Part II of Fred Haise’s February 2020 interview about the shuttle’s Approach and Landing Tests:
Was there any carryover in training from your years in Apollo, flying to the moon and back, and now flying an orbiter in the atmosphere?
There was no connection at all. The shuttle’s more like an airplane, and very complicated in some respects compared to Apollo. Apollo, like Orion, was a capsule. Once you got it into the atmosphere, blunt end first, it was stable. It would not tumble—you didn’t have to worry about that. With an offset center of gravity, entry steering in a capsule is via roll. By stealing a bit of drag, the path can be moved left, right, or up- or downrange depending on roll angle.
By contrast, the shuttle had a very complex control system that went through a number of modes to get you down from orbit to subsonic where it behaved more like a real airplane.A
The original designs that came in on the proposals were for an all-metal vehicle. There was no tile system. We had several problems early in the program; one was a big weight problem being driven by the reference mission that had been set up. That challenge caused a weight-reduction effort where we blunted the crew cabin and nose, and took 25 percent out of the wing area. The payload bay doors used to fair smoothly in at the back, and that [squaring off of the doors] didn’t matter much aerodynamically, in terms of how it flew, but it did cause higher drag. That put us into peak heating that we could not handle with metals proposed like columbium, titanium, and Inconel-X. The secondary structure was going to be aluminum.
What happened was that Lockheed and NASA Ames Research Center had been doing some work on new materials that allowed us to develop the tile system. I worried about the tiles coming off throughout the whole program. Needing other savings, the program canceled the second Enterprise test vehicle. So, we didn’t have a backup test vehicle. Our structural test article, OV-99, through limiting the loads it was subjected to, became the flight orbiter Challenger. And we deleted all fatigue tests, which wasn’t too big of a technical risk because by then we knew we were not going to fly 24 flights a year. Dropping the fatigue tests seemed OK, but after I left NASA and went to Grumman, I thought about it, and I called Aaron Cohen and asked him if we’d saved any of the smaller test articles we had to use for fatigue testing, because I worried about the tile system bonding.
Particularly with the “SIP” [stress isolation pad] problem: for a while we had tiles coming off. And I was worried about that throughout the program. We later had the ET [foam] hitting the leading edge of the wing on Columbia, but I was also worried about tiles coming off from the flight loads.
Look for Part 3 of Fred’s interview here.