I just had a thought like "What if some UFO aduction experiences people claim to have are actually people being kidnapped by the CIA" 
The kind of stories I'm thinking about often go like: "I was driving on an empty road in the middle of nowhere. I saw a bright light," and then either "I remember nothing but had lost time" or "I remember being experimented on by aliens and then put back in my car."
My tinfoil hat side is thinking like, these stories started happening around the time the US admitted to experimenting with abuse, torture and psychoactive drugs in Project MK-Ultra. Alien abduction stories were the most prevalent during this time. (CW: Just a heads up. If you want to read the rest of this post or anything else about MK-Ultra, be warned that it's pretty horrible, and involves some of the most disgusting torture I have ever read about. Death to America.)
Of the surviving documents released to the public about MK-Ultra, the CIA admits to: "kidnapping people it deemed "expendable" to undertake various types of torture and human experimentation on them. The prisoners were interrogated while being administered psychoactive drugs, electroshocked and subjected to extremes of temperature, sensory isolation and the like to develop a better understanding of how to destroy and to control human minds."
Part of me wonders how many of these alien abduction stories are just people being kidnapped, drugged with powerful hallucinogens, experimented on and then released with the suggestion conditioned into their mind that it was aliens.
The most famous alien abduction story is that of Barney and Betty Hill, an interracial couple that were both civil rights leaders, definitely people that the CIA would want to fuck with, especially during rising tensions with the Soviet Union, the US government was suspicious of minorities and anyone interested in their rights.
https://en.wikipedia.org/wiki/History_of_aviation#
I think the "Pioneer era" of aviation history (1903-1914) was probably preceded by more flight than is widely acknowledged, perhaps because the patrons of these unrecognized early aviators had the incentive and capability to obscure any developments in aviation they had made, both for reasons related to personal economic gain (think 1800s capitalist class, protecting r&d investment in a tech not ready for market), and/or to state security (think the relations of that same class to emergent state, their proto-intelligence/security apparatuses) - basically the Reconstruction Era deep state MIC had steampunk Black Helicopters, and they were using them to do UFO-coded psyops
Consider the "Mystery airship" phenomena https://en.wikipedia.org/wiki/Mystery_airship
I especially love this particular encounter in illustrating the way this all prefigures the relationship between the UFO phenomena and the CIA (and adding on, to drive home the relevance here more broadly: "cults" -> trafficking/blackmail/recruitment -> black ops, strategy of tension, anti-communism)
👀
Consider Rufus Porter's failure to bring his "aeroport" airship to market in 1853 https://newenglandaviationhistory.com/rufus-porters-aeroport-airship-1853/
Consider posthumous "outsider artist" Charles Dellschau's "Sonora Aero Club" active 1850-1858, purportedly as part of a wider secret society called "NYMZA" https://en.wikipedia.org/wiki/Charles_Dellschau#Posthumous_recognition
the Confederate helicopter is right there
https://airandspace.si.edu/stories/editorial/plans-little-known-confederate-helicopter
for further reading, this semi-satirical(?) piece about the "secret history" of "anti-gravity" tech has a lot of relevant details
https://zapatopi.net/blog/?post=202006037850.the_secret_of_apergy_gravitys_second_phase
and here's a fun 3 part series on the "Mystery airships" in vintage magazine Fate, with lots of details related to the above stories but which ultimately ties it all to aliens
https://archive.org/details/Fate_Magazine_278_v26n05_May_1973_/page/n83/mode/2up
https://archive.org/details/Fate_Magazine_279_v26n06_June_1973_/page/n95/mode/2up
https://archive.org/details/Fate_Magazine_280_v26n07_July_1973/page/n59/mode/2up