Sweat, Sidney; McKay, Therman; Hayden, Joe; and Powell, Luther

Sweat, Sidney; McKay, Therman; Hayden, Joe; and Powell, Luther

Instrumentation Unit: IBM as contractor, LVDA/DC, and ST-124-M

University of Alabama in Huntsville Archives and Special Collections, Huntsville, Alabama

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Interviews

Audio

ohc_stnv_000047_A

Bilstein, Roger E.

Sweat, Sidney; McKay, Therman; Hayden, Joe; and Powell, Luther

[00:00:00] RB: The story concerning the delivery, I'm not exactly sure, of the first instrument unit, flight unit, floating down to Tennessee and all that…would you care to recapitulate that for me? Which unit was it? Which IU was it?

[00:00:23] Sidney Sweat: I've been trying to forget that ever since it happened, Roger.

[00:00:25] RB: I get this chuckle over here. [laughs]

[00:00:27] SS: Lou was very much a part of that too. Let me kind of set the stage for you. We were running behind on the delivery of that instrument unit. One of the reasons that we were behind on it was because we were having to make a significant number of changes in the instrumentation—the instrumentation also which fed into the flight control computer, the LVDA, and the LVDC. We were rapidly approaching the point that we could not accommodate the stack schedule—that's the schedule where they put the IU on the stack at the Cape. Center management called a bunch of us together and said, “How are we going to accommodate this?” The idea was presented to center management that, you know, it takes quite a bit of time in transit to go all the way down the Mississippi to New Orleans and around the Cape. Why don't we look at these modifications and do them in transit? We got quite a bit of reluctance on it. Luther and I and some of the people in the [inaudible] office sat down and developed the details with IBM and found out, yeah, it's feasible. But to make it work, we were going to have to continuously shuttle hardware along the Mississippi to meet the barge at various points as the hardware was literally built and as the drawings were finished.

[00:01:55] RB: This is one of the enclosed barges then?

[00:01:57] SS: Yes. To make a long story short, we pulled all the data together and worked out a detailed schedule on it. We assigned two people that would, in fact, we'd be in constant radio communication with them, “Hey, fellas, we need these bolts, we need these transistors, diodes, capacitors, and so on. We'll meet you at Biloxi, Mississippi tomorrow afternoon at four o'clock.” Well, we made one of our airplanes available and a bunch of guys in pickup trucks and so on. They kept replenishing our supply of parts, and as the mod kits were built from the drawings, they would deliver them to us. We worked on the barge and successfully completed that darn thing by the time we got to New Orleans.

[00:02:43] RB: Okay, but now in all the stuff I read, there's a great detailed explanation about the IBM clean rooms and the global clean rooms and all this quality control. Now, did you guys rig up some special polyethylene rooms inside? How did you do that?

[00:02:59] SS: Absolutely. On the enclosed barge, there is a built-in environmental system.

[00:03:05] RB: That's right, I'd forgotten that.

[00:03:07] SS: We'd built, fabricated, a polyethylene shroud that went around that we could have a positive pressure in the area for the technicians to work in. That way we were able to maintain the cleanliness level. Now, we did set a ground rule when we started out. We did not break into the ST-124 pneumatic system. That's the one that has the most stringent environmental control. But we did open up and go into the environmental—the ECS system as we called it—the environmental control system, the water-methanol.

[00:03:44] RB: Right, right, right.

[00:03:46] SS: So, in fact, we were anxiously waiting for KSC to run their first test specimen to see if we had maintained the cleanliness level, and we had maintained it right within spec.

[00:03:59] RB: But you were also replacing, you say, diodes and capacitors, and everything else in the memory banks?

[00:04:04] SS: No, no, no, no, no. These were just in the electrical distributors.

[00:04:09] RB: Oh, okay. So, in other words, the flight computer and the launch vehicle digital adapter were never [inverted?]. Okay. That's the other thing that bothered me because the story was vague, and it's outlined.

[00:04:22] SS: Yes, well, we had to be very selective on those components, which we could, in fact, open. Of course, we had a very limited capability on board the barge from our ability to put in transistors and diodes and then our ability to test them.

[00:04:39] RB: There's one other thing you may not want to comment on. Somewhere, too, in the back of my mind, part of the equipment that was put on board was several cases of beer. Is that correct? [laughs]

[00:04:51] SS: No. That's totally erroneous. No way. In fact, they didn't even have beer in the galley on the barge.

[00:05:02] RB: Is that right? Dry barge? [laughs]

[00:05:04] SS: Dry barge. But the food…I've got to tell you about this. You know, usually when you're working sixteen, eighteen hours a day, you lose a lot of weight, but the chef on board that barge was something else. I literally gained 12 pounds on that trip.

[00:05:27] RB: One of the things that I've tried to do, and I've been working on a revised draft of, is go back and treat the development of the unit logic devices and triple modular redundancy and all this kind of stuff. But the one thing that really grabs me and trying to get a hold of the instrument unit story is how much input Marshall made on this thing up to 1964 when I think is when IBM took over the full contract and how much input IBM was making before and after that date. Can any of you help elucidate that problem?

[00:06:02] Joe Hayden: I can, I guess, start on it. Marshall was responsible for the design of the IU in the early stages. I believe that IBM took over the maintainability of the design starting with 501 and 205 as I recall. The checkout of 201 to 204 was a Marshall responsibility, and the design was a Marshall responsibility. Marshall in effect turned over a design to IBM then IBM was responsible with continuing with that design and maintaining the design.

[00:06:46] RB: Okay. Excuse me, before going further, could you identify yourself for the purposes of my microphone here?

[00:06:53] JH: I am Joe Hayden.

[00:06:53] RB: OK, thank you. Now, so my question is this, who really came up with the TMR and ULD concepts, stuff like that?

[00:07:04] [inaudible due to overlapping speakers]

[00:07:26] Luther Powell: ULDs is based on the technology that was used in the 360 line. That’s what it was an early application of what IBM called the SLTs: Standard Logic Technologies. Now, the ULDs [per se?] the circuits in the ULDs were Marshall designed. In other words, they did not take off the [shelf?] SLTs. They had to be designed specifically for the Saturn application. They required the defining a certain number of types. I don’t know how many types we had…fourteen, or something like that, types of ULDs, Unit Logic Devices. The mechanical aspects of it was completely different because the SLTs were pins. They had pins that plugged in sort of like. We went with a new design with what we called C-clips. They go around and clipped them on.

[00:08:22] RB: This is interesting then. So in this instance could you say that there was a departure from some original constraints that you only use off the shelf hardware?

[00:08:31] LP: Well, at that point in time, there wasn’t technology in off the shelf hardware. It was a question at that time whether you went with integrated circuits or whether you went with the so-called ULDs, the clip chip type of technology.

[00:09:00] SS: Roger I don't understand your statement there—the departure from the ground rule to use off the shelf hardware.

[00:09:07] RB: Okay, well, these are just kind of general things that on almost every stage including the IU, there were documents that came out, and they all said for a general term “One of the things we want to do is use the existing components, take off the shelf hardware. We don’t want to get involved in using new technology that’s not really tried and tested and get into a hassle.” This is what I was getting at.

[00:09:34] JH: [Inaudible] find gold. There were very few components which were off the shelf. In fact, the only ones that come to mind are maybe some TM components. But the majority of the hardware was designed and built for Saturn.

[00:09:43] SS: And some plumbing maybe.

[00:09:49] RB: TM components?

[00:09:50] JH: Telemetry.

[00:09:52] RB: Telemetry, okay.

[00:09:53] JH: Instrumentation. Like Motorola had some equipment that could be used, but very little off the shelf hardware for Saturn.

[00:10:01] RB: Okay because that’s one of the things that struck me about using the magnesium-lithium for the chassis. Apparently that was a fairly unique thing to be doing for the application in the instrument unit. Now again who made the decision to go to that? Was that an IBM decision or was that Marshall decision?

[00:10:17] JH: All of the decisions were made by Marshall. Again, there were contractors involved. You and I know when it came time or maybe there were recommendations proposed by the contractors, but the decisions were all Marshall before the final decision. Even when IBM had the responsibility for maintaining the design, Marshall still had the final authority.

[00:10:42] LP: It was a bigger question in that mag-lith [inaudible] cooling [inaudible]

[00:10:51] Therman McKay: One of the [inaudible] on mag-lith, [JB?] had mentioned to me earlier that Herman Gilmore and Marshall had done a lot of work in the area of mag-lith, and it had sort of become an accepted alloy to be used. Using mag-lith, [inaudible] they were able to shave some sixty-five pounds from the weight from the DA/DC. Plus it didn’t have toxicity problems. Beryllium, which was used by the way in the platform system, remained a part of its strength and its stability for use in gimbals. But I think…

[00:11:33] LP: You said weight on the cold plate too. If you’re going to cool the thing, you gotta move weight from the cold plate. So all that…

[00:11:41] JH: But again the thing you said that IBM has been the contractor that recommended that approach. I don’t know. I don’t go back that far.

[00:11:50] RB: Let me ask, let me explain why I’m on this because as I said I started out on this covering somebody else’s tracks, and there is a lack of documentation. The only thing I had to go with was a bunch of stuff from Aviation Week and Space Technology, and they’re kind of vague. Of course, I got the impression that the reporter had gone to IBM, and the feedback that comes back was this was a great thing that IBM did. This is what I’m trying to find out: where did IBM make inputs, and where did the Marshall design input?

[00:12:19] SS: To really answer that, Roger, you’re going to have an understanding about a change control system. As Joe pointed out, IBM assumed design responsibilities for the instrument unit for 501 and 205. All the instrument units prior to that time, Marshall had designed and developed and turned over to IBM under prime contractor’s award is what was referred to as a technical baseline.

[00:12:48] RB: Okay.

[00:12:49] JH: Excuse me, Sid, I don’t mean to interrupt, but I guess we need to make the point here though that even prior to that time, LVDA/DC were [GSE?] but still made by IBM at Owego under a contract that we had with Owego. IBM was a corporation still building the DA/DC for the government even prior to the contract.

[00:13:14] SS: The change control system that I’m going to allude to was applicable even back during that period of time. The contractor is limited in the type of change he can make a decision on and implement. We had various classifications of changes. Now any change that involved a material change of this significance—we’re talking about the mag-lith—or any other change that would have affected some compatibility of a component’s ability to integrate with another one, all of those decisions were passed on to Marshall who made the ultimate decision. Some of them were recommended by the contractor. He’d come through with what we referred to as an ECP—Engineering Change Proposal—but that’s all it was. He proposed the change, but the government made the decision as to whether or not that change would be implemented.

[00:14:13] JH: I think that what he’s getting at is even prior to that time, we had to have a unit. Who came up with all the original ideas of just how the unit could be built? [Inaudible] these fellas [inaudible] specific case was done, the government would propose to a contractor for a proposal to build a black box to the government’s requirements and specifications for that black box. The contractor would build that black box. Most of the details of how it be built would be left up to the contractor, again, with the government’s approval. I would expect IBM had a major role in recommending or determining just how the DA/DC would be built.

[00:15:04] RB: Including the mag-lith.

[00:15:05] JH: I don’t know about the details of that.

[00:15:09] LP: I don’t know the details either, but as I recall there was a major input from [inaudible] materials.

[00:15:18] RB: IBM?

[00:15:21] TM: No, Marshall.

[00:15:22] JH: I guess we’re all kind of guessing that far back. It’s really before our time. [Inaudible] I thought we were going to talk about the normal process that we go through.

[00:15:36] LP: Talk about the technology, and we kinda drop back on some of the research IBM had done previously. As far as owning the ULDs, the government paid for setting up lines up in Fishkill to do those things.

[00:15:55] TM: It’s a hybrid system.

[00:15:58] JH: I think his thing though is “Who thought it up? Who decided this is the way we ought to go?” [Inaudible] with the government, but did IBM come up and say, “Hey, this is a good idea. This is the way to go”? I don’t know what kind of recommendations.

[00:16:14] LP: We talked about this yesterday. One good example—I don’t know whether you were in the program or not—was the debate about how many memory modules we have. We had the monthly design—Luther, you might have been there—they designed the back panels with a maximum of six memory modules. This was on one of the engineering models. We sat there and told them, “We wanted eight memory modules in that machine.” They said, “Well, you don’t need eight.” [Inaudible] requirement, we told them we want eight. We went up there a month later, that back panel was laid out for six memory modules in there. It hit the fan, we had to get that. We accepted that machine because of schedule problems. Later on, we had to send that back and retrofit it. But the design changed, right there. So that’s the type of thing that you get into.

[00:17:12] RB: You wanted the extra two on there for test purposes and testability and mission [inaudible]?

[00:17:18] TM: It turned out that Saturn IB could use six memory modules, but the Saturn V had to have eight.

[00:17:29] LP: Seven, seven and a half. Whatever it is.

[00:17:30] TM: All boxes were designed to have eight, but only used six in the IB.

[00:17:38] JH: [Inaudible] program information [inaudible]

[00:17:46] RB: As long as we’re on that too, in the instrument unit for the IB and Saturn V were both identical?

[00:17:53] JH: The IUs were identical with small differences, one being the number of memories.

[00:18:05] [LP?]: Do you want to stick with the DC?

[00:18:07] TM: I think that’s what he’s talking about at the computer data adapter interface [inaudible due to overlapping speakers]

[00:18:14] RB: There were variations in terms of the overall IU for the 1B and the Saturn V, but not that much as I understand. Basically, a kind of similar thing. Maybe I’m going back too far, but the other thing that gets me, I’m very, very [on query?] as to when the change was made in the early Saturn Is from the kind of tubular cruciform guidance system they had to the [slice?]?

[00:18:45] JH: Well, vehicle-wise 201 and 501 were the first ones of the present configuration.

[00:18:53] RB: Yeah, but I thought there was also Saturn I instead of having that…

[00:18:57] SS: SA-10 was the last crucible we had. SA….

[00:19:01] TM: SA-1, 2, 3, and 4 had an instrument compartment for the IU equipment. Then in SA-5 we flew the first tubular canister type, which had…The reason I remember because that was the ST-90S platform flying in control, then the ST-124-1 being a passenger, and that fed into a guidance signal processor at that time rather than a DA/DC. For the last five Saturn Is, you had that. They were at ninety degrees. It had its own…It was pressurized because at that time it was felt the environment was needed.

[00:19:54] [LP?]: First flight was 201.

[00:20:04] JH: First IU in the present configuration was 201.

[00:20:10] RB: Another question, very simple. What does the ST stand for?

[00:20:18] TM: Platform? Stable table. That’s the old terminology. That’s just uh…

[00:20:25] SS: [Inaudible] very sophisticated.

[00:20:30] [LP?]: They coined the name stable table, and they just tried to give [inaudible] started calling it ST-80.

[00:20:36] RB: I ran across it, and all of a sudden, I was doing all this writing, and it occurred to me that I didn’t know what ST stood for. I made calls around Houston, and this guy said, “I’ve been working on it for twenty years and never gave it thought. I don't know what it stands for.”

[00:20:50] TM: It’s a stable reference or a stable platform. The early term they used was table. It means a reference point.

[00:21:01] RB: Now there’s another question here, somewhere apparently early in the definition of the instrument unit, there was a decision to go to digital as opposed to analog, and that’s about as much as I know about it.

[00:21:14] JH: Again, that’s only with the guidance computer. The control computer is still analog.

[00:21:20] RB: The guidance computer, okay.

[00:21:22] JH: The guidance computer [inaudible].

[00:21:24] RB: Can you explain to me the logic and the trade offs involved?

[00:21:38] [LP?]: As opposed to some of the earlier flights like Jupiter? Basically, because they went to a different guidance scheme. They went from a delta minimum to [inaudible]. The thing was [inaudible] polynomial expansion was about thirty terms in there somewhere. It was [inaudible].

[00:22:05] RB: So was that not really a big decision or was it a very large decision?

[00:22:11] : [LP?]: I think to have adaptive mode was a big decision but then [inaudible] hardware in a number of areas. The computing system or the guidance [inaudible].

[00:22:23] TM: It was a necessary decision to do what they wanted to do.

[00:22:27] [LP?]: The decision was a direct derivative the mission requirements.

[00:22:31]: RB: Can you expand on that a little bit for me?

[00:22:33]: [LP?]: Take the LOR concept. The big discussion with all of the agencies, “How will you get [inaudible]?” [Inaudible] or whether you go to...I think it was about three concepts that had been discussed.

[00:22:47]: RB: [Inaudible] mode and so on.

[00:22:48] LP: [Inaudible] LOR because of the size of the vehicle, the capacity, fuel, [inaudible] so forth, they [inaudible] have adaptive mode. [Inaudible] calculations and speed of that in order to economize on fuel [inaudible] primary [inaudible] fuel economy. [Inaudible] We’ve been looking at that thing for a year or two years until we really thought it was going to [inaudible]. We were looking at the time of developing the Pershing. [Inaudible] Pershing [inaudible].

[00:23:39] JH: There was the other thing though [inaudible].

[00:23:44] RB: Okay, another question now. After going through all this stuff of getting the computers and everything and so on, they weren’t even used in the boost phase. Can you explain to me why then? As I understand anyway, there was no active guidance system used in the first stage boost phase for either the Saturn IB or the Saturn V.

[00:24:07] JH: Let me tell you what I recall. Somebody correct me if I’m wrong. The main concern, of course, you’re going to Max Q [inaudible] boost phase. I think they wanted to be sure they didn’t have any attitude [inaudible] Max Q. In other words, you’re trying to correct, pick the best path, and you may have an undesirable attitude as the way I recall it. I’m sure that’s one reason.

[00:24:33] RB: An undesirable attitude would create sloshing problems or bending moments?

[00:24:38] JH: If you have too large angle of attack going to Max Q, you’ll have vehicle break up. Does anybody else…

[00:24:49] RB: So in other words, that thing was set just to bore straight up?

[00:24:52] [LP?]: That’s right.

[00:24:53] RB: Was there any gimbaling at all?

[00:24:54] JH: It goes up straight and then it rolls to the proper attitude, then it pitches over and flies on a preset trajectory through the boost phase.

[00:25:07]: RB: After the roll and tilt then there was no gimbaling of the engines? It just bored straight on up?

[00:25:13]: JH: It was gimbaled to keep it on course.

[00:25:17] TM: Keep attitude.

[00:25:22] RB: As I understand it then, if there were any perturbations or deviations or something occurred that the computer sensed those and stored them up and the changes and corrections were made then during the S-2 and S-4B boost phase.

[00:25:37] JH: The vehicle stored up the information to know what its position was and knowing its position and knowing after that its attitude and its velocity and acceleration because they [inaudible].

[00:25:51] TM: The guidance mode. It would enter the guidance mode, and it was shooting for one spot out there.

[00:25:58] RB: This brings me to another…I don’t know, maybe you guys didn’t get a copy of this, but I’ve got a list of questions here. One of them, and I’ll be very humble about it, an explanation of inertial guidance that I can understand. [laughs] I really need that I’m afraid. I’ve tried to write some stuff. I’ve got some general ideas, but I’m really not sure. When I talk about inertial guidance…

[00:26:19] SS: I think Luther has the book there that…

[00:26:22] RB: Is it a star reference guidance system or an internal reference guidance system? Can somebody help me on this?

[00:26:32] TM: Inertial guidance is not a star reference. It’s a reference that you establish on the ground prior to lift off where you have the platform oriented to the local vertical in two axes, yaw and pitch, and you have it aligned an azimuth to a theodolite reference, which is a first order geodetic survey, which is shot into the platform system to align in it in roll or azimuth. The other two axes are aligned to a plumb line through the center of the earth by pendulums mounted on the platform system, air bearing pendulum. Now that’s your reference. That’s where you’re starting from. You know exactly where you are when you start. Once you lift off, you drop the alignment system, and the platform goes inertial or space-fixed. It just maintains the reference. It has three stabilizing gyros that gives you this stable table or stable reference that you operate from. Throwing out any errors due to drift and what not, theoretically the platform system is always exactly in the same position from the time you start to the time you end the mission. Now that’s attitude. Those signals are fed from resolvers. You have resolvers on the gimbals of the platform that’s [keyed?] out through the computer and detects errors between the platform system and the vehicle. Then those signals are fed back to the control system to make corrections to keep the vehicle on the proper attitude. It’s an instantaneous thing though, and you’re constantly maintaining the vehicle and the attitude relative to the platform system with these pre-programmed tilt programs and everything factored in too. But the whole purpose of the stable reference there is it didn’t allow you a way to navigate, so then mounted on the platform, you have accelerometers, integrating accelerometers that produce the acceleration and velocity data that eventually becomes position data to tell you the point that you want to hit out there.

[00:28:59] RB: But these are being constantly compared are they not with a program stored in the guidance computer?

[00:29:06] TM: Yeah, you’re looking at where you are versus where you ought to be. So inertial when you limit your question to just “What is inertial guidance?” is your talking about platform. The platform is a pretty straight forward part of it. It’s just a reference you set up using gyros that you can operate from. Then you use accelerometers to [cinch?] your accelerations in all three axes.

[00:29:36] JH: It helps you to navigate, but then your computer has to come up with guidance calculations and send signals to the control system now that has to send signals to the actuators on the stages to direct the thrust so that the vehicle is going in the right direction. By the way, I’ve just taken some pages out of one of our technical manuals that’s on navigation guidance and control system, and I think this will give you the information that you need. I do want to come back to your other question though that you had. It does say here that “During the first stage flight of either the S-1B or S-1C,” which of course is the first stage of either one of [inaudible], “the vehicle transverses the dense portion of the atmosphere where the high aerodynamic pressure occurs to avoid excessive structural loads caused by guidance maneuvers, no guidance constraints are applied during the flight phase. Open loop guidance in the form of a timed tilt program is used. Path adaptive guidance begins with ignition of the second stage, either the S-2 for the…” [tape cuts out]

[00:30:46] RB: …Consider the instrument unit as a stage? What is the…

[00:30:51] JH: A non-propulsive stage.

[00:30:52] RB: A non-propulsive stage.

[00:30:54] JH: That’s my own opinion of it.

[00:30:55] [LP?]: Von Braun coined a good phrase [inaudible] it’s the brain inside. That’s the way he referred to it quite often.

[00:31:07] JH: You can always get that debate. There’s a project office for the IU just like there’s a stage project office. You look at [inaudible] no propulsion system.

[00:31:22] TM: We didn’t have any de-tanking problems that we had to scrub.

[00:31:31] RB: [laughs] There’s another question I’ve got now. Again, I’m getting into the same murky waters as the origin of the mag-lith chassis, and this is the ST-124 itself. Was it a Marshall concept? Did Marshall give the plans to Bendix and say, “Here, build me an ST-124”? How did that come about?

[00:31:48] TM: They didn’t give them the plans. Bendix people are packaging experts and platform design. They built the ST-120 that’s still flying in the Pershing. ST-124 evolved from that to some extent, but Marshall in the form of ABMA was involved in the development of the Pershing platform ST-120. I’d have to say that Marshall was very actively involved in the design of the 124. When I say design, I’m talking about basic concepts for what it will do, that it will have dual prism alignment to allow you to maintain a reference and drive your platform to any firing azimuth as opposed to the way ballistic missiles had to be aligned and shoot right over [the San Juan?]. Those were all things that were concepts that were worked together with Bendix but Marshall had a very heavy hand in designing the 124. When they went into production, and Bendix got the contract, then Bendix had the job of actually packaging that concept into the hardware, which is what they did. But if you look at the ST-124 platform and go down to the museum and look at an SG-66 platform that flew in the V-2, you will be amazed. The SG-66 wasn’t designed by Bendix, but some of the people that worked on the SG-66 also worked on the ST-124. I'd have to say that…

[00:33:40] LP: [Inaudible] designed it. Look back at the old ST-80 and ST-90 and [LVDC?]. [All the way back?]

[00:33:46] RB: I was going to say [inaudible].

[00:33:50] TM: The point I’m trying to make is when you talk design, I’m talking about basic concepts. When you get into packaging, Bendix may have come up with a good idea on how the servo end should operate.

[00:34:03] JH: The packaging is very similar to the V-2.

[00:34:08] TM: I’m saying if you go look at that old SG-66, then look at a ST-124, it really strikes you as strange to see the two sitting there, one of them 1930 something and one of 1960.

[00:34:27] RB: What’s the difference between the ST-124 and the ST-124-M?

[00:34:32] TM: Well, the ST-124-1 and -2 were the first 124 platforms built, and they flew in the Saturn I vehicle. It was a predecessor to the dash M, and the M only means modified. The platform that flew in Saturn I had a redundant pitch gimbal built in. The yaw and roll were 360 degrees of freedom, and pitch was limited to [twenty-three?], but it had a redundant gimbal that had its own servo loop that would then program as you had to pitch over. They changed this in the dash M to make yaw the axis that was limited to plus or minus forty-five degrees. The other two axes had 360. That gave you full freedom in pitch, which is helpful when you’re in orbit, you know, and you’re maintaining attitude of the vehicle, you just rotate around the platform. But with a platform like the dash 1 and dash 2, [inaudible] you’re constantly having to program [inaudible]. So there was a difference, it was just updated and modified to the present configuration. Those flew in 201, 501, and…

[00:36:06] RB: Again, I’m thinking about the structure of the ST-124 and the computer chassis. They’re both integrally cooled, right?

[00:36:19] TM: Yes, in a little different form. The DA/DC actually had drilled passages within the mag-lith to allow the coolant to flow through the body of the system. In the 124, the way they adapted it was to form the covers such that on the covers the ball had coolant passages through them. The actual frame in the platform has no coolant through it. The covers—see you can see the lines there—it was formed by taking two layers and putting graphite in, and you press these together and then blew it up—actually inflated it. That’s the way the coolant passages were made, one on each side.

[00:36:41] RB: Oh okay, I never understood that.

[00:37:10] TM: The frame of the platform system, which is beryllium, did not have coolant passages in it. It would have been real difficult to do that like it was done in the DA/DC because it’s not a symmetrical box.

[00:37:27] RB: Beryllium is lighter than the mag-lith, correct?

[00:37:31] TM: It’s strong too. It’s very stable. It has high strength. It has that toxicity problem, which was considered when they built the platform system, but they elected to go with it. I think…

[00:37:49] RB: That’s why I’m trying to find out why they decided to go with beryllium in one case and not in the other one.

[00:37:56] TM2: One reason is you had two different groups of people working. I don’t know how that fits, but I think that has a lot to do with it.

[00:38:10] RB: The beryllium decision you think maybe came out of the Bendix shop as opposed to the Marshall shop?

[00:38:15] TM: A lot of the beryllium on the platform was going to be buried into the platform where you made the casting of the DA/DC, both of them. You [wouldn’t?] have had all the beryllium showing. The covers on the platform are not beryllium.

[00:38:32] RB: The whole thing is just a big ball as I recall seeing it…

[00:38:34] TM: The covers—the main part of it that shows—is not beryllium. There’s a lot of beryllium inside the platform, see? All of your gimbals are beryllium.

[00:38:47] RB: Is this necessity for the rigidity and accuracy then that made beryllium much more attractive for the ST-124 as opposed to mag-lith?

[00:38:55] TM: It’s a very good material to use for gimbals. It’s very light weight. It’s very strong, and they wanted accuracy. They’re able to machine it and mount it and know that later it’s right where you put it. It worked out real good. I don’t believe the toxicity problem turned out to be as bad as...

[00:39:20] RB: But it’s a fairly small thing. It didn’t weigh all that much. What was it, 196 pounds? That doesn’t sound right, but…

[00:39:25] TM: The platform? 117. Well, that’s for the inertial assembly.

[00:39:31] RB: Why not use steel? Does steel weigh that much more?

[00:39:35] TM: Let me give you a good example of why. If everybody thought that way, the weight would go up in a way you wouldn’t have a payload. There was a statement that was made that if every solder joint in the Saturn V was over-soldered to the point that it had as much solder as you’d do in your shop at home—instead of dressing it down to the point where it’s a neat and lightweight joint—if every solder joint in the Saturn built up too big, it would take away the entire payload capability of Saturn V, which was 37,000 pounds.

[00:40:20] RB: And the other thing too, in the upper stages, it’s a one-to-one trade-off, as I understand too. So you save thirty pounds, that’s exactly thirty pounds that you put on the payload.

[00:40:28] TM: It's 117 pounds for the inertial assembly. If you asked the question, “Why go with 117 when you could’ve gone with 140 or 50?” Well, it’s just a…

[00:40:39] JH: Also, back when all that was designed, I’m not so sure how good a handle Marshall had on the [capability?] of the vehicle and what the other parts were going to weigh too, see? Like the structure. We went all out on the honeycomb structure to make it lighter and all of this for [inaudible] necessary [inaudible] payload capability.

[00:41:04] RB: Okay, well, I’ve kept some of you gentlemen beyond your time. I’ve also got to go off now myself, go back to an interview that was interrupted. Is there anything you could add to help the poor historian here, you think? Any comments you’d like drop in here before I turn this thing off?

[00:41:23] LP: I got a document here. [Inaudible] I think it’s a pretty good document on the guidance, navigation, and control that goes in the platform. Got pictures in here. Computers…

[00:41:35] JH: What’s the date on it?

[00:41:36] LP: 1964.

[00:41:38] SS: That’s also an antique.

[00:41:40] JH: I was just thinking I had pulled some pages out of I think it’s a more current [inaudible] out of the astrionics handbook [inaudible].

[00:41:52] RB: Anything will help.

[00:42:05] JH: Here’s some pages that came out [inaudible]. I don’t know your specific question.

[00:42:09] RB: This was just kind of pulled out of a hat. I had a very limited group of documents to work with. This is just one of the things I came across. That particular event occurred while 501 was in the checkout, so there was a momentary flap about it, whether the flap was really large and created horrendous problems or just one of the many things that happens during checkout. I didn’t know, so I stuck it in there, maybe it would jog somebody’s memory.

[00:42:42] JH: It was a pretty large flap that the problem was revealed during the checkout of 503 at IBM. There was a failure of the flight control computer, which was traced through a cracked solder joint in the FCC. Because of the nature of the problem, there was a concern about all of the critical hardware, not just the FCC. There was a requirement to recycle the FCC for 501. In fact, they disassembled it, inspected it for cracked solder joints, and reworked it by actually providing what’s called [inaudible] to strengthen the joints. There was also a requirement to inspect other critical hardware [inaudible] details on those. The problem, of course, there’s been a lot said about cracked solder joints before and after that. What happens is that because of the design—the way the components are mounted on the board, the [inaudible] fuse, and the differences in the thermal coefficients—you build up stresses on the joint. Because the joints are stressed, that causes the crack. Even though you’ve got a good solder joint, it cracks within the solder. That was a rather expensive exercise. In fact, I have just three documents associated with that activity. There was a lot of [scurrying?] around, a lot of rework activity that was necessary before 501 got off. You also mentioned questions about testing. I’m not sure what you’re after there.

[00:44:25] RB: That was just a general question because I wasn’t able to find out a whole lot about testing. I wasn’t really sure what all was involved in that. I didn’t have any information about it. I know the propulsive stages went through all kinds of testing and checkout at MTF and everywhere else.

[00:44:43] JH: That’s the thing that bothers me a little bit. If you look at that document, there’s just volumes and volumes of the other stages in there, and the IU is almost nothing. As far as the test program, well, of course, I didn’t bring the book…Here it is. Here is the test plan for the IU. This is a very high level, but there were many tests at the IU level, not to speak of all the qualification of the hardware etc. We have quite a bit of detail on that. This goes back to ‘65. Now what I’ve done—again not being sure just what you were looking for—I have taken some pages out of the general test plan that list the various IU level tests that were performed. I’ve also identified on a separate sheet some additional IUs that were scheduled and tested after this plan was written, and I’ve given you the reason why. I haven’t counted them up, but there must have been ten or twelve IU level tests.

[00:45:50] RB: That sounds like it will give a base to start on some of this thing again..

[00:45:55] JH: I would like to see it if the history of Saturn comes out, I would like the IU to get some recognition, you know? Like [inaudible], it’s the brains of the vehicle, and without it, you’re not going to go very far.

[tape ends]

0:46:16