Actually there is evidensc in ancient egypt that there was beings with the knowledge of flight.Artifacts obviously resembling aircraft were found in a dudes tomb.So the knowledge of flight has been around for ages.So if your wondering if aliens colonized earth theres your evidence
.It looks like a golden bird with swept wings and a very 1950's jet look to it
Bull-sheeyit. We weren't colonized by aliens...
... you see, what happened is that our world was ALREADY consumed by a nuclear war... thousands upon thousands upon thousands of years ago. Almost all traces of that lost civilization have been destroyed, buried, and forgotten. What few relics and ancient stories remain, have been passed down throughout the generations as inspired thoughts, or a work of art. It's in our religious dogmas and our ceaseless asking of the question 'why?'
We have become what we are because, in sensing their imminent demise, those who came before saw fit to leave us clues...tucked away not in ancient tombs or temples... but instead embedded in our very genetic code.
Now, on a more on-topic note, since things seem to have gotten slightly derailed there at the end...
The Enclave could -not- have had the resources to construct a fleet of vertibirds, develop and prototype not one but TWO new power armor models... and maintain an active, standing army all from aboard that oil rig alone.
The fact of the matter is, the rig may have been HUGE... but it just plain and simple wasn't -that- big.
They have to have had labs on the mainland. There HAVE to be population centers, from which they get their recruits. There obviously need to be factories for the manufacturing of their weapons and armor and vehicles... all of which it is openly stated they have the capability to produce... so yeah... even if I wasn't one of those strange folks who wanted to see the Enclave from a different point of view than 'Generic Bad Guy #2...logic dictates there is much more to them than initially is let on, by both developer and game statements.
As for the NCR? I think they may very well maintain a small fleet of aircraft... but in all likeliness, it's probably nothing more than the same salvaged crap as their Power Armor... BoS leftovers.
Eh.... it's hard to say for sure...