Ares I Launch, Under Water

Status
Not open for further replies.
K

kyle_baron

Guest
Ok, this is a theoretical question, involving putting the 5 segment SRB, under water, in the Atlantic.&nbsp; Therefore, the rocket will be half under water.&nbsp; Similar, but not exactly the same as a submarine launched missle.&nbsp; Are there any advantages of buoyancy (less weight), less noise, and no flame trench to get wrecked?&nbsp; What are the disadvantages?&nbsp; I couldn't think of any. <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
G

gawin

Guest
<p>One thing that you should know is that most sub launched missiles do not ignite until they are above the surface of the sea. They are "shot" out of there launch tubes usually with a compressed gas or simple compressed air.</p><p>&nbsp;</p><p>A good view of the ignition can be seen here at aprox 1 min into the video.</p><p>&nbsp;http://www.youtube.com/watch?v=GwHZsiDZzDU</p><p>&nbsp;hope this helps you out.&nbsp;</p>
 
C

Cygnus_2112

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ok, this is a theoretical question, involving putting the 5 segment SRB, under water, in the Atlantic.&nbsp; Therefore, the rocket will be half under water.&nbsp; Similar, but not exactly the same as a submarine launched missle.&nbsp; Are there any advantages of buoyancy (less weight), less noise, and no flame trench to get wrecked?&nbsp; What are the disadvantages?&nbsp; I couldn't think of any. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;No advantages and not viable.</p><p>&nbsp;It wouldn't float, it would sink and not be "half" under water.&nbsp; the water/air pressure would affect ignition. The casings rust in water.&nbsp;&nbsp; </p>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Ok, this is a theoretical question, involving putting the 5 segment SRB, under water, in the Atlantic.&nbsp; Therefore, the rocket will be half under water.&nbsp; Similar, but not exactly the same as a submarine launched missle.&nbsp; Are there any advantages of buoyancy (less weight), less noise, and no flame trench to get wrecked?&nbsp; What are the disadvantages?&nbsp; I couldn't think of any. <br />Posted by kyle_baron</DIV></p><p>Submarine-launched ballistic missiles do not ignite under water.&nbsp; It they ignited while water blocked the exit plane of the nozzle there would be a severe over-pressurization and the motot would probably blow up.&nbsp; They are launched by a gas generator which puts them clear of the surface before ignition.&nbsp;Iin addition there is a baffle in the nozzle that is designed to keep water out of it and to break at a mangeable pressure.&nbsp; 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.</p><p>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.</p> <div class="Discussion_UserSignature"> </div>
 
Q

qso1

Guest
<p>From just a cost standpoint alone, it would be cheaper to simply repair the flame trench. I'm sure the trench has been heavily damaged and subsequently repaired from past missions. Consider how you'd have to get the LV to an underwater launch mount, another expensive piece of GSE, that is, a structure underwater to support the LV prior to launch.&nbsp;</p> <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>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;No advantages and not viable.</DIV></p><p>&nbsp;</p><p>Why am I not surprised at that statement?&nbsp; Actually, I've been expecting it.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /></p><p>&nbsp;</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It wouldn't float, it would sink and not be "half" under water.</DIV></p><p>&nbsp;</p><p>Ok, then submerge Ares I up to the service module.&nbsp; At that point it still may not float, but it could be close to weightlessness.</p><p>&nbsp;</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> the water/air pressure would affect ignition.</DIV></p><p>&nbsp;</p><p>As Dr. Rocket stated, breakable baffles.</p><p>&nbsp;</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The casings rust in water.&nbsp;&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>&nbsp;</p><p>The casings fall in the ocean after SRB seperation.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Submarine-launched ballistic missiles do not ignite under water.Replying to:<BR/><DIV CLASS='Discussion_PostQuote'></p><p>&nbsp;</p><p>Understood.</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp; It they ignited while water blocked the exit plane of the nozzle there would be a severe over-pressurization and the motot would probably blow up.</DIV></p><p>&nbsp;</p><p>Understood, back-pressure is involved.&nbsp; Aren't SRB's simple motors, involving vanes near the bottom?&nbsp; I would think those could be beefed up.</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;In addition there is a baffle in the nozzle that is designed to keep water out of it and to break at a mangeable pressure.</DIV></p><p>&nbsp;</p><p>Understood, something similar would be needed for an SRB.</p><p>&nbsp;</p><p>&nbsp;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.</DIV></p><p>&nbsp;</p><p>Understood, but the nozzle on the SRB is wide, and the water would provide some back pressure to the nozzle, compared to air.&nbsp; In this instance, back pressure is good.</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>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. <br />Posted by DrRocket</DIV></p><p>&nbsp;</p><p>Yeah, yeah, yeah, an explosion, I get it.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" /><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Consider how you'd have to get the LV to an underwater launch mount, another expensive piece of GSE, that is, a structure underwater to support the LV prior to launch.&nbsp; <br />Posted by qso1</DIV></p><p>&nbsp;</p><p>Understood, but consider the near weightlessness at liftoff, and the acceleration advantage.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Understood, back-pressure is involved.&nbsp; Aren't SRB's simple motors, involving vanes near the bottom?&nbsp; I would think those could be beefed up.&nbsp;&nbsp;Understood, something similar would be needed for an SRB.&nbsp;&nbsp;&nbsp;Understood, but the nozzle on the SRB is wide, and the water would provide some back pressure to the nozzle, compared to air.&nbsp; In this instance, back pressure is good.&nbsp;&nbsp;Yeah, yeah, yeah, an explosion, I get it.&nbsp; <br />Posted by kyle_baron</DIV></p><p>SBRs are probably more complicated that you think, but the complication is in the design and not in a lot of moving parts.&nbsp; There are no vanes in the SRBs.&nbsp; You might be thinking of fin-like features in the propellant grain, but they are there to provide initial surface area and are not relevant to the questions at hand.&nbsp; In the case of the shuttle,&nbsp; the fins slots in the grain are in the head end.</p><p>The problem with igniting underwater is not just a little back pressure.&nbsp; You have to move the water out of the way to get the gasses flowing, and until that is done the back pressure communicates with the interior pressure of the motor.&nbsp; That water has a lot of mass and takes too long to get out of the way.&nbsp; In the meantime the motor pressure is going up very rapidly and the burn rate is going up with it.&nbsp; The motor will probably burst.&nbsp; It will, technically, probably not be an explosion, but the distinction will be lost on a nearby observer.</p><p>The Titan IV SRB was tested vertically in a test stand with a water spray.&nbsp; Steps were taken to keep any significant amount of water away from the nozzle exit plane at ignition.&nbsp; That was a long way from a submerged ignition. </p><p>The flow in a rocket nozzle is choked at the throat and supersonic in the nozzle cone.&nbsp; The transition from nothing to choked flow takes place very quickly, as soon as chamber pressure hit the critical value which is only about double ambient pressure.&nbsp; You want to get the flow established quickly and to get any nozzle obstructions out the way as soon as possible.&nbsp; You simply cannot tolerate having to move a lot of water out of the way.&nbsp; Creating a bunch of shock waves in the nozzle cone is a bad idea, unless it is very carefully controlled as in liquid injection thrust vector control systems (but that uses a very small amount of injectant).<br /></p> <div class="Discussion_UserSignature"> </div>
 
C

Cygnus_X_1

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Why am I not surprised at that statement?&nbsp; Actually, I've been expecting it.&nbsp; &nbsp;&nbsp;&nbsp;Ok, then submerge Ares I up to the service module.&nbsp; At that point it still may not float, but it could be close to weightlessness.&nbsp;&nbsp;&nbsp;As Dr. Rocket stated, breakable baffles.&nbsp;&nbsp;&nbsp;The casings fall in the ocean after SRB seperation. <br />Posted by kyle_baron</DIV></p><p>the statement is true.&nbsp; There is no advantage.<br />It will never float.&nbsp; It will sink.&nbsp; It would need huge floatation devices.</p><p>So what that the casing fall into the ocean after separation.&nbsp; They are done with the mission and it doesn't matter that they rust (which they do).</p> <div class="Discussion_UserSignature"> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The problem with igniting underwater is not just a little back pressure.&nbsp; You have to move the water out of the way to get the gasses flowing, and until that is done the back pressure communicates with the interior pressure of the motor.&nbsp; That water has a lot of mass and takes too long to get out of the way.&nbsp; In the meantime the motor pressure is going up very rapidly and the burn rate is going up with it.&nbsp; The motor will probably burst.</DIV></p><p>&nbsp;</p><p>How long do you think the SRB will be under water, when the rocket is near weightless, and the thrust is 2.8 million lbs?&nbsp; It's going to jump right out.&nbsp; I guess, less than 2 sec.&nbsp; unless the back pressure explosion occurs in milli seconds, the rocket will be air borne.</p><p>Also, the "motor" is the ignitor at the top of the SRB in this diagram:</p><p>http://upload.wikimedia.org/wikipedia/en/d/d8/SpaceShuttleSolidRocketBooster.png</p><p>&nbsp;</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;The flow in a rocket nozzle is choked at the throat and supersonic in the nozzle cone.&nbsp; The transition from nothing to choked flow takes place very quickly, as soon as chamber pressure hit the critical value which is only about double ambient pressure.&nbsp; You want to get the flow established quickly and to get any nozzle obstructions out the way as soon as possible.&nbsp; You simply cannot tolerate having to move a lot of water out of the way.&nbsp; Creating a bunch of shock waves in the nozzle cone is a bad idea, ..... <br />Posted by DrRocket</DIV></p><p>&nbsp;</p><p>Again, a short time span.&nbsp; Also, the nozzle cone on the SRB is short and wide, for minimum shock waves.</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;How long do you think the SRB will be under water, when the rocket is near weightless, and the thrust is 2.8 million lbs?&nbsp; It's going to jump right out.&nbsp; I guess, less than 2 sec.&nbsp; unless the back pressure explosion occurs in milli seconds, the rocket will be air borne.Also, the "motor" is the ignitor at the top of the SRB in this diagram:http://upload.wikimedia.org/wikipedia/en/d/d8/SpaceShuttleSolidRocketBooster.pngAgain, a short time span.&nbsp; Also, the nozzle cone on the SRB is short and wide, for minimum shock waves. <br />Posted by kyle_baron</DIV><br />&nbsp;</p><p>I don't know how many large solid rockets you have been involved with, but I have been in on the technical work for quite a few, including SLBMs and space boosters, including the shuttle SRBs.&nbsp; What part of "blow up" don't you understand ?</p> <div class="Discussion_UserSignature"> </div>
 
D

dragon04

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;How long do you think the SRB will be under water, when the rocket is near weightless, and the thrust is 2.8 million lbs?&nbsp; It's going to jump right out.&nbsp; I guess, less than 2 sec.&nbsp; unless the back pressure explosion occurs in milli seconds, the rocket will be air borne.Also, the "motor" is the ignitor at the top of the SRB in this diagram:http://upload.wikimedia.org/wikipedia/en/d/d8/SpaceShuttleSolidRocketBooster.pngAgain, a short time span.&nbsp; Also, the nozzle cone on the SRB is short and wide, for minimum shock waves. <br /> Posted by kyle_baron</DIV></p><p>Buoyancy and weightlessness are two different things, and at the bottom of it all, the Earth is still pulling Ares I towards its center at a force of 1G. </p> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I don't know how many large solid rockets you have been involved with, but I have been in on the technical work for quite a few, including SLBMs and space boosters, including the shuttle SRBs.</DIV></p><p>&nbsp;</p><p>Maybe that's part of the problem, when you're conditioned to see things one way.</p><p>&nbsp;</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> What part of "blow up" don't you understand ? <br />Posted by DrRocket</DIV></p><p>&nbsp;</p><p>The part I don't understand is the timing.&nbsp; The amount of time it would take to "blow up".&nbsp; I assume we're talking about blowing up the 1/2" thick steel casing of the SRB.&nbsp; Care to take a stab at it?&nbsp; In any case, I would think that 2.8 million lbs. of thrust would move a lot of water very quickly.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Maybe that's part of the problem, when you're conditioned to see things one way.&nbsp;&nbsp;&nbsp;The part I don't understand is the timing.&nbsp; The amount of time it would take to "blow up".&nbsp; I assume we're talking about blowing up the 1/2" thick steel casing of the SRB.&nbsp; Care to take a stab at it?&nbsp; In any case, I would think that 2.8 million lbs. of thrust would move a lot of water very quickly. <br />Posted by kyle_baron</DIV></p><p>We'll I've seen a large rocket motor case overpressurize and blow up on ignition in about 60 milliseconds.&nbsp; That is about the length of time it takes to blink twice.</p> <div class="Discussion_UserSignature"> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>We'll I've seen a large rocket motor case overpressurize and blow up on ignition in about 60 milliseconds.&nbsp; That is about the length of time it takes to blink twice. <br />Posted by DrRocket</DIV></p><p>&nbsp;</p><p>Well, that raises some questions:</p><p>1.&nbsp; Was it a 1/2" steel shuttle SRB case, or some other (aluminum) rocket case?</p><p>2.&nbsp; What was the pressure, and reason for it blowing up?<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Well, that raises some questions:1.&nbsp; Was it a 1/2" steel shuttle SRB case, or some other (aluminum) rocket case?2.&nbsp; What was the pressure, and reason for it blowing up? <br />Posted by kyle_baron</DIV></p><p>&nbsp;No, it was about 1/2&nbsp; inch thick graphite composite, considerably stronger than steel.&nbsp; It blew up because of pressure due to inhibited gas flow.</p><p>&nbsp;EDIT: Correction, that case was a bit over 3/4 in thick.</p> <div class="Discussion_UserSignature"> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;No, it was about 1/2&nbsp; inch thick graphite composite, considerably stronger than steel.&nbsp; It blew up because of pressure due to inhibited gas flow.&nbsp;EDIT: Correction, that case was a bit over 3/4 in thick. <br />Posted by DrRocket</DIV></p><p>&nbsp;</p><p>I understand your position.&nbsp; Pardon me for asking these direct questions, but I get the feeling that you're hiding some information.</p><p>&nbsp;</p><p>1.&nbsp; Was it specifically an SRB casing?</p><p>2.&nbsp; How large was this casing?&nbsp; Was it the length of a shuttle SRB?<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I understand your position.&nbsp; Pardon me for asking these direct questions, but I get the feeling that you're hiding some information.&nbsp;1.&nbsp; Was it specifically an SRB casing?2.&nbsp; How large was this casing?&nbsp; Was it the length of a shuttle SRB? <br />Posted by kyle_baron</DIV></p><p>It was a large solid rocket motor.&nbsp; I am hiding nothing of importance, but&nbsp; I am not going to go into detail into the nature of the specific program.&nbsp; The bottom line is that your idea of igniting a large solid rocket motor while&nbsp;largely submerged will not work and the failure would be spectacular.&nbsp; It is an issue of fluid dynamics.&nbsp; <br /></p> <div class="Discussion_UserSignature"> </div>
 
C

Cygnus_2112

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Maybe that's part of the problem, when you're conditioned to see things one way.&nbsp;&nbsp;&nbsp;The part I don't understand is the timing.&nbsp; The amount of time it would take to "blow up".&nbsp; I assume we're talking about blowing up the 1/2" thick steel casing of the SRB.&nbsp; Care to take a stab at it?&nbsp; In any case, I would think that 2.8 million lbs. of thrust would move a lot of water very quickly. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>The problem is that you aren't "conditioned" in engineering/physics </p><p>&nbsp;1.&nbsp; Floating in water doen't mean there is no gravity. </p><p>2.&nbsp; there would be more drag in the water</p><p>3.&nbsp; The water would impede the startup of the rocket more than air&nbsp;</p><p>4.&nbsp; Being in water means it would be lower and have to fly further.&nbsp; minor but still a difference&nbsp;</p>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Maybe that's part of the problem, when you're conditioned to see things one way.&nbsp;&nbsp;&nbsp;The part I don't understand is the timing.&nbsp; The amount of time it would take to "blow up".&nbsp; I assume we're talking about blowing up the 1/2" thick steel casing of the SRB.&nbsp; Care to take a stab at it?&nbsp; In any case, I would think that 2.8 million lbs. of thrust would move a lot of water very quickly. <br />Posted by kyle_baron</DIV></p><p>Look, I've been focusing on the catastrophic failure aspects of this nutty idea, but let's take a siimple look at the physics, even if it did not result in a loud noise and a fireball.</p><p>That rocket is not going to float.&nbsp; It is too dense, and if there were enough free volume to provide positive buoyancy, you would add more propellant.&nbsp; So, if you put it in water, the net force is still down.&nbsp; To raise it to the surface you need to&nbsp;apply a force over the submerged length of the rocket, and force times distance is work.&nbsp; That work must be supplied by the thrust of the motor once it is ignited.&nbsp; So you are consuming some of the available energy from the operation of the rocket in simply bring the rocket to the level of the surface of the water.&nbsp; This is not a big effect, but whatever effect there is happens to be negative.&nbsp; You would be better off launching from a raised platform, but again not enough better off to make much difference, unless you do something like they do on Pegasus and launch from an aircraft, but that is really just adding a stage to the enterprise.</p><p>Even if the damn thing did float, the added delta v would be no more than you might see when a fishing bobber pops up to the surface.&nbsp; Not enough to care about.</p><p>So, no the problem is not that people are not flexible in their their thinking.&nbsp; There is a reason that launch systems are designed by professionals.</p> <div class="Discussion_UserSignature"> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;&nbsp;1.&nbsp; Floating in water doen't mean there is no gravity. </DIV></p><p>&nbsp;</p><p>I believe everyone knows that.</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>2.&nbsp; there would be more drag in the water</DIV></p><p>&nbsp;</p><p>Yes, some what.</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>3.&nbsp; The water would impede the startup of the rocket more than air</DIV></p><p>&nbsp;</p><p>Ok, now we're comming to the next issue, that I wanted to discuss.&nbsp; Obviously, the rocket would have to be elevated off the ocean floor, and have flame trenches modified into&nbsp;vacant tunnels with blast baffles, to initialize the start up of the&nbsp;SRB.&nbsp; Very similar to what we have now.&nbsp; As I understand it, once&nbsp;the SRB is&nbsp;lit, it is a self-sustaining process.&nbsp;</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>4.&nbsp; Being in water means it would be lower and have to fly further.&nbsp; minor but still a difference&nbsp; <br />Posted by Cygnus_2112</DIV></p><p>&nbsp;</p><p>Yes, very minor.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Look, I've been focusing on the catastrophic failure aspects of this nutty idea</DIV></p><p>&nbsp;</p><p>OK, why don't you take a break, and not focus on these aspects (if it's too dificult for you).&nbsp; I really don't care what you might think of my "theoretical idea".</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That rocket is not going to float.&nbsp; It is too dense</DIV></p><p>&nbsp;</p><p>&nbsp;Well, let's see here, the (1st stage SRB) has open spaces (inside)&nbsp;near the top, and bottom (elec tunnels) and is filled with with a substance which has the density of a pencil eraser.&nbsp; The larger&nbsp;2nd stage, &nbsp;is filled with&nbsp;LIQUID hydrogen and LIQUID oxygen.&nbsp; None of this sounds too dense to me.&nbsp;</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Even if the damn thing did float, the added delta v would be no more than you might see when a fishing bobber pops up to the surface.&nbsp; Not enough to care about.</DIV></p><p>&nbsp;</p><p>Of course, but that's not what I'm saying.&nbsp; I'm saying, take the fishing bobber and apply 2.8 million lbs. of force to it.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" /></p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>So, no the problem is not that people are not flexible in their their thinking.&nbsp; There is a reason that launch systems are designed by professionals. <br />Posted by DrRocket</DIV></p><p>&nbsp;</p><p>That's a no-brainer.&nbsp; Yet, the professionals "have to be told" what to design.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" />&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p><br /><br />&nbsp;</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
D

DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;OK, why don't you take a break, and not focus on these aspects (if it's too dificult for you).&nbsp; </p><p>&nbsp;<font color="#0000ff">?</font>???</p><p>I really don't care what you might think of my "theoretical idea".&nbsp;</p><p><font color="#0000ff">No, a&nbsp;theoretical idea in engineering is one that complies with known physics.&nbsp; This one doesn't pass that test.</font>&nbsp; <font color="#0000ff">You really could do with a basic physics class.&nbsp; And that fact that you don't care what comes of an analysis of your concept using basic physics speaks volumes.</font></p><p>&nbsp;&nbsp;Well, let's see here, the (1st stage SRB) has open spaces (inside)&nbsp;near the top, and bottom (elec tunnels) and is filled with with a substance which has the density of a pencil eraser.&nbsp;</p><p><font color="#0000ff">There are no electrical tunnels inside the case of a solid rocket motor.&nbsp; That&nbsp; propellant that you&nbsp;"think"&nbsp;has the density of pencil eraser has a specific gravity of about 1.8.</font>&nbsp; <font color="#0000ff">And there is alot of it.</font> <font color="#0000ff">The free volume is, as I told you before, relatively small prior to ignition.&nbsp; If you had a lot of unnecessary free volume you would add propellant.&nbsp; The only reason for the free volume at all is to allow proper gas flow and to obtain sufficent surface area to produce high mass flow.</font></p><p><font color="#0000ff">BTW every try to float a pencil eraser ?&nbsp; Sinks like a rock.</font></p><p>&nbsp;The larger&nbsp;2nd stage, &nbsp;is filled with&nbsp;LIQUID hydrogen and LIQUID oxygen.&nbsp; None of this sounds too dense to me.&nbsp;&nbsp;</p><p><font color="#0000ff">Liquid oxygen has a specific gravity of about 1.14 (more dense than water).&nbsp; Liquid&nbsp;hydrogen is quite light with a specific gravity of only 0.071 but both are contained in&nbsp;vessels of quite a bit higher density and both sit ON TOP of the solid rocket motor in the Ares I vehicle.&nbsp; So even if you could float the vehicle using the upper stages, which you won't, as soon as the upper stages broke the surface, any buoyancy would be negated.&nbsp; So assume that the upper stages are so light that they float the solids with no immersion of the upper stages at all (you can't do this, but takei it as a very optimistic assessment).&nbsp; Then the vehicle is still starting from a lower position than it would if launched at the level of the water for a net performance decrease.&nbsp; So when it blows up, it will be below the level of a normal launch pad.</font></p><p><font color="#0000ff">I know it&nbsp;does not sound too dense to you.&nbsp; That is because you are being quite dense and don't know&nbsp;what you are talking about.</font>&nbsp;</p><p>&nbsp;Of course, but that's not what I'm saying.&nbsp; I'm saying, take the fishing bobber and apply 2.8 million lbs. of force to it.&nbsp; &nbsp;&nbsp;That's a no-brainer.&nbsp;</p><p><font color="#0000ff">It certijnly is a no brainer.&nbsp; The applied thrust has nothing to do with increasing the delta v above what you would get without submerging the rocket.&nbsp; You might want to try applying some brains.&nbsp; Maybe you have a friend.</font></p><p>&nbsp;Yet, the professionals "have to be told" what to design.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p><p><font color="#0000ff">No they don't.&nbsp; And certainly&nbsp;not by the likes of you.&nbsp; What the professionals are given is a mission to be accomplished, not instructions on how to perform that mission.</font>&nbsp;</p><p><br />Posted by kyle_baron</DIV></p> <div class="Discussion_UserSignature"> </div>
 
K

kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> <font color="#0000ff">I know it&nbsp;does not sound too dense to you.&nbsp; That is because you are quite dense and don't know&nbsp;what you are talking about.</font>&nbsp;<br />Posted by DrRocket</DIV></p><p>"I am quite dense."&nbsp; I believe that you've commited an offense here.&nbsp; I take that as a personal attack.&nbsp; In the spirit of this heated debate, I will let this one slide.&nbsp; However, if you do it again, I will complain to the moderators, and you will be suspended, or banned. <br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
Status
Not open for further replies.

ASK THE COMMUNITY

TRENDING THREADS

Latest posts