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#1400 by roma847 on 04 Feb, 2018 22:18
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Hi friends,
and here are the AFTSs, where one can hardly distinguish the two kinds with the naked eye, to the left the FUDs, and to the right the FXDs.
Of course, they now have to be freed from the rest of the supporting wax necessary for printing before they come fully into their own.
Only at higher magnification one can recognize the dividing lines between the individual segments, whereby the surface of the finer-grained structure of the FXD (right) feels a bit finer.
But of the feared and often described stepped structure of 3D prints is no trace, which has pleasantly surprised me.
And as one can see, the ring fits perfectly in the SRB Aft Skirt,
as well as the nozzle into the ring, which proves that I must have measured well and the parts have been printed exactly.
And so I really like the 3D AFTC Ring much more better than the spartan part of the Airfix Kit, to whom the Revell ASTC comes relatively close.
I suspect that the dividing lines between the segments become even more visible after cleaning and can still be seen after painting, so that the silver foil insulation strips can still be glued on well.
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#1401 by roma847 on 04 Feb, 2018 23:38
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Hello everybody,
quickly a small addendum to the ASTCs, which are tailor-made for the Airfix Shuttle Stack (1/144).
But one can use them also for the Revell Stack, as one can see on this image.
Since the inner diameter of the Revell Aft Skirts is slightly larger than for Airfix, it might therefore be advisable to glue an Evergreen Strip 0,25 mm x 1,0 mm around the ASTC ring. Then the ring would probably fit even better.
Or I could ask my ARC friend and 3D modeler Joe (crackerjazz) if he could enlarge the ASTC rings for the Revel Kit to Ø 33,5 mm.
And finally, the still remaining test with the Bare-Metal Foil (New Improved Chrome), of which still 24 thin strips (1 mm) must be glued after the painting of the rings, for what a lot of patience should be necessary again.
For this I have cut a longer 1 mm wide strip. Then the very thin film can be easily removed from the carrier strip, then each short pieces of it were cut off,
and glued to the half tube (to the left of the green line) as well as onto the Airfix ring and pressed and smoothed with a Q-Tip. These are the two stripes to the right of the Liquid Chrome strip that I have recently applied with the Pumpmarker.
And as one can see, the Bare-Metal Foil is sticking firmly even still after some hours. Let's see what it tomorrow will look like, hopefully not as with some of the previous stripes, but rather still unchanged firm, wherefore I precautionally press both thumbs.
And the chrome luster of the stripes is in my opinion completely sufficient, so that I would be fully satisfied with this result, if it stayed so.
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#1402 by roma847 on 05 Feb, 2018 23:14
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Hello everybody,
and even after a day, the strips are still gluing unchangedly in place, so that the decision for the Bare-Metal Foil (New Improved Chrome) has fallen.
Then I wanted to see how the stripes on the ASTC would look like, and was pleasantly surprised again.
Cutting these approx. 7 mm long and 1 mm wide strips and gluing over the dividing lines between the segments, however, proved to be the expected delicate matter, because one has hellishly to take care when handling with cutter and/or tweezers, so that the very thin foil does not tear off.
And as one can see, the dividing lines under the stripes are becoming slightly visible, but the same can also be seen on this photo from the STS-43 at a higher magnification.
Source: flickr.com (NASA on The Commons)
All in all, a completely successful matter with these 3D-ASTCs, which was worth all the effort.
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#1403 by mike robel on 06 Feb, 2018 00:18
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Glad that is coming together for you, Manfred.
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#1404 by roma847 on 06 Feb, 2018 12:16
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Thanks Mike,
I am pleasantly surprised myself by the quality of the AFTCs, which shows that Shapeways is on a good way.
I can recommend you the parts with a clear conscience.
And also after two days, the state of the Bare-Metal Foil stripes is unchanged stable,
and looks very well.
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#1405 by Ronpur50 on 06 Feb, 2018 22:56
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Those look great!! I am waiting on my new grid fins from Shapeways now. I love that place!
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#1406 by roma847 on 07 Feb, 2018 15:30
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Thanks Ron,
I have seen them in your thread, those also look awesome.
I fully agree with you, that one can really fall in love with these 3D parts.
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#1407 by roma847 on 08 Feb, 2018 22:16
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Hello everybody,
after having been more intensively involved with the AFTC rings that have been printed meanwhile by Shapeways and tested by me, I want to go back to the 3D modeling of the Intertank wherewith Michael Key had started last December, what I've been posting about.
Therefor I had sent him in the result of my research my drawing and the estimated Stringer dimensions without and with foam insulation, where actually only the dimensions with foam insulation for his 3D modeling are relevant.
Thereupon he had to adjust his 3D model once again, which I as a 3D rookie have not imaginated so complicated, but which should turn out to be a fallacy.
At the beginning of the year he told me that he has meanwhile modeled another version with these stringer dimensions, given by me,
Source: shapeways.com/forum (Michael Key)
consisting of each 26 Stringers in the two Thrust Panels and of each 40 Stringers in the intervening Stringer Panels.
But somehow I immediately stumbled over his number of 40, that's totally 80 stringers in the Stringer panels, which I was very surprised because I dimly remembered a number 108 in our German Raumcon discussions, wherewith the confusion around numbers and terms started at the beginning of my project start (11/2011).
After intensive researches I finally found the explanation in the System Definition Handbook SLWT, in which the Intertank structure is described quite well.
Source: Space Shuttle/External Tank System Definition Handbook SLWT
After that one has to distinguish the following terms:
While in the six Skin/Stringer Panels (45°) there are each 18 of these Stringers,
one speaks in the two Thrust Panels of Ribs, whereby in each case 26 parallel ribs as well as seven circumferential ribs are integrated in these panels,
Therewith was clarified at least the number of stringers, namely 108, which showed that Michael Key's 3D model had with totally only 80 too little stringers.
And now I had to explaine this fact heavy-heartedly Michael Key, whereby I was afraid that he would lynch me for it.
Thereupon he was very disappointed and had initially thrown in the towel quite frustrated.
But of course, I did not want to give up that fast ...
On the other hand, it would probably have been more useful to distribute the Stringer number onto the circumference of the eight 45° panels, whose drawing he had also been given by me. But in hindsight one is always smarter than before ...
In the meantime, I did it my way both for the six Stringer Panels and for the two Thrust Panels with following results and sent it to him, in the hope that he would have an insight as well as a good will.
Long story short, therewith I obviously had affected his honor, so that he was ready to go on. But I had to confirm to him that it would finally remain, in each case 54 stringers in the Stringer panels (135°) and in each case 26 ribs in the two Thrust panels (45°), whereupon I gave him my word and was jolly glad.
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#1408 by roma847 on 10 Feb, 2018 23:39
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Hello everybody,
there are progresses to be reported of Michael Key's intertank modeling.
After the number of Stringers (108) and that of the Ribs (52) have been clarified, we now have to clarify some further details on the Intertank, which are marked in this image, some of which have already been integrated into Michael's model.
Source: NASA
Here are his latest 3D pictures, whereby I wondered at first about these six plates in the Access Door,
that I've never seen before.
Furthermore, I noticed that the size and location of the Access Door (AD) and the Carrier Plate (CP) cannot be quite right,
Source: shapeways.com/forum (Michael Key)
which is why I determined them more precisely based on photos, wherefore I used the agreed reference size 1 Stringer+Valley = 1,3 mm.
At first I used this great direct view of the Carrier Plate, which has almost no perspective distortions, what should be considered.
For the determination and conversion of the measures, the following explanation of my numbers in the photos with and without mm is necessary, so that one does not get confused.
Numbers without mm are measured values in the respective photo, and Numbers with mm are the converted measurements in 1/144.
And if one compares this photo with his model, stands out that the distance D2 of the Carrier Plate from the Thrust Panel is too large because it should be only 2 Stringer+Valley (2,6 mm).
Source: NASA
With this distance and the determined dimensions of the Carrier Plate of 3.5 mm x 5.0 mm (W x H) I am afterwards in this photo of the Access Door boarded, which unfortunately is not so distortion-free in the area of the door.
And in this photo one can see that the door is flat and has no attached panels.
Source: NASA
Here's a similar picture at which the access door panel is removed, which is attached with 44 flat profile screws.
Source: NASA
Thus, the Access Door and the Carrier Plate would have the following dimensions:
Access Door: 9,1 mm x 7,7 mm (W x H)
Carrier Plate: 3,5 mm x 5,0 mm (W x H)
As one can see in the following image, the Fairings of the LO2 Feedline (17'') and of the GH2 Press. Line (2'') were added, as well as the LH2 PAL Ramp and the LO2 PAL Ramp, as well as the Supports for the two Press. Lines and the associated Cable Trays.
Thereto Michael has suggested to omit the two thin Press. Lines and the Cable Trays, as they would go beyond the intertank anyway and could possibly break off during printing or transport.
He was worried about the PAL Ramps. While the LO2 PAL Ramp could survive at the top, he fears that the LH2 PAL Ramp could probably break because it's very long and thin. So he asked if he should cut them off at the ends of the Intertank, which I agree with.
Since I anyway want to insert the LO2 Feedline and the Press, he should omit them away, but not the Cable Trays, because I could continue them to the front and backwards.
Then I still showed him these two photos, on which one can see that the bottom plates of the Fairings are flush with the stringers and not put onto, what he has accepted and wants to change.
Source: NASA
Source: NASA
These were essentially my hints and correction wishes.
Regarding of his plates attached on the Access Door, which I had queried, he sent me this photo here, which surprised me, since I did not have seen it yet.
That's why I asked him if he had any source, whereby it could possibly be a Mock-up.
I believe that shows once again that a timely and consensual coordination of such details is important for a smooth process, that's why one never stops learning.
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#1409 by roma847 on 11 Feb, 2018 17:38
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Hello everybody,
let's go step by step on our way to the goal, here are the next images of Michael Key's 3D modeling.
As one can see in this image, he has omitted both the six plates in the door and adjusted their size, as well as he had corrected the distances of the AD and the CP from each other and from the Thrust Panel.
Source: shapeways.com/forum (Michael Key)
The position of the CP, however, remained unchanged and still sits too high up, although I had already marked it in this last image,
Source: NASA
what one can also see in this photo.
Source: forum.nasaspaceflight.com (Jester)
Furthermore, it is noticeable that the bottom plate of the large LO2 Fairing admittedly is flush with the stringers, but not that of the small LH2 Fairing,
Source: shapeways.com/forum (Michael Key)
which is still to be corrected, according to the following photo, but hopefully will not cause any problems.
Source: NASA
Then here are two more images of the small supports of the GH2/GO2 Press. Lines (2''), first with the indicated lines,
Source: shapeways.com/forum (Michael Key)
and here the final design without the lines, whereby the thin wires (Ø 0.3 mm) will separately be inserted later and covered with small caps.
Source: shapeways.com/forum (Michael Key)
Now I hope that these last changes can also be considered by him, according to which an upload of the 3D model to Shapeways nothing would stand in the way.
But Michael Key wanted to be honest and told me, that there are some very small parts in this model that could possibly overstrain Shapeways' possibilities, so the model might not pass their inspections the first time around. That would be normal, and Shapeways would let him know the problem, which he would correct.
That's why I'm very curious, but initially his modified model is still due.
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#1410 by DaveS on 11 Feb, 2018 17:43
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That's most certainly a mock up. I think it might the ET mock-up that used to be by the KSCVC. I have attached a photo of the Intertank Access Door of the STS-31 ET. Also do note the roundness of the foam covering the stringers. It isn't angular like the foam used on the later SLWT ETs.
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#1411 by roma847 on 12 Feb, 2018 08:49
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Thanks Dave for the great pic.
It would be even better, you would send me a matching photo of the Access Door of the ET-8 that was used for the STS-6 shuttle stack.
But as far as Foam insulation is concerned, you may be right, because the LWT Intertank stringers were still not milled at the time, as one can see in this photo of the ET-8.
Source: retrospaceimages.com (J. L. Pickering)
But that does not matter, because if my 3D printed Intertank with all its narrow 108 stringers and 52 ribs will have been airbrushed, then everything will look so half-rounded, I hope.
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#1412 by roma847 on 12 Feb, 2018 16:53
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Hello everybody,
once again to this photo of the Access Door, that was shown by Michael Key, whose source was previously unknown.
A friend from the ARC Forum (southwestforests) has found the same photo in this Article, that was published by Jacques van Oene. 
Source: spaceflightinsider.com (Jacques van Oene)
By the end of 2012, this Original Test-ET (1977-80) had been exhibited on the KSC-Visitor Complex, but 2013 had to give place for the new Atlantis Exhibition Hall, in front of whose entrance since then there is standing a huge Mock-up ET with boosters.
And in this Article I found many other interesting photos of this ET, including also this photo of the Carrier Plate, which is just five stringers above the Access Door, as we now know.
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#1413 by DaveS on 12 Feb, 2018 17:06
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Thanks Dave for the great pic.
All the LWT Intertank Access Doors were the same just like they were for the later SLWTs. Also I think the attached chart will be of great help as it shows the exact locations of each stringer on the Intertank.
It would be even better, you would send me a matching photo of the Access Door of the ET-8 that was used for the STS-6 shuttle stack.
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#1414 by roma847 on 13 Feb, 2018 07:56
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Thanks Dave,
all that is missing is the source, which simply belongs to it, would you please so kind?
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#1415 by DaveS on 13 Feb, 2018 10:14
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It comes from the SLWT Systems Definition Handbook Vol. 2.
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#1416 by roma847 on 14 Feb, 2018 21:41
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Thanks Dave,
somehow that sounded familiar to me, one just has to know where to look for.
But the SLWT was the third and last generation of External Tanks, the LWTs during the earlier missions looked a bit simpler.
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#1417 by DaveS on 14 Feb, 2018 21:58
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Thanks Dave,
AFAIK the stringers didn't change between the tank versions. The main changes came from the material used to manufacture the actual propellant tanks.
somehow that sounded familiar to me, one just has to know where to look for.
But the SLWT was the third and last generation of External Tanks, the LWTs during the earlier missions looked a bit simpler. -
#1418 by roma847 on 16 Feb, 2018 20:40
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Hello everybody,
and now back to the 3D Intertank, where Michael Key is coming down the stretch after his considering of my last little changes.
And just now DaveS was coming out with this interesting photo of the Access Door at STS-31 (1990), unfortunately again without source.
But after I've found the image in Google, I recognized it from the URL, according to which it comes from the collection of George Gassaway, which I know by now.
Source: georgesrockets.com (George Gassaway)
And since I found a similar photo of the STS-30 (1989), I suspect that since the use of the Leightweight Tanks (LWT), starting at STS-6, such doors were installed, which apparently also had a foam insulation.
Source: georgesrockets.com (George Gassaway)
For this also militates this photo of my friend James MacLaren, which also shows such a door in the background. The image shows the Challenger on Pad 39-B, probably during the preparation for her fateful final mission STS-51L (1986), what I still will find out.
Source: forum.nasaspaceflight.com (James MacLaren)
Consequently the photo used so far for the 3D modeling shows a Graphite-Composite door, as has been used later on the Super Lightweight Tanks (SLWT),
Source: NASA
like here at the STS-133 (2011).
Source: NASA
For Michael Key's 3D-Modeling this realization is coming too late unfortunately, but which is not a problem, because I can glue this door with the two handles later on, especially since it is very small (9 mm x 8 mm), as one can see here.
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#1419 by saturnapollo on 16 Feb, 2018 20:52
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Manfred
Amazing stuff as always. If you have never used Bare Metal Foil before, you should clean it first with a metal cleaning solvent (like Brasso) on a very soft cloth (to avoid scratches). Even with the Ultra Bright Chrome you will find you will remove a layer, almost like oxidation layer and the finished result is far brighter.
cheers,
Keith
