> this might have worked were it not for the fact that one of the steel rods in the balloon rigging was 91 centimeters long. US Air Force engineers didn’t realize it at the time, but 91 centimeters happened to correspond to one of the frequencies used by Soviet early-warning radar. This caused the otherwise inconsequential rod to resonate and glint like a mirror on Soviet radar screens.

This is fascinating. I wonder how unlucky they got - what the tolerance on something like this is, presumably 91.1 cm would still resonate but 96 cm would not?

Also, if a possible failure mode is "if any of the rods in the construction of this stealth device exactly matches the enemy's secret number, the mission will be detected" that seems like it would lead to some very fun design constraints. Are there any examples of designers taking this into account and building a device with every component the same size?