Kenneth Gomez’s We Don’t Know As Much As We Think We Do discusses the fact that many of our aircraft, including the Space Shuttle, are based on a world and economy of high maintenance, and whether or not we know as much as we think we do when it comes to efficiency, durability, and standards.
One of the issues with building reusable space transports are those of maintenance and inspection…
…How applicable is this cautionary tale to the design of space transports? Well somewhat, but not quite as much as one might think. Fatigue is (usually) a phenomenon that occurs as a result of a large number of cycles (assuming that the stress is reasonable–obviously, one can fatigue a paper clip to failure in just a few extreme twists back and forth with a pair of pliers). It’s a real concern for aircraft that are in the air a lot, with many takeoffs and landings, and continuous buffeting from the air.
A space transport has two things going for it. First of all, it spends little time in the atmosphere, which is where most of the structural stress occurs, at least that due to aerodynamics. In space, it’s actually a quite benign environment, from a structural standpoint. Second, if we ever get to the number of flights of a single space transport that even start to approach the cycle life of an air transport, we’ll have clearly solved the problem of space access, even if we occasionally (as in the aircraft industry) lose a vehicle to structural fatigue.
But regardless of what this means for spaceship design, I think that Airbus has some big problems, until they understand this issue better. And now that Boeing is also using composites for primary structure, they need to get on top of it as well.
