Ares I: Thrust Occiliation (TO)

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kyle_baron

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With all due respect to the 7 brave astronauts who died in the Challenger accident in 1986, why not put a few holes into the sides of the SRB to reduce POGO or TO for Ares I?&nbsp; Of course you would lose some thrust, depending on the size of the holes, but you'd also reduce the pressure buildup with in the core of the SRB.&nbsp; There would be no weight penalties involved like other alternatives.&nbsp; And if Nasa decides to add another 1/2 segment to the stack, there may be thrust to waste, in this solution. <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>With all due respect to the 7 brave astronauts who died in the Challenger accident in 1986, why not put a few holes into the sides of the SRB to reduce POGO or TO for Ares I?&nbsp; Of course you would lose some thrust, depending on the size of the holes, but you'd also reduce the pressure buildup with in the core of the SRB.&nbsp; There would be no weight penalties involved like other alternatives.&nbsp; And if Nasa decides to add another 1/2 segment to the stack, there may be thrust to waste, in this solution. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>That's how you shut off an SRM and it wouldn't fix the problem and it would cause more problems </p><p>&nbsp;</p><p>Also if it would to were to work, it would be bad engineering.&nbsp; It would be like having an 8 cylinder engine and only supplying fuel to 6 cylinders.&nbsp; The fix is to use a 6 cylinder engine, not modify the 8 cylinder engine. &nbsp; </p>
 
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MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>With all due respect to the 7 brave astronauts who died in the Challenger accident in 1986, why not put a few holes into the sides of the SRB to reduce POGO or TO for Ares I?&nbsp; Of course you would lose some thrust, depending on the size of the holes, but you'd also reduce the pressure buildup with in the core of the SRB.&nbsp; There would be no weight penalties involved like other alternatives.&nbsp; And if Nasa decides to add another 1/2 segment to the stack, there may be thrust to waste, in this solution. <br />Posted by kyle_baron</DIV><br /><br />That is a preposterous idea. Thrust leaking out is what blew up Challenger. Holes in the side, even facing away from the tank, would cause huge problems. This idea belongs in the dustbin; do not pass go, do not collect $200. <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>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;That's how you shut off an SRM and it wouldn't fix the problem and it would cause more problems</DIV></p><p>Please elaborate.&nbsp; I know the ignitor is at the top of the SRB.&nbsp; Are you saying that the ignitor wouldn't work?</p><p>&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;&nbsp;Also if it would to were to work, it would be bad engineering.&nbsp; It would be like having an 8 cylinder engine and only supplying fuel to 6 cylinders.&nbsp; The fix is to use a 6 cylinder engine, not modify the 8 cylinder engine. &nbsp; <br />Posted by Cygnus_2112</DIV></p><p>Isn't POGO or TO wasted&nbsp; thrust movement with in the SRB?&nbsp; Maybe the holes don't have to be full openings.&nbsp; Maybe they could just be a type of spring loaded-pressure relief valve.</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That is a preposterous idea. Thrust leaking out is what blew up Challenger. Holes in the side, even facing away from the tank, would cause huge problems. This idea belongs in the dustbin; do not pass go, do not collect $200. <br />Posted by MeteorWayne</DIV></p><p>No need to get emotional, MW.&nbsp; This is my 1st strike.&nbsp; I get two more, before I'm out.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" />&nbsp;<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Please elaborate.&nbsp; I know the ignitor is at the top of the SRB.&nbsp; Are you saying that the ignitor wouldn't work?&nbsp;Isn't POGO or TO wasted&nbsp; thrust movement with in the SRB?&nbsp; Maybe the holes don't have to be full openings.&nbsp; Maybe they could just be a type of pressure relief valve. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>ICBM's blow holes in the top of the motor to shut them down. &nbsp; The SRB wouldn't light with holes, it needs pressure to operation. &nbsp;&nbsp; TO is a pressure oscillation and is present in all solid motors.&nbsp; </p><p>Relief valves wouldn't stop the problem and the valves themselves wouldn't be able to function in a motor. &nbsp; </p>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;ICBM's blow holes in the top of the motor to shut them down. &nbsp; The SRB wouldn't light with holes, it needs pressure to operation. &nbsp;&nbsp; TO is a pressure oscillation and is present in all solid motors.</DIV></p><p>Thank you for the explanation.</p><p>&nbsp;</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Relief valves wouldn't stop the problem and the valves themselves wouldn't be able to function in a motor. &nbsp; <br />Posted by Cygnus_2112</DIV></p><p>I was thinking that the relief valves would be a protrusion, on the outside casing of the SRB.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>No need to get emotional, MW.&nbsp; This is my 1st strike.&nbsp; I get two more, before I'm out.&nbsp; &nbsp; <br />Posted by kyle_baron</DIV><br /><br />That's not emotional at all. It's called rational.</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>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I was thinking that the relief valves would be a protrusion, on the outside casing of the SRB. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>In or on a motor, the problem is the hole.&nbsp; The propellant insulates the casing.&nbsp; The casing never come in contact with the combustion </p>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>With all due respect to the 7 brave astronauts who died in the Challenger accident in 1986, why not put a few holes into the sides of the SRB to reduce POGO or TO for Ares I?&nbsp; Of course you would lose some thrust, depending on the size of the holes, but you'd also reduce the pressure buildup with in the core of the SRB.&nbsp; There would be no weight penalties involved like other alternatives.&nbsp; And if Nasa decides to add another 1/2 segment to the stack, there may be thrust to waste, in this solution. <br />Posted by kyle_baron</DIV></p><p>Polgo is a phenomena that is limited to liquids.&nbsp; Solids can&nbsp;exhibit a&nbsp;phenomena associated with acoustic burning, but the rumored problem is even a bit different from the classic acoustic burning issue.&nbsp; </p><p>The last time that I checked the thrust oscillation problem had basically gone away.&nbsp; This was to be confirmed with upcoming testing.&nbsp; In any the case the concern that was raised was the result of speculation and not the result of empirical data, so it is a bit early to start worrying too much.&nbsp; Drilling holes in and SRB case will quickly cause a failure.&nbsp; It is a seriously bad idea --- much worse even than the idea of igniting underwater.&nbsp; A great deal of the effort spent in manfacturing a solid is directed at making certain that there are NO leaks, not even tiny ones in the rocket motor case or the various seals.</p><p>In any case, the hypothetical thrust oscillation problem was of quite low&nbsp;frequency and the hypothetical effect was on the humans on board.&nbsp; The fix, should it be needed, was to provide isolation to the humans.&nbsp; The problem was never one of acoustic instability or a catastrophic rocket failure.<br /></p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;In or on a motor, the problem is the hole.&nbsp; The propellant insulates the casing.&nbsp; The casing never come in contact with the combustion <br />Posted by Cygnus_2112</DIV></p><p>I was thinking that the "hole" would be a piece of steel pipe with holes in it, from the core to the relief valve (located outside the casing).&nbsp; The steel pipe can burn up, along with the propellent.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In any case, the hypothetical thrust oscillation problem was of quite low&nbsp;frequency and the hypothetical effect was on the humans on board.&nbsp; The fix, should it be needed, was to provide isolation to the humans.&nbsp; The problem was never one of acoustic instability or a catastrophic rocket failure. <br />Posted by DrRocket</DIV><br /><br />This is how bad it is:</p><blockquote>"Think mice in a paint can in your local paint store, with the can on the vibrator/mixer. Not a pretty sight. <br /><br />Hitting +/- 6.4 g at 110 seconds and continuing till SRB sep at ~128 seconds will leave your brains in an awful state.<br /></blockquote><p><br />Chuck,<br />That's what I thought but I was told that a paint shaker is actually a lot less powerful.&nbsp; &nbsp;They typically oscillate around 4-6Hz and with less than half the force.<br /><br />I mentioned the head of a jack-hammer previously because I've been told that it would be in the right frequency range (~15Hz) and the force equates to about 7-8g acceleration at the tip which isn't far off.<br /><br />I can't find a closer "real world" example of the forces yet - but if anyone else can find one it would be nice to have another example to use" <img class="smiley" src="http://nsf.breakie.com/Smileys/default/smiley.gif" border="0" alt=":)" title="Smiley" /><br /><br />Ross. </p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;ICBM's blow holes in the top of the motor to shut them down. &nbsp; The SRB wouldn't light with holes, it needs pressure to operation. &nbsp;&nbsp; TO is a pressure oscillation and is present in all solid motors.&nbsp; Relief valves wouldn't stop the problem and the valves themselves wouldn't be able to function in a motor. &nbsp; <br />Posted by Cygnus_2112</DIV></p><p>The mechanism is a bit more subtle.&nbsp; Solid rockets can use a couple of different thrust terminatin mechanisms.&nbsp; One fairly common one is a kidney cut on the forward dome, from a shaped charge..&nbsp; That shuts down the motor in&nbsp;three ways.&nbsp; First it opens up a lot of area on the forward dome and with that one loses thrust just from the change in pressure times area.&nbsp; Second it causes a rapid depressurization of the motor and a high negative dP/dt can extinguish the propellant grain.&nbsp; Third, the cases in ICBMs are composite cases and when the fibers are cut the case loses most of its burst strength and and the case can come apart, basically disintegrating the motor.&nbsp; Those thrust termination systems are desisgned to not only shut down the motor but to render it nonn-propulsive and confine it to a pre-establlished corridor so that the pieces don't do any damage coming down.&nbsp; The other thrust termination system is a longitudinal cut for essentially the full length of the cylinder section of the case using a shaped charge.&nbsp; that completely eliminates all hoop strength in the case, cuts the propellant as well, and actually ignites the propellant along the cut.&nbsp; The motor, comes apart quickly due to the internal pressure.&nbsp; This method is also used to destroy motors that have been scrapped.&nbsp; It ignites the propellant but the motor is never propulsive, so it burns on the ground, usually in a pit.</p><p>Actually the SRM might well light with holes, as long as they are not really big.&nbsp; After all it lights with the&nbsp;hole that we call the nozzle throat.&nbsp; And as noteed above the propellant will light if you fire a shaped charge along cylinder -- but the burning at low pressure is pretty slow.&nbsp;</p><p>Not lighting is the least of the problems.&nbsp; Solid rockets are designed to operate with the fire coming out the back end.&nbsp; Venting the hot (5000 -- 6000 F ) gases from any other hole can be hazardous.&nbsp; It is done occassionally for extremely short durations -- such as the thrust reversal used on the third stage Minuteman III.&nbsp; But it is never&nbsp;done for a prolonged period of time.&nbsp; And since most of the case interior is covered by propellant, except at the end of burn,&nbsp;any holes drilled in the case would&nbsp;have to penetrate several feet of propellant into the centerbore.&nbsp; Ther are some serious&nbsp;propellant structural problems with&nbsp;doing that.&nbsp; There would be a huge vena contracta flow effect and a lot of bad propellant deformation if you did anything quite that dumb.&nbsp; Propellant fracture would be highly likely and once that starts anything can happen -- including simply blowing up the motor.</p><p>A&nbsp;solid rocket motor is not some&nbsp;kids flute.&nbsp; Drilling holes in the motor would not help much with the acoustics.&nbsp; It would&nbsp;just alter some harmonic frequencies at best and&nbsp;result in a catastrophic rocket failure at worst.&nbsp; The worst is&nbsp;more likely than the best.</p><p>You are quite correct about the use of&nbsp;valves with this sort of solid rocket motor.&nbsp; Like all&nbsp;large launch vehicles the SRB propellant contains quite a bit of aluminum.&nbsp; The aluminum is needed for performance, and is what provides for high flame temperature.&nbsp; But the aluminum oxide, also known as slag, would quickly condense on valve parts and cause them to cease functioning.&nbsp; Use of valves has been studied in&nbsp;R&D projects for solids.&nbsp; It has been pretty much a miserable failure.&nbsp; You are also&nbsp; correct in that even if the valves worked they would not be of much help with an acoustic oscillation problem.&nbsp; <br /></p> <div class="Discussion_UserSignature"> </div>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>This is how bad it is:"Think mice in a paint can in your local paint store, with the can on the vibrator/mixer. Not a pretty sight. Hitting +/- 6.4 g at 110 seconds and continuing till SRB sep at ~128 seconds will leave your brains in an awful state.Chuck,That's what I thought but I was told that a paint shaker is actually a lot less powerful.&nbsp; &nbsp;They typically oscillate around 4-6Hz and with less than half the force.I mentioned the head of a jack-hammer previously because I've been told that it would be in the right frequency range (~15Hz) and the force equates to about 7-8g acceleration at the tip which isn't far off.I can't find a closer "real world" example of the forces yet - but if anyone else can find one it would be nice to have another example to use" Ross. <br />Posted by kyle_baron</DIV><br />&nbsp;</p><p>And what is your data source for how bad it is?&nbsp; Now how bad somebody thinks it&nbsp; might be.&nbsp; But how bad it is based on real no-kidding data.</p><p>The only information I have heard, and it came from people involved at the time, was that some analysis had caused the issue to be raised.&nbsp; One thing that I can tell you for sure is that acoustic analyses of solid rocket motors are notoriously inaccurate and tend to predict problem when none really exist.</p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;In or on a motor, the problem is the hole.&nbsp; The propellant insulates the casing.&nbsp; The casing never come in contact with the combustion <br />Posted by Cygnus_2112</DIV></p><p>&nbsp;</p><p>Understood.&nbsp; I was thinking that the hole (steel tubing) could have an interior ablative liner, so that the combustion would not occur with in the tubing, and ignite the surrounding propellent.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In any case, the hypothetical thrust oscillation problem was of quite low&nbsp;frequency and the hypothetical effect was on the humans on board.&nbsp; The fix, should it be needed, was to provide isolation to the humans.&nbsp; The problem was never one of acoustic instability or a catastrophic rocket failure. <br />Posted by DrRocket</DIV></p><p>&nbsp;</p><p>There was talk at NasaSpaceflight.com that the TO would cause bearing damage to the J2X 2nd stage engine.&nbsp; Probably where it gimbals.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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kyle_baron

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Actually the SRM might well light with holes, as long as they are not really big.</DIV></p><p>&nbsp;Exactly what I was getting at.&nbsp;</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;&nbsp;&nbsp; And since most of the case interior is covered by propellant, except at the end of burn,&nbsp;any holes drilled in the case would&nbsp;have to penetrate several feet of propellant into the centerbore.&nbsp; Ther are some serious&nbsp;propellant structural problems with&nbsp;doing that.&nbsp; There would be a huge vena contracta flow effect and a lot of bad propellant deformation if you did anything quite that dumb.</DIV></p><p>&nbsp;How would the Venturi effect be huge, if the hole was small, compared to the centerbore of the SRM?&nbsp; As the rocket burns, the centerbore of the SRM increases and the tubing hole length decreases.&nbsp; Quite the opposite of what you propose.</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You are quite correct about the use of&nbsp;valves with this sort of solid rocket motor.&nbsp; Like all&nbsp;large launch vehicles the SRB propellant contains quite a bit of aluminum.&nbsp; The aluminum is needed for performance, and is what provides for high flame temperature.&nbsp; But the aluminum oxide, also known as slag, would quickly condense on valve parts and cause them to cease functioning.&nbsp; Use of valves has been studied in&nbsp;R&D projects for solids.&nbsp; You are also&nbsp; correct in that even if the valves worked they would not be of much help with an acoustic oscillation problem.&nbsp; <br />Posted by DrRocket</DIV></p><p>I was thinking that there would be 2 holes (4 max.) on opposite sides of the rocket acting as a pressure (thrust)release, which may actually increase the efficiency (ISP) of the SRM.&nbsp; This is actually attacking the root of the problem, rather than treating the symptoms.&nbsp; Similar, but not exactly like the abort motor:</p><p>http://www.nasa.gov/mission_pages/constellation/multimedia/las_jettison.html</p><p>Aluminum Oxide is a light fluffy powder found on exterior aluminum surfaces as a white corrosion.&nbsp; The Check Valves or pressure relief valves are simple open or closed high pressure valves.&nbsp; How can a light powder affect the fast acting high pressure valves?&nbsp; You make it sound like these valves are a delicate instrument that has small orifices which will clog easily.&nbsp; Nothing could be further from the truth.&nbsp; Especially, if they're covered in an ablative material.&nbsp;</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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Cygnus_2112

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;</p><p>1. the rocket burns, the centerbore of the SRM increases and the tubing hole length decreases.&nbsp; Quite the opposite of what you propose.&nbsp;</p><p>&nbsp;2.&nbsp; I was thinking that there would be 2 holes (4 max.) on opposite sides of the rocket acting as a pressure (thrust)release, which may actually increase the efficiency (ISP) of the SRM.&nbsp; </p><p>3.&nbsp; This is actually attacking the root of the problem, rather than treating the symptoms.&nbsp; S</p><p>4.&nbsp; lAluminum Oxide is a light fluffy powder found on exterior aluminum surfaces as a white corrosion.&nbsp; The Check Valves or pressure relief valves are simple open or closed high pressure valves.&nbsp; How can a?&nbsp; You make it sound like these valves are a delicate instrument that has small orifices which will clog easily.&nbsp; Nothing could be further from the truth.&nbsp; Especially, if they're covered in an ablative material.&nbsp; <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>1.&nbsp; No, the propellant around the hole would burn too causing more problems</p><p>2&nbsp; There is no way it can increase the ISP.&nbsp; Gas is being wasted.</p><p>3.&nbsp; It doesn't attack anything, since it doesn't fix the problem</p><p>4.&nbsp; " light powder affect the fast acting high pressure valves" just like a sand blaster.&nbsp; </p><p>&nbsp;</p><p>This is just another nonviable idea </p>
 
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DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;&nbsp;&nbsp;How would the Venturi effect be huge, if the hole was small, compared to the centerbore of the SRM?&nbsp;</p><p><font color="#0000ff">I said vena contracta, not venturi.&nbsp; They have nothing in common.</font></p><p><font color="#0000ff">And the venturi effect would in fact be huge if the hole was small compared to the centerbore IF the flow velocity in the centerbore were high.&nbsp;&nbsp;The ration of hole sizes is not the important point.&nbsp; But the velocity in the centerbore is not very high.&nbsp; One in fact designs solid rocket motors carefully to make sure that the centerbore velocity is not too high. </font></p><p><font color="#0000ff">Do you know anything at all about fluid dynamics ?</font></p><p>&nbsp;As the rocket burns, the centerbore of the SRM increases and the tubing hole length decreases.&nbsp; Quite the opposite of what you propose.</p><p><font color="#0000ff">Since I didn't propose anything, I have no idea what you are talking about.&nbsp; Of course the centerbore increases and your additional holes decrease in length, assuming that the vehicle has not experienced a catastrophic failure.&nbsp; So what?</font>&nbsp;</p><p>&nbsp;I was thinking that there would be 2 holes (4 max.) on opposite sides of the rocket acting as a pressure (thrust)release, which may actually increase the efficiency (ISP) of the SRM.</p><p><font color="#0000ff">Since Isp is a measure of thrust produced per pound of propellant consumed, physics would show that exhausting propellant in a direction normal to the&nbsp; thrust vector would only reduce Isp.&nbsp; By what possible mechanism do think your scheme would increase Isp?&nbsp; Isp is not a measure of efficiency, it is a measure of performance.&nbsp; Do you know what Isp is?</font>&nbsp; </p><p>&nbsp;This is actually attacking the root of the problem, rather than treating the symptoms.&nbsp; Similar, but not exactly like the abort motor:http://www.nasa.gov/mission_pages/constellation/multimedia/las_jettison.htmlAluminum Oxide is a light fluffy powder found on exterior aluminum surfaces as a white corrosion.&nbsp;</p><p><font color="#0000ff">Gee I didn't know that.&nbsp; Then what was that 4500 lbs of aluminum slag (analyzed to be mostly aluminum oxide) that we&nbsp;chiseled out of the aft end of Titan motors, or the slag that caused a total redesign of the first state of SICBM, or the reason that we put a forward pivot point flexseal in Delta GEM vectorable motors, or the material that I watched forming in x-rays taken of static motor firings.?&nbsp; As usual, you don't know what in the hell you are talking about.</font></p><p>&nbsp;</p><p>&nbsp;The Check Valves or pressure relief valves are simple open or closed high pressure valves.&nbsp; How can a light powder affect the fast acting high pressure valves?&nbsp;</p><p><font color="#0000ff">As noted it is not a light powder, but occurs in rocket motors as a molten material that is rock-like when it cools on available surfaces.&nbsp; I have developed check valve applications that worked with non-aluminized propellants and even then condensibles were a major consideration.&nbsp; Work with other propellants has also been performed and the check valves don't work.</font></p><p>&nbsp;&nbsp;You make it sound like these valves are a delicate instrument that has small orifices which will clog easily.&nbsp; Nothing could be further from the truth.&nbsp; Especially, if they're covered in an ablative material.</p><p><font color="#0000ff">You apparently don't understand either check valves, propellants, or ablative materials.&nbsp;&nbsp; This is the most incredible string of misconceptions, fallsehoods, and illogic that you have yet put together.&nbsp; And your string of such is pretty impressive.</font></p><p><font color="#0000ff">Before you launch into another such littany of idiocy I suggest that you take some time and learn a bit of physics, chemistry, and at least the rudiments of propulsion and rocket design.&nbsp; You are so far out in left field that you are not even in the game anymore.</font></p><p>&nbsp;</p><p>Posted by kyle_baron</DIV></p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'> Replying to:<br /><div class="Discussion_PostQuote">&nbsp;&nbsp;&nbsp; </div><div class="Discussion_PostQuote"><font color="#0000ff">I said vena contracta, not venturi.&nbsp; They have nothing in common.</font></div><p class="Discussion_PostQuote"><font color="#0000ff">http://en.wikipedia.org/wiki/Vena_contracta</font></p><p class="Discussion_PostQuote">http://en.wikipedia.org/wiki/Venturi_effect</p><p class="Discussion_PostQuote">It's close enough for what we're discussing here.</p><p class="Discussion_PostQuote">&nbsp;&nbsp;</p><p class="Discussion_PostQuote">&nbsp;I was thinking that there would be 2 holes (4 max.) on opposite sides of the rocket acting as a pressure (thrust)release, which may actually increase the efficiency (ISP) of the SRM.</p><p class="Discussion_PostQuote"><font color="#0000ff">Since Isp is a measure of thrust produced per pound of propellant consumed, physics would show that exhausting propellant in a direction normal to the&nbsp; thrust vector would only reduce Isp.&nbsp; By what possible mechanism do think your scheme would increase Isp?&nbsp; Isp is not a measure of efficiency, it is a measure of performance.&nbsp; Do you know what Isp is?</font>&nbsp;</p><p class="Discussion_PostQuote">&nbsp;http://en.wikipedia.org/wiki/Specific_impulse</p><p class="Discussion_PostQuote">Since you have a problem reading, I'll quote the important parts:</p><p><strong>Specific impulse</strong> (usually abbreviated <em>I</em><sub>sp</sub>) is a way to describe the efficiency of rocket and jet engines. It represents the impulse (change in momentum) per unit of propellant. The higher the specific impulse, the less propellant is needed to gain a given amount of momentum. <em>I</em><sub>sp</sub> is a useful value to compare engines, much like "miles per gallon" is used for cars. A propulsion method with a higher specific impulse is more propellant-efficient.</p><p class="Discussion_PostQuote">&nbsp;This is actually attacking the root of the problem, rather than treating the symptoms.&nbsp; Similar, but not exactly like the abort motor:<font color="#003399">http://www.nasa.gov/mission_pages/constellation/multimedia/las_jettison.htmlAluminum</font> Oxide is a light fluffy powder found on exterior aluminum surfaces as a white corrosion.&nbsp;</p><p class="Discussion_PostQuote"><font color="#0000ff">Gee I didn't know that.&nbsp; </font><font color="#0000ff">Then what was that 4500 lbs of aluminum slag (analyzed to be mostly aluminum oxide) that we&nbsp;chiseled out of the aft end of Titan motors, or the slag that caused a total redesign of the first state of SICBM, or the reason that we put a forward pivot point flexseal in Delta GEM vectorable motors, or the material that I watched forming in x-rays taken of static motor firings.?&nbsp; As usual, you don't know what in the hell you are talking about.</font></p><p class="Discussion_PostQuote"><font color="#0000ff">We're not talking about the ends of the motors, we're talking about the openings near the top!&nbsp; Do you know which end is up, and which end is down?&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;Anyhow, I doubt the 4500 lbs was after one firing of the motor.&nbsp; It would also be interesting to see how much aluminum oxide was on the outside casing of the Challenger SRB, which by the way, DID NOT BLOW UP FROM THE LEAK.</font></p><p class="Discussion_PostQuote">&nbsp;&nbsp;You make it sound like these valves are a delicate instrument that has small orifices which will clog easily.&nbsp; Nothing could be further from the truth.&nbsp; Especially, if they're covered in an ablative material.</p><p class="Discussion_PostQuote"><font color="#0000ff">You apparently don't understand either check valves, propellants, or ablative materials.&nbsp;&nbsp; This is the most incredible string of misconceptions, fallsehoods, and illogic that you have yet put together.&nbsp; And your string of such is pretty impressive.</font></p><p class="Discussion_PostQuote"><font color="#0000ff">Before you launch into another such littany of idiocy I suggest that you take some time and learn a bit of physics, chemistry, and at least the rudiments of propulsion and rocket design.&nbsp; You are so far out in left field that you are not even in the game anymore.</font></p><p class="Discussion_PostQuote"><font color="#0000ff">Your arrogance and intimidation is most impressive.&nbsp; You must think that "You're a Legend in your own mind".&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" /></font></p><p class="Discussion_PostQuote"><font color="#0000ff">I will continue to put forth alternative ideas in spite of your critisizims, since you don't have any original ideas of your own.&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" /></font></p><p class="Discussion_PostQuote"><font color="#0000ff">I just want to say to the other posters, to feel free to express your ideas, inspite of this professional bully.&nbsp; I'm sure that other open minded professionals, will at least consider them, and put their own knowledge towards the solution.</font></p><p class="Discussion_PostQuote">&nbsp;</p><p class="Discussion_PostQuote">&nbsp;</p><br />Posted by DrRocket</DIV><br /> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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DrRocket

Guest
<br /><div class="Discussion_PostQuote"><font color="#0000ff">I said vena contracta, not venturi.&nbsp; They have nothing in common.</font></div><p class="Discussion_PostQuote"><font color="#5574b9">http://en.wikipedia.org/wiki/Vena_contracta</font></p><p class="Discussion_PostQuote"><font color="#003399">http://en.wikipedia.org/wiki/Venturi_effect</font></p><p class="Discussion_PostQuote">It's close enough for what we're discussing here.</p><p class="Discussion_PostQuote"><font color="#ff0000">Only someone with a complete and total lack of knowledge of fluid dynamics would make such a statement.&nbsp; So I guess you are correct, it is good enough for you.</font></p><p class="Discussion_PostQuote">&nbsp;&nbsp;</p><p class="Discussion_PostQuote">&nbsp;I was thinking that there would be 2 holes (4 max.) on opposite sides of the rocket acting as a pressure (thrust)release, which may actually increase the efficiency (ISP) of the SRM.</p><p class="Discussion_PostQuote"><font color="#0000ff">Since Isp is a measure of thrust produced per pound of propellant consumed, physics would show that exhausting propellant in a direction normal to the&nbsp; thrust vector would only reduce Isp.&nbsp; By what possible mechanism do think your scheme would increase Isp?&nbsp; Isp is not a measure of efficiency, it is a measure of performance.&nbsp; Do you know what Isp is?</font>&nbsp;</p><p class="Discussion_PostQuote">&nbsp;<font color="#003399">http://en.wikipedia.org/wiki/Specific_impulse</font></p><p class="Discussion_PostQuote">Since you have a problem reading, I'll quote the important parts:</p><p><strong>Specific impulse</strong> (usually abbreviated <em>I</em><sub>sp</sub>) is a way to describe the efficiency of <font color="#003399">rocket</font> and <font color="#003399">jet</font> engines. It represents the <font color="#003399">impulse</font> (change in momentum) per unit of <font color="#003399">propellant</font>. The higher the specific impulse, the less propellant is needed to gain a given amount of momentum. <em>I</em><sub>sp</sub> is a useful value to compare engines, much like "miles per gallon" is used for cars. A propulsion method with a higher specific impulse is more propellant-effic</p><p><font color="#ff0000">I really don't care what you copied out of Wikipedia or some such other reference.&nbsp; Isp is&nbsp;indeed impulse imparted per pound of propellant consumed, or equivalently thrust per pound of propellant of propellant consumed per second.&nbsp; But you cannot increase Isp by directing the gas in some direction normal to the thrust vector, which was your proposal.&nbsp; Physics simply does not support that.&nbsp; In addition, efficiency is, in engineering and physics, used to denote the ability of a machine or process to perform near some ideal.&nbsp; Isp is not an efficiency, but rather a figure of merit for performance of either a propellant formulation or of an engine.&nbsp; </font></p><p>&nbsp;</p><p>&nbsp;This is actually attacking the root of the problem, rather than treating the symptoms.&nbsp; Similar, but not exactly like the abort motor:<font color="#003399">http://www.nasa.gov/mission_pages/constellation/multimedia/las_jettison.htmlAluminum</font> Oxide is a light fluffy powder found on exterior aluminum surfaces as a white corrosion.&nbsp;</p><p class="Discussion_PostQuote"><font color="#0000ff">Gee I didn't know that.&nbsp; </font><font color="#0000ff">Then what was that 4500 lbs of aluminum slag (analyzed to be mostly aluminum oxide) that we&nbsp;chiseled out of the aft end of Titan motors, or the slag that caused a total redesign of the first state of SICBM, or the reason that we put a forward pivot point flexseal in Delta GEM vectorable motors, or the material that I watched forming in x-rays taken of static motor firings.?&nbsp; As usual, you don't know what in the hell you are talking about.</font></p><p class="Discussion_PostQuote"><font color="#0000ff">We're not talking about the ends of the motors, we're talking about the openings near the top!&nbsp; Do you know which end is up, and which end is down?&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;Anyhow, I doubt the 4500 lbs was after one firing of the motor.&nbsp; It would also be interesting to see how much aluminum oxide was on the outside casing of the Challenger SRB, which by the way, DID NOT BLOW UP FROM THE LEAK.</font></p><p class="Discussion_PostQuote"><font color="#ff0000">It doesn't matter if your holes are near the top, near the bottom or anywhere else so long as they direct the gas in some direction other than aft.&nbsp; I am glad that you doubt the slag was formed from one firing of the motor.&nbsp; Just how many times do you think you can fire such a motor?&nbsp; HINT: THE CORRECT ANSWER IS 1.</font></p><p class="Discussion_PostQuote">&nbsp;&nbsp;You make it sound like these valves are a delicate instrument that has small orifices which will clog easily.&nbsp; Nothing could be further from the truth.&nbsp; Especially, if they're covered in an ablative material.</p><p class="Discussion_PostQuote"><font color="#0000ff">You apparently don't understand either check valves, propellants, or ablative materials.&nbsp;&nbsp; This is the most incredible string of misconceptions, fallsehoods, and illogic that you have yet put together.&nbsp; And your string of such is pretty impressive.</font></p><p class="Discussion_PostQuote"><font color="#0000ff">Before you launch into another such littany of idiocy I suggest that you take some time and learn a bit of physics, chemistry, and at least the rudiments of propulsion and rocket design.&nbsp; You are so far out in left field that you are not even in the game anymore.</font></p><p class="Discussion_PostQuote"><font color="#0000ff">Your arrogance and intimidation is most impressive.&nbsp; You must think that "You're a Legend in your own mind".&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" /></font></p><p class="Discussion_PostQuote"><font color="#0000ff">I will continue to put forth alternative ideas in spite of your critisizims, since you don't have any original ideas of your own.&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" /></font></p><p class="Discussion_PostQuote"><font color="#ff0000">You might try basing your ideas on facts and real physics.&nbsp; So far you have missed the application of both.&nbsp; I doubt that you have any notion whatever of what my original ideas or have been.&nbsp; Original, useful, ideas are not put forth in a public forum.&nbsp; </font></p><p class="Discussion_PostQuote"><font color="#0000ff">I just want to say to the other posters, to feel free to express your ideas, inspite of this professional bully.&nbsp; I'm sure that other open minded professionals, will at least consider them, and put their own knowledge towards the solution.</font></p><p class="Discussion_PostQuote"><font color="#ff0000">I really rather like new fresh ideas, and encourage them.&nbsp; One thing that is utterly true is that to get to a good idea you usually have to come up with several that are not so good.&nbsp; But it is important to recognize the difference and not belabor the bad ones.&nbsp; It is in fact generally a good idea to review your own ideas somewhat critically and not openly espouse those that are particularly stupid.&nbsp; Everybody has dumb ideas.&nbsp; But most recognize them and put them aside before publishing them, and at least stop trying to defend them vehemently in the face of overwhelming logic.&nbsp; One also ought to refrain from making strong positive assertions that are completely wrong, utterly wrong.&nbsp; </font></p><p class="Discussion_PostQuote"><font color="#ff0000">Before you start on a solution, you first need to have a problem, and know that you have a problem.&nbsp; This thrust oscillation issue has been raised and is being studied, but until there is test firing in which the pressure can actually be measured you don't know that you really have a problem requiring any design solution at all.</font></p> <div class="Discussion_UserSignature"> </div>
 
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DrRocket

Guest
<p>Before redesigning the entire Area 1 vehicle it might be a good idea to understand the problem and what is already being studied and considered.&nbsp; Note especially that the concern is not based on any direct 5-segment SRB test data.&nbsp; You should also know that analysis of acoustic phenomena with solid rockets is extremely difficult and notoriously inaccurate.</p><p><font face="Arial" size="2">&nbsp;</font><font face="Arial" size="2" color="#0000ff">http://www.nasa.gov/pdf/221186main_toft_checkpoint_report.pdf</font><font face="Arial" size="2">.</font></p> <div class="Discussion_UserSignature"> </div>
 
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DrRocket

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>With all due respect to the 7 brave astronauts who died in the Challenger accident in 1986, why not put a few holes into the sides of the SRB to reduce POGO or TO for Ares I?&nbsp; Of course you would lose some thrust, depending on the size of the holes, but you'd also reduce the pressure buildup with in the core of the SRB.&nbsp; There would be no weight penalties involved like other alternatives.&nbsp; And if Nasa decides to add another 1/2 segment to the stack, there may be thrust to waste, in this solution. <br />Posted by kyle_baron</DIV></p><p>Suppose&nbsp; that you tell us precisely in terms of real physics and&nbsp; basic cause and effect:</p><p>1.&nbsp; The effects that you intend to cause with your proposal.</p><p>2.&nbsp; Ancillary effects that might also occur.</p><p>3.&nbsp; Whether those effects are beneficial or detrimental and why.</p><p>I will give you a starting hint.&nbsp; Relieving the pressure in the core of the SRB is not a good thing.&nbsp; That motor is designed to operate and produce a very specific pressure profile, and the thrust is proportional to the pressure.&nbsp; So if you reduce the pressure you reduce the thrust.&nbsp; Reduce it enough and you won't get to orbit.</p><p>The notion of thrust to waste is an interesting one.&nbsp; If there is thrust to waste on this vehicle it will be a breakthrough concept in rocketry.&nbsp; Thrust to waste is an oxymoron, rather like money to burn.&nbsp; The difficulty in producing adequate thrust and delta v is the major reason why it is so difficult and so expensive to put payloads into orbit.</p><p><br /><br />&nbsp;</p> <div class="Discussion_UserSignature"> </div>
 
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kyle_baron

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Suppose&nbsp; that you tell us precisely in terms of real physics and&nbsp; basic cause and effect</DIV></p><p>Because you've changed your tone, I will answer your questions to the best of my knowledge.</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>1.&nbsp; The effects that you intend to cause with your proposal.</DIV></p><p>The vibration, occilation, etc. is an excessive pressure energy, that is dissipated thru the entire structure of the rocket.&nbsp; I see this as wasted energy efficiency.&nbsp; Taking this wasted energy, removing it, and placing it outside the rocket, as a thrust in the direction of the SRB thrust, is the goal.&nbsp; Keep in mind, that this&nbsp;would not be&nbsp;a constant thrust, but more of a pulsed thrust.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>2.&nbsp; Ancillary effects that might also occur.</DIV></p><p>I don't know of any additional effects.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>3.&nbsp; Whether those effects are beneficial or detrimental and why.</DIV></p><p>I would say they are beneficial to the crew, and the 2nd stage motor bearing.&nbsp; Why?&nbsp; Brain damage might occur it the astronauts, and the gimbal bearing in the 2nd stage motor might jam.</p><p>&nbsp;Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I will give you a starting hint.&nbsp; Relieving the pressure in the core of the SRB is not a good thing.&nbsp; That motor is designed to operate and produce a very specific pressure profile, and the thrust is proportional to the pressure.&nbsp; So if you reduce the pressure you reduce the thrust.&nbsp; Reduce it enough and you won't get to orbit.The notion of thrust to waste is an interesting one.&nbsp;&nbsp; <br />Posted by DrRocket</DIV></p><p>I'm not arguing with that.&nbsp; My issue is with the excessive pressure that causes the T.O.</p><p>&nbsp;</p><p>I would be interested in your comments about the Challenger SRB leak, and the SRB not blowing up.&nbsp; I was wondering if you could analyze this in terms of the physics which were involved.<br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>
 
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Cygnus_2112

Guest
<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>.&nbsp; My issue is with the excessive pressure that causes the T.O. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>It is not cause by excessive pressure .&nbsp; It is an acoustical phemomena </p>
 
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