The Construction of Space Shuttle Launch Complex 39-B
A very personal and technical written and photographic history, by James MacLaren.
Tracking the Steel: Page 3 - Orbiter Mold Line Grating Panels Elevation 135.
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This is the area of the Orbiter Mold Line (Mold Line is the curve, the exact shape, of the exterior surface of the Orbiter, at any given elevation or location.) at elevation 135'-7" which is the main floor of both the RSS as a whole, and the Payload Changeout Room in particular.
And this is one of those areas where you're swinging your 4 million pound high-rise hotel around to come up right next to, but not quite touching your multi-billion dollar Space Shuttle, and yeah, this whole place is pretty excitable when it comes to precision of dimensions.
This is one of those places where you really have to get it right, ok?
And this is, alas, also one of those places where things got butchered, and then things got re-butchered, in a way that has caused us to lose all ability to see what we had to work with by way of contract drawings when I made this field sketch.
Sigh.
This is where the damnable OMS Pod Heated Purge Covers wound up going (for a while, anyway), and a few years after the work shown in this field sketch was done, we had to come along and torch every bit of this steel off the tower and replace it with heavily-modified steel, to make room for a damnable thing that down to this very day, forty full years later, has the power to cause my blood pressure to rise to alarming levels, which damnable thing was belatedly discovered, by those who designed it and who dictated that it be implemented, to be an astoundingly Bad Idea, verging on being perhaps even a criminally Bad Idea, and which damnable thing was then hastily removed (or at least those parts of it which survived intact following the mishap), and all of the RSS Floor Steel in this area was, again, ripped out and redone a second time, but by that time I was already gone, and in the process of attempting to slay a different (but equally insane) dragon just down the beach at Space Launch Complex 41, modifying that tower for the Titan IV Program. Gah! More of this to come. MUCH more. But not right now, ok?
For now, it's enough to know that this area got heavily revised with significant alterations to what I was personally involved in, with furnishing and installing, on both sets of drawings, 79K04400 for Pad A, and 79K14110 for Pad B.
And then it got heavily revised a second time, after I was gone, and it's this set of alterations which somebody was very careful to insert into the older drawing packages (79K04400 and 79K14110), thus blinding us to that intermediate state of alterations which revolved around the installation of the hated OMS Pods Heated Purge Covers.
And most of the original installation in this area of the Orbiter Mold Line at elevation 135'-7", and most of that first big revision, which greatly changed the original installation (again, on both sets of drawings, for both pads), was very carefully removed from both sets of drawings, but they missed a few things along the way.
And it's these very few, missed things, which we will be encountering more or less randomly, and most of which are quite inconspicuous (which is why they missed them) and none of which are very well suited for showing us what things looked like, before they were modified, that are going to become what we're most interested in.
We have become archaeologists, sifting through the dirt at the base of a modern skyscraper, searching for a paltry few remaining pottery shards that were not ground to dust in the intervening centuries, trying to piece together a long-lost civilization for which no other evidence of any kind remains.
And this is all we'll ever have for me to use in the telling of the stories down here, and the missed things are irregularly applied between drawing packages (79K04400, 79K14110, and even 79K24048, which we're not going to be getting into here at all until we get to Part 2 of these Stories, and which came after 79K14110, and which still managed to miss a few things going all the way back to The Beginning), and further irregularly applied on individual drawings, so some of what you're going to be seeing is going to be extraordinarily misleading, so try to stay on focus with what I'm pointing out on whatever drawings we'll be forced into using, and if things look a little (or even a LOT) self-contradictory in the area of the Orbiter Mold Line at elevation 135'-7" maybe kind of just let that go for the time being and hope that we'll eventually be able to wrap this up and tie it all together, later on somewhere, ok?
And, of course, if that's not bad enough, none of the 79K04400 or 79K14110 drawings that I have, revised or otherwise, show the actual Mold Line steel, anyway.
The very best we can do, the very closest we can come to the original configuration of this steel, turns out to be a 79K14110 drawing package Architectural drawing, A-25, and it's pretty poor for our present purposes, but at least it does show an Orbiter Mold Line kickplate, although it's mislabeled as 2"x6"x¼" BENT ⅊ CURB (TYP), just as if it's the same thing that goes around the rest of PCR Main Floor perimeter that the Insulated Metal Panels tie to, and it's very definitely NOT the same thing, and it also has eency-weency little Handrail Sockets, just like the ones shown here on M-83, which of course you'd never expect to find on something in direct contact with a solid wall of insulated-metal paneling that's seventy-five feet tall, further confirming that what we're seeing here really is the Orbiter Mold Line, but without any of the underlying steel that holds up this kickplate.
And here's the corresponding 79K04400 view of things for Pad A (mind the elevations, ok?), which, curiously enough, is also drawing A-25, and it's showing us the outer surface of the Orbiter itself, which of course our Orbiter Mold Line steel needed to match exactly, at a slight stand-off distance, which would be filled by the Inflatable Seal (which is the only thing on the structure of the whole tower that actually touches the orbiter), along with the edge of the PCR Floor (that the Inflatable Seal is perforce attached to), but there's no indication of a kickplate or any handrail sockets, so this one's not as good, but it's at least useful, and since we're here, please take note of the fact that back in the very beginning, back when this drawing was first produced in 1975, they hadn't even settled on a name for the OMS Pod, and instead were calling it the "APS Proturbance", and I find that somehow quaint and endearing, but that's very definitely just me being me.
I'm not exactly sure why the Orbiter Mold Line steel is missing from my drawings (although I do have some sneaking suspicions about it perhaps being swept under the same rug that The Affair of the OMS Pod Heated Purge Covers got swept under, but I digress), but it very definitely is missing, and at least as of the time of this writing, no drawing of any kind, showing this original Orbiter Mold Line steel, has ever shown up, and, needless to say, if that ever changes, then you can rest assured that I'll be coming back to these words and revising them accordingly.
But for now, all you get is the PCR Floor Steel that held up the Mold Line stuff, which was a weldment made from a very complexly-curved C8x11.5 with 7 short, straight, "stub" pieces that tied it back to the rest of the PCR Floor Steel with welded connections.
So we'll just have to do the best we can with what we've got, but we've at least got something, and that something is of course my field sketch, which you're seeing at the top of this page.
And we're working with a copy of that original sketch, and this particular copy is from a time when copier machines were still being figured out, and in those olden days, copier machines used tightly-wound rolls of funny slick special-treated paper that was fed through the bowels of the thing, processed with wet chemicals, and then sliced off with a shear to give you your individual pages, and the resulting copies always came out looking a little "off" and the fidelity wasn't the best either, but it's all we're gonna have for this one, so... ok.
Let's start out with such contract drawings as we have, to get ourselves located.
Be advised that not only none of the drawings I'm about to link to will be able to give us a proper representation of what was going on when I made the sketch, but that the Pad B drawings are in certain ways much worse, so I'm gonna be flipping back and forth between A Pad drawings and B Pad drawings, and mind the elevations, and keep your eye on the title block, looking for 79K14110 (Pad B) and 79K04400 (Pad A) so as you'll stand a fighting chance of making proper sense of this stuff.
RSS Main Floor, elevation 135'-7". Which is a combined 79K04400/79K14110 "frankendrawing" (we first encountered it back on Page 6) which I have had to create in order to allow you to visualize things as they really were at the time, as opposed to the endless, devious, and greatly-misleading hodgepodge of unidentified and unexplained revisions and alterations which the drawings in both packages, both 79K04400 and 79K14110, are infested with.
We're down at elevation 135'-7" (Pad B, remember?) which is the Floor of the Payload Changeout Room, and that means we're mating our RSS to the Space Shuttle just aft of the Payload Bay Doors, in a little nook of sorts between the main straight part of the Orbiter's fuselage and the tail-end of the Orbiter, and what happens is you're in a place where the Mold Line of the Orbiter becomes quite complex because you're dealing with the main outline of the fuselage, the OMS Pods, and a little bit of the Orbiter's Tail, all at the same time.
And the drawing you're about to see is no damn good at all, and everything outside of the blue and red shaded areas is wrong wrong wrong, and came much later, long after I had created the field sketch up at the top of the page, and must be ignored. Ditto every other drawing I'm going to be using to help you visualize this stuff, on this page. ALL of them contain no end of changes and revisions that occurred long after I made my sketch, and all of that stuff is going to confuse the hell out of you if you look at it too closely... so... fair warning.
And it looks like this on my 79K04400 drawing which we have to use because it's better quality, but... Pad A, so mind the elevations). And they give you a gap, but it's not much of a gap, and when you swing your thirteen-story high-rise hotel around, and take dead aim on that Space Shuttle sitting right there, completely defenseless against the insane 4 million pound mass and unstoppable force of your hotel...
...and you're running your steel hotel up to within just a very few inches of that Space Shuttle sitting right there in front of it...
...you're running the front bumper of your thirteen-story high, four-million pound, steel hotel up to just about the width of your hand with outstretched fingers, from a basket made out of eggshells, with a six-month old infant in it, and the six-month old infant needs the services of your steel hotel, which is on wheels, so you can't park the damn thing any farther away, and...
...let's not get this one wrong, ok?
...well then, that would be plenty bad enough all by itself, but then they had to go and liven things up a little, and they gave us this outrageous precision-curved shape to close in on...
...with a steel hotel!...
...about a hundred feet up in the air with a steel hotel...
...and yeah, you'd best have all of your dimensions correct before you go doing a thing like that.
If you go back and look at that drawing again, you can see that something's wrong somehow, and there's no way we're going to be able to swing our hotel around into the position shown, against a complicated curved-shape like that, without hitting the Space Shuttle, and of course that's not going to work out very well, so they made part of the Payload Changeout Room floor (and also the Antenna Access Platform far overhead up at elevation 198'-7½") mobile, in the form of Flip-up Platforms that get raised up out of harm's way as the RSS is closing in on the Orbiter, and then, once the RSS has been locked down in the mated, service position, which it needs to be in for work to get done on the Space Shuttle, they lower those flip-up platforms, and the PCR Floor becomes complete once again, and the Inflatable Seals that line the entire outline of the Big Opening in the PCR can be inflated, causing them to come into (nice soft) direct contact with the Orbiter, all the way around, just outside the perimeter of the Payload Bay Doors, and by that means they seal the area around the Payload Bay, and can then work with their Payload (or whatever else that might be in that same area) in a fully-compliant clean room environment.
And here's a nice isometric view, showing you where those flip-up platforms are located, and now you know what's going on with that end of things, but be advised that a close look at the shape of the PCR floor steel in the area where it's cut out to accommodate the Orbiter disagrees with the shape of this same area in my field sketch, as well as some of the other reference drawings I'm linking to (where the bulges of the OMS Pods meet the Orbiter's fuselage, in particular), and that's because we're stuck with the final incarnation of this stuff in what you're seeing here, and it disagrees pretty strongly with its initial incarnation,which is what I was working with, and I've warned you about that already, and I'm warning you about it once again here and now, because it will mislead you, if you give it so much as half a chance to do so, ok?.
There really is a lot (and we haven't even scratched the surface yet) that has to happen for the RSS to swing around and mate with the Orbiter.
So ok.
In addition to those flip-ups, we also need to be very careful when closing in on our Space Shuttle with the RSS along the full length of the Orbiter's fuselage, on either side of the Payload Bay.
They're not directly germane to our field sketch, but while we're here, we may as well get acquainted with the Side Seal Panels too, since they're part of the same system that provides a seal around the Orbiter's Payload Bay to allow us to do clean-room work inside of it.
And with the Side Seal Panels, there's some interestingness with the precise, exact, direction this part of the RSS (out on Column Line C, which makes an amazing, and to most people, a completely-unexpected, difference), closes in on the Orbiter from, but right now we'll let that one go, and return to it later, and for now just keep things reasonably (I hope) simple.
It's all about clearance, and it's all about not bashing into the Orbiter and destroying it, and you need to give yourself a little margin, lest you have yourself a billion-dollar oopsie.
So the whole thing is constructed to let it move out of the way, and then return back to where it belongs, once we're mated, so as we can provide ourselves with a nice clean-room seal.
So the Side Seal Panels have to be able to pivot around out of the way too.
And there's some funny human psychology that enters the picture right here, in the form of expectations.
And people, without even realizing they're doing it, expect the Side Seal Panels to open up, to pivot around out of the way, with a motion that would cause them to swing around open, like a box lid, with the side of the box lid opening, up and out of the way.
But that's not what happens.
There's nowhere to go for the Side Seal Panels to open up by swinging outward, away from the interior of the Payload Changeout Room, where they'd be out of the way.
You'll hit the Canister Guide Rails (a serious piece of hardware that cannot be relocated out of the way, elsewhere, about which more, later on some time) if you try to do that.
And even if you stop short, before you hit the Canister Guide Rails, you've still got a problem, because instead of hitting them, you're now simply blocking them, blocking access to them, and without access to them, the Canister can't be lifted into place (or lowered, either), and no Canister equals no Payload, and that kind of defeats the whole purpose of the Space Shuttle, so that's out, and on top of that, the Side Seal Panels must also be swung into place to seal the Canister when it's lifted into place, in the exact same fashion as they seal the Orbiter, and in the end, you just swing the Side Seal Panels inward to provide clearance, and be done with it, then and there.
So the Side Seal Panels open up, by swinging inward, getting completely out of the way of everything, (which means the flip-ups must also be flipped into their up position, to make room for the Side Seal Panel to come swinging in toward them) and there's just something funny about that inward swing that goes against the grain of human expectations, and people invariably look at that, and say, "Why'd they have to go and do it that way?"
And really, you should open up both drawings, one in one tab, and then the other in another tab, and then you can blink back and forth between them, and that way you can get a good idea of what's really going on here. Otherwise, it's pretty hard to visualize, and this is a pretty complicated area, so we need all the help we can get, right?
And now you know.
Now you know why they had to go and do it that way.
So ok.
So let us get back to my field sketch and see what's going on. Let's see what I was doing up on high steel that day, all those many long years ago.
And first of all we need to figure out what it is that we're looking at in the first place.
And what we're looking at in my sketch is the original version of how the RSS Floor Steel transitioned into the 8-inch channel-framing, which carried the curved 8-inch channel which matched the Orbiter's mold line, and which carried the inflatable seal in this area.
Got it?
Mostly ten-inch wide-flanges for the actual RSS Floor, transitioning to C8 channel iron, carrying one long bizarrely-curved C8 channel with its back facing toward the Orbiter, and which also (because it was the terminal end of the floor steel in this area, and beyond which was an open drop of eighty feet all the way down to the Pad Deck) carried a standard 4" Kick Plate.
Kick Plates (also called Toe Plates, and I will flip back and forth between these two differing names for the one single item, and I will do so more or less randomly, so get ready for that, too, ok?) were everywhere. Every edge, of every platform (with VERY few exceptions) on both towers, was lined on its far edge, where the open drops started, with one-quarter inch thick, by four inches high, steel toe plates, which were either welded directly to the handrails surrounding the platform, down at the level of the steel-bar grating or deck plates, or, as in this case, where there was no fixed handrail (it was removable posts only, with safety chains between the removable posts, and more often than not, the damn handrails in this area were in the way, so they simply removed them, and there was nothing there at all to keep you from going over the edge) the toe plate was welded directly to whatever framing steel that it was on the far edge of.
Ok?
Got all that?
So once again, here's the best I can do, using the Pad A drawing, to show you the first incarnation of the supporting C8x11.5 framing (and here's the third incarnation on a Pad B drawing, if you'd like to see how things finally wound up in this area, after I was already gone) which was back there not only holding up the long convolutedly-curved inflatable-seal perimeter carrier channel, but also holding up the steel-bar grating panels, which held up the quarter-inch smooth steel deckplates which actually made up the flooring here.
And while we're here, this is a perfect opportunity to take a closer look at that third, and final, incarnation of this steel, and notice if you please, that there's no flip-up platform on the Column Line 4.6 side of this floor steel!
What happened?
Did they remove the right OMS Pod from the Space Shuttle so as the RSS could mate cleanly without fear of banging into the orbiter?
Of course not.
But.
I mentioned earlier on this page that "there's some interestingness with the precise, exact, direction this part of the RSS (out on Column Line C, which makes an amazing, and to most people, a completely-unexpected, difference), closes in on the Orbiter from" and the fact that it's all hard-welded steel over on the Line 5 side of things, with no flip-up (the exact outline of which I have shaded blue and placed as an overlay on the all-welded floor steel over there), and thus there's nowhere for the Side Seal Panel over on this side to go anymore, is a direct result of that, and we're not going to be getting into it right now, but we definitely will be getting into it later, and it just goes to show how tricky this stuff can get, even when you're looking right at it, squarely in the eyes, and how certain implications can go unnoticed, by everybody, including the top people in this field, for literal years before somebody finally looks at it again, for the umpteenth time, and suddenly goes, "Ah HA!" and realizes what it really means, and then takes steps accordingly.
And, just for fun, I'll give you another little clue, which you can see for yourself in the form of the big roll-up door on the front of the RCS Room, which is not centered. It's offset noticeably to one side. And it's offset to the side for the very same reason they froze the right Side Seal Panel in place and removed the flip-up platform and replaced it with all-welded floor steel. But they had the RCS Room door-offset all figured out from the beginning, whereas it took them literal years to realize they could dispense with the mobile stuff on the front right side of the PCR, too.
And this is also where I have to make a confession. I confess to doctoring up some of the contract drawings which I've linked to on this page, to include a missing flip-up platform down on the PCR Floor, on the right-hand side, so you can see things the way they were, when I was working with the field sketch that started this whole crazed journey off in the first place. And maybe a couple of other things, too. But it's strictly so as you can actually see what I was dealing with at the time, ok? There is no malice. There is no conspiracy. There is no hidden agenda. There is only the desire that you understand exactly what was going on at the time, ok? For which understanding, a little doctoring-up was required, because of all the butchery this area of floor steel (and the drawings which we're stuck with trying to use to show it) underwent. A little alteration of things on the drawings. But only just a little. Only where it was absolutely necessary, ok?
But we're not here for any of that other stuff, right now.
We're here for the field sketch, ok?
We'll come back to "Ah HA!" and all the rest of it later on, ok? I promise.
So.
The floor panels of 1½" steel-bar grating in this area were themselves covered in quarter-inch smooth steel deckplates, but that deckplate steel came later on, and was not part of my outing on the tower this day.
But the grating panels...
Well that turns out to be the whole purpose of my little sojourn out on the iron that day.
And there were questions back at Sheffield's fabrication shop about the exact dimensions for the grating panels that would be resting on top of the "stub" support framing channels in this area, where the grating panels would be butted up against the kick plate at the very edge of the floor steel, and yours truly was sent out there, with a tape measure and a clipboard, and instructed to get out there, on the open steel framing eighty free and clear feet above the Pad Deck (Remember, there was no grating yet. There was no nothing yet, just air wafting around between the edges of the steel channels which are only 2 inches wide.) and get the as-built dimensions along the backs of the channels (not shown as such on the sketch, and instead just given as places to get a real-world dimension to check against the dimensions shown on the drawings (a lot of which turned out to be ¼" off, and this is a place where it needs to be right), which I did, everywhere except for one place where the PCR Main Doors were in the way at the time) that tie the rest of the floor steel to that curved perimeter channel with the kick plate on it.
And this is how they do it.
Some times, it's more trouble to trust some calculated over-fussy dimension or other, and instead, you just blaze away with the progress of the job until you get to the place where you're going to be needing that over-fussy dimension, and then just go up on the iron and measure the damn thing as it really exists in the real world, and that way save yourself a lot of potential headache and expense in the form of possibly getting it very-unpleasantly wrong somehow.
And of course it was no end of fun clambering around on the iron that day (I climbed trees a lot when I was a little kid, and it was always fun to be up in the air crawling around in the branches, so maybe that's where it comes from, but really, I do not know.) hanging out with the ironworkers, marveling at the view, relishing the fact that I was not cooped up in some stupid trailer somewhere, and just generally way beyond thankful for the dumb, stupid, luck, that put me out there in the first place.
So yeah. Big 135'-Grating-Panel Fun!
Yaaaaaay!
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