Apollo Guidance Computer Activities

AGC Conference 3 - Systems Engineering and Specifications

Apollo Guidance Computer History Project

Third conference

November 30, 2001

Systems Engineering and Specifications

JACK POUNDSTONE: Yes. That’s what we were worried about. Well, the other issue perhaps was a failing of the lack of formal systems engineering. In fact, you guys never really had a spec for what you were building.

ELDON HALL: That was beneficial.

JACK POUNDSTONE: There was one place where it was not beneficial. As I recall, you never had a spec for fire until after the accident.

ELDON HALL: Until after the accident. Neither did anybody else have the spec.

CLINE FRASIER: Oh, I think North American had one. I take a different point of view. Fire was something that concerned NASA from day one particularly because they were going to be in a 5 PSI oxygen environment and so people did pay some attention to that. And there were a number of tests done at 0 Gs in C-135s in 100 percent oxygen. I remember seeing a movie, where the fire gets lit and the fire goes out quickly. It was not considered that the fire was going to spread in 0 G. People were concerned about fire, flammable stuff, but not anything like to the degree after the fire. And the IMU had a layer of polyurethane foam insulation around it, which in 100 percent oxygen will burn like that. But not at 0 G. Then it was after the fire that people went through and looked at every single thing to see whether it would burn. And even after the fire, for quite a while North American kept their big Plexiglas panel that was now painted with fire retardant paint because of the electroluminescent displays. After a test the same kind of panel is going to be put on for the guidance system controls. The test was run at AC where they put a hot wire on it in a chamber with either 5 or 16 PSI oxygen. It was quite a spectacular movie. You got this little flame going initially from this hot wire and then of course you get poof. And here would go this little explosion of burning plastic out and then poof and poof and poof. And when people saw that movie, they decided that all these panels had to be changed to be aluminum. So there was a lot of focus on fire.

JACK POUNDSTONE: But that wasn’t passed down to the guidance.

CLINE FRASIER: Oh, yes. Absolutely. The panel on the guidance system was covered with a solid piece of aluminum with the letters engraved out over an electroluminescent panel. On the DSKY, it had originally some plastic back there and you ended up with a piece of glass over it. And the glass kept cracking in vacuum testing, over and over and over again. Took a long time to get that right - I remember cracked glass.

ELDON HALL: That was after the fire.

JACK POUNDSTONE: I never saw a spec on flammability until after the fire. I remember that.

ELDON HALL: I don’t know, you never saw a spec on flammability at all.

ED BLONDIN: Kind of like the spec on cockpit doors. (laughter)

JACK POUNDSTONE: That's right. Do you have that spec? But typically, if you’d have been a sub to North American, they’d have written you a big spec. It’d have a lot of mistakes, but you’d have a spec.

ED BLONDIN: Did you ever read the Army spec on cookies? So help me God, they have a spec on them, orr at least they did. Instead of going out and buying cookies, they had to spec them.

CLINE FRASIER: Did you ever read the specs around the M16, the M16 ammunition, then how that led to all the jamming problems. I mean, it’s crazy.

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