Lunokhod 2 Posted March 25, 2013 Share Posted March 25, 2013 Thanks for you kind words again Pete. Good to know someone out there is on the same page as me re structures.......imagine a 747 in the Science Museum in London with it skin removed.......now that would be a display. Thanks also Lunokhod2 ....this would have frit me to death a time ago but........... I started this build last October. I abandoned a 1/2" build some years ago because at this scale you really need the Grumman engineering drawings as virtually everything should go in and as there were some 20000 + at the rate of 400 per week between 1965 & 1966 alone ( ref Moon Lander by Thomas J Kelly - a great read and I highly recommend it )............. There will have to be quite a lot of guesswork on this build but sticking to sound engineering principles, hopefully at 3/8" the model will look OK. The S/CAT site was ( v.sadly past tense it seems ) excellent. But working from photos is difficult because of dimension distortions through perspective etc. I could not get things to match up, but then I found this last summer http://heroicrelics.org/info/lm/lm-structural.html problem solved at a stroke.......wonderful........ LT4 ended up as Snoopy. Re the drawings from Vincent Meens' wonderful model. Perhaps he did not find the NASA appendix A configuration description ( will give the web site when I find it amongst my mounds of stuff ...apols ) Quote : " The midsection is formed by two segments of a cylinder.........The cylindrical segments have a radius of 92.0 inches. " Which is of course also the diameter of the crew section and makes perfect structural sense. But these things nag at me ...the dimensioned drawings above do not give this radius and seem to look similar to, not only Vincent's drawing but some of the Grumman manufacturing pics but......I work with a planospheric magnifying glass so shoving a ref photo from 'Building Moonships by Joshua Stoff ' under it and viewing slightly to one side..........viola.........camera distortion .... so it 92" radius it is. Works on my model too. I aint going to argue with NASA.......... So beware dimensioning from photos. Will try for a pic later do demonstrate. Building Pete......well ...yeh....started on paper Micromodels in the late forties. Spaceships....Jetex and balsa wood and tissue paper. There was a Worlds Collide rocket Jetex kit on ebay recently and it went for nearly £400 ............remember the kit coming out ...21/6 ? and I was on 6d a week pocket money. Ah happy days........ Have a look. Cheers John http://www.ebay.co.uk/itm/WHEN-WORLDS-COLLIDE-JETEX-KIT-ZYRA-SPACESHIP-ROCKET-WILMOT-MANSOUR-1951-/310583132918?nma=true&si=UWYkiPZXE%252B5QPZ6YzOo2UiQEkEQ%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557 Hello John, Although I worked with many pictures I used for the mid section the following drawing from Grumman. 92" is the diameter of the crew compartment but the mid sections radius are 46.457" which gives diameters of about 93". For my model I used as an X reference the centre of the crew compartment which is at +X252". Quote Link to post Share on other sites
johnbuck Posted March 25, 2013 Author Share Posted March 25, 2013 (edited) Hi Vincent Many thanks indeed for that. So what do we do about the midsection ?? The Nasa technical server that refers to the midsection is down at the moment but I did print it off when I found it and it is as I quoted above - 92"radius I did um and r over this a good deal , these things do nag at me, as I had a copy of your drawings of your gorgeous model from 2/3 years back. Having said that I am not familiar with the drawing you have kindly put up. Could this be an early LTA ? rather than LT4. Do you have a date for this drawing ? There are also minor dimension discrepancies I notice. Another Nasa ref http://www.hq.nasa.gov/alsj/LM04_Lunar_Module_ppLV1-17.pdf gives a elliptical minor axis of the mid section as 56" but there is no indication of the major axis, so assuming that the foci of the ellipse represent the upper and lower decks levels ie 61" apart we have a major axis of 82.3" which does give a 92" radius as measured from the focus........ don't think my maths is up to this !! A further thought : a narrower midsection would be stronger in depression ( docking ? ascent ? ) and lighter overall wouldn't it...........mmmmmmm Any further thoughts. Which one of us is going to start again ???????????!!!!!!!!!!!! Can any one else out there help ? Good stuff this........... Best wishes John Edited March 26, 2013 by johnbuck Quote Link to post Share on other sites
johnbuck Posted March 25, 2013 Author Share Posted March 25, 2013 (edited) depression !!!!!!!!!!!!!!............a Freudian slip perhaps........... of course I meant compression......apologies to all And many thanks stevenichols for your kind comment. Its much appreciated Cheers John Edited March 25, 2013 by johnbuck Quote Link to post Share on other sites
Lunokhod 2 Posted March 26, 2013 Share Posted March 26, 2013 Dear John, As you can see below my calculation based on the blueprint gives me a semi minor axis of 28.727" ie a minor axis of about about 57.5" (drawing on the left below). I modified it with 56" and you can see that the difference is really minor and only 0.04" at 1/32. The second picture shows the difference between the 57.5" and the 56" and you can see the difference is really minor. What puzzled me in your picture was the general appearance and in particular the ratio between the width of the mid-section and the width of the floor and roof. It should be about 1.6 whereas on you picture it is in the order of 1.3. The problem with a 1.3 ratio is that you will have difficulty inserting the PLSS, storage compartments and the Environmental Control Subsystem Quote Link to post Share on other sites
johnbuck Posted March 26, 2013 Author Share Posted March 26, 2013 (edited) Hello Vincent Most interesting........Many thanks and I see exactly where you are coming from but........ Using the NASA references given in my previous posts and the Grumman drawing SK17-32-34 from http://heroicrelics.org/info/lm/lm-structural.html I have re-drawn it out and I come up with the same profile. The 92" radius and the 82.8" major axis do come within a gnats whisker and the difference agrees with your calculations pretty closely as shown. I approximate one would have to increase the deck separation by 24" as shown by the dotted line otherwise. Is there a fundamental error somewhere ? Hey ho........it's what scratch building is all about............ Best wishes John Edited March 26, 2013 by johnbuck Quote Link to post Share on other sites
johnbuck Posted March 27, 2013 Author Share Posted March 27, 2013 (edited) Hello Vincent, yup....there is a fundamental error....me ....I even show it in the drawing above so repeating the mistake yet again !!!! A senior moment writ very large indeed....... 92" DIAMETER...yes but I should have worked with the RADIUS shouldn't I. Oh dear........... I loved the Billy Bunter of Greyfriars School stories as a youngster and and when he, Bunter, did something incredibly stupid ( which was frequent ) his friend Hurree Jamset Ram Singh, an Indian prince, would say " Bunter - your thickfulness is terrific ! " an accusation I level at myself with increasing frequency is seems, except that this time my thickfulness is MEGA terrific !!!!! So the question now is do I put this scratchbuild on hiatus or go back to the scratchbuild of Jules Verne's Columbiad which is about two thirds finished. I shall start hacking away and then see how I feel by the end of the day. Hey ho...its a learning experience...........as long as one does LEARN from it. So all you potential scratch builders out there BE WARNED. Treble checking your dimensions is not enough.........Hopefully non of you will, or have done anything as fundamentally flawed as this. But ....if the HST couldn't focus initially ( see http://www.ssl.berkeley.edu/~mlampton/AllenReportHST.pdf a most interesting read )..... gotta give myself some comfort., Thank you Vincent for your discussion re this. It is really is much appreciated. In a way am glad its me and not you........such a beautiful LM you built. I now take my scalpel in my hand and.......... Best wishes John Edited March 27, 2013 by johnbuck Quote Link to post Share on other sites
K2Pete Posted March 27, 2013 Share Posted March 27, 2013 So the question now is do I put this scratchbuild on hiatus or go back to the scratchbuild of Jules Verne's Columbiad which is about two thirds finished. I shall start hacking away and then see how I feel by the end of the day. Hey ho...its a learning experience...........as long as one does LEARN from it. Aw-w gee-e-ez, don't let a little miscalculation dissuade you from continuing this build John. I mean, it's not like you placed the Oxidizer tank near the front hatch ... Nobody's gonna hold your feet to the fire about an interior radius ( just how noticeable would this be anyway? ) But if you do abandon this build and continue with the Jules Verne build, don't be shy about posting pix on the Sci-Fi forum ... Pete Quote Link to post Share on other sites
johnbuck Posted March 27, 2013 Author Share Posted March 27, 2013 Thanks Pete It is VERY noticeable. Vincent is quite right. Should I wish to fit out the midsection later ( and I do want to keep that option open ) I would not be able to get the items Vincent mentions in. Have started hacking. The aft bulkhead is now successfully off at least...I need a tea break. Cheers John Quote Link to post Share on other sites
Lunokhod 2 Posted March 27, 2013 Share Posted March 27, 2013 Dear John, Using powerpoint I drew a further midsection using the 56" minor axis ellipse. In order to meet the floor and ceiling I had to adapt the major axis and I found a value of about 78" not very far from your 82.8". On this second image I superimposed the green midesection and the ellipse midsection which match almost perfectly. My midsection of course is a bit larger since the minor axis was about 57.5". Looking at your drawing I think I found the error, you probably mixed-up minor axis and the more usual semi-minor axis which means that your 92" radius should be a diameter. As I am writing this message I can see your late message where you discovered the error. I feel very sorry for you. I hope you will be able to correct it without too many difficulties Quote Link to post Share on other sites
johnbuck Posted March 27, 2013 Author Share Posted March 27, 2013 (edited) Thanks Vincent for all your trouble but I think the saga continues. Please m'lud I retract my previous confession...I think.....or do I ? ( having just removed the aft bulkhead ) In the NASA Appendix A Configuration Description ( their tech server is still down so cannot give the web ref. ) my quote above IS correct ie 92" RADIUS...."the cylindrical segments have a radius of 92.0 inches" and in my drawing above the ellipse with the 82.8 " described is so very close - about 0.75". I used this calculator http://www.cleavebooks.co.uk/scol/callipse.htm but the Grumman drawing you posted....well...DOES say 46.457" radius. On reflection, referring to your drawings, I am inclined now to think that the Appendix A technical writer who wrote radius when he meant diameter should be sat under a Thiokol SRB and think about the trouble he has caused before I press the button.... I feel better. PLEASE SIR ..IT WASN"T ME. This has always been a problem with scratchbuilding hasn't it - not having all the information to hand. Again thanks for the Grumman drawing. I never came across this in all my researches. Never mind ...part of life's rich pattern Cheers John Edited March 27, 2013 by johnbuck Quote Link to post Share on other sites
johnbuck Posted March 27, 2013 Author Share Posted March 27, 2013 OK Guys...something positive out of this.... now have a model of the LM ascent stage remnants after LM-5 crashed into the moon !!! The forward bulkhead had to be scrapped as did the mid section skin assemblies but the aft bulkhead, tunnel and upper/lower decks were saved plus the cant frames. Cheers John So before and after : ' When a thing is once begun never leave it 'till its done; be the labour great or small do it well or not at all ' from a 1950's hobbies book Quote Link to post Share on other sites
niart17 Posted March 27, 2013 Share Posted March 27, 2013 Wow, all that beautiful work...gone. Well, I''m sure your rebuild and fix will be even better (though I don't know how it could be much better!) You sir have my respect! Bill Quote Link to post Share on other sites
K2Pete Posted March 27, 2013 Share Posted March 27, 2013 I'm almost sorry you learned how to post pix ... But, you're a brave man. And tell me, the error looks to be almost microscopic ... am I interpreting Vincent's drawing correctly, in that the Red and Green overlays are yours and M Meens? You 2 gents are setting the bar way too high for us mere 'eyeballers'! :lol: Pete Quote Link to post Share on other sites
j-love Posted March 27, 2013 Share Posted March 27, 2013 What tha ... :blink: Quote Link to post Share on other sites
stevenichols Posted March 27, 2013 Share Posted March 27, 2013 (edited) John, I'am at a loss for words here. Other than a Grumman engineer and yourself who would have known. I know how you feel though finding a potential issue with a scratchbuild after you have progressed this far. Hang in there mate, your skills have all of our attention. Edited March 27, 2013 by stevenichols Quote Link to post Share on other sites
johnbuck Posted March 27, 2013 Author Share Posted March 27, 2013 (edited) Thanks Guys for your sympathy ....really appreciated but... The difference is quite significant in fact, approximately 12" on the overall centre width of the midsection hence the very differing profiles. It comes down to to the different information Vincent and I have. Vincent has the primary source of a Grumman drawing whilst i had only the NASA technical reports where the information given is different to that primary drawing. It looks as though the tech reports have cumulative errors ie starting by referring to diameter when they meant radius which gives a 56" approximate ( tech report does say approximate ) minor axis to the ellipse as later mentioned in another summaryt. From comparing my drawing and Vincent's overlays it does look as though the tech reports dimensions working out were just co-incidental. These things happen.... I will carry on with the build so as to get back to the 'chopping up point' but then may switch over and finish ? off the Columbiad. Variety is the spice of life is it not. So Pete,as requested I will post some pics of that build over on the sci-fi forum. Probably tomorrow if I get time. Its all imagination, well almost, in that build so no constraints. Great fun.......... Thanks to everyone for your invaluable support Cheers John ps whilst discussing this over dinner this evening my wife referred to us, rather charmingly, as a bunch of loonies, affectionately I think, I hope ( if a pun rather apt ) !!! Years ago she worked for MAP ...Model and Allied Publications and apparently we, all model makers that is, were known in the office as " the no socks brigade '.....true, honest injun........ I digress.......... Edited March 27, 2013 by johnbuck Quote Link to post Share on other sites
crackerjazz Posted March 27, 2013 Share Posted March 27, 2013 I've no doubt you'll rebuild this to something better in no time, John. Man, you guys are good. They way you exchange all those ideas and calculations with Vincent makes my jaw drop while I read. It truly is rocket science. Quote Link to post Share on other sites
johnbuck Posted March 31, 2013 Author Share Posted March 31, 2013 Hi Folks OK so these are the new mid-section longerons profiled to the Grumman drawing that Vincent kindly posted. There is quite a difference as you can see. On looking back on all the material, I have I gotten to wondering again why the NASA tech reports appear to be ‘wrong’…..The 92†Radius ‘fitting’ almost exactly the 82.8 minor axis of the ellipse mentioned in another report just seems, on reflection, just too much of a co-incidence. Remembering my school geometry : an ellipse is part of a cone cut at an angle – a circle being a specially defined section of a cone. Why define the mid-section profile in terms initially of an ellipse unless this is involved with the original structural stress calculations ? With this narrower profile, whilst reducing the mid section/cabin volume, it would increase in equal measure the volume available for modules outside the mid section pressure vessel for eg. Enlarged capacity RCS/ helium tanks. Lunar sample mass / EVA increased 5 and 10 times respectively between Apollo 11 & 17. http://www.lpi.usra.edu/science/kring/lunar_exploration/evaSampleMass.pdf For the J missions perhaps. I wonder…………anyone have any thoughts on this ? Quote Link to post Share on other sites
johnbuck Posted April 12, 2013 Author Share Posted April 12, 2013 Hi Guys, Just thought I would let you know that am almost back on track. As you can see the mid section skin assemblies now have the profile according to Vincent’s Grumman drawing and it does make quite a difference to the volume. Still wondering about the J series though. That is going to bug me for ever. Took the opportunity to make a couple of small corrections, change the appearance of the sectioning ( more 'mechanical' looking now I think. The longerons will be cut out when the bulkheads go on in order to maintain the structural integrity ) and add a lot more lovely rivets according to the pics that habu2 kindly posted. A little bit of a clean-up, two repairs on the tunnel support frames and then I can get on with the forward bulkhead which had to be scrapped in the re-work Cheers John Quote Link to post Share on other sites
j-love Posted April 12, 2013 Share Posted April 12, 2013 Looking great. I'm glad to see it coming back together. Quote Link to post Share on other sites
johnbuck Posted April 13, 2013 Author Share Posted April 13, 2013 Thanks j-love for the encouragement...appreciated Should be worth it in the end. Am now working on the forward bulkhead of the ms. Keep thinking of Manfred. My alterations have been nothing compared to his. Am keeping my fingers crossed for him. Cheers John Quote Link to post Share on other sites
crackerjazz Posted April 13, 2013 Share Posted April 13, 2013 Glad to see you're making great progress, John : ) And great rivetwork as always. It should be smooth sailing from here on in. Quote Link to post Share on other sites
johnbuck Posted April 14, 2013 Author Share Posted April 14, 2013 Thanks crackerjazz for your kind words. Smooth sailing.............am not that kind of optimist I'm afraid. However - we shall see. Cheers John Quote Link to post Share on other sites
K2Pete Posted April 15, 2013 Share Posted April 15, 2013 It's great to see you back on the horse John! And I think all of us optimistic viewers will negate your pessimism regarding this build ... no matter how long it takes! ... we shall see ... indeed! Pete Quote Link to post Share on other sites
spaceman Posted April 15, 2013 Share Posted April 15, 2013 Hi John, fantastic detailed work as providing off, how do you create these lots of small rivets? Have you a special tool for it? Quote Link to post Share on other sites
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