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Space Forum / Shuttle / August 2007A Fix for Shuttle ET Aft Strut
It doesn't seem to be easy to contact the right people in NASA about suggestions, so I'm posting here in the hope that it'll get some consideration, and perhaps even an acknowledgement from Leroy Kane or John Shannon! It seems obvious to me, but I think the solution here is not to spend more millions dealing with bits of unpredictable icing and foam falling off, but instead to neutralize them. The vast majority of the foam problems have been solved, this should just tidy up the last annoyances. I've just made a rough CG animation illustrating a cheap and lightweight modification of the aft external tank struts, which I believe could be quickly and easily applied to the three ETs currently on the production line without any adverse side effects. It's only a gut feeling idea to show the principle - a final version could be different. All it does is to slice, dice and deflect any debris away from the orbiter tiles, if they do happen to hit the strut. The 120 frame PovRay animation (1Mb XVid) should speak for itself. http://www.haveland.com/anim/shuttle_et_strut_fix.avi Comments welcome... Andy. >All it does is to slice, dice and deflect any debris away from the >orbiter tiles, if they do happen to hit the strut. Yep. And also slices and dices and deflects the airflow and/or shockwaves in that area. Whether for weal or woe I cannot say. >Comments welcome... So what happens when a piece of debris smaller than your 'fin' spacing (not particularly difficult) hits the strut and deflects into the Shuttle anyhow? D.  SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL > >All it does is to slice, dice and deflect any debris away from the > >orbiter tiles, if they do happen to hit the strut. > > Yep. And also slices and dices and deflects the airflow and/or > shockwaves in that area. Whether for weal or woe I cannot say. I'd guess that streamlining the airflow over a very unaerodynamic round (and not even elliptical) strut would have to be an improvement, and worth investigating, no? > >Comments welcome... > > So what happens when a piece of debris smaller than your 'fin' spacing > (not particularly difficult) hits the strut and deflects into the > Shuttle anyhow? Consider the angle of attack and rebound - if the debris hits the strut on the 'flat' at present, then it *will* rebound and hit the shuttle. If it hits the modified strut's blade then it will be deflected much more obliquely and laterally, or sliced up and the pieces deflected obliquely and laterally. If any shuttle-facing velocity component remains then the fins should help to deflect them. At the very least it would prevent a rebound with an acute angle, which does the real damage. Andy. >> >All it does is to slice, dice and deflect any debris away from the >> >orbiter tiles, if they do happen to hit the strut. [quoted text clipped - 5 lines] >round (and not even elliptical) strut would have to be an improvement, >and worth investigating, no? I'd guess you don't know much about aerodynamics do you? (I don't either, but at least I have the balls and the honesty to say so.) Not to mention the fact that if streamlining the strut was worth doing, don't you think they would have done it? >> >Comments welcome... >> [quoted text clipped - 12 lines] >At the very least it would prevent a rebound with an acute angle, >which does the real damage. You use those words, I do not think they mean what you think they mean. D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL > >> >All it does is to slice, dice and deflect any debris away from the > >> >orbiter tiles, if they do happen to hit the strut. [quoted text clipped - 8 lines] > I'd guess you don't know much about aerodynamics do you? (I don't > either, but at least I have the balls and the honesty to say so.) I know a little about aerodynamics, but of course not everything. I'm a programmer with a passion for science and have worked on molecular dynamics modelling. I'm not an aerodynamicist, and do not profess to be an expert on anything except web application programming. I do have intuition based on 40 years of reading everything I can find on science! I also resent your implication that I don't have balls and honesty, because nowhere have I, or claimed to be an expert. One doesn't need to be an expert in a discipline to have bright ideas in it, frequently this is the case in across disciplines. I just had an idea that I am sure is worth looking at, not selling snake oil, and would of course would stand corrected with empirical evidence. Credit where due etc. > Not to mention the fact that if streamlining the strut was worth > doing, don't you think they would have done it? Of course, like if preventing foam was worth doing, they would have done it years ago too... Or sticking the orbiter on top of the fuel tank instead of the side? Amazing really how on Earth it ever got off the ground. > You use those words, I do not think they mean what you think they > mean. Use a little imagination! > -Resolved: To be more temperate in my postings. > Oct 5th, 2004 JDL Why is this here??? Regards, Andy. > I know a little about aerodynamics, but of course not everything. A little knowledge is a dangerous thing, especially when it comes to something as complex as the aerodynamics of the shuttle stack when it goes through max-Q. If this were easy, the fixes to the ET wouldn't be coming in waves, all the fixes would have been made to the first return to flight ET. Jeff Signature"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett's Familiar Quotations (1919) >> I know a little about aerodynamics, but of course not everything. > [quoted text clipped - 4 lines] > >Jeff I don't profess to know anything about aerodynamics, especially when it comes to the shuttle stack, but it sure looks to me like there would be a bunch of drag from your modification. But hey, I would mail it to everybody at NASA, somebody may look at it and think its great. Send it to everybody at all the centers, Bill Gurstemeyer (I know I misspelled that one), Mike Griffin, John Shannon, Wayne Hale, everybody, also send it to the tank factory at Michoud LA. Send it to the PAO. I would redo it as a power point presentation though. You may be on to something here, I don't think so, but hey, nothing ventured.... Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches" SignaturePosted via a free Usenet account from http://www.teranews.com On Aug 22, 6:26 pm, Jim in Houston <nospamjamesgoo...@sbcglobal.netnospam> wrote: > I don't profess to know anything about aerodynamics, especially when > it comes to the shuttle stack, but it sure looks to me like there > would be a bunch of drag from your modification. I think it would rather reduce drag as sharp things travel easier than blunt things, which is why rockets have pointy ends! :-) The current struts are cylindrical and not at all aerodynamic. It should help a little to borrow from the design of golf balls and put lots of little indentations on the strut, but not enough to make it worthwhile. There is a lot to be said for "If it ain't broke, don't fix it"... but this mission showed that the strut needs another look and a cheap fix, though it doesn't seem to be high risk. The blades I envisage would be made from aluminium sheets, or titanium if feeling extravagant, and wouldn't weigh much at all, but would have to withstand the forces and stay in place. The longitudinal blades would be a triangular box cross-section with reinforcing struts inside. The lateral fins could be angled slightly away from the orbiter instead of parallel. Even a basic strut with lateral fins a little like a heatsink should be enough to catch or deflect any pieces. Future struts could be made to have the longitudinal sharp edge built in. > But hey, I would mail it to everybody at NASA, somebody may look at it > and think its great. Send it to everybody at all the centers, Bill [quoted text clipped - 5 lines] > ventured.... > Jim in Houston. Jim, thanks very much for the encouragement! No, I really don't want to make a nuisance of myself with a bee in my bonnet - nobody likes an a.shole, especially a pushy one, no matter how good their ideas are! I'd rather just try and whisper it into the ear of someone qualified to consider it and not reject it out of hand without at least without an explanation why. Nor do I want to oversell it with powerpoint presentations.. I'm an engineer. The audience are engineers. I try to see things as they *are* as far as possible without wrapping up in gloss! Anyway... I'll repeat the urls here just this once for any latecomers... :-))) Strut fix - http://www.haveland.com/anim/shuttle_et_strut_fix.avi XVid codec - http://www.xvidmovies.com/codec/ Regards, Andy. >On Aug 22, 6:26 pm, Jim in Houston ><nospamjamesgoo...@sbcglobal.netnospam> wrote: [quoted text clipped - 5 lines] >I think it would rather reduce drag as sharp things travel easier than >blunt things, which is why rockets have pointy ends! :-) On the Shuttle stack - that's kinda the equivalent of worrying about the extra drag caused by the edge of a bumpersticker on the driver's side door of a tractor-trailer rig. The bigger worry, from an aerodynamics point of view, isn't the changes in drag - but the changes in airflow and shock patterns around the strut and how they may impinge on the ET and the Orbiter. (It's actually possible (AIUI) to *increase* drag this way.) It's possible to make things worse (for example) by creating a shockwave that impinges on one or the other. That's going to be very expensive to validate. >I'd rather just try and whisper it into the ear of someone qualified to >consider it and not reject it out of hand without at least without an >explanation why. You'd have gotten a very different reaction if you had asked - rather than announcing. And that's a key thing here, what you claim to want, and your behavior are consistently inconsistent with each other. D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL >If this were easy, the fixes to the ET wouldn't be coming in > waves, all the fixes would have been made to the first return to flight ET. The impression I have been given is that post Columbia, NASA focused only on fixing known problem areas as opposed to doing a complete ET design validation. AKA: wait for problem to become known before adressing it. What I'd like to know is whether NASA ever considered putting all the non-standard protrusions such as fuel lines etc either on the side of the ET or on the other side so that any foam shedding wouldn't impact the shuttle itself. This would leave a smooth even surface of foam facing the shuttle and thus far less problematic. >>If this were easy, the fixes to the ET wouldn't be coming in >> waves, all the fixes would have been made to the first return to flight ET. > >The impression I have been given is that post Columbia, NASA focused >only on fixing known problem areas as opposed to doing a complete ET >design validation. That's what most people do in the real world - because it's works and is essentially the only rational way to do it. Sociopaths who want the shuttle to fail might think differently however. >AKA: wait for problem to become known before adressing it. Well, duh. You can't adress an unknown problem can you? Nor can you ensure that a 'complete ET design validation' (whatever that is in English) will discover all the problems. >What I'd like to know is whether NASA ever considered putting all the >non-standard protrusions such as fuel lines etc either on the side of >the ET or on the other side so that any foam shedding wouldn't impact >the shuttle itself. This would leave a smooth even surface of foam >facing the shuttle and thus far less problematic. Only you (and few other loons) would even think about trying this. D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL On Aug 22, 3:49 pm, "Jeff Findley" <jeff.find...@ugs.nojunk.com> wrote: > > I know a little about aerodynamics, but of course not everything. > > A little knowledge is a dangerous thing, especially when it comes to Jeff, you're quite right... but a lot of knowledge can also lead to over confidence and errors for different reasons. Someone unsure will likely be more thorough in checking their hypotheses. Actually, if knowledge is measured pretty much on a scale of infinity, the difference between a little knowledge and a lot of knowledge really becomes insignificant - they are both relative, with increasing knowledge leading to decreasing uncertainty. The key is to have a level of knowledge that is *enough* for the solution in hand, the rest is nice to have but not needed. > something as complex as the aerodynamics of the shuttle stack when it goes > through max-Q. If this were easy, the fixes to the ET wouldn't be coming in > waves, all the fixes would have been made to the first return to flight ET. Yes, not trivial, but I'd guess that max-Q is mainly a problem at the head end with the very high pressures. An amount of cavitation forms behind the bow shock forming a bubble of rarified air or a vacuum and the air will try rush back in from the sides further down to close the cavity. If the cavity closes higher up then the aerodynamic impact of my modification would be more significant, but it is streamlined enough to cut through the air anyway, as well as its primary function to deflect any debris harmlessly. Aerodynamic performance should be increased as a side effect, but only a real simulation will reveal this. I wonder if jettisonable leading edge wing shields would have been quicker and cheaper than the billions spent on fixing the foam! Andy. [...] > The 120 frame PovRay animation (1Mb XVid) should speak for itself. Recommendations for where to get the codecs? /dps >[...] >> The 120 frame PovRay animation (1Mb XVid) should speak for itself. > >Recommendations for where to get the codecs? > >/dps Yeah, I wasn't able to run it either. Jim in Houston. Contrary to popular opinion RN does not mean Real Nerd! Teddy Roosevelt's mother said: "Fill what is empty, empty what is full, and scratch where it itches" SignaturePosted via a free Usenet account from http://www.teranews.com >[...] >> The 120 frame PovRay animation (1Mb XVid) should speak for itself. > >Recommendations for where to get the codecs? Don't bother. D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL > >[...] > >> The 120 frame PovRay animation (1Mb XVid) should speak for itself. > > >Recommendations for where to get the codecs? > > Don't bother. Hey! Feel free to criticise if you like, but there's no need to be so derisory -- I'm only contributing a valid suggestion which I believe will help solve a problem. I spent hours putting it together! Andy. >> >[...] >> >> The 120 frame PovRay animation (1Mb XVid) should speak for itself. [quoted text clipped - 5 lines] >Hey! Feel free to criticise if you like, but there's no need to be so >derisory I will treat your suggestion in whatever manner I deem appropriate. If you don't want it discussed, don't post here. If you can't stand the heat, don't post here. This is a public forum and we are not bound by what you regard as proper criticism. (And derision is itself a form of criticism.) And if you want criticism - here is it, short and sweet. It's likely to be too heavy, and it will be too expensive. Suggestion rejected, case closed. >I'm only contributing a valid suggestion which I believe will help solve >a problem. No, you are suggesting a wild-a.s solution without a moments thought to the total effects on the _whole stack_ of your scheme. >I spent hours putting it together! The value of an idea is intrinsic to the idea itself - not to the amount of time creating pretty presentations. D. SignatureTouch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL > [...] > [quoted text clipped - 3 lines] > > /dps Sorry, forgot to mention: http://www.xvidmovies.com/codec/ It's a pretty useful codec. Cheers, Andy. > It doesn't seem to be easy to contact the right people in NASA about > suggestions, so I'm posting here in the hope that it'll get some [quoted text clipped - 6 lines] > foam problems have been solved, this should just tidy up the last > annoyances. You do realize that NASA already has a fix in the works for the area that produced this particular debris? The first of the tanks with the modified brackets in place will be delivered early next year. The problem is that they have the three current configuration tanks that will either have to be modifed now, or flown as-is. -Mike On Aug 23, 1:33 am, mdice...@seds.lpl.arizona.edu wrote: > > It doesn't seem to be easy to contact the right people in NASA about > > suggestions, so I'm posting here in the hope that it'll get some [quoted text clipped - 13 lines] > will either have to be modifed now, or flown as-is. > -Mike Thanks Mike, yes, indeed I do, and my idea would deal with the 3 in the pipeline, and the subsequent ETs too. Cheers, Andy. |
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