The Construction of Space Shuttle Launch Complex 39-B

A very personal and technical written and photographic history, by James MacLaren.

Page 45: Components Visible From End of Hammerhead Crane.

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And now that I've been given the opportunity to fail miserably at telling you where you are and what it feels like, we're going to return to the same image we saw on the previous page and approach it in a more businesslike manner and identify what's actually visible here.

This identifying of features is going to presume you've read everything that came before, all the way back to Page 1, and that you have the requisite familiarity with things to keep us from repeating ourselves with each new identification, and in that way, at least try to keep things a little less long-winded.

If you've forgotten, or if you simply glossed over and never really understood in the first place, no worries.

You can narrow in on things I've already covered by hitting a specialty google search as follows:

site:16streets.com/39-B/ followed by a space (very important to get that space in there) and then after that, the thing you're looking for, and the thing you're looking for may or may not benefit from putting it inside of quotation marks.

So. If I wanted to see what's already been covered regarding Hangers Framing and Ladders, elevation 100' to 211', I could punch it into the google search bar in one of two ways:

Without quotes around what I'm searching for:

site:16streets.com/39-B/ Hangers Framing and Ladders, elevation 100' to 211'

Or with quotes around what I'm searching for.

site:16streets.com/39-B/ "Hangers Framing and Ladders, elevation 100' to 211'"

Give it a whirl. See what it renders up. Even if it turns out that the quoted version is nowhere to be found, verbatim, google is pretty good at taking a "best guess" approach to things, and it will very often get you to where you're trying to go, even with a slight mistake or two in the search terms. Get a feel for how it works. It's not a giveaway, and you're oftentimes going to find more (sometimes much more) than one result when searching this way, including images as well as actual web pages, and you're probably going to have to scroll down, or search the web page you got taken to for any matching terms (try to keep on-page searches brief, just a word or three), and for some things it's going to be easier, and for some things are going to be harder, and for some things it won't work at all, and...

Energy in, energy out. Work put in, results taken out.

You know the drill. I couldn't spoon feed it to you, even if I wanted to, and as it turns out, I do not want to, anyway.

So you get to do a little work, if you want to get a little smarter about this stuff. It's the way of the world, and those who are willing to put in the work are the ones who get the best results.

Also, please keep in mind that google does not own the world. Duckduckgo.com actually rendered better search results than google did. Startpage.com found nothing at all. Bing.com did pretty good, but introduced a completely spurious page (Page 41, actually) for unknowable reasons. There are plenty more search engines out there than this very small sampling, so... who's to say? And even if one page does well one day, that's no guarantee that the same page will do well a different day even with the exact same search terms, because they're always tweaking their algorithms, and nothing stays put, nothing stays the same, and change is the only constant.

Having said all the foregoing, I'm not going go out of my way to make it more difficult, and I'm going to be tossing links as we go, but if I miss something, or if a link I might give turns out to not be fully-explanatory, then give this little search trick a go, and see what it spits back at you when you ask it something.

Ok?

Ok.

And for now, let's start with something new.

Let's start with something there will be no referring to from previous pages, and while we're at it, we'll make it something that's quite recognizable in the photograph, and we'll also make it something that's pretty important in the big-picture view of things.

Let's start with the pair of strongbacks that support the Orbiter Access Arm, which is what the astronauts who flew on the Space Shuttle walked across to get to the hatch and enter the Orbiter.

The OAA was the last thing firmly attached to the earth, that the crew would ever touch, prior to engine ignition and commencement of flight.

In certain ways, the OAA is a pretty scary thing, and an awful lot of unsaid things get spoken wordlessly whenever people's feet tread upon its grating.

The OAA itself had yet to be hung on the tower (we did that a few years later, when I returned to the Pad working for Ivey's Steel Erectors, and I have a lot of good pictures of it, but for now, we're going to stay on the timeline and work things as they occurred, using the photographs at hand).

Here are the two strongbacks, highlighted and labeled for you.

And I guess we'll start of with, "Why strongback? Why do we need a strongback? What's it do?"

We have previously encountered strongbacks before, back on Page 36 when we were talking about the LRU and the CAP that replaced it, but at that time I was hammering you pretty good with a blizzard of strange new things, and decided I'd just pass over it in the interests of not murdering you with information overload.

And we learn that a strongback is a structure that gives strength to something that, on its own, does not have enough to properly stay put and do its job without help.

The version of Wikipedia I'm referring to as I write these words (It changes over time. Everything changes. So be careful, ok?) invokes both "beam" and "girder" to tell us about strongbacks, but in my own experience out on the Pad, strongbacks were most always trusses, having two, or sometimes more, longitudinal members, connected to each other with a fair bit of closely-spaced diagonal and horizontal bracing, and when we look at our OAA Strongbacks, that's pretty much what we're seeing.

So ok. So now that we know what it is and how it is, let's look into why it is.

The two strongbacks in our photograph are both identified as being associated with the Orbiter Access Arm, but in fact, what they're beefing up is the FSS from which the OAA hangs, and the Struts which run between the FSS and the Hinge Column, from which the OAA Latchback hangs.

In this instance, our strongbacks are stiffening up the FSS and the Struts, which otherwise might flex or perhaps twist a little as the OAA was actuated between its extend and retract positions, and also serve to keep them from bending, because of the increased static loads imparted into them by the mere weight of the OAA, wherever it is, and if the FSS moves, well then the OAA that's hanging off of it moves too, and there's a Space Shuttle over there, inches away, and no, we do not want our moved OAA to go banging into the side of our Space Shuttle and break it.

Both the FSS and the Struts are plenty strong enough to stand there and hold themselves and everything that's tied to them up, but when you introduce the OAA into the mix, then you're going to need a little more muscle to stiffen things up.

Structural loadings are funny things, and can come at you from funny directions which are not always directions you might be expecting them to be coming at you from.

Despite its rock-hard outward appearances and feel, steel is actually a surprisingly twangy kind of rubber, and it's far more mobile and bendy than people imagine it to be, and this goes double for heavy iron. Heavy iron is heavy because of the loads (both static and dynamic) it must carry, and those loads can, and do, cause the steel to move around a little, and for the people who design and build large stuff, steel is what they like to use the most because, as with rubber, it will return to its original shape and configuration after you quit bending it, so long as you don't bend it too far.

The OAA moved, and the loads associated with it moving it were dual in nature, with one aspect of it relating to the dynamic forces (including transient and very-hard-to-deal-with things like the wind) that you might find yourself seeing as the actual movement was underway, including simply starting and stopping, and another aspect of it relating to the fact that, without regard to any movement, the static forces it was putting into the structure(s) that supported it would be altered, greatly, by simple virtue of it being in any given position throughout the full range of its ability to move from here to there and of course all points in between, and while we're at it, let us not forget the loads introduced into the structure by the people and equipment that may or may not be getting held up in the air by it as they are using it for its intended (and sometimes maybe not so intended) uses, or perhaps hmm... maybe a little rocket exhaust too, once every now and again?

It gets hairy.

And it gets hairy fast.

And it's stuff like this that demands highly-trained people who can, rigorously and mathematically account for all of it.

Because... if you get somebody who just sort of slaps at things, and who's idea of "research" might go no further than listening to some fool on the television (possibly quite popular, but still very much a fool nonetheless) sitting at a desk looking into a camera and speaking into a microphone, or perhaps watching a few dubious (although wildly popular) YouTube videos, or perhaps sharing a few even more dubious (and perhaps even more wildly popular) social media postings, memes, rants, and spoutings; you're going to find yourself without any real understanding of what's really going on, and at some point, you're going to be walking directly into the teeth of a whirling buzzsaw, and...

And you do not want your bridge, or your building, or your Orbiter Access Arm, falling to the ground, and killing everybody in the immediate vicinity as it does so.

One day I'll tell you about what it felt like when me and Jack Petty were up on the roof of the RCS Room, on the RSS, looking into hoist issues with the ET Access Platforms (that came a gnat's whisker from killing one of our ironworkers and wound up "only" breaking his leg instead), and the Boeing TTV (Terminate, Test and Validate) people started swinging the Hammerhead Crane around briskly, testing/checking who knows what, and it's quite the arresting sensation to suddenly feel the solidity of the tower you're standing on disappear in an instant, and get replaced by something closer to the sensation of standing on a wave-rocked boat

But this is not, nor will it ever be, a document to examine the mathematical fullness of the calculations that must be successfully undertaken to give us full understanding of things, so we'll give it a rest and go no further, and perhaps let the solutions to the equations which have already been worked out, and which we already have in our possession, tell us the tale instead.

The contract drawings.

And we'll start with drawing number A-1 just to get an overall look at things, and on A-1 we see the OAA Strongback, but we do not see the Latchback Strongback, but that's ok. For letting us know in a generalized sense of "Where the hell are we, anyway?" A-1 will do just fine, with or without any considerations of the Latchback.

And just for fun, let's punch a Hammerhead Crane into A-1 and get a sense of the field of view, what was visible, and where we were when the photograph at the top of this page was taken.

So ok. So now that we've got the broad-brush sense of things, let's dig a little further down into the why's and wherefore's of our strongbacks.

And on drawing S-13 we've got a pretty good plan view (looking down from above) of both strongbacks.

Over on the left side of the drawing, we can see that for the OAA, they've added in a small special-cut grating panel, where the astronauts would be exiting the main floor level of the FSS through the "doorway" in the strongback, with a curved cutout to fit up against the similarly-curved grating end-piece on the OAA, and when the arm rotated, the grating would always be properly covering the opening (straight drop, one hundred fifty feet free and clear, to the concrete of the Pad Deck), but since the arm had yet to be hung, they were careful to leave the existing fixed perimeter handrail that runs along that side of the FSS in place, to keep some unfortunate from going over the side through the opening in the strongback, and we cut that handrail later, when we hung the arm.

Interestingly enough, you can see that handrail, clearly, in the photograph, and you can just as clearly see that the small grating panel had yet to be furnished and installed.

So.

Intermediate condition.

Construction site.

Very common occurrence.

Ok. Over on the right side of the drawing, we can see that the support steel for the Latchback Strongback is actually quite a bit more complex and tricky than it is for the OAA Strongback, and this is because, over there in the area of the Struts, between the Hinge Column and the FSS, there's really nothing there to hang something from, and so they had to devise a weirdy hanger setup coming down off the Strut to carry a pair of fairly hefty W14x82's which in turn carried the strongback itself. All of this stuff needed to be quite stiff to handle the loads it would see carrying the OAA, latching the OAA, and releasing the OAA, and if memory serves the whole thing was rated for being able to do that with the OAA getting buffeted by 40 knot winds or the exhaust plume from the Space Shuttle immediately following liftoff, and...

Yeah.

This stuff ain't easy, right?

Right.

For maximum strength at least possible weight, the Latchback Strongback hanger arrangements and support steel had to all be lined up square with the Latchback itself (which was a very sturdy and surprisingly complicated thing, and neither it nor the service platform which lived immediately beneath it is seen in the photograph because it did not get hung on the iron until it was time to hang the OAA itself, and that came a few years later), and the Latchback itself had to be lined up square with the OAA, and the OAA, in its retracted, out-of-everybody's-way position, sits at an angle of six degrees off of the alignment of everything else up there, and... oh boy. Such jolly fun it is, getting all this stuff to come cleanly together and do its job at the least expense of weight and space envelope, and the additional financial and scheduling costs associated with additional weight and space envelope, and... oh boy.

Years later, when I was working for Ivey Steel, Jack Petty and I took a drive over to A Pad very early in the morning, and we grabbed a few photographs of Discovery on its second rollout to the Pad, prior to it's first launch as STS-41D (One day I'll tell you the stories surrounding the on-pad abort, that precipitated the rollback to the VAB which necessitated a second rollout, and some of it is quite radical, but not now, ok?), and by sheerest chance, they had somehow set the MLP down on its support pedestals a little bit out of spec in the predawn darkness, and found that they had to jack it back up on the crawler, back away from the MLP Mount Mechanisms a little bit, and then head back in, to set it down correctly, and for that reason, they also had to retract the OAA and get it out of the way before they could back out, and we arrived, by complete dumb luck, while they were in the process of retracting the OAA.

So.

I took my pictures, and it just so happens that one of the images turns out to be fairly instructive regarding the whole OAA Latchback system, and although it's not particularly loud and clear, it's very definitely visible in there, and here it is all nice and labeled up for you, so that you can see how all this stuff works together.

And now we can return to the drawings and see things in elevation view, and get a look at the way they were forced to put the Latchback Strongback together as a result of the constraints imposed by having to locate it out there in the middle of nowhere on the Struts.

And then get a look at how the OAA was supported by its own strongback and how they pretty much went one level on the FSS above and below all of the load-bearing areas, to keep things from wanting to twist or bend.

The OAA was supported at the back of its truss with a pair of large, heavy, Hinge Boxes, and further supported with a cable that was attached to a bracket farther up on the FSS, which, on its other end, attached to the OAA truss behind the white room, and finding pictures which show all that is a surprisingly difficult thing to do. NASA doesn't seem to have been particularly interested in this part of things, and nobody else seems to have been interested in it, either.

So we'll work with what we can, and let you see the whole thing, Hinge Boxes, Support Cable, and Support Cable Bracket, or at least as much as we can, which is a lot less than we'd like to be able to, especially with the Hinge Boxes, which are near-totally obscured by a lot of intervening stuff.

Here's the original NASA image, just so you can see things in their original visual state.

The OAA was a substantial item, and it didn't just move, it could, in times of dire need, move abruptly, and swinging a 65 foot long object that weighs over 50,000 pounds through 70 degrees of travel in 30 seconds is going to be putting one hell of a lot of twisting force into whatever's attaching it to the FSS, in effect trying to twist it off the tower, and it carried people, not least amongst which are the astronauts who would be flying on the Space Shuttle, and it demanded exceedingly robust support, not only to simply keep it up in the air hanging off the tower without falling to the ground, but to also keep it rock-solid in place, because, as a required part of its job, it was going to be coming very close to, but not quite hitting, no end of fabulously-expensive things at either end of its envelope of travel, and if they were off by just a weency little bit...

... and... nope, we're not going to be taking any chances with any of that, and "When it doubt, make it stout," and that's exactly what they did, and in the end it all worked perfectly, and they never had any problems of any kind on that end of things with it.

And from here, I'm not sure if I want to belabor the issue of identifying discrete components in our photograph up at the top of the page via the method of adding paragraph after endless paragraph of words words words, and instead, in consideration that many of you will by now have a bit of a feel for what's what, and where's where, I'm going to mark up our photographs from the top of the page and the page before this one, and insert them here, below this paragraph, as clickable links to the marked-up fully-labeled originals which I also placed at the top of Page 1 at the very beginning of these essays.

Back then, you had no prayer of understanding the things you were seeing, nor the labels peppered around all over the place.

But by now, you do. So go ahead and click it. Click it and render it full-size, and read it.


And from the page before...

Click it. Click it and render it full-size, and read it. All of it. Every last bit of it.

Give the images a click, bring them up to full size, and then, when you have a little free time, wander around in there.

Treat treat them like a city map.

Treat them like a place you have never been to in person, but which interests you and causes you to want to learn your way around it, just a little bit.

Treat them like a place that you might have, in some parallel existence, called home.

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