Since you made a jab at the little green men scenario earlier, i thought i'd present you with this.
Consider the following points.
1) The psychometric evaluations of first world air force pilots - Think live munitions, carried on billion dollar aircraft over cities populated with civilians and also in war zones.
2) The people best able to identify all aircraft, form private to military, including ATA, ATS, STA, STS, ICB missiles, are air force pilots.
3) There are only two types of aircraft in the human inventory(that we know of) capable of any decent speed and altitude - Fixed and Rotary wing. Both leave clearly identifiable markers that no pilot, military or not, in unfamiliar with.
Here is a video, released by the Pentagon about two years ago. Captured on a Ratheon targeting system aboard an F18 Super Hornet.
It comes with the actual audio recording of the pilots comms.
The pilot in question is this guy, and here is an interview that he gave. Note his credentials, his rank at retirement and the fact that he makes no bones about what he saw. You're a bit older, so my guess is that you probably know that "loons" don't get to become fighter pilots with 3500 hours of flight time, let alone squadron commanders in the world's premier air force. Neither his rank or his testimony are opposed by the DOD.
To make it easy, i'll ask you just one question, with a bonus one after.
Explain to me how that craft, travelling at that speed, identified as hot by its white color in infrared, leaves ZERO signature?
As an added extra, it'd also be great if you could explain how the craft adopts a vertical position without altering its trajectory.
Note1: The only reasonable explanation would be that it's a US experimental/prototype craft being tested. If that was the case, then the Pentagon would not approve this video for release, for obvious reasons. The first time the enemy should see it is when it's firing missiles at them.
Note2: Even if it were an electrically powered craft, you'd still see a vague heat plume since its moving parts would heat up and the heat would seize the system were it not evacuated. The infrared cameras would cause you to see a plume of heated air.