Quote:
Originally Posted by donquixote99
Rotor blades can't go 40,000 rpm. They loose thrust efficiency as the they go supersonic. They would also make continuous sonic booms that would incapacitate unprotected persons in a wide area. Of course, I suppose that's the main goal, eh? Here's wikipedia on an early experiment with a supersonic propeller aircraft. Note that the propeller was supersonic, but the plane wasn't.... Republic XF-84H Thunderscreech |
My stated diameter was a questimation, they where at least 4' in diameter. I could not see the actual blades, only a halo at the circumference, like maybe each had a rim or hoop around it. They were not silent, but surprisingly quiet.
It made noise just like a normal RC quadcopter, except the sound had more 'energy' to it. No down draft came off of it that I noticed. It was about 20 to 25 feet off the ground, about 70 feet from where I was sitting.
My assumption that it belong to the DHS is also just that; an assumption based on conjecture and hearsay (over-heard from other people talking about their sightings of the drone). And a published report that the DHS had been conducting flood plane mapping for insurance purposes in our area.