Authors: David Hitt,Heather R. Smith
“We not only wanted to land on ten-thousand-foot runways, but we were going to be an airline,” Mattingly said, explaining that since the shuttle would be a reusable aircraft with, ideally, a short turnaround time,
decided to turn to airline officials for help with how to do that.
So people went out and got contracts with American Airlines to teach us how to do maintenance and training, and we had people come in and start giving classes on how you give instructional courses and how we do logistics [in] the airlines. For a couple of years, we studiously tried to follow all that, and finally after a good bit it became clear that, you know, if there is anybody that’s going to explain this to someone, it’s going to have to be us explaining it to ourselves. That’s where it evolved back into the way we had done things in the earlier programs.
Developing the systems was very much a group effort, Mattingly recalled.
I remember when we first started building the flight control schematics. Those are the most magnificent educational tools I’ve ever seen. I’ve never encountered them in any other organization. I don’t know why. I used to carry around a couple of samples and give them to people and say, “This is what you really need.” And they’d say, “Oh, that’s all very interesting,” and then nothing ever seemed to happen. But working with people to put those drawings together, and then understand what they meant and develop procedures and things from, was a massive effort. During those days the Building 4 [at Johnson Space Center] and the building behind that, where flight control teams had some other offices, the walls were just papered with these things. People would go around, and they’d walk by it and look at it, and they’d say, “That’s not right.” They’d draw a little red thing on it and say, “See me.” And it was an evolutionary process going on continuously.
The shuttle was built with redundant systems. The idea was it should be able to suffer loss of any piece of equipment and still be able to fly safely. It
was called “fail op, fail safe,” meaning that one failure wouldn’t affect normal operations and that a second failure could affect the way the vehicle operated but not its safety.
That generally led to a concept of four parallel strings of everything. And that was great, but now how do you manage it, and what do you do with it? Now, a schematic has all of these four strings of things, sometimes they’re interconnected, and you could study those things, you’d pull those long sheets out, and you go absolutely bonkers—“Oh no. This line’s hooked to that. I forgot that.” Trying to figure out how this all works. So you’d go get your colored pencils out, and you’d color-code them. By now the stack of these things is building up, and I’m really getting frustrated in doing this dog-work job just before—I had to spend many, many hours for each drawing to get it sorted out before you were ready to use the drawing. So I said, “We’ve got to take these things and get them printed in color, right off the bat.”
And so my friends in the training department said, “Well, you’re probably going to have to talk to Kranz about that. He’s not that enthusiastic about it.” I thought, “Oh God.” So I got an audience with Gene and went over and sat in his office and explained to him what we were doing in trying to get the training program started and how we were trying to get ready to do that, and I really wanted to get these things printed in color so that it would make it easier for people. I knew color printing would be a little more expensive, but it would sure save a lot of time. He said, “No. We’re not going to do that.” I was just overwhelmed. I said, “Gene, why?” He didn’t say a word, he just turned and looked at his desk, and there on his desk, right in the corner, was this big mug filled with colored pencils. And he says, “That’s how you learn.” And so that was the end of the story. I don’t know, I’ll bet today they’re still black and white. But that was Gene’s method of learning, and he figured that by having to trace it out, he had learned a lot, so he felt that others would benefit from that exercise. Even if they didn’t appreciate it, they would benefit.
The process of how the orbiter cockpit was designed would produce rather interesting and, in some cases, counterintuitive results, Mattingly said. He was part of a working group on controls and displays with fellow astronaut Gordon Fullerton, which made decisions about the center console.
If you sit in the orbiter, the pilot and commander are sitting side by side in the center console. It was one of the few places when, if you put on a pressure suit,
. . . you could see and touch. I mean, you can see the instrument panel. Stuff up here gets really above your head, gets really hard to see. It’s in close, so it’s difficult for some of us older people to focus, and you can’t see a lot. You have to do it by feel, which isn’t a good thing to do with important things. So the mobility was small, and this was prime real estate. We all knew it. As we went on with the program, every time someone said, “Oh, we’ll just put this here [in the center console],” we’d say, “No.” We’d have a big office meeting. We’d all agree that, no, that’s not that important. We can put that here, we can do this. Well, after working on this thing for years, there’s practically nothing that’s important on the center console. We kept relegating everything to somewhere else, and it’s now the place where you set your coffee when you’re in the [simulator]. We protected that so hard, and poor old Gordo fought and fought for different things, and we’d think something was good, and then after we’d learn about what it really did and how it worked, we’d say, “No. You don’t need that.”
Then there was the question of how the Space Shuttle would fly. Each airplane flies slightly differently, or feels slightly different to a pilot flying it, and the only way to really understand exactly how a plane flies is to fly it. Further, a pilot’s understanding of how airplanes fly is, to some extent, limited by the variety of airplanes he or she has flown. Those differences are rooted in the physical differences in the airplane’s control systems, a factor that means something entirely different with the computer-aided fly-by-wire controls of the shuttle. “There is a military spec that publishes about flying qualities, handling qualities of airplanes,” Mattingly said.
It started back in World War II, I guess, maybe even before. It tells you all of the characteristics that have to go into making a good airplane, like how many pounds of force do you put on a rudder pedal to push it. Well, even dumb pilots finally figured out that with an electric airplane this maybe isn’t really relevant. Then the engineers wanted to just throw out all of the experience and say, “Hey, we’ll just make it cool and you’ll like it.” So we went on a crusade to rewrite this document, which turned out to be one of the most interesting projects I’ve ever been in, because it required rethinking a lot of the things that we all took for gospel. Every airplane that a pilot flies is the Bible on how airplanes fly. Fortunately, in the office we had people who had flown a lot of different kinds of airplanes. But nevertheless, that shapes your image. And now you get into something that’s totally different, and there’s a tendency to want to make
this new airplane fly like the one you like the most. The software guys contributed to this bad habit by saying, “Hey, it’s software. You tell us what you want, we’ll make it fly.” I remember one time they gave us a proposal that had a little dial and you could make it a
-51 or a
-33 or a
-86 or a 747. “Just tell me what you want.” We had a lot of naive ideas when we started.
While the computer for the Space Shuttle allowed many things that were groundbreaking at the time in the world of avionics, Mattingly pointed out that they were still quite primitive compared to modern standards.
I don’t remember the original size of the computer, but it had a memory that was miniscule by today’s standards, but it was huge compared to Apollo. By the time we finished this program, we had this horrendous debate about going to what we called double-density memory that would expand it. It was still nothing, and the only reason management did not want to change to it was for philosophic reasons. And
finally said, “Look, you guys said you wanted to buy off-the-shelf hardware. Let me tell you, you are the only people in the world with that version of a computer. So if you want to stay with the rest of the world, you’re going to have to take this one.” And fortunately, we did, and still it was miniscule. Today I think they’ve upgraded it several more times so that it isn’t nearly the challenge. But that caused us to partition the functions in prelaunch and ascent and then get out of orbit and do some servicing things and then another load for reentry.
Don Peterson, who was selected as an astronaut in 1969 and flew one shuttle mission, said the orbiter computer systems were quite complicated.
My little desktop computer at home is about a hundred times faster and it has about a hundred times more capacity than the computers that were flying on the orbiter. They were afraid to change the computers very much because part of the flight control scheme is based on timing. If you change the computer, you change the timing, and you’d have to redo all the testing. There are thousands of hours of testing that have gone into there, and they know this thing works, and they’re very loathe to make those kinds of changes. They can’t change the outside of the vehicle for the same reason; that affects the aerodynamics. So they can change some things in that vehicle, and they [improved] some of it. But they’re not going to make big, drastic changes to the control systems. It’s just too complicated and too costly. The flight control system on the orbiter is almost an experimental design. In other words, they built the system and then they tested it and
tested it and tested it. They just kept changing little bits and pieces, primarily in the software, until it all worked. But if you went back and looked at it from a theoretical point of view, that’s not very pretty. You know what I mean? It’s like, gee, there doesn’t seem to be any consistent deep underlying theory here. It’s all patchwork and it’s all pieced together. And in a sense, that’s true. But that’s why they would be very loathe to try to make big changes to that, because putting all that stuff together took a long, long time.
Working on a project with so many systems that all had to be integrated but that were being developed simultaneously was an interesting challenge, recalled Mattingly. “Within the office, we were all trying to stay in touch with all these things going on in each of these areas to keep them somewhat in sync from the cockpit perspective. So that gave us a lot of insight into all of these tasks that people were doing,” he said.
We even found, for instance, that as part of this development program, people working with thermal protections systems, the structure guys found that they were discovering limitations that were going to be imposed on the vehicle downstream that we weren’t thinking about—if you fly in the wrong regimes, you will get yourself into thermal problems. Yet nothing in our flight control work or displays was considering that. We had never encountered anything like that before. So the guys, by working all these different shops, were picking up these little tidbits and we were trying to find ways to look ahead.
Another major change, Mattingly said, was developing and testing the flight control software for the shuttle. “We learned quickly that the man-machine interface is the most labor intensive part of building all this software,” he said, explaining that the code dedicated to computer control of the vehicle made up less of the software—and less of the time it took to develop it—than the code related to the interface that would allow the astronauts to control use of that software to control the vehicle. In addition, he said, a conflict arose because of the computer use needed to develop and test that software. To the engineers who were using those computers to design the vehicle, the time the astronauts spent testing and practicing with the flight control software seemed like “video games.”
We ended up building a team of people: Joe Gamble, who was working the aerodynamics; Jon Harpold, doing guidance; and Ernie Smith, who was the flight
control guy. They all worked in
[Engineering and Development]. We all got to going around together in a little team, and we would all go to the simulators together, and we would all study things. We built a simulator from Apollo hardware that was called . . .
, the Interim Test Station. We had a couple of people—Roger Burke and Al Ragsdale were two sim engineers that had worked on the
[Command Module Simulator] and the
[Lunar Module Simulator]. They were very innovative, and they took these things before we had the Shuttle Mission Simulator that was back in the early part of the design and went to the junkyard and found airplane parts and built an instrument panel out of spare parts and had a regular chair that you sat in and had different control devices that we had borrowed and stolen from places. These folks were so innovative; they could hook it all up.
“They took the initial aerodynamic data books and put them in a file so we could build something that would try to fly,” Mattingly said.
We even took the lunar landing scene television. In the Lunar Module Simulator they had a camera that was driven by the model of the motion and it would fly down over the lunar surface, and so you can see this thing, and that was portrayed in the
as what you’d train to. So they adapted that to a runway. We tried to build a little visual so we could have some clues to this thing, put in a little rinky-dink
[cathode-ray tube] so we could play with building displays. And we got no support from anybody. I mean, this wasn’t space stuff. And it is probably one of those things I was most proud of, because we were able to get this thing into someplace where we could actually tinker with how we’re going to fly the vehicle and what we’re going to do and what the aerodynamics mean. It was only possible because we had these two simulator guys who were wizards at playing with software and this team from
who joined us.