocean. Truax's basic idea was to produce a low-cost heavy launcher. To lower the cost of operation, the rocket itself was launched from the ocean, requiring little in the way of support systems. A large ballast tank system attached to the bottom of the first-stage engine bell was used to "hoist" the rocket vertical for launch. http://www.astronautix.com/lvs/searagon.htmThe launch vehicle would be fuelled with RP-1 kerosene in port, then towed horizontally to a launch point in the open ocean. It would then be filled with cryogenic liquid oxygen and hydrogen from tankers or produced by electrolysis of sea water by a nuclear aircraft carrier (such as the CVN Enterprise in the painting). After fuelling, the tanks at the launcher base would be flooded, and the vehicle would reach a vertical position in the open ocean. Launch would follow. The concept was proven with tests of the earlier Sea Bee and Sea Horse vehicles http://www.astronautix.com/lvs/seabee.htmSeabee was a brief proof of principle program to validate the sea-launch concept for Sea Dragon. A surplus Aerobee rocket was modified so that it could be fired underwater. The rocket worked properly the first time in restrained mode. Later tests were made with various approaches to readying the unit for repeat firings. This proved to be so simple that the cost of turn-around was found to be about 7% of the cost of a new unit. http://www.astronautix.com/lvs/seahorse.htmThe engine was first fired several meters above the water, then lowered and fired in successive steps until reaching a considerable depth. Firing from underwater posed no problems, and there was substantial noise attenuation. In actual operation, it was planned to tow the missile to its launch site, flood attached compartments so that the missile rode vertically in the water, and then fire it. <br />Posted by kyle_baron</DIV></p><p>Interesting. But this has nothing whatever to do with</p><p>1. Improving performance by launching submerged.</p><p>2. Ability to ignite a solid rocket with the nozzle obstructed and not cause the case to rupture almost immediately.</p><p>It has to do with a concept for reducing the costs associated with conventional launch site operations. It apparently came to nothing.</p><p>You can operate rockets under water, if you avoid ignition with the nozzle obstructed and pay attention to fluid dynamics. Just such a concept was considered for supercavitating torpedoes. But if you try to launch the Ares 1 submerged the result will be tragic.</p><p>Better restrain the sarcasm. It might backfire.</p> <div class="Discussion_UserSignature"> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Hmmmmm......I could be very sarcastic here, but I've decided to restrain myself<br /> Posted by kyle_baron</DIV></p><p>Because you would be making an a$$ of yourself since this is not applicable to the SRB of the Ares I.</p><p> </p><p>Also, it has a drawback that it has to lift the water in the flooded ballast tanks until they drained in flight. </p>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In the summer of 1962, I was working for R.C.Truax at Aerojet's Advanced Development Dept. I was running calculations on first stage boosters of 20, 40, 60, 80 and 100 MILLION LB THRUST Sea Dragon 1st stages! We were also working on designs that utilized self-pressurizing boosters, utilizing hypergolic propellants that were liquid under their own vapor pressures. All you had to do was open the valves at the bottom of the tanks, the liquid boiled at the top of the liquid column, pressurizing and feeding the propellants. Pressures could be increased by either cooling the propellant prior to loading, or heating the tanks. (For the Aerobee proof-of-concept vehicle, they wrapped the tanks in an electric blanket! Worked like a charm! Of course, ISP went to h--l, and combustion chamber pressure had to be lower than the tank pressure plus the pressure drop across the injector head. Which didn't give you much leaway. So far as ISP was concerned, who cared...with a 100M LB thrust 1st stage? Anyhow, it was a lot of fun for a college kid.Ad Luna! Ad Ares! Ad Astra! <br />Posted by trailrider</DIV></p><p>Thank you for your personal experiences! But, how did the exhausts work under water?<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You can operate rockets under water, if you avoid ignition with the nozzle obstructed and pay attention to fluid dynamics. <br />Posted by DrRocket</DIV></p><p>And that's all I wanted to show, at this time. Thank you. By avoiding ignition with the nozzle obstructed, do you mean a secondary explosion? And how is that avoided?<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Because you would be making an a$$ of yourself since this is not applicable to the SRB of the Ares I. <br />Posted by Cygnus_2112</DIV></p><p> </p><p>Ouch!<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Also, it has a drawback that it has to lift the water in the flooded ballast tanks until they drained in flight. <br />Posted by Cygnus_2112</DIV></p><p>Ok, but I'd like to go back to this question and answer:</p><p> </p><p>Replying to:</p><div class="Discussion_PostQuote"> Does 4,000-5,000 lbs. of polyurathane foam on the 2nd stage, qualify as a huge floatation device? <br />Posted by kyle_baron</div><p> </p><p>no, not compared to the 2 million lb or so vehicle. That is insignificant, only a couple of percent. Hardly would make a difference </p><p> </p><p>If that's true, then I should immediatly throw out my 2 lb life preserver that wraps around my upper torso, and allows my 200 lb body, to remain afloat. I believe 2/200 comes out to 1%.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
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