Ares V with a Conical Core, and a Trig Problem

[kyle_baron]

<p><strong>With the problem of base&nbsp;heating of the engines in the core( by the SRB's) why not just widen the base, &nbsp;to allow more space for the engines?&nbsp; I'm thinking of an inverted cone geometry, for the Ares V 1st stage.&nbsp; There is no law that says stages have to be symetrical cylinders, is there?&nbsp; The 1st stage would be roughly 8.4-10m in diameter at the top, and I'm GUESSING around 12m at the bottom.</strong></p><p><strong>Now, this is where the trig problem occurs.&nbsp; I would like a mathematical solution&nbsp;for the maximum size base possible, given the parameters of the SRB's.&nbsp; The SRB thrust vector system can pivot the nozzle 6 Deg. from vertical.&nbsp; That means, with a conical core, the SRB's will be + or - 6 Deg. from vertical, with the thrust still pointing straight down.&nbsp; The length of the 1st stage&nbsp;is 64m.&nbsp; Is this enough information to calculate the maximum diameter of the base, with the SRB's parallel to the conical core?&nbsp;&nbsp;</strong></p><p><strong>Thanks,&nbsp;</strong></p><p><strong>Kyle&nbsp;&nbsp;</strong>&nbsp;</p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

 

[trailrider]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>With the problem of base&nbsp;heating of the engines in the core( by the SRB's) why not just widen the base, &nbsp;to allow more space for the engines?&nbsp; I'm thinking of an inverted cone geometry, for the Ares V 1st stage.&nbsp; There is no law that says stages have to be symetrical cylinders, is there?&nbsp; The 1st stage would be roughly 8.4-10m in diameter at the top, and I'm GUESSING around 12m at the bottom.Now, this is where the trig problem occurs.&nbsp; I would like a mathematical solution&nbsp;for the maximum size base possible, given the parameters of the SRB's.&nbsp; The SRB thrust vector system can pivot the nozzle 6 Deg. from vertical.&nbsp; That means, with a conical core, the SRB's will be + or - 6 Deg. from vertical, with the thrust still pointing straight down.&nbsp; The length of the 1st stage&nbsp;is 64m.&nbsp; Is this enough information to calculate the maximum diameter of the base, with the SRB's parallel to the conical core?&nbsp;&nbsp;Thanks,&nbsp;Kyle&nbsp;&nbsp;&nbsp; <br />Posted by kyle_baron</DIV></p><p>Kyle:</p><p>The tangent of 6 deg. = .1051&nbsp; Multiply that by 64m and you get 6.727, which is the DIFFERENCE of the radius between the top and bottom of the core.&nbsp; The diameters will be twice that PLUS the diameter at the top of the stage, whatever it is.&nbsp; If you use an 8.4m forward end, then (2 x 6.727) + 8.4 = 21.85m at the base.&nbsp; This would be a big problem for construction and handling.</p><p>However, your basic assumption, that the SRB nozzles could deflect + or - 6 degrees as the reason for the 6 deg. slope, would, IF the nozzles were aligned along the BOOSTERS' centerlines.&nbsp; But, if that were true, you would be deflecting the nozzles full over "into the stops" in order to have the thrust vector parallel to the booster centerline.&nbsp; You wouldn't have any deflection left to yaw the vehicle.&nbsp; What you'd have to do would be to angle the NOZZLE centerline parallel to the vehicle's.&nbsp; The problem with that is that you would probably incur some losses in booster performance, plus resulting in increased erosion of the nozzle throat on the outside of the exhaust stream "bend".&nbsp; If you were to use liquid boosters, like the Soyuz do, you could bend the feed lines and you wouldn't incur such losses.</p><p>(Note: those who have been out of school and work a LOT less longer than I have, feel free to jump all over my trig! <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-embarassed.gif" border="0" alt="Embarassed" title="Embarassed" />&nbsp</p><p>Ad LEO! Ad Luna! Ad Ares! Ad Astra!</p>

 

[windnwar]

<p>Everything i've seen the issue with the base heating of the engines is actually has more to do with the RS-68's heating each other in such a tight space and the ablative nozzles not having any real reserves to deal with that additional heat flux in such a close proximity. If the SRB's are part of the issue as well then they would be simply on top of it. </p><p>I think manufacturing wise, making a conical structure would greatly increase the machining costs and comlexity. Handling the structure alone would have to be quite difficult. </p> <div class="Discussion_UserSignature"> <p> </p><p><font size="2" color="#0000ff">""Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein"</font></p> </div>

 

[trailrider]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Everything i've seen the issue with the base heating of the engines is actually has more to do with the RS-68's heating each other in such a tight space and the ablative nozzles not having any real reserves to deal with that additional heat flux in such a close proximity. If the SRB's are part of the issue as well then they would be simply on top of it. I think manufacturing wise, making a conical structure would greatly increase the machining costs and comlexity. Handling the structure alone would have to be quite difficult. <br />Posted by windnwar</DIV><br /><br />Re: the RS-68 "hot bottom" problems are correct... IIRC, the nozzle extensions on the RS-68 are not cooled, but have ablative material INSIDE, which protects the nozzle from <em>internal</em> heating, but not external heating from adjacent engines.&nbsp; There has been a rumor floating around that Ares V.? might go for Space Shuttle Main Engines, simplified for single use only.&nbsp; Since the SSME nozzles are <em>regeneratively cooled</em> heating from adjacent engines wouldn't be as serious a problem...one that could probably be mittigated using Refrasil and Epon potting.</p><p>But all this will be academic if President Obama and Congress don't press for an American manned program beyond Low Earth Orbit!&nbsp; We will just have to see...</p><p>Ad LEO! Ad Luna! Ad Ares! Ad Astra!</p>

 

[kyle_baron]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Kyle:The tangent of 6 deg. = .1051&nbsp; Multiply that by 64m and you get 6.727, which is the DIFFERENCE of the radius between the top and bottom of the core.&nbsp; The diameters will be twice that PLUS the diameter at the top of the stage, whatever it is.&nbsp; If you use an 8.4m forward end, then (2 x 6.727) + 8.4 = 21.85m at the base.&nbsp; This would be a big problem for construction and handling.Ad LEO! Ad Luna! Ad Ares! Ad Astra! <br />Posted by trailrider</DIV></p><p><strong>Thank you for your trig answer!&nbsp; Does this mean that the SRB nozzle wouldn't have to pitch the max. 6 deg, with the thrust pointing straight down, for a 12 m base?&nbsp; If a 6 deg pitch is equivalent to a 22m base, would a 3 deg pitch be equivelent to an 11m base?&nbsp; Sorry for my ignorance in trig, but I was thinking that with a 12m base, more engines could be squeezed in for more thrust, whether they be the SSME or RS-68.</strong><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

 

[trailrider]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Thank you for your trig answer!&nbsp; Does this mean that the SRB nozzle wouldn't have to pitch the max. 6 deg, with the thrust pointing straight down, for a 12 m base?&nbsp; If a 6 deg pitch is equivalent to a 22m base, would a 3 deg pitch be equivelent to an 11m base?&nbsp; Sorry for my ignorance in trig, but I was thinking that with a 12m base, more engines could be squeezed in for more thrust, whether they be the SSME or RS-68. <br />Posted by kyle_baron</DIV></p><p>Roughly speaking, yes, mathematically.&nbsp; But that still doesn't tell us whether there would be enough spacing between RS-68 engines to take care of the base heating ("hot bottom") problem.&nbsp; IIRC, the current base diameter with the straight-sided tank is 10m, and they are having problems getting the spacing without resorting to drag-producing flared fairings around the engines.</p><p>I think we'd need more data on the heat transfer calculations between the adjacent engines and the RS-68 nozzles.&nbsp; IMHO, I think we are going to see some major redesigns, if, indeed, we have a manned space program beyond LEO! I noticed in the President's inaugural speech, he made NO mention of any aspirations for scientific programs beyond the surface of the Earth!&nbsp; This may not mean anything.&nbsp; Or it could sound the death knell of America in space.&nbsp; We'll just have to see...&nbsp; Until then,</p><p>Ad LEO! Ad Luna! Ad Ares! Ad Astra!</p>

 

[kyle_baron]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Roughly speaking, yes, mathematically.&nbsp; But that still doesn't tell us whether there would be enough spacing between RS-68 engines to take care of the base heating ("hot bottom") problem.&nbsp; IIRC, the current base diameter with the straight-sided tank is 10m, and they are having problems getting the spacing without resorting to drag-producing flared fairings around the engines.</DIV></p><p><strong>Exactly.&nbsp; Which is why a wider base is needed.</strong></p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;I think we are going to see some major redesigns, if, indeed, we have a manned space program beyond LEO! I noticed in the President's inaugural speech, he made NO mention of any aspirations for scientific programs beyond the surface of the Earth!&nbsp; This may not mean anything.&nbsp; Or it could sound the death knell of America in space.&nbsp; We'll just have to see...&nbsp; Until then,Ad LEO! Ad Luna! Ad Ares! Ad Astra! <br />Posted by trailrider</DIV></p><p><strong>First of all, take a deep breath and relax.&nbsp; We're going to the moon!&nbsp; Nasa now has a Big Brother - the MILITARY.&nbsp; The Military talking:&nbsp; "Little brother, you need an extra $3 Billion/yr.&nbsp; to keep the Shuttle going, and to save thousands of jobs in Florida, and the aerospace industries?&nbsp; No problem, here ya go, take it."&nbsp; "How about an extra $2 Billion/yr. to accelerate the Constellation Program?&nbsp; We may have to tighten our belt here, but we can do it, here ya go."&nbsp; Anything else you need, little brother?"</strong></p><p><strong>The Military Budget is so BIG, money can easily be siphoned (or moved around) with no problems.&nbsp; This is how it works in the real world.&nbsp; Also, Obama's pick for Nasa Administrator said we're going to the moon.</strong><br /></p> <div class="Discussion_UserSignature"> <p><font size="4"><strong></strong></font></p> </div>

 

[Bytor_YYZ]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Exactly.&nbsp; Which is why a wider base is needed.First of all, take a deep breath and relax.&nbsp; We're going to the moon!&nbsp; Nasa now has a Big Brother - the MILITARY.&nbsp; The Military talking:&nbsp; "Little brother, you need an extra $3 Billion/yr.&nbsp; to keep the Shuttle going, and to save thousands of jobs in Florida, and the aerospace industries?&nbsp; No problem, here ya go, take it."&nbsp; "How about an extra $2 Billion/yr. to accelerate the Constellation Program?&nbsp; We may have to tighten our belt here, but we can do it, here ya go."&nbsp; Anything else you need, little brother?"The Military Budget is so BIG, money can easily be siphoned (or moved around) with no problems.&nbsp; This is how it works in the real world.&nbsp; Also, Obama's pick for Nasa Administrator said we're going to the moon. <br /> Posted by kyle_baron</DIV></p><p>&nbsp;</p><p>How can one be so clueless?&nbsp; The DOD is not taking over NASA nor is the DOD providing any funding for NASA </p>