I do not agree with Jacques Vallée's theory that UFOs change to fit technology of the time, essentially evolving to fit our acceptance...That to me is equivalent to implying UFOs are projections or staged events from some higher source who created them, like from some cosmic trickster...I think that is a real stretch...Its my opinion these airships have nothing to do with UFOs as we understand UFOs today as being visitors from other planets in space craft...I think these airships were either secret prototypes a few years ahead of its time but human designed in secret...The narrator made the comment that few of the designs were used in later years when we had stable flying machines built, which is one of many indicators of these likely being very early prototype ships...I have also thought that maybe this was a bleeding of realities, many these airships were from a parallel world, similar to ours, but that's a hypothesis that could never be proven nor could there be an evidence to support that...They were likely very early prototypes and secret experiments of ours...
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