Space Shuttle Launch Pad 39A with Challenger STS-6 (1:144)

[spacerunner]

Thanks Lex for your nice words, I'm glad if you like my work.
With every detail I learn something new of this ingenious technique, stay tuned.

[spacerunner]

Hello everybody,

and now to the Part 1, which is small, but looks relatively simple, although in this image it is half hidden by the Distribution box.


Source: georgesrockets.com (George Gassaway)

After I had punched it with the Chisel cutter out of an ABS Plate (1 mm) and smoothed the edges, it was glued at this point, directly in the corner between the Distribution box and the Cable Tray,



as one can see in these two images.





Then it went on with the Part 2, whose shape one can only partially see in the photos, which has made the determination of the dimensions more difficult. Therefore, here again for a better distinction the color-coded Parts (1-6) with their partially hidden contours.


Source: forum.nasaspaceflight.com (DaveS)

In the next photo, it looks like Part 2 is directly adjacent to the green end part of the Crossbeam (Ball interface fitting), what I first assumed, but which is not the case. On the other side, it is directly adjacent to the LO2 Feedline Bracket, what one can clearly see in the zoom.


Source: NASA

And from this image I have determined some dimensions of the parts, whereby in my experience for the determination of Heights one should also use a Reference height, and for Widths accordingly a Reference width too.



Since this is still not enough to be able to scratch the parts, I've analyzed this already several times shown photo (rotated) for the remaining dimensions, which is very well suited because of its high zoom resolution.


Source: forum.nasaspaceflight.com (DaveS)

However, this image is very confusing due to the many dimensions, which is why Part 2 can be seen here again separately.

Strictly speaking, the bottom of the part is not flat, but has down this triangular extension, but which I have not marked here and will suppress, since with about 0,4 mm it should be almost "invisible" and can be safely neglected ...



With these dimensions, I've then tried to scratch the part, whereby I first wanted to place it in an Evergreen strip (1 mm x 2 mm),



but which seemed a bit too puny to me. Therefore, I will start another trial with an ABS Plate (1 mm) too.



Previously I had drilled the opening for the GO2 Press. Line (Ø 0,4 mm) into the Umbilical Plate and threaded the Nickel Silver Rod on a trial basis.



That should be enough for today.

[spacerunner]

Hello friends,

today first again the experiment with Part 2 on a ABS Plate (1 mm), in which the slope should come out better than with the narrow Evergreen profile (1 mm x 2 mm). This time I have also taken into account this triangular extension on the bottom, which could be eliminated if necessary.



The punching with the Chisel cutter went relatively well, so that the contour had to be filed then only slightly,



what was again the same tricky procedure as the first time, because the part was barely could kept between the fingernails, but only in the tweezers tip, and even then slipped again and again.



In this image, one can see both parts in comparison, whereby the new part looks much more precise, whereby the lower extension is about 0,5 mm.



And this is roughly the mounting position right next to the outer LO2 Feedline Bracket,



which of course I have tested by laying up the part, and what looks pretty good for now.





Only at the point marked in red, I have to take away a little bit of the Crossbeam (Ball Interface Fitting), so that the narrow strip can advance a bit further, so that the tip of the part will be lined up precisely with the Feedline Bracket.



Next, with Part 3, the probably most complicated assembly group of the LO2 Umbilical comes along, which presumably will be built from several components.



With that, in particular, the connection point of the channel running diagonally forward to the LH2 Cable Tray must be determined even more precisely, which unfortunately is in hiding and so far could only be hinted at.
So all in all, a rather tricky matter in a confined space, which is why every handle wants to be well considered.

[spacerunner]

Hello everybody,

let's continue with the adjustment of Part 2, for which here beside the Crossbeam (Ball Interface Fitting) the announced narrow recess was cut out with the Mini saw blade.



And as one can see, it's only a small cut, but leads to a clear improvement!



Speaking of Original arrangement, I'm not sure anymore when I take a closer look at my black and white reference photo of the tank ET-8, which as is well known was to be the firstly flown Lightweight Tank (LWT), that was used since STS-6. Only at STS-7 was used a Standard Weight Tank (SWT) once again, for whatever reason.

Unfortunately, the resolution of the photo is not exhilarating even in the zoom, and the area of interest to me is in the dark and is unfortunately also obscured by the Vertical Strut.


Source: forum.nasaspaceflight.com (Jester)

But if you bend your eyes and look more closely, one recognizes, I believe, that especially the obliquely upwards running part of the Cable tray behind the support (Part 2) seems to be much narrower than on the previously considered images, which however, from later missions, where starting from STS-91 the Super Lightweight Tank (SLWT) was used, which had been modified again.



To the following photo I will still inquire DaveS, from which mission it originates.


Source: forum.nasaspaceflight.com (DaveS)

And this photo shows the ET-122 at the last mission of the Endeavor (STS-134).


Source: NASA
Let's see if I can get some more information from DaveS, because sometimes he still has cool photos in his hindquarters, which have already solved some riddles.

[spacerunner]

Hello everybody,

and DaveS' answer was not long in coming. He can not remember the mission from which his great photo came from, but as far as he knows, the Cable trays did not change during the Shuttle program and remained same from ET-1 (STS-1) to ET-138 (STS-135), which I did not want to believe at first.

Because similar to here on the ET-8-Photo,


Source: forum.nasaspaceflight.com (Jester)

also on this photo of ET-129 (STS-126) at first glance the obliquely rising CT part (red arrow) in front of the middle strut seems to be lower than the horizontal part (yellow arrow) behind the strut.


Source: NASA

And also on this great photo of DaveS it looks similar at first. This photo gives the widest possible insight to below the Crossbeam, where one can see the further course of the cable tray very well.


Source: forum.nasaspaceflight.com (DaveS)

And so my previous perception is obviously an optical illusion, as I have now recognized in the zoom, if one waits until the zoom bar disappears at the bottom of the screen.



In it one can see a dark area in the lower part of the oblique rise, which I have not recognized so far. This is evidently a dark taped area similar to that at the top of the CT bow below the plate (Part 4).


It becomes even clearer if one goes to 100% zoom in full-screen mode.



And if one takes a closer look at this image of the ET-129, one can see the same dark lower part in the zoom.


Source: NASA

Therefore I suppose that also the Cable Tray on the ET-8 looked exactly the same, only that one could not see the area even in the zoom, especially because it did lay completely in the dark too.



This confirms the statement of DaveS, that the Cable Trays did not change during the Shuttle Program, wherewith I now finally can go over to scratching the Part 3.

In doing so, I will essentially focus on the following known images.


Source: NASA



All I have still to do is think about how to proceed in the most appropriate way.

In any case, I will scratch the bow and the slant as separate parts and then connect. Since the bow with 1,5 mm x 6 mm x 4 mm is relatively small, the question arises, whether I am file out the whole part, or just the actual bow (Part 3.1), and then glue on the two tiny Parts 3.2/3.3?

How do you think about it?

[spacerunner]

Hello friends,
do you really have no opinion? What a shame ... But I will continue anyway.

Because the bow incl. the TPS Cladding on the LO2 Side compared to the one on the LH2 Side is nearly "huge", as can be seen here at the ET-118 (STS-115),



it would be an unnecessary and vain effort trying to file out the whole part, as for the LH2 Umbilical.



So I'm going to bend an Evergreen profile (1 mm x 1,5 mm) again using my proven Balsa-aided Bending Technique under hot air around a Balsa stencil.

For this I first printed this drawing as a template on a scale of 1:144 in order to search for a corresponding Balsa stencil for the bow,


Source: System Definition Handbook SLWT, Vol. II (Lockheed Martin)

and have actually found one in my Balsa collection. One only has to keep in mind that the Cable tray in the drawing has no TPS cladding and is therefore a bit thinner than in reality.



And then it went to the Balsa-bending table, on which the rectangular profile was clamped in a known manner between two small Balsa boards.



Thereafter, the Hot air gun was started and the rod bent under the stream of hot air around the template, fixed immediately and once more blown on hot again.



After the bow could cool off for a while and this shape was "frozen", I removed the small board and could convince me of the success of the bend.



And so I could go on,



and have immediately marked the Length (6 mm) and the Height (4 mm) of the bow.



Now I still have to determine the end point of the part in front of the Crossbeam. Then I also know how long the Part 3.4 may be and can then scratchen this.
Anyway, I'm very satisfied so far and I hope it stays that way.

[beckychestney]

Opinion? You're talkin' WAY above my pay grade!

[spacerunner]

No problem, Becky, I have already decided for the second variant.

Hello everybody,

next, I've cut off the two tiny Closeouts from an Evergreen strip (0,25 mm x 1,5 mm), as well as sanded a bit,



and glued them on the bow (Part 3.1).



With it then I have checked the arrangement of the bow together with the center support (Part 2) and the provisional Part 3.4 for which I used a Profile bar (1,5 mm x 1,5 mm),



what already looked pretty neat.



Here's for comparison the scale drawing of this arrangement,



which I've provisionally laid on locally, in order to see if or how the size fits, which also looks quite well.



So far so good, but since with it neither the endpoint of the Cable Tray in front of the Crossbeam nor the length could be determined, I came up with the idea, to bend a complete CT-Dummy out of a Strip (1,0 mm x 1,5 mm) and to test its location locally according to my previous measures.

After that was done in no time,



I've marked the height up to the Umbilical plate (about 7 mm), as well as the distance to the slant (6 mm),



where I've bent it after the upper cut.



The length of the CT Dummy from the Crossbeam to the endpoint under the Umbilical plate I have measured with 11 mm.



And then I've tried this dummy locally, whereby the positioning was a pretty tricky affair.

And as one can see, the part fits quite well,



and hits roughly onto the slant of the LH2 Cable Tray below the Crossbeam, which seems quite plausible.



With these dimensions, I can now scratch the remaining parts on both sides of the previous bow.



That's it for today.

[spacerunner]

Hello friends,

but with the attaching of further parts that's another story, which is why I've thought of everything twice again plenty, especially since it is in the combination of such filigree parts not to millimeters, but rather by decimillimeters. And wether at the end the exact installation dimension of the Cable Tray would come out is more than doubtful, or but coincidence.

Therefore, one does not get along without fitting, which is why it is better to proceed step by step, i.e. scratching one part at a time and preferring to test better safe than sorry to be able still to correct in between.

Thus, the CT-Dummy had done its duty and could be set aside.

But already with to try on the parts one has a lot of trouble to bring these small parts into position and then measure distances, what one can see in this image. Because in order to lay up the profile bar for the slant next to the central support, I had to put (with breath hold) a spacer in between.



Therefore, it seemed appropriate to glue first the Center support (Part 2), so as to have a fixed point for the further procedure. Before that, I've placed the support several times on the outer LO2 Feedline Bracket and juggled back and forth, and finally made even smaller corrections (height/width) until I was satisfied with its position and then it could finally be glued.



Because if the size and location of this support would not be right, would not fit the slant, as well as the subsequent bow too.



And now, by laying on of the intended Profile bar (1,5 mm x 1,5 mm), I was able to more accurately determine the required length of the Slant (Part 3.4) than before, because the support could not slip anymore. But before I shorten the rod to the final length, I may be want to make a few minor modifications. At least the lower tip of the bar under the support should become still slightly bevelled.



In order to be able to adapt the bow with the lower Closeout to the support, I had to first shorten a bit the upper part of the bow in order to attach it to the Umbilical plate and to be able to test the position.

And also for this a special substructure was needed to get to the appropriate height. Above the black marking, it will then go on with the Parts 4-6.



But as one can see, the front part with the Closeout fits quite well under the support, so now still only the front slant has to be made to fit.

[spacerunner]

Hello everybody,
well, this slanted front part of the Cable Tray(Part 3.4) really has it in it and has almost already become to a nightmare of my sleepless nights ...

But meanwhile I'm of the opinion that one edge more or less doesn't matter, and therefore I will be content with an approximate solution, especially since later one cannot see this part under the orbiter from the outside anyway.

The biggest difficulty in interpreting the course of the contours in the front area was this red circled notch directly under the Center support, which I have yet still decided to do,


Source: NASA

which can be clearly seen again on this image section.


Source: forum.nasaspaceflight.com (DaveS)

And in this image one can also see the front area relatively well, where I will then orient myself during scratching,


Source: NASA

especially since this is only a short stub of about 5 mm length anyway, as one can see here.



For the upper closeout, I've glued a Strip (0,25 mm x 1,5 mm x 3 mm),



and the lateral closeout will follow next in a similar way, wherewith I will then content myself.